WorldWideScience

Sample records for benthos

  1. Bottom dwelling animals: Benthos

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.

    biomass. Benthos also play a vital role in the marine food cahin and in the recycling of essential lifesustaining elements like carbon, nitrogen and phosphorus in the marine ecosystem. Besides, benthos are considered the best indicators of environmental...

  2. Benthos of the Narmada estuary

    Digital Repository Service at National Institute of Oceanography (India)

    Varshney, P.K.; Govindan, K.; Desai, B.N.

    Distribution of benthos in relation to environmental characteristics has been studied along a stretch of 55 km in the Narmada Estuary. Higher abundance of macro and meio fauna were noticed along the upper and lower reaches of the river respectively...

  3. Marine benthos - A future perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.

    on firm substrates (rocks, corals etc), 20% on sandy/muddy bottoms and only 5% of the total are planktonic. Many benthic animals within the sediment perform periodic vertical migration. Benthos are mostly either filter feeder or browsers or deposit feeders...

  4. Benthos

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Parulekar, A.H.

    . The distribution of benthic faun in space and time showed wide variation in density and biomass. At some places the density may be as poor as 1 individual/m sup(2), while on the other hand it may be as high as 3000 individual/m sup(2). The benthic biomass also...

  5. Benthos of Cochin backwaters receiving industrial effluents

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Venugopal, P.

    Faunal composition of benthos and its spatial and temporal distribution at 9 stations in the northern limb of the Cochin backwaters are studied. An industrial belt is located about 18 km upstream of barmouth, and the effluents are discharged...

  6. Benthos of Beypore and Korapuzha estuaries of North Kerala

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Sankaranarayanan, V.N.; Venugopal, P.

    The benthos from Beypore and Korapuzha estuaries were studied for one year. Environmental features, sediment characteristics and organic carbon content were estimated. Benthic density was high during monsoon and postmonsoon in both the estuaries...

  7. Deep sea benthos of the western and central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.; Ingole, B.S.; Harkantra, S.N.; Ansari, Z.A.

    Quantitative investigations on deep sea benthos from 112 stations between lat. 21 degrees N-21 degrees S and long. 51 degrees E-94 degrees E and in the depth range of 1500 to 6000 m, revealed a rich biota having relatively low species diversity...

  8. Ecology of North American Arctic continental shelf benthos: a review

    Science.gov (United States)

    Carey, Andrew G.

    1991-08-01

    The zoogeography, ecology, and biology of continental shelf invertebrate benthos along the arctic coast of North America from Alaska to western Greenland are reviewed. Environmental influences are noted and the life histories as well as the food sources of the fauna are summarized. The existence of regionally associated, characteristic community structures, centred upon the northern Bering Sea and the eastern Chukchi Sea, the Beaufort Sea, the Canadian Archipelago, the eastern Canadian Arctic, and western Greenland, is indicated. Early field research was exploratory and fragmented. Since 1940 more extensive studies oriented toward surveys and environmental baselines have been conducted. Over the last few decades physiological ecology studies of selected species have been undertaken to better understand adaptations to polar conditions. Recent Canadian research has included long-term field experiments on the effects of oil spillage in arctic waters as well as quantitative studies of benthos across the Archipelago and within fiords and other specialized environments. This research has suggested the need for basic biological and ecological research from the level of species through complete ecosystems in arctic waters. Additional studies on the long-term effects of pollution should be undertaken in the colder regions where it is likely that biological processes are slower and the effects of pollution are more long-lasting. Specifically, the ability to define pelagic-benthic coupling in Canadian arctic waters would provide insight into the role of the benthos in low productivity arctic ecosystems. In summary co-operative international research programmes on continental shelf benthos throughout the Arctic Basin and its surrounding seas should be undertaken. Knowledge of the range of shelf environments will provide insight into the controlling physical and biological features of the environment as well as the role of the seafloor within the arctic environment.

  9. Fatty acid transformation in zooplankton: from seston to benthos

    DEFF Research Database (Denmark)

    Tiselius, Peter; Hansen, Benni Winding; Calliari, Danilo

    2012-01-01

    to 90% polyunsaturated FAs (PUFAs). Sedimentation of bulk particulate organic carbon did not vary significantly with season (coefficient of variation, CV = 33%), while pigment (CV = 49%) and in particular faecal pellet fluxes (CV = 100%) were highly variable as a result of copepod feeding activity....... Copepod feeding, pellet production and egg production were all high after the spring bloom and in summer and autumn. Overall, 5 to 25% of the sedimenting FAs were affected by copepod feeding activities, and the supply of PUFAs to the benthos was significantly enhanced by copepod grazing activity. SAFAs...

  10. Lipophilic pigments from the benthos of a perennially ice-covered Antarctic lake

    Science.gov (United States)

    Palmisano, A. C.; Wharton, R. A. Jr; Cronin, S. E.; Des Marais, D. J.; Wharton RA, J. r. (Principal Investigator)

    1989-01-01

    The benthos of a perennially ice-covered Antarctic lake, Lake Hoare, contained three distinct 'signatures' of lipophilic pigments. Cyanobacterial mats found in the moat at the periphery of the lake were dominated by the carotenoid myxoxanthophyll; carotenoids: chlorophyll a ratios in this high light environment ranged from 3 to 6.8. Chlorophyll c and fucoxanthin, pigments typical of golden-brown algae, were found at 10 to 20 m depths where the benthos is aerobic. Anaerobic benthic sediments at 20 to 30 m depths were characterized by a third pigment signature dominated by a carotenoid, tentatively identified as alloxanthin from planktonic cryptomonads, and by phaeophytin b from senescent green algae. Pigments were not found associated with alternating organic and sediment layers. As microzooplankton grazers are absent from this closed system and transformation rates are reduced at low temperatures, the benthos beneath the lake ice appears to contain a record of past phytoplankton blooms undergoing decay.

  11. Benthos of the shelf region along the west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Harkantra, S.N.; Nair, A; Ansari, Z.A; Parulekar, A

    Distribution and abundance of benthos in the depth range of 10-70 m were studied. A definite relationship was observed between benthic biomass, organic carbon, nature of substrata and demersal fish catch. Benthic biomass varied from 0.12 to 190.5 g...

  12. Sediment Dwelling Benthos as Indicator Species for Pollution Monitoring of Mamala Bay, Oahu, Hawaii, 1993-1994 (NODC Accession 9900121)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A multifaceted study of the sediment dwelling benthos was conducted in Mamala Bay to identify suitable species as indicators of sewage enrichment. There are five...

  13. Oxygen as a driver of early arthropod micro-benthos evolution.

    Directory of Open Access Journals (Sweden)

    Mark Williams

    Full Text Available BACKGROUND: We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS: The PO(2 of modern normoxic seawater is 21 kPa (air-equilibrated water, a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2 of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2. Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2 levels. The PO(2 of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2. Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian oxygen-levels that increased the PO(2 gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2. Ostracods became the numerically

  14. ZOOBENTHOS OF THE MIDDLE CASPIAN. BENTHOS COMMUNITIES OF THE CASPIAN SEA

    Directory of Open Access Journals (Sweden)

    S. A. Guseinova

    2014-01-01

    Full Text Available Abstract. Aim. Industrialization of Caspian oil and gas supplies requires a serious approach to the problem of protecting and preserving the region’s unique environment that, in fact, represents a property of international commons. The article studies into the impact of the Caspian modified waters on the benthos faunistic composition.Methods. Zooplancton and zoobenthos hydrobiology material was collected in the Central Caspian survey loop. Samples were collected in spring and summer in 2002 – 2007 in the western part of the Caspian Sea (Dagestan offshore location of the Caspian Sea from Smirnovsky Midstream Sandbank and Pearl Bank till Derbent latitude on “Tsada” vessel. They were collected from 25 stations located on ten standard parallel latitude logs with depth scope of 8–100 m from 0, 10, 25, 100 m horizons. These samples were used as a material for characterizing phyto- and zooplankton.Results. The benthic can be considered the most stable communities of the marine environment as they are the most resilient to quantity and modifications. Heterogeneous and variable ecosystem (biotope is typical of the areas with strong currents as the organic quality, quantity and physic-chemical properties are marked by variability.Location. The Caspian zoobenthos state as well as the features of the Caspian Sea benthos communities characterize the ecology of the Caspian Sea and give a true view of the situation in the drilling sites. This will help predict and avert negative effect of hydrocarbon production on the Caspian Sea ecosystem. Main conclusions. Water modification must be intensive, long-lasting and frequent for it to have an impact on benthos.

  15. The Role of Physical-Chemical Factors in Structuring Subtidal Marine and Estuarine Benthos.

    Science.gov (United States)

    1983-06-01

    mollusk shells (shell hash), and other detrital frag- ments such as ostracods, foraminifera tests, fecal pel- lets, and sponge spicules (Kirtley and...Al A11 81 11 ROLE O P YSICAL CHEMICAL FACIORS IN STRUCTURING 4 SBTIAL MARINE AND..U) ARMY ENG NEER WATERWAY EXAPERIMENT STAAION I CKSBURG NIS ENVIR...CHEMICAL US A 0yC.op FACTORS IN STRUCTURING SUBTIDAL of Eng r MARINE AND ESTUARINE BENTHOS by David R. Kendall 0’) Environmental Laboratory T. U. S. Army

  16. Effects of natural and human-induced hypoxia on coastal benthos

    Digital Repository Service at National Institute of Oceanography (India)

    Levin, L.A.; Ekau, W.; Gooday, A.J.; Jorissen, F.; Middelburg, J.J.; Naqvi, S.W.A.; Neira, C.; Rabalais, N.N.; Zhang, J.

    to dominate oxygen dynamics on the shelves of the central Benguela ecosystem off Namibia (Monteiro et al., 2008) and Oregon (Grantham et al., 2004), and off India (Naqvi et al., 2006). Larger-scale climate modes associated with Kelvin waves such as El Ni... benthos are permanently hypoxic. During El Ni˜no events, strength- ened influence from equatorial water masses oxygenates the shelf and deepens the upper boundary of the OMZ off Peru (Helly and Levin, 2004), whereas El Ni˜no causes a shoaling of the OMZ...

  17. Functional groups of macro-benthos of selected sites of upstream of Hron River and Hnilec River

    International Nuclear Information System (INIS)

    Rufusova, A.

    2011-01-01

    The author used six functional groups of macro-benthos based on 'species traits', which are indicated with the Greek letters α to ζ. In the work authors applied this method to the macroinvertebrate communities of selected sites of upstream of the Hron River and the Hnilec River. The method appropriately captured increasing gradient of anthropogenic changes in the direction of the river continuum. Although the method was used for Slovak rivers for the first time, it seems to be promising for use in the future. (author)

  18. Effects of natural and human-induced hypoxia on coastal benthos

    Directory of Open Access Journals (Sweden)

    L. A. Levin

    2009-10-01

    Full Text Available Coastal hypoxia (defined here as <1.42 ml L−1; 62.5 μM; 2 mg L−1, approx. 30% oxygen saturation develops seasonally in many estuaries, fjords, and along open coasts as a result of natural upwelling or from anthropogenic eutrophication induced by riverine nutrient inputs. Permanent hypoxia occurs naturally in some isolated seas and marine basins as well as in open slope oxygen minimum zones. Responses of benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H2S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide. They are hypothesized to provide a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids, often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages.

    Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below

  19. Data integration for European marine biodiversity research: creating a database on benthos and plankton to study large-scale patterns and long-term changes

    NARCIS (Netherlands)

    Vandepitte, L.; Vanhoorne, B.; Kraberg, A.; Anisimova, N.; Antoniadou, C.; Araújo, R.; Bartsch, I.; Beker, B.; Benedetti-Cecchi, L.; Bertocci, I.; Cochrane, S.J.; Cooper, K.; Craeymeersch, J.A.; Christou, E.; Crisp, D.J.; Dahle, S.; de Boissier, M.; De Kluijver, M.; Denisenko, S.; De Vito, D.; Duineveld, G.; Escaravage, V.L.; Fleischer, D.; Fraschetti, S.; Giangrande, A.; Heip, C.H.R.; Hummel, H.; Janas, U.; Karez, R.; Kedra, M.; Kingston, P.; Kuhlenkamp, R.; Libes, M.; Martens, P.; Mees, J.; Mieszkowska, N.; Mudrak, S.; Munda, I.; Orfanidis, S.; Orlando-Bonaca, M.; Palerud, R.; Rachor, E.; Reichert, K.; Rumohr, H.; Schiedek, D.; Schubert, P.; Sistermans, W.C.H.; Sousa Pinto, I.S.; Southward, A.J.; Terlizzi, A.; Tsiaga, E.; Van Beusekom, J.E.E.; Vanden Berghe, E.; Warzocha, J.; Wasmund, N.; Weslawski, J.M.; Widdicombe, C.; Wlodarska-Kowalczuk, M.; Zettler, M.L.

    2010-01-01

    The general aim of setting up a central database on benthos and plankton was to integrate long-, medium- and short-term datasets on marine biodiversity. Such a database makes it possible to analyse species assemblages and their changes on spatial and temporal scales across Europe. Data collation

  20. Changes in benthos associated with mussel (Mytilus edulis L. farms on the west-coast of Scotland.

    Directory of Open Access Journals (Sweden)

    Thomas A Wilding

    Full Text Available Aquaculture, as a means of food production, is growing rapidly in response to an increasing demand for protein and the over-exploitation of wild fisheries. This expansion includes mussels (family Mytilidae where production currently stands at 1.5 million tonnes per annum. Mussel culture is frequently perceived as having little environmental impact yet mussel biodeposits and shell debris accumulate around the production site and are linked to changes in the benthos. To assess the extent and nature of changes in benthos associated with mussel farming grab and video sampling around seven mussel farms was conducted. Grab samples were analysed for macrofauna and shell-hash content whilst starfish were counted and the shell-hash cover estimated from video imaging. Shell-hash was patchily distributed and occasionally dominated sediments (maximum of 2116 g per 0.1 m(2 grab. Mean shell-hash content decreased rapidly at distances >5 m from the line and, over the distance 1-64 m, decreased by three orders of magnitude. The presence of shell-hash and the distance-from-line influenced macrofaunal assemblages but this effect differed between sites. There was no evidence that mussel farming was associated with changes in macrobenthic diversity, species count or feeding strategy. However, total macrofaunal count was estimated to be 2.5 times higher in close proximity to the lines, compared with 64 m distance, and there was evidence that this effect was conditional on the presence of shell-hash. Starfish density varied considerably between sites but, overall, they were approximately 10 times as abundant close to the mussel-lines compared with 64 m distance. There was no evidence that starfish were more abundant in the presence of shell-hash visible on the sediment surface. In terms of farm-scale benthic impacts these data suggest that mussel farming is a relatively benign way of producing food, compared with intensive fish-farming, in similar environments.

  1. A synthesis of bentho-pelagic coupling on the Antarctic shelf: Food banks, ecosystem inertia and global climate change

    Science.gov (United States)

    Smith, Craig R.; Mincks, Sarah; DeMaster, David J.

    2006-04-01

    The Antarctic continental shelf is large, deep (500-1000 m), and characterized by extreme seasonality in sea-ice cover and primary production. Intense seasonality and short pelagic foodwebs on the Antarctic shelf may favor strong bentho-pelagic coupling, whereas unusual water depth combined with complex topography and circulation could cause such coupling to be weak. Here, we address six questions regarding the nature and strength of coupling between benthic and water-column processes on the continental shelf surrounding Antarctica. We find that water-column production is transmitted to the shelf floor in intense pulses of particulate organic matter, although these pulses are often difficult to correlate with local phytoplankton blooms or sea-ice conditions. On regional scales, benthic habitat variability resulting from substrate type, current regime, and iceberg scour often may obscure the imprint of water-column productivity on the seafloor. However, within a single habitat type, i.e. the muddy sediments that characterize much of the deep Antarctic shelf, macrobenthic biomass appears to be correlated with regional primary production and sea-ice duration. Over annual time-scales, many benthic ecological processes were initially expected to vary in phase with the extraordinary boom/bust cycle of production in the water column. However, numerous processes, including sediment respiration, deposit feeding, larval development, and recruitment, often are poorly coupled to the summer bloom season. Several integrative, time-series studies on the Antarctic shelf suggest that this lack of phasing may result in part from the accumulation of a persistent sediment food bank that buffers the benthic ecosystem from the seasonal variability of the water column. As a consequence, a variety of benthic parameters (e.g., sediment respiration, inventories of labile organic matter, macrobenthic biomass) may act as "low-pass" filters, responding to longer-term (e.g., inter

  2. Seasonal trophic activity of the aquatic morphotype of Atelognathus patagonicus (Anura, Neobatrachia and prey availability in the littoral benthos of a permanent pond in Argentinean Patagonia

    Directory of Open Access Journals (Sweden)

    María Elena Cuello

    2009-12-01

    Full Text Available The diet of the aquatic morphotype of Atelognathus patagonicus was studied in frogs collected from the Laguna Verde pond (Laguna Blanca National Park, Neuquén, Argentina. The content of 35 gastrointestinal tracts of post-metamorphic specimens from November 2003 to April 2006 was related to the composition of the benthos in their microhabitat. Number, size, occurrence and relative importance of preys, diversity of the diet, trophic niche breadth and electivitywere estimated for each season of the year. The diet consisted of aquatic arthropods. The composition of both the benthos and the food (number and occurrence of organisms in the diet were dominated by the amphipod Hyalella sp. The relative importance (IRI of Hyalella sp. in the diet was over 99% in summer and autumn, and 100% in winter and spring. Diptera and Copepoda in summer, and Dytiscidae and Ostracoda in autumn, had seasonal IRI values ≤ 0.2%. Trophic niche breadth was very low in summer and autumn, and null (= 0 in winter and spring. The mean number of preys per individual was highest in spring (19 preys/frog and lowest in winter (4 preys/frog. Frogs continued with their trophic activity in winter, even when the surface of the pond was frozen. There is a correspondence between the frogs’ main food item and its presence in the benthos.

  3. The evolution of jaw protrusion mechanics is tightly coupled to bentho-pelagic divergence in damselfishes (Pomacentridae).

    Science.gov (United States)

    Cooper, W James; Carter, Casey B; Conith, Andrew J; Rice, Aaron N; Westneat, Mark W

    2017-02-15

    Most species-rich lineages of aquatic organisms have undergone divergence between forms that feed from the substrate (benthic feeding) and forms that feed from the water column (pelagic feeding). Changes in trophic niche are frequently accompanied by changes in skull mechanics, and multiple fish lineages have evolved highly specialized biomechanical configurations that allow them to protrude their upper jaws toward the prey during feeding. Damselfishes (family Pomacentridae) are an example of a species-rich lineage with multiple trophic morphologies and feeding ecologies. We sought to determine whether bentho-pelagic divergence in the damselfishes is tightly coupled to changes in jaw protrusion ability. Using high-speed video recordings and kinematic analysis, we examined feeding performance in 10 species that include three examples of convergence on herbivory, three examples of convergence on omnivory and two examples of convergence on planktivory. We also utilized morphometrics to characterize the feeding morphology of an additional 40 species that represent all 29 damselfish genera. Comparative phylogenetic analyses were then used to examine the evolution of trophic morphology and biomechanical performance. We find that pelagic-feeding damselfishes (planktivores) are strongly differentiated from extensively benthic-feeding species (omnivores and herbivores) by their jaw protrusion ability, upper jaw morphology and the functional integration of upper jaw protrusion with lower jaw abduction. Most aspects of cranial form and function that separate these two ecological groups have evolved in correlation with each other and the evolution of the functional morphology of feeding in damselfishes has involved repeated convergence in form, function and ecology. © 2017. Published by The Company of Biologists Ltd.

  4. Comparison of benthos and plankton for Waukegan Harbor Area of Concern, Illinois, and Burns Harbor-Port of Indiana non-Area of Concern, Indiana, in 2015

    Science.gov (United States)

    Eikenberry, Barbara C. Scudder; Olds, Hayley T.; Burns, Daniel J.; Dobrowolski, Edward G.; Schmude, Kurt L.

    2017-06-06

    During two seasonal sampling events in spring (June) and fall (August) of 2015, the U.S. Geological Survey collected benthos (benthic invertebrates) and plankton (zooplankton and phytoplankton) at three sites each in the Waukegan Harbor Area of Concern (AOC) in Illinois and in Burns Harbor-Port of Indiana, a non-AOC comparison site in Indiana. The study was done in cooperation with the U.S. Environmental Protection Agency and the Illinois Department of Natural Resources. Samples were collected concurrently for physical and chemical parameters (specific conductance, temperature, pH, dissolved oxygen, chlorophyll-a, total and volatile suspended solids in water samples; particle size and volatile-on-ignition solids of sediment in dredge samples). The purpose of the study was to assess whether or not aquatic communities at the AOC were degraded in comparison to communities at the non-AOC, which was presumed to be less impaired than the AOC. Benthos were collected by using Hester-Dendy artificial substrate samplers and a Ponar® dredge sampler to collect composited grabs of bottom sediment; zooplankton were collected by using tows from depth to the surface with a 63-micrometer mesh plankton net; phytoplankton were collected by using whole water samples composited from set depth intervals. Aquatic communities at the AOC and the non-AOC were compared by use of univariate statistical analyses with metrics such as taxa richness (number of unique taxa), diversity, and a multimetric Index of Biotic Integrity (IBI, for artificial-substrate samples only) as well as by use of multivariate statistical analyses of taxa relative abundances.Although benthos communities at Waukegan Harbor AOC were not rated as degraded in comparison to the non-AOC, metrics for zooplankton and phytoplankton communities did show some impairment for the 2015 sampling. Across seasons, benthos richness and diversity were significantly higher and rated as less degraded at the AOC compared to the non

  5. Utilisation d'une sonde fluorimétrique benthique (la BenthoTorch, bbe) pour mesurer la croissance des diatomées, algues vertes et cyanobactéries périphytiques en plans d'eau

    OpenAIRE

    Roubeix, V.

    2015-01-01

    / Une sonde fluorimétrique benthique, la BenthoTorch (bbe) a été acquise par le pôle Onema-Irstea d'Hydroécologie des Plans d'eau pour développer un indice fonctionnel de production primaire dans les plans d'eau. Cet indice sera basé sur la dynamique de croissance du périphyton sur des substrats artificiels. Il constituerait un outil de diagnostic du fonctionnement écologique des systèmes lentiques, particulièrement utile dans le cadre du suivi de mesures de restauration. La BenthoTorch me...

  6. Temporal changes in the benthos along a pollution gradient: Discriminating the effects of natural phenomena from sewage-industrial wastewater effects

    International Nuclear Information System (INIS)

    Ferraro, S.P.; Swartz, R.C.; Cole, F.A.; Shults, D.W.

    1991-01-01

    As pollution from the Los Angeles County Sanitation Districts (LACSD) outfalls decreased between 1980 and 1983, the macrobenthic community partially recovered and surficial (0-2 cm deep) sediment contamination and toxicity decreased at 60 m water depth along a pollution gradient from the outfalls. Pollution from the LACSD outfalls continued to decrease but macrobenthic conditions and surficial sediment quality deteriorated 1 km, was unchanged 3 km, and improved 5-15 km from the LACSD outfalls between 1983 and 1986. The net effect of natural phenomena is indicated when ecosystem changes occur in the opposite direction from that expected under prevailing pollution conditions. The authors data suggest that the net effect of natural phenomena (e.g. winter storms, El Nino) on the benthos was greater than LACSD wastewater effects 1 km, about equal to LACSD wastewater effects 3 km, and less than the LACSD wastewater effects 5-15 km from the outfalls at the LACSD 1983-86 mass emission rate. Since natural phenomena may have an effect on the benthos = or > 3 years of LACSD wastewater effects, short-term benthic changes must be interpreted cautiously at the study site

  7. Seasonal and Spatial Variations of Macro Benthos in the Intertidal Mudflat of Southern Yellow River Delta, China in 2007/2008

    Science.gov (United States)

    Zou, Li; Yao, Xiao; Yamaguchi, Hitomi; Guo, Xinyu; Gao, Huiwang; Wang, Kai; Sun, Mingyi

    2018-04-01

    In order to examine the seasonal and spatial distributions of benthic animals in the intertidal mudflat of the southern Yellow River Delta, field investigations were carried out in 2007 and 2008 and multiple methods were applied. Results showed that, the biomass of macro benthos ranged at 0.75-1151.00 g wet m-2 and averaged at 156.31 g wet m-2, in which Mactra veneriformis accounted for 75.6%-93.4% of the total macro benthic biomass. More than 90% of macro benthos inhabited in the middle and low tide lines, and higher biomass occurred in early summer and lower in winter. Statistical analysis showed that: 1) M. veneriformis growth was primarily favored at higher temperature and lower salinity; 2) after long time interaction, benthic bivalve grazers led to patching distributions of Chlorophyll a (Chl a); 3) macro benthic biomass positively related with Chl a when the concentration of Chl a was low, but they were negatively related when Chl a concentration was high; and 4) furthermore, the biomass of benthic bivalves peaked in the sediment with median grain size about 0.55 mm, but decreased gradually in coarse or fine sediments. The secondary productivity ranged at 0.37-283.68 g m-2yr-1 and averaged at 47.88 g m-2 yr-1, in which 69.7% was contributed by M. veneriformis It was estimated that primary production was transformed to secondary production at a rate of 6.87% approximately, which implies that there is a local sustainability of high bivalve production.

  8. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil

    Science.gov (United States)

    Longo, G. O.; Morais, R. A.; Martins, C. D. L.; Mendes, T. C.; Aued, A. W.; Cândido, D. V.; de Oliveira, J. C.; Nunes, L. T.; Fontoura, L.; Sissini, M. N.; Teschima, M. M.; Silva, M. B.; Ramlov, F.; Gouvea, L. P.; Ferreira, C. E. L.; Segal, B.; Horta, P. A.; Floeter, S. R.

    2015-01-01

    The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most “pristine” areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open

  9. Between-Habitat Variation of Benthic Cover, Reef Fish Assemblage and Feeding Pressure on the Benthos at the Only Atoll in South Atlantic: Rocas Atoll, NE Brazil.

    Directory of Open Access Journals (Sweden)

    G O Longo

    Full Text Available The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp. prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos

  10. Bentho-pelagic divergence of cichlid feeding architecture was prodigious and consistent during multiple adaptive radiations within African rift-lakes.

    Directory of Open Access Journals (Sweden)

    W James Cooper

    2010-03-01

    Full Text Available How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success.Specimens from 87 genera of cichlid fishes endemic to Lakes Tanganyka, Malawi and Victoria were dissected in order to examine the functional morphology of cichlid feeding. We quantified shape using geometric morphometrics and compared patterns of morphological diversity using a series of analytical tests. The primary axes of divergence were conserved among all three radiations, and the most prevalent changes involved the size of the preorbital region of the skull. Even the fishes from the youngest of these lakes (Victoria, which exhibit the lowest amount of skull shape disparity, have undergone extensive preorbital evolution relative to other craniofacial traits. Such changes have large effects on feeding biomechanics, and can promote expansion into a wide array of niches along a bentho-pelagic ecomorphological axis.Here we show that specific changes in trophic anatomy have evolved repeatedly in the African rift lakes, and our results suggest that simple morphological alterations that have large ecological consequences are likely to constitute critical components of adaptive radiations in functional morphology. Such shifts may precede more complex shape changes as lineages diversify into unoccupied niches. The data presented here, combined with observations of other fish lineages, suggest that the preorbital region represents an evolutionary module that can respond quickly to natural selection when fishes colonize new lakes. Characterizing the changes in cichlid trophic

  11. The Influence of the Disturbed Continuity of the River and the Invasive Species— Potamopyrgus antipodarum (Gray, 1843), Gammarus tigrinus (Sexton, 1939) on Benthos Fauna: A Case Study on Urban Area in the River Ruda (Poland)

    Science.gov (United States)

    Spyra, Aneta; Kubicka, Justyna; Strzelec, Małgorzata

    2015-07-01

    The progressive degradation of aquatic ecosystems and ecohydrological role of rivers is one of the most important global environmental issues. The loss of the ability of rivers to self-purify waters due to the disturbances of river continuity cause a lack of biological life in parts of rivers or even in an entire river. The appearance of alien species in degraded aquatic environments is an increasingly common phenomenon and constitutes one of the threats to biodiversity. The aim of the study was to evaluate the possible impact of alien species Potamopyrgus antipodarum (Gray, 1843) and Gammarus tigrinus (Sexton, 1939) on native invertebrates as well as the influence of environmental factors on the occurrence benthos fauna including also alien species. The study conducted in industrial area, in the River Ruda (Poland), showed that at the sites at which the occurrence of the two alien species was observed, the density of native benthos and diversity decreased significantly. CCA analysis showed that non-native species occurred in fast water velocity and that their presence was associated with high values of conductivity, hardness, and a high chloride content. The arrival of new species from other geographical areas is one of the factors that influences the species balance in native aquatic fauna. The number of alien species in freshwater ecosystems probably will increase in the future as new aliens are moved outside of their native ranges.

  12. Benthos off Cochin, Southwest coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Harkantra, S.N.; Parulekar, A.H.

    Macro-invertebrate benthic fauna off Cochin mainly composed of polychaeta (82.45%), crustacea (7.62%), mollusca (5.92%), sipuncula (2.25%), nemertinea (0.96%) and echinodermata (0.80%). The maximum population density and biomass values were 304 plus...

  13. The Status of Benthos in Lake Ontario

    Science.gov (United States)

    The benthic community of Lake Ontario was dominated by an amphipod (Diporeia spp.) prior to the 1990’s. Two dreissenid mussel species D. polymorpha (zebra) and D. bugensis (quagga) were introduced in 1989 and 1991 via ballast water exchange. D. bugensis was observed as deep as 85...

  14. Benthos of the EEZ of India

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Ingole, B.S.; Parulekar, A.H.

    stream_size 13 stream_content_type text/plain stream_name India_EEZ_1996_74.pdf.txt stream_source_info India_EEZ_1996_74.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  15. Abyssal benthos of the Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.; Harkantra, S.N.; Ansari, Z.A.; Matondkar, S.G.P.

    and the type of substratum. Contribution of macro and meiofauna to the total standing crop was in the ratio of 31 to 1. High benthic biomass and rich fauna are consequences of high organic production in the euphotic zone. The correlation between biomass...

  16. The future of Arctic benthos: Expansion, invasion, and biodiversity

    Science.gov (United States)

    Renaud, Paul E.; Sejr, Mikael K.; Bluhm, Bodil A.; Sirenko, Boris; Ellingsen, Ingrid H.

    2015-12-01

    One of the logical predictions for a future Arctic characterized by warmer waters and reduced sea-ice is that new taxa will expand or invade Arctic seafloor habitats. Specific predictions regarding where this will occur and which taxa are most likely to become established or excluded are lacking, however. We synthesize recent studies and conduct new analyses in the context of climate forecasts and a paleontological perspective to make concrete predictions as to relevant mechanisms, regions, and functional traits contributing to future biodiversity changes. Historically, a warmer Arctic is more readily invaded or transited by boreal taxa than it is during cold periods. Oceanography of an ice-free Arctic Ocean, combined with life-history traits of invading taxa and availability of suitable habitat, determine expansion success. It is difficult to generalize as to which taxonomic groups or locations are likely to experience expansion, however, since species-specific, and perhaps population-specific autecologies, will determine success or failure. Several examples of expansion into the Arctic have been noted, and along with the results from the relatively few Arctic biological time-series suggest inflow shelves (Barents and Chukchi Seas), as well as West Greenland and the western Kara Sea, are most likely locations for expansion. Apparent temperature thresholds were identified for characteristic Arctic and boreal benthic fauna suggesting strong potential for range constrictions of Arctic, and expansions of boreal, fauna in the near future. Increasing human activities in the region could speed introductions of boreal fauna and reduce the value of a planktonic dispersal stage. Finally, shelf regions are likely to experience a greater impact, and also one with greater potential consequences, than the deep Arctic basin. Future research strategies should focus on monitoring as well as compiling basic physiological and life-history information of Arctic and boreal taxa, and integrate that with projections of human activities and likely ecosystem consequences to facilitate development of management strategies now and in the future.

  17. Biogeomorphological implications of microscale interactions between sediment geotechnics and marine benthos: a review

    Science.gov (United States)

    Murray, John M. H.; Meadows, Azra; Meadows, Peter S.

    2002-09-01

    At the foundations of biogeomorphological processes in the sea lie interactions between the activities of marine benthic animals and the geotechnical properties of their sedimentary environments. The potential significance of these interactions, which take place at a microscale level of millimetres to metres, for the large-scale geomorphology of the seabed has rarely been appreciated. In the context of this review, large-scale is defined as greater than 50 m to hundreds of kilometres. The present review addresses this link, drawing examples from a wide range of marine environments, including estuaries, the intertidal zone, continental shelves and slopes, and the deep sea. It firstly considers sediment stabilisation, slope failure, sediment mixing, biodeposition, sediment compaction, and hydrodynamic effects. This is followed by a consideration of two extremes of the ecological pyramid—the effects of marine meiofauna and marine vertebrates. The final section draws attention to the central role of faunal mucus and extracellular polymeric material (ECPM) in many of the microscale interactions that we describe. The implications of these microscale biological processes and features are discussed in terms of their influence on and control of the large-scale geomorphology of the seabed.

  18. Changes in the deep-water benthos of eastern Lake Erie between 1979 and 1993

    Energy Technology Data Exchange (ETDEWEB)

    Dermott, R.; Kerec, D. [Fisheries and Oceans, Burlington, Ontario (Canada)

    1995-06-01

    In order to examine changes of the benthic community and benthic biomass as a result of mussel colonization, a survey of the deep-water benthic fauna in eastern Lake Erie was repeated in 1993 using the same sites and methods as in a 1979 survey. During 1979, the community beyond 30 m was dominated by oligochaete worms and the burrowing amphipod Diporeia, which represented 50 and 40% of the total benthic biomass respectively. By 1993, quagga mussels (Dreissena bugensis) formed over 90% of the benthic biomass. Mussels were present at all 13 sites. Densities of individuals >2 mm in length averaged 3,241 mussels m{sup -2}. Of these mussels, 97% were quagga mussels. Total density of all sizes retained on a 180 {mu}m sieve averaged 34,800 mussels m{sup -2} but total biomass decreased from 1.58 to 0.98 g m{sup -2}. The density of the amphipod Diporeia was reduced from 1,844 in 1979 to 218 m{sup -2} in 1993. While present at all sites during 1979, Diporeia remained common only at two sites and were absent at 8 of the 13 sites in 1993. The native fingernail clams, Pisidium spp., were reduced from 327 to 82 m{sup -2}. No significant reduction occurred in the worm and chironomid populations, however the dry biomass of the chironomids was reduced from 0.07 to 0.0008 g m{sup -2}. These reductions may be due to competition with the mussels for freshly settling algae. The meiofauna, which included small nematodes, ostracods, and harpacticoids retained on a 180 {mu}m sieve, all increased in density. Perhaps they benefited from an increase in the detritus deposited as pseudofeces around the mussels.

  19. Simulation Modeling of Zooplankton and Benthos in Reservoirs: Documentation and Development of Model Constructs.

    Science.gov (United States)

    1980-03-01

    large green algae increased. 112. Anabaena affinis and A. flos- aguae were rarely consumed by the zooplankton and were unaffected by increased grazing...in grazing rate is virtually nonexistent, other evidence (primarily for 97 Ix 40 . 0 0 0 ’-0 m 0.- 0 a 0 E- o r 4C ~Q o0 0 R0.0 0 0 0 0 00C co bo N0...zooplankton feed on particles of 100 pm or less. Little quantitative data exist on the feeding of predatory zooplankton and virtually nothing suitable for

  20. Application of the Benthic Ecosystem Quality Index 2 to benthos in Dutch transitional and coastal waters

    NARCIS (Netherlands)

    Loon, van W.M.G.M.; Boon, A.R.; Gittenberger, A.; Walvoort, D.J.J.; Lavaleye, M.; Duineveld, G.C.A.; Verschoor, A.J.

    2015-01-01

    The Benthic Ecosystem Quality Index 2 (BEQI2) is the Dutch multi-metric index (MMI) for assessing the status and trend of benthic invertebrates in transitional and coastal waters for the Water Framework Directive (WFD). It contains the same indicators, i.e. species richness, Shannon index and

  1. Big River Benthos: Linking Year Round Biological Response to Altered Hydrological Regimes

    Science.gov (United States)

    2017-04-02

    ecological response to altered flow regimes and help document benefits of restoring connectivity between secondary channels and the Mississippi River main...term ecological response to this temporary loss of habitat connectivity, or the mitigation thereof, is unknown. 3 Figure 1. Aerial photographs...of (a) Prairie Point Secondary Channel dike field, and (b) Ludlow Secondary Channel dike field; both dikes with environmental notches constructed

  2. PBDE and PCB accumulation in benthos near marine wastewater outfalls: The role of sediment organic carbon

    International Nuclear Information System (INIS)

    Dinn, Pamela M.; Johannessen, Sophia C.; Ross, Peter S.; Macdonald, Robie W.; Whiticar, Michael J.; Lowe, Christopher J.; Roodselaar, Albert van

    2012-01-01

    Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in sediments and benthic invertebrates near submarine municipal outfalls in Victoria and Vancouver, B.C., Canada, two areas with contrasting receiving environments. PBDE concentrations in wastewater exceeded those of the legacy PCBs by eight times at Vancouver and 35 times at Victoria. Total PBDE concentrations in benthic invertebrates were higher near Vancouver than Victoria, despite lower concentrations in sediments, and correlated with organic carbon-normalized concentrations in sediment. Principal Components Analysis indicated uptake of individual PBDE congeners was determined by sediment properties (organic carbon, grain size), while PCB congener uptake was governed by physico-chemical properties (octanol-water partitioning coefficient). Results suggest the utility of sediment quality guidelines for PBDEs and likely PCBs benefit if based on organic carbon-normalized concentrations. Also, where enhanced wastewater treatment increases the PBDEs to particulate organic carbon ratio in effluent, nearfield benthic invertebrates may face increased PBDE accumulation. - Highlights: ► Physical receiving environment affects PBDE bioaccumulation by benthic invertebrates. ► PBDE uptake is correlated with organic-carbon normalized sediment concentrations. ► PBDE and PCB congener uptake are governed by different properties. ► PBDE sediment quality guidelines may benefit by using organic carbon-normalized data. ► Enhanced wastewater treatment may mean increased benthic invertebrate PBDE bioaccumulation. - The physical receiving environment affects the accumulation of PBDEs by benthic invertebrates near submarine municipal outfalls, and uptake of PBDE congeners is governed by different properties than for PCB congeners.

  3. Understanding Small-Scale Processes Controlling the Bioavailability of Organic Contaminants to Deposit-Feeding Benthos

    DEFF Research Database (Denmark)

    Forbes, T. L.

    1999-01-01

    Proceedings of the NATO Advanced Research Workshop on Biogeochemical Cycling in Marine Sediments held at Hel, Poland, August 1997.......Proceedings of the NATO Advanced Research Workshop on Biogeochemical Cycling in Marine Sediments held at Hel, Poland, August 1997....

  4. THE MAIN NUTRIENTS CONCENTRATION FROM INTRA TISSUE WATER OF BENTHOS ORAGANISMS FROM MURES BASIN

    Directory of Open Access Journals (Sweden)

    DANA POPA

    2008-05-01

    Full Text Available In the hydrographic basin of Mures river, aboard an altitude gradient, were taken samples of intra tissue waters from benthonic organisms for research the nutrients concentrations. The reference point was represented by a dairy caw farm where the agricultural fields of this is applied the organic fertilization with manure. The intra tissue water samples from benthonic organisms were prelevated in spring and autumn and the prelevate dates are the same with spread manure dates. At the intra tissue water level, concentrations value of N and P are bigger at the second data prelevations than first data prelevations and we can conclude that the benthonic oligochetas activity increase, more than, they density increase in Mures basin. The high concentrations of NH4 show as that Mures basin is a zone characterized by high degree of anoxia and this fact is supported by significant differences between seasonal prelevations. The explication is the manifestation to the cumulated and at distance effects of introduction in water to some organic products, very probably washed from neighborhoods agricultural field. Were calculated values of Student test for seasonal comparisons and were founded significant differences between nutrients concentration values at first and second prelevations.

  5. Worldwide Analysis of Sedimentary DNA Reveals Major Gaps in Taxonomic Knowledge of Deep-Sea Benthos

    DEFF Research Database (Denmark)

    Sinniger, Frédéric; Pawlowski, Jan; Harii, Saki

    2016-01-01

    in the deep sea, they also expose the difficulties in exploiting metabarcoding datasets resulting from the lack of taxonomic knowledge and appropriate reference databases. Overall, our study demonstrates the promising potential of eDNA metabarcoding to accelerate the assessment of deep-sea biodiversity...... for pure and applied deep-sea environmental research but also emphasizes the necessity to integrate such new approaches with traditional morphology-based examination of deep-sea organisms....

  6. The benthos of South Lake, St Lucia following a period of stable ...

    African Journals Online (AJOL)

    and reptile predators is dependent on the biomass and variety of benthic invertebrates. The present survey was conducted in conjunction with, and ...... FORBES, A.T. & HILL, B.J. 1969. The physiological ability of a marine crab Hymenosoma orbiculare Desm. to live in a sub- tropical freshwater lake. Trans. roy. Soc. s.

  7. Annual changes in abundance of non-indigenous marine benthos on a very large spatial scale

    DEFF Research Database (Denmark)

    Thomsen, Mads S.; Wernberg, Thomas; Stæhr, Peter Anton

    2008-01-01

    to quantify annual nation-wide changes in abundance of non-indigenous soft-bottom invertebrates (from grab samples) and hard-bottom macroalgae (from diver based percent cover values) in Denmark. Based on criteria of being either abundant (constituting >1% of the entire Danish assemblages) or increasing...... in abundance, NIMS of particular interest were found to be Mya arenaria and Bonemaissonia hamifera (abundant), Crepidula fornicata, Ensis americanus, Neanthes succinea (a cryptogenic species), Marenzelleria spp. (increasing), and Sargassum muticum (abundant and increasing). In addition, new and/or warm......-water eurohaline NIMS such as Gracilaria vermiculophylla and Crassostrea gigas, should be given attention as these species are expected to increase in the future. Finally, species not included in existing monitoring programs (hard-bottom estuarine invertebrates, fish, parasites, highly mobile species) should also...

  8. Changing Levels of Predation on Benthos as a Result of Exploitation of Fish Populations

    NARCIS (Netherlands)

    Hansson, S.; Frid, C.L.J.; Ragnarsson, S.A.; Rijnsdorp, A.; Steingrimsson, S.A.

    1999-01-01

    In many coastal areas fishing constitutes the dominant anthropogenic impact on coastal ecosystems. That fishing has altered the abundance and size spectra of fish communities is beyond doubt. We use time series of the abundance, in the North Sea, of 8 demersal fish species and data on food

  9. The Lives and Times of the Narragansett Bay Benthos: Biodiversity Trends over 182 Years

    Science.gov (United States)

    Narragansett Bay has high benthic invertebrate biodiversity that supports many ecosystem functions and services. A master list was compiled of all benthic species collected from the Bay beginning in 1862, including a U.S. Bureau of Commercial Fisheries survey in 1871 and studies ...

  10. Communities and coexistence of benthos in northern limb of Cochin Backwaters

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Jayalakshmy, K.V.; Venugopal, P.

    Occurrence and coexistence of benthic communities of 9 stations in the northern limb of Cochin Backwaters (Kerala, India) where an industrial belt (mostly chemical industries) is located are studied. Polychaetes with 30 species are the most common...

  11. Benthos and demersal fishery resources assessment in the shelf region of Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Harkantra, S.N.

    The potential of exploitable demersal fishery resources is estimated to be 0.4 million metric tones per year (m.m.t.y.) and 0.25 m.m.t.y. respectively based on benthic biomass production and the food pyramid concept, in the shelf region of Indian...

  12. Benthos microalgae of the Lebyazhy'i Ostrova Reserve in the Black Sea

    Directory of Open Access Journals (Sweden)

    Darya S. Balycheva

    2017-08-01

    Full Text Available The paper presents for the first time a list of the benthic microalgae of the Lebyazhy'i Ostrova Reserve, including the Karkinitsky Gulf and Sary-Bulatsky liman. During 2015 and 2016, 78 taxa were found: Bacillariophyta – 69, Cyanoprokaryota – 6, Haptophyta – 3. In the Karkinitsky Gulf 45 taxa were found, in the Sary-Bulatsky liman – 56 taxa. The Czekanovski-Sorensen similarity coefficient between these locality is 46%. The basis of the flora is diatoms: Cocconeis scutellum, Entomoneis alata, Halamphora coffeiformis, Nitzschia scalpelliformis, Pleurosigma angulatum, Pl. elongatum, Psammodictyon panduriforme, including Coronia daemeliana, Surirella striatula, Tryblionella circumsuta, which are rare for the microphytobenthos of the Crimean coast of the Black Sea. According to different classifications, dominant algae are benthic (86%, marine (49% and cosmopolite (30% species. Two potentially toxic species of diatoms, H. coffeiformis and Pseudo-nitzschia calliantha, were found once, 20 species of saprobionts – indicators of water quality were found. A comparison of the floras in the protected regions of the Black Sea between the Lebyazhy'i Ostrova Reserve and the Kazachya Bay Sanctuary showed 38 common species of benthic diatoms, in the Karadag Nature Reserve – 43 and in the Kazantip Nature Reserve (Azov Sea – 21. The total microalgae abundance of the epilithon of the stones of the Sary-Bulatsky liman varied from 81,000 to 331,000 cellscm-2, biomass – 0.012–0.018 mgcm-2, number of species – 11–13. A significant contribution was made by cyanobacteria, their average abundance reached 256,000 cellscm-2 and biomass – 0.007 mgcm-2. The abundance of diatoms varied from 48,000 to 75,000 cellscm-2, the biomass reached 0.011 mgcm-2 with the dominance of Seminavis ventricosa. The obtained data have shown the necessity of regular monitoring of the microphytobenthos of the Lebyazhy'i Ostrova Reserve in order to identify the qualitative and quantitative characteristics of mass, rare, toxic species and aquatic environment quality estimating using indicator species of microalgae.

  13. Benthos of the Gorda Ridge axial valley (NE Pacific Ocean): Taxonomic composition and trends in distribution

    Science.gov (United States)

    Carey, A. G.; Stein, D. L.; Rona, P. L.

    Distribution and relative abundance of invertebrate mega-epifauna and benthic fishes were studied in the Gorda Ridge central rift valley off southern Oregon and northern California, USA. Faunal distribution and relative abundance were correlated with location, geological setting, substrate type, and depth. Bottom photographs and videotapes were from 1985-1986 cruises by the US Geological Survey and the US National Oceanic and Atmospheric Administration. Voucher specimens were collected by rock dredge, fish trap, and the Deep Submergence Vehicle (DSV) Sea Cliff. Location rather than substrate appears to have more effect on the overall taxonomic composition of the mega-epifauna in the northern and southern parts of the rift valley. Within each location, substrate type, i.e. soft sediments and rock outcrops, and percentage cover of these substrates appear to influence the existing faunal composition. Characteristic fauna are associated with each substrate type, e.g. crinoids, gorgonians and sponges (Demospongiae) on rocky surfaces. In the southern sediment-filled Escanaba Trough, deposit-feeding organisms, particularly ophiuroids, asteroids and holothuroids, are interspersed with stalked suspension feeders, such as hexactinellid sponges and pennatulids. Epifaunal community structure in the northern and southern sectors differs, even on similar substrate combinations. Except for the ubiquitous macrourids, fish species distributions may be correlated with substrate type. Abundant particulate material in the bottom water layer probably accounts for large concentrations of suspension and detritus feeding epibenthos.

  14. The benthos and ichthyofauna of Baixo São João, Ponta do Ouro ...

    African Journals Online (AJOL)

    A preliminary reef survey was conducted in July 2015 at Baixo São João, southern Mozambique, to investigate the merits of protecting it within a sanctuary. This involved point intercept analysis of photo-quadrat transects recorded in the northern, central and southern parts of the reef, on the reef top and its inshore and ...

  15. Application of the Benthic Ecosystem Quality Index 2 to benthos in Dutch transitional and coastal waters

    NARCIS (Netherlands)

    Van Loon, W.M.G.M.; Boon, A.R.; Gittenberger, A.; Walvoort, D.J.J.; Lavaleye, M.S.S.; Duineveld, G.C.A.; Verschoor, A.J.

    2015-01-01

    The Benthic Ecosystem Quality Index 2 (BEQI2) is the Dutch multi-metric index (MMI) for assessing the status and trend of benthic invertebrates in transitional and coastal waters for the Water Framework Directive (WFD). It contains the same indicators, i.e. species richness, Shannon index and AMBI,

  16. Distribution of deep-sea benthos in the proposed mining area of Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.

    to assess the impact on the benthic biota from mining activities in the Indian Basin. Several studies have been con-ducted in the Pacific and Atlantic Oceans to understand the relationship betwen artificialimpact and biological reaction (the BIE Project.... 1989. Early diagnostic proceses afecting nutrients in theporewater of central Indian Ocean cores. Marine Geology86:57–66.Parulekar,A. H.,S. N. Harkantra,Z. A. Ansari,and S. G. P. Matondkar. 1982. Abyssal ben- thos of the central Indian Ocean. Deep...

  17. Excretion is Faster Than Diagenesis for Nutrient Recycling in Lake Michigan Benthos

    Science.gov (United States)

    Aguilar, C.; Cuhel, R. L.

    2013-12-01

    Regeneration of phytoplankton growth nutrients including ammonium (NH4+) and phosphate (HPO4=) occurs in aquatic systems worldwide through biogeochemical processes of diagenesis. Organic matter falling to the bottom accumulates in sediments, and bacterial decomposition removes oxygen from the sub-surface. Anaerobic metabolism is energetically inefficient, and bacteria a few cm below the surface respire or ferment organic matter into carbon dioxide or organic acids, excreting nitrogen (NH4+) or phosphorus inorganic 'waste'. Subsurface production of bacterial metabolic products often leads to sharp gradients in porewater concentrations of NH4+ and HPO4=, which drive diffusive flux out of the sediments into overlying water. Aquatic systems with totally aerobic water overlying anoxic sediment (e.g., Lake Michigan) have muted efflux of certain inorganic nutrients arising from organic matter decomposition. For example, NH4+ is oxidized to nitrate in the upper few mm of surficial sediments by nitrifying bacteria. Strong subsurface porewater gradients, especially of redox- or geochemically-reactive compounds, often decline to low values well below the sediment-water interface, indicating transformation by sediment bacterial populations, or by purely geochemical processes such as calcium hydroxyphosphate (apatite) precipitation. For these, little flux to the water column occurs. In Lake Michigan, neither NH4+ nor HPO4= escapes substantially from the biogeochemical barriers between their diagenetic sources and overlying waters, either before or after ecosystem alteration by invasive quagga mussels (QM). Silicate and total CO2 evade unimpeded in the same cores. The organic matter deposited from the water column is also the nutrition of benthic bivalve filter feeders such as QM in Lake Michigan, or the Asian Clam in San Francisco Bay. In animal metabolism for energy production, only the carbon component is oxidized through respiration, with NH4+ (from protein) and HPO4= (from nucleic acids and lipid) being excreted. Oddly, the highest quality food resources (low C:N and C:P ratios) lead to the greatest excretion of N and P nutrients in healthy organisms with high metabolic rates. This suggestion is borne out by the spatial distribution of QM excretion rates in transects across seamount-like bathymetric features in south-central Lake Michigan. On the upstream side and plateaus of Northeast and Sheboygan Reefs, where freshly advected bottom water flows across mussel communities, excretion rates in summer 2013 varied around 0.8 and 30 nmol/animal/hr (HPO4= and NH4+ respectively) for robust young adult mussels 15-20mm in length. On the downstream slope, where particles are likely reprocessed several times, nutritional quality and excretion rates were lower, especially for NH4+. Inshore shallow stations have similar rates to upstream nutrient-sufficient populations. Excretion size spectrum regressions combined with population size frequency analyses enable estimation of areal flux. N:P excretion ratios (30-40) are greater than Redfield, and consistent with growing animals nearing their late summer spawning effort. Several years of trophic gradient transects for mussel excretion, and pre- vs. post-QM porewater profiles will support these conclusions.

  18. The impact of agricultural runoff on stream benthos in Hong Kong, China.

    Science.gov (United States)

    Neumann, Michael; Dudgeon, David

    2002-07-01

    We investigated three small streams in the New Territories of Hong Kong, China. In each stream, we compared the benthic macroinvertebrate fauna of one site immediately upstream of an area of agricultural land (market gardening) with a second site immediately downstream. Each pair of sites was < 300 m apart. Samples were taken at the end of the dry season (March 2000) and again (April 2000) just after heavy rainfall had caused runoff from the fields. The total number of taxa at the downstream sites was the same as that in the upstream sites in March. In April, the total taxon richness was lower at the downstream localities although this difference was statistically significant in only one stream. The acute toxic effect of runoff became clearer when focusing on the group of sensitive benthic fauna. The grouping was done by ranking the relatively physiological tolerance to organotoxins following the relevant literature (Bull. Environ. Contam. Toxicol. 67 (2001) 360). All streams showed a significant downstream decrease in the number of sensitive taxa in April, while in two of three streams the number of relatively tolerant taxa increased. Ordination (by n-MDS) confirmed this pattern. It revealed a marked temporal trend in all streams resulting from a decrease of sensitive taxa downstream that was not apparent at the upstream sites. The size of the observed effects varied among streams, and may have reflected differences in the composition of the agricultural runoff.

  19. Benthos and substratum characteristics of prawn culture fields in and around the Cochin backwater

    Digital Repository Service at National Institute of Oceanography (India)

    Aravindakshan, P.N.; Balasubramanian, T.; Devi, C.B.L.; Nair, K.K.C.; Gopalakrishnan, T.C.; Jayalakshmy, K.V.; Kutty, M.K.

    Benthic ecology of certain selected seasonal and perennial prawn fields in the Cochin Backwaters, Kerala, India was studied for understanding the environmental factors controlling the abundance of the major groups of macrobenthos which form...

  20. Chemical and benthos data collected from CTD, bottle, and other instruments in the Chukchi Sea in 2009-2010 as part of the Chukchi Sea Offshore Monitoring in Drilling Area - Chemical and Benthos (COMIDA-CAB) project (NODC Accession 0095566)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This accession contains physical, chemical, and biological data collected during research cruises for the Chukchi Sea Offshore Monitoring in Drilling Area (Chemical...

  1. River-Borne Sediment Exports, Sedimentation Rates, and Influence on Benthos and Leaflitter Breakdown in Southern Caribbean Mangroves (uraba, Colombia)

    Science.gov (United States)

    Blanco, J. F.; Taborda, A.; Arroyave, A.

    2011-12-01

    Deposition of river-borne sediments is a major issue in coastal ecosystems worldwide, but no study has been conducted in Neotropical mangroves. Mangroves in the Urabá Gulf (Southern Caribbean coast of Colombia) receive one of the highest sediment loads (crop district. Annual sedimentation rates were computed based in monthly samplings (2009-2010) in mangrove fringes across the Turbo River Delta using bottom-fixed 1L-cylinders (n=15). A significant spatial variation (0.04-0.9 ton m-2 yr-1) was observed among sampling stations within the delta, but the highest trapping occurred on river's main channel (2.54 ton m-2 yr-1). Temporal variation was smaller than spatial variation. Monitoring (twenty 1-m2 quadrats x 3 sites x 12 months) of a dominant mangrove-floor gastropod (Neritina virginea) observed a positive increase of density (4-125 ind. m-2: One-way ANOVA: p<0.001) along a sedimentation gradient (monthly means for low and high sedimentation sites: 3-69 kg m-2 yr-1). The role of N. virginea on leaflitter breakdown relative to sedimentation level was experimentally tested in a black mangrove (Avicennia germinans) stand by using 180 wire-mesh cages (15 x 15 x 25 cm) placed on the forest floor as experimental units, to prevent snail and crab access. After clearing existing snails and litter from the muddy bottom, each cage was placed and 1 senescent leaf of A. germinans and 7 snails were introduced (previously weighed) (snail abundance was similar to background densities). Three levels of area-weighed sedimentation rates (1, 3 and 18 g per cage) were daily added to test the impacts of the field-observed sedimentation gradient. The experiment was carried out during one month. Fresh leaf mass was different among treatments during the first week, increasing in proportion to the sedimentation rate probably due to leaf soaking. However, there was no difference in fresh leaf weight loss (average: 67%) among sediment levels after one month. Fresh weight loss (range: 81.6-4.4%) was observed in the snails during the early stage of the experiment. Significant differences were observed but not related to sediment levels. After one month, the snails gained weight (<1, 5, and 12%) in proportion to increased sediment levels (1, 3 and 18 g per day and cage). These results suggested that sedimentation levels observed in the study area are not detrimental for N. virginea populations and for their feeding activities. They also suggested that this species may cope with increased sedimentation by shifting feeding from leaflitter to sediments. However, the dominance by N. virginea (in number and biomass) in the study area may indicate that siltation is harmful for sensitive gastropods and for the entire benthic community, also including bivalves, decapods and polychaetes.

  2. Thoughts on controls on evolution and dispersal of benthos in the Magellan-Scotia Sea region: a workshop proposal

    Directory of Open Access Journals (Sweden)

    Michael R.A. Thomson

    2005-12-01

    Full Text Available The Scotia Arc and the Scotia Sea comprise a geologically young feature of the Earth’s surface that evolved over the last 40 million years (Ma or so, between the southern tip of South America and the northern tip of the Antarctic Peninsula. With the notable exception of the much younger South Sandwich Islands, the islands, banks and seamounts of the arc represent dispersed fragments of a previous continental link between southern South America (Magellan region and the Antarctic Peninsula. The benthic marine shelf faunas of the region are the focus of the IBMANT (Investigación Biolólogica Marina en Magallanes relacionada con la Antártida programme, and those of the surrounding oceanic deeps are the focus of ANDEEP (Antarctic Benthic Deep-Sea Biodiversity. Elucidating the potential relationships between the faunas of the region and the profound geographical, oceanographic and climatic changes undergone by the region in later Cenozoic time is hampered by significant unknowns in the geological history, the expense of further geoscientific exploration to fill these, and a general lack of communication between the biological and geological science communities. It is suggested that the time is opportune for a truly multidisciplinary workshop at which all the involved science communities have much to gain from the others.

  3. The use of in situ photography in studies of the deep-sea benthos at I.O.S

    International Nuclear Information System (INIS)

    Lampitt, R.S.; Rice, A.L.; Thurston, M.H.

    1984-01-01

    Photography has been a part of benthic biology studies at IOS since 1975. It has been used in several modes and as an adjunct to a number of other techniques. A substantial body of valuable data has been obtained about the abundance, distribution and behaviour of deep sea species, about seasonal changes of the sea floor and about the rates of some fundamental biological processes. Most of the data could not have been obtained using any other technique and we expect photography to continue to form an important part of the IOS programme both independently and in conjunction with other systems. (author)

  4. 2002 Benthic Grab Data for Catlett and Goodwin Islands on the York River in Chesapeake Bay, Virginia (Ches_2002benthos)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set represents the benthic community information gathered from grab sampling in 2002 (56 stations).In Fall/Winter 2002, researchers from the Virginia...

  5. Benthos of Adjacent Mangrove, Seagrass and Non-vegetated Habitats in Rookery Bay, Florida, U.S.A.

    Science.gov (United States)

    Sheridan, P.

    1997-04-01

    Benthic faunal abundances and biomasses in adjacent mangrove, seagrass and non-vegetated mud habitats were compared in Rookery Bay, Florida, U.S.A. Although all habitats were intertidal, mangroves received the shortest duration of flooding, and non-vegetated mud received the longest. Replicate cores were taken at high tide in each habitat in July, September and December 1988, and in April 1989. Seagrass substrates were low organic content sands, whereas mangrove and non-vegetated substrates were high organic content sandy clays. Over 300 taxa were recorded, most of them relatively rare, and only 32 taxa were considered dominant (averaging ≥636 individuals m -2or five core -1in any habitat at a given time). Seagrass and non-vegetated mud faunas were more diverse than those of mangrove substrates. Total densities were always higher in red mangrove ( Rhizophora mangle) peat than elsewhere, averaging 22 591 to 52 914 individuals m -2. Densities in mixed seagrasses ranged between 6347 and 23 545 individuals m -2, while those in non-vegetated mud ranged between 3611 and 22 465 individuals m -2. Biomasses, however, were always higher in either seagrasses (15·7-87·4 g wet weight m -2) or non-vegetated mud (11·9-26·2 g m -2) than in mangroves (3·6-8·2 g m -2). Tanaids and annelids were the numerical dominants, reaching maximum densities of 35 127 and 31 388 m -2, respectively, in mangroves. Annelids were also the dominant biomass in most habitats each month. Variation in densities of most of the 32 dominant taxa were related to habitat not time. Each habitat harboured four to eight taxa that were significantly more abundant there than in alternate habitats. Feeding guild analysis indicated few differences among habitats, as surface deposit feeders and carnivores were predominant. Red mangrove appear capable of functioning in a manner similar to intertidal marsh habitats by providing high densities of small prey items for mobile consumers able to exploit the intertidal zone during high tide. Experimental verification of this function remains necessary.

  6. Drift of Zooplankton, Benthos, and Larval Fish and Distribution of Macrophytes and Larval Fish during Winter and Summer, 1985.

    Science.gov (United States)

    1986-01-01

    that lake herring is an abundant species which supports a major sport fishery in the St. Marys River. Goodyear et al. (1982) reported that lake...c00Cce CIa IX (Ne- -1-4 0-4-I (~)t - 100 4) V4-4 4 04 - 0 0p u . 0 L Co Al %lWjrA Iw%-U-l,.VI 0-"-6WL4L%,ll,~ u rlIw ,)M X U-’ 09 -’ vP- vmr mm% -10 N

  7. Responses of Herbivorous Fishes and Benthos to 6 Years of Protection at the Kahekili Herbivore Fisheries Management Area, Maui.

    Directory of Open Access Journals (Sweden)

    Ivor D Williams

    Full Text Available In response to concerns about declining coral cover and recurring macroalgal blooms, in 2009 the State of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA. Within the KHFMA, herbivorous fishes and sea urchins are protected, but other fishing is allowed. As part of a multi-agency monitoring effort, we conducted surveys at KHFMA and comparison sites around Maui starting 19 months before closure, and over the six years since implementation of herbivore protection. Mean parrotfish and surgeonfish biomass both increased within the KHFMA (by 139% [95%QR (quantile range: 98-181%] and 28% [95%QR: 3-52%] respectively. Most of those gains were of small-to-medium sized species, whereas large-bodied species have not recovered, likely due to low levels of poaching on what are preferred fishery targets in Hawaii. Nevertheless, coincident with greater biomass of herbivores within the KHFMA, cover of crustose coralline algae (CCA has increased from ~2% before closure to ~ 15% in 2015, and macroalgal cover has remained low throughout the monitoring period. Strong evidence that changes in the KHFMA were a consequence of herbivore management are that (i there were no changes in biomass of unprotected fish families within the KHFMA; and that (ii there were no similar changes in parrotfish or CCA at comparison sites around Maui. It is not yet clear how effective herbivore protection might eventually be for the KHFMA's ultimate goal of coral recovery. Coral cover declined over the first few years of surveys-from 39.6% (SE 1.4% in 2008, to 32.9% (SE 0.8% in 2012, with almost all of that loss occurring by 2010 (1 year after closure, i.e. before meaningful herbivore recovery had occurred. Coral cover subsequently stabilized and may have slightly increased from 2012 through early 2015. However, a region-wide bleaching event in 2015 had already led to some coral mortality by the time surveys were conducted in late 2015, at which time cover had dropped back to levels recorded in the KHFMA in 2012.

  8. Biomarkers of bentho-pelagic coupling in antarctica: a spatio-temporal comparison in the weddell sea

    OpenAIRE

    Elias Piera, Francyne

    2014-01-01

    La Antártida es una masa de tierra y hielo rodeada por un mar con una plataforma continental profunda, caracterizado por temperaturas bajas y bastante constantes. La estacionalidad de luz y la capa de hielo son los responsables del aumento de la producción primaria de fitoplancton en primavera-verano y del flujo vertical de materia orgánica particulada (MOP), compuesto por fitoplancton fresco, excrementos del zooplancton y detritus. Los suspensivoros, así como otros organismos sésiles y vágil...

  9. beta-diversity and species accumulation in antarctic coastal benthos: influence of habitat, distance and productivity on ecological connectivity.

    Directory of Open Access Journals (Sweden)

    Simon F Thrush

    Full Text Available High Antarctic coastal marine environments are comparatively pristine with strong environmental gradients, which make them important places to investigate biodiversity relationships. Defining how different environmental features contribute to shifts in beta-diversity is especially important as these shifts reflect both spatio-temporal variations in species richness and the degree of ecological separation between local and regional species pools. We used complementary techniques (species accumulation models, multivariate variance partitioning and generalized linear models to assess how the roles of productivity, bio-physical habitat heterogeneity and connectivity change with spatial scales from metres to 100's of km. Our results demonstrated that the relative importance of specific processes influencing species accumulation and beta-diversity changed with increasing spatial scale, and that patterns were never driven by only one factor. Bio-physical habitat heterogeneity had a strong influence on beta-diversity at scales 40 km. Our analysis supports the emphasis on the analysis of diversity relationships across multiple spatial scales and highlights the unequal connectivity of individual sites to the regional species pool. This has important implications for resilience to habitat loss and community homogenisation, especially for Antarctic benthic communities where rates of recovery from disturbance are slow, there is a high ratio of poor-dispersing and brooding species, and high biogenic habitat heterogeneity and spatio-temporal variability in primary production make the system vulnerable to disturbance. Consequently, large areas need to be included within marine protected areas for effective management and conservation of these special ecosystems in the face of increasing anthropogenic disturbance.

  10. Response of benthic fauna to different pollutants: Some case studies and relevance of benthos to environmental impact assessment

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Ingole, B.S.; Furtado, R.

    With rapid rate of urbanization, industrial growth and varieties of anthropogenic changes, the use of biological parameters as monitors of environment is being increasingly appreciated. As compared to plant, the animal communities have been used...

  11. 1954-IJBCS-Article-Andry T.Kabré

    African Journals Online (AJOL)

    hp

    Tableau 1 : Macroinvertébrés échantillonnés au niveau du plan d'eau de Bama. Macroinvertébrés. Février. Mars. Avril. Mai. Juin. Juillet. Total Benthos Total Benthos Total Benthos Total Benthos Total Benthos Total Benthos. COLEOPTERES. Hydrophilidae. 421. 67. 358. 230. 1059. 677. 904. 462. 336. 190. 26. 0. Dytiscidae.

  12. Reconstruction of long-term changes in lake water chemistry, zooplankton and benthos of a small, acidified high-mountain lake: magic modelling and palaeolimnogical analysis

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, E.; Appleby, P.; Bitušík, P.; Curtis, C.; Fott, J.; Kopáček, Jiří; Pražáková, M.; Rose, N.; Strunecký, O.; Wright, R. F.

    2002-01-01

    Roč. 2, č. 2 (2002), s. 127-138 ISSN 1567-7230 Grant - others:EC(XE) MOLAR ENV4-CT95-007; EC(XE) EMERGE EVK1-CT1999-00032 Keywords : modeling * palaeolimnology * hydrochemistry Subject RIV: DA - Hydrology ; Limnology

  13. Light and vision in the deep-sea benthos: I. Bioluminescence at 500-1000 m depth in the Bahamian islands.

    Science.gov (United States)

    Johnsen, Sönke; Frank, Tamara M; Haddock, Steven H D; Widder, Edith A; Messing, Charles G

    2012-10-01

    Bioluminescence is common and well studied in mesopelagic species. However, the extent of bioluminescence in benthic sites of similar depths is far less studied, although the relatively large eyes of benthic fish, crustaceans and cephalopods at bathyal depths suggest the presence of significant biogenic light. Using the Johnson-Sea-Link submersible, we collected numerous species of cnidarians, echinoderms, crustaceans, cephalopods and sponges, as well as one annelid from three sites in the northern Bahamas (500-1000 m depth). Using mechanical and chemical stimulation, we tested the collected species for light emission, and photographed and measured the spectra of the emitted light. In addition, in situ intensified video and still photos were taken of different benthic habitats. Surprisingly, bioluminescence in benthic animals at these sites was far less common than in mesopelagic animals from similar depths, with less than 20% of the collected species emitting light. Bioluminescent taxa comprised two species of anemone (Actinaria), a new genus and species of flabellate Parazoanthidae (formerly Gerardia sp.) (Zoanthidea), three sea pens (Pennatulacea), three bamboo corals (Alcyonacea), the chrysogorgiid coral Chrysogorgia desbonni (Alcyonacea), the caridean shrimp Parapandalus sp. and Heterocarpus ensifer (Decapoda), two holothuroids (Elasipodida and Aspidochirota) and the ophiuroid Ophiochiton ternispinus (Ophiurida). Except for the ophiuroid and the two shrimp, which emitted blue light (peak wavelengths 470 and 455 nm), all the species produced greener light than that measured in most mesopelagic taxa, with the emissions of the pennatulaceans being strongly shifted towards longer wavelengths. In situ observations suggested that bioluminescence associated with these sites was due primarily to light emitted by bioluminescent planktonic species as they struck filter feeders that extended into the water column.

  14. Inventory of vegetation and benthos in newly laid and natural ponds in Forsmark 2012; Inventering av vegetation och bottenfauna i nyanlagda och naturliga goelar i Forsmark 2012

    Energy Technology Data Exchange (ETDEWEB)

    Qvarfordt, Susanne; Wallin, Anders; Borgiel, Micke [Sveriges Vattenekologer AB, Vingaaker (Sweden)

    2013-01-15

    SKB plans to build a repository for the spent nuclear fuel. The repository is planned to be built in Forsmark and constitutes installations above and below ground. The building and operation of the construction will involve activities that might affect the nature in the area. The impact means, among other things, that a small water body, which today is a reproduction site for the red listed pool frog (Rana lessonae), will disappear. The lost locality for the pool frog has been compensated by creating four new ponds in the Forsmark area. This study is part of the follow-up of these new habitats. The aim is to describe the plant and animal communities in the ponds, and follow the succession, i.e. the development of the habitats. The study also includes two natural ponds that will serve as reference objects. The survey of vegetation and invertebrate fauna in the ponds was conducted in October 2012. The results show that the new ponds had low coverage of submersed vegetation and the species composition in the plant communities differed between the ponds. The reference ponds also had different plant communities, both in terms of species composition and coverage. This indicates that the species composition of the plant communities in the new ponds will likely depend on physical factors specific to the respective pond, but that higher vegetation coverage can be expected over time in all new ponds. The reference ponds had similar animal communities that differed from the animal communities in the new ponds. The similar species composition in the reference ponds, despite the variety of plant communities, suggests that similar animal communities are likely to develop in the new ponds, even if the plant communities continues to be different. Water chemical sampling has also been conducted in the ponds during 2012. A comparison of the inorganic environment (with regard to analysed ions) showed that the reference ponds had relatively similar ion compositions with little variation compared to the new ponds. The organic environment with respect to nutrients and organic carbon was similar in five of the ponds. The pond, AFM001420, differed from the others, with higher levels of total nitrogen, total organic carbon (TOC) and total phosphorus during the sampling period. The sampling methods used in the survey gave results that describe the ponds plant and animal communities well. The results are also suited for statistical analysis, which means that changes in communities over time is likely to be detectable.

  15. Hydrographic and Ecological Effects of Enlargement of the Chesapeake and Delaware Canal. Appendix IV. Benthos of Delaware Waters in and Near C and D Canal.

    Science.gov (United States)

    1973-09-01

    grab and dredge samples, - as well as in fish stomachs , was Gammarus daiberi, Garveia frau— - ciscana, Linanodrilus op., Neomysis americana, Crangon...stations in the last three sampling periods of this project to supplement the regular I infaunal sampling schedule. Salinity , dissolved oxygen, water... Gammarus daiberi (Table III) . This species was only recently described (Bousfield , 1969), as separate from Gammarus fasciatus, a common fresh water

  16. Observation of alive benthos under a sharp hypoxia and high H2S concentrations inside the microbial mats (methane seeps in the shallows of Black Sea)

    Science.gov (United States)

    Gulin, M.

    2009-04-01

    In 2008 experimental as well as in situ investigations were implemented for studying of vitality and locomotion activity of the micro- and meiobenthos associated with the gas seeps. Research area: near-shore shallow field with the gas seeps, southern sector of Tarkhankut Cape, NW Crimea Peninsula, Black Sea. Cuvette LDO-oxymeter coupled with other sensors and also life-time diagnostics of the organisms including microscopic video filming were used for this case. Concentrations of dissolved methane in the pore space of microbial mats were varied from 27 to 1076 µL/cm3 (220 on average). Content of organic matter of the uppermost seep mats was approximately in 50 times higher than at the background stations. Probably, such enrichments is attractive for benthic organisms. At the same time, H2S-pollution of seep microbiotope environment is detected as critical (Eh = -400/-460 mV). Near to the gas seeps alive and active Polychaeta, Nematoda, Harpacticoida and Ciliata were found. It is important, that anoxia-adapted organisms of the last two groups were quickly died at contact with air.

  17. El Niño and similar perturbation effects on the benthos of the Humboldt, California, and Benguela Current upwelling ecosystems

    Science.gov (United States)

    Arntz, W. E.; Gallardo, V. A.; Gutiérrez, D.; Isla, E.; Levin, L. A.; Mendo, J.; Neira, C.; Rowe, G. T.; Tarazona, J.; Wolff, M.

    2006-03-01

    To a certain degree, Eastern Boundary Current (EBC) ecosystems are similar: Cold bottom water from moderate depths, rich in nutrients, is transported to the euphotic zone by a combination of trade winds, Coriolis force and Ekman transport. The resultant high primary production fuels a rich secondary production in the upper pelagic and nearshore zones, but where O2 exchange is restricted, it creates oxygen minimum zones (OMZs) at shelf and upper slope (Humboldt and Benguela Current) or slope depths (California Current). These hypoxic zones host a specifically adapted, small macro- and meiofauna together with giant sulphur bacteria that use nitrate to oxydise H2S. In all EBC, small polychaetes, large nematodes and other opportunistic benthic species have adapted to the hypoxic conditions and co-exist with sulphur bacteria, which seem to be particularly dominant off Peru and Chile. However, a massive reduction of macrobenthos occurs in the core of the OMZ. In the Humboldt Current area the OMZ ranges between mega- and macrofauna occupy a dominant role as in the nearshore strip. The Benguela Current OMZ has a similar upper limit but remains shallower. It also hosts giant sulphur bacteria but little is known about the benthic fauna. However, sulphur eruptions and intense hypoxia might preclude the coexistence of significant mega- und macrobenthos. Conversely, off North America the upper limit of the OMZ is considerably deeper (e.g., 500-600 m off California and Oregon), and the lower boundary may exceed 1000m. The properties described are valid for very cold and cold (La Niña and "normal") ENSO conditions with effective upwelling of nutrient-rich bottom water. During warm (El Niño) episodes, warm water masses of low oxygen concentration from oceanic and equatorial regions enter the upwelling zones, bringing a variety of (sub)tropical immigrants. The autochthonous benthic fauna emigrates to deeper water or poleward, or suffers mortality. However, some local macrofaunal species experience important population proliferations, presumably due to improved oxygenation (in the southern hemisphere), higher temperature tolerance, reduced competition or the capability to use different food. Both these negative and positive effects of El Niño influence local artisanal fisheries and the livelihood of coastal populations. In the Humboldt Current system the hypoxic seafloor at outer shelf depths receives important flushing from the equatorial zone, causing havoc on the sulphur bacteria mats and immediate recolonisation of the sediments by mega- and macrofauna. Conversely, off California, the intruding equatorial water masses appear to have lower oxygen than ambient waters, and may cause oxygen deficiency at upper slope depths. Effects of this change have not been studied in detail, although shrimp and other taxa appear to alter their distribution on the continental margin. Other properties and reactions of the two Pacific EBC benthic ecosystems to El Niño seem to differ, too, as does the overall impact of major episodes (e.g., 1982/1983(1984) vs. 1997/1998). The relation of the "Benguela Niño" to ENSO seems unclear although many Pacific-Atlantic ocean and atmosphere teleconnections have been described. Warm, low-oxygen equatorial water seems to be transported into the upwelling area by similar mechanisms as in the Pacific, but most major impacts on the eukaryotic biota obviously come from other, independent perturbations such as an extreme eutrophication of the sediments ensuing in sulphidic eruptions and toxic algal blooms. Similarities and differences of the Humboldt and California Current benthic ecosystems are discussed with particular reference to ENSO impacts since 1972/73. Where there are data available, the authors include the Benguela Current ecosystem as another important, non-Pacific EBC, which also suffers from the effects of hypoxia.

  18. El Niño and similar perturbation effects on the benthos of the Humboldt, California, and Benguela Current upwelling ecosystems

    Directory of Open Access Journals (Sweden)

    W. E. Arntz

    2006-01-01

    Full Text Available To a certain degree, Eastern Boundary Current (EBC ecosystems are similar: Cold bottom water from moderate depths, rich in nutrients, is transported to the euphotic zone by a combination of trade winds, Coriolis force and Ekman transport. The resultant high primary production fuels a rich secondary production in the upper pelagic and nearshore zones, but where O2 exchange is restricted, it creates oxygen minimum zones (OMZs at shelf and upper slope (Humboldt and Benguela Current or slope depths (California Current. These hypoxic zones host a specifically adapted, small macro- and meiofauna together with giant sulphur bacteria that use nitrate to oxydise H2S. In all EBC, small polychaetes, large nematodes and other opportunistic benthic species have adapted to the hypoxic conditions and co-exist with sulphur bacteria, which seem to be particularly dominant off Peru and Chile. However, a massive reduction of macrobenthos occurs in the core of the OMZ. In the Humboldt Current area the OMZ ranges between <100 and about 600 m, with decreasing thickness in a poleward direction. The OMZ merges into better oxygenated zones towards the deep sea, where large cold-water mega- and macrofauna occupy a dominant role as in the nearshore strip. The Benguela Current OMZ has a similar upper limit but remains shallower. It also hosts giant sulphur bacteria but little is known about the benthic fauna. However, sulphur eruptions and intense hypoxia might preclude the coexistence of significant mega- und macrobenthos. Conversely, off North America the upper limit of the OMZ is considerably deeper (e.g., 500–600 m off California and Oregon, and the lower boundary may exceed 1000m. The properties described are valid for very cold and cold (La Niña and "normal" ENSO conditions with effective upwelling of nutrient-rich bottom water. During warm (El Niño episodes, warm water masses of low oxygen concentration from oceanic and equatorial regions enter the upwelling zones, bringing a variety of (subtropical immigrants. The autochthonous benthic fauna emigrates to deeper water or poleward, or suffers mortality. However, some local macrofaunal species experience important population proliferations, presumably due to improved oxygenation (in the southern hemisphere, higher temperature tolerance, reduced competition or the capability to use different food. Both these negative and positive effects of El Niño influence local artisanal fisheries and the livelihood of coastal populations. In the Humboldt Current system the hypoxic seafloor at outer shelf depths receives important flushing from the equatorial zone, causing havoc on the sulphur bacteria mats and immediate recolonisation of the sediments by mega- and macrofauna. Conversely, off California, the intruding equatorial water masses appear to have lower oxygen than ambient waters, and may cause oxygen deficiency at upper slope depths. Effects of this change have not been studied in detail, although shrimp and other taxa appear to alter their distribution on the continental margin. Other properties and reactions of the two Pacific EBC benthic ecosystems to El Niño seem to differ, too, as does the overall impact of major episodes (e.g., 1982/1983(1984 vs. 1997/1998. The relation of the "Benguela Niño" to ENSO seems unclear although many Pacific-Atlantic ocean and atmosphere teleconnections have been described. Warm, low-oxygen equatorial water seems to be transported into the upwelling area by similar mechanisms as in the Pacific, but most major impacts on the eukaryotic biota obviously come from other, independent perturbations such as an extreme eutrophication of the sediments ensuing in sulphidic eruptions and toxic algal blooms. Similarities and differences of the Humboldt and California Current benthic ecosystems are discussed with particular reference to ENSO impacts since 1972/73. Where there are data available, the authors include the Benguela Current ecosystem as another important, non-Pacific EBC, which also suffers from the effects of hypoxia.

  19. Deep Water Survey Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The deep water biodiversity surveys explore and describe the biodiversity of the bathy- and bentho-pelagic nekton using Midwater and bottom trawls centered in the...

  20. Corpus Christi EFH Trawling Effects 2001-2002

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — We compared sediments and benthos of two adjacent zones of the middle Texas coast, one of which was closed to shrimp trawling for 7 months. Findings indicated that...

  1. Benthic studies in south Gujarat estuaries

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.; Varshney, P.K.; Desai, B.N.

    Benthic biomass and faunal composition in relation to various environmental conditions of the four South Gujarat estuaries namely the Auranga, Ambika, Purna and Mindola were studied and compared. Mean population density of benthos in Auranga, Ambika...

  2. Kahekili, West Maui, Hawaii Fish and Benthic Data from Surveys in January and August 2008 (NODC Accession 0065597)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish and benthos baseline surveys were made at 155 sites of the near shore region off Kahekili Beach Park, West Maui in January and August, 2008. Survey sites were...

  3. Influence of Chironomidae (Diptera) faecal pellet accumulation on lake sediment quality and larval abundance of pestiferous midge Glyptotendipes paripes

    Czech Academy of Sciences Publication Activity Database

    Frouz, Jan; Lobinske, R. J.; Ali, A.

    2004-01-01

    Roč. 518, - (2004), s. 169-177 ISSN 0018-8158 Institutional research plan: CEZ:AV0Z6066911 Keywords : Chironomidae * benthos * ecosystem engineers Subject RIV: EH - Ecology, Behaviour Impact factor: 0.653, year: 2004

  4. Ecological evaluation of two prawn culture fields in the Cochin Backwater based on premonsoon diurnal observations

    Digital Repository Service at National Institute of Oceanography (India)

    Balasubramanian, T.; Viswakumar, M.; Venugopal, P.

    to be rich in nutrients and primary production and have a detritus dominated simple food chain aided by a substratum predominantly of fine sand, silt and clay, rich in organic content and benthos. These shallow, semienclosed systems have temperature between...

  5. Benthic fauna of southwest and southeast coasts of India

    Digital Repository Service at National Institute of Oceanography (India)

    Devi, K.S.; Sheba, P.; Balasubramanian, T.; Venugopal, P.; Sankaranarayanan, V.N.

    Benthos, sediments characteristics and organic matter content were studied along southwest and southeast coasts of India. Number of groups/species varied with the stations and also with the depths. Population density was very low in southeast coast...

  6. Biological observations off Sutrapada, Veraval (Gujarat)

    Digital Repository Service at National Institute of Oceanography (India)

    Nair, V.R.; Govindan, K.; Gajbhiye, S.N.; Lodh, N.M.

    Biological production potential off Veraval was evaluated based on the contribution of phytoplankton, zooplankton and benthos. The study was made along three transects covering four months during 1984-85. The mean phytoplankton count, zooplankton...

  7. Laguna Madre System 1995-1998

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Study compared densities of nekton, benthos, and seagrass among newly deposited dredged sediments and nearby and distant natural seagrass sites over a three year...

  8. Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

    OpenAIRE

    P. Stief

    2013-01-01

    Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal–microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal–microbe interactions in the benthos of aquatic ecosystems: (i) e...

  9. Chesapeake Bay Low Freshwater Inflow Study. Biota Assessment. Phase I. Volume II.

    Science.gov (United States)

    1980-08-01

    divided into macro- (greater than 0.5 mm), meio - (0.5 - 0.1 mm), and micro -benthos (less than 0.1 mm) (Coull 1973). Of these, only the macro-benthos...organisms (particularly by the meio - and micro- components), as well as zooplankton and fish, excrete nitrogen- ous and phosphorous containing compounds...animal and plant cells supply energy to decomposers. -266- * The ambient temperature of the environment directly or indirectly controls the rates of

  10. Management of Bottom Sediments Containing Toxic Substances: Proceedings of the U.S./Japan Experts Meeting (12th) Held in Yokohama, Japan on 11-14 November 1986

    Science.gov (United States)

    1992-04-01

    tions in the overlying water column, sediment may serve as a source or sink for contaminants in the ambient environment (Gunnison, Engler, and Patrick...disposal facility and into the ambient environment or down into the ground water. Similar concerns have been expressed with respect to undesir- able...cirrifera - + 0(0.2-2.0) meio - Harpacticoida a Q(less than 30) Q(less than 0.7) benthos Macro- Number of species + benthos Number of individuals + a x

  11. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. When does fishing lead to more fish? Community consequences of bottom trawl fisheries in demersal food webs.

    Science.gov (United States)

    van Denderen, P Daniel; van Kooten, Tobias; Rijnsdorp, Adriaan D

    2013-10-22

    Bottom trawls are a globally used fishing gear that physically disturb the seabed and kill non-target organisms, including those that are food for the targeted fish species. There are indications that ensuing changes to the benthic invertebrate community may increase the availability of food and promote growth and even fisheries yield of target fish species. If and how this occurs is the subject of ongoing debate, with evidence both in favour and against. We model the effects of trawling on a simple ecosystem of benthivorous fish and two food populations (benthos), susceptible and resistant to trawling. We show that the ecosystem response to trawling depends on whether the abundance of benthos is top-down or bottom-up controlled. Fishing may result in higher fish abundance, higher (maximum sustainable) yield and increased persistence of fish when the benthos which is the best-quality fish food is also more resistant to trawling. These positive effects occur in bottom-up controlled systems and systems with limited impact of fish feeding on benthos, resembling bottom-up control. Fishing leads to lower yields and fish persistence in all configurations where susceptible benthos are more profitable prey. Our results highlight the importance of mechanistic ecosystem knowledge as a requirement for successful management.

  13. Invasive mussels alter the littoral food web of a large lake: stable isotopes reveal drastic shifts in sources and flow of energy.

    Directory of Open Access Journals (Sweden)

    Ted Ozersky

    Full Text Available We investigated how establishment of invasive dreissenid mussels impacted the structure and energy sources of the littoral benthic food web of a large temperate lake. We combined information about pre- and postdreissenid abundance, biomass, and secondary production of the littoral benthos with results of carbon and nitrogen stable isotope analysis of archival (predreissenid and recent (postdreissenid samples of all common benthic taxa. This approach enabled us to determine the importance of benthic and sestonic carbon to the littoral food web before, and more than a decade after dreissenid establishment. Long term dreissenid presence was associated with a 32-fold increase in abundance, 6-fold increase in biomass, and 14-fold increase in secondary production of the littoral benthos. Dreissenids comprised a large portion of the post-invasion benthos, making up 13, 38, and 56% of total abundance, biomass, and secondary production, respectively. The predreissenid food web was supported primarily by benthic primary production, while sestonic material was relatively more important to the postdreissenid food web. The absolute importance of both sestonic material and benthic primary production to the littoral benthos increased considerably following dreissenid establishment. Our results show drastic alterations to food web structure and suggest that dreissenid mussels redirect energy and material from the water column to the littoral benthos both through biodeposition of sestonic material as well as stimulation of benthic primary production.

  14. Distribution of polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT) in Barcelona harbour sediments and their impact on benthic communities

    International Nuclear Information System (INIS)

    Martinez-Llado, Xavier; Gibert, Oriol; Marti, Vicens; Diez, Sergi; Romo, Javier; Bayona, Josep Maria; Pablo, Joan de

    2007-01-01

    Sediments have long been recognised as a sink for many contaminants like polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT), which by virtue of their nature can strongly adsorb onto sediments affecting the benthic community inhabiting them. Using geographical information systems, this study reports and combines the results of several already existing studies along Barcelona harbour in order to assess the potential ecological impacts of these contaminants on the benthos of the harbour ecosystem. Chemical analysis indicated low to moderate contents of PAHs and high contents of TBT in sediments in Barcelona harbour. Comparison against existing sediment quality guidelines (SQGs) indicated that acutely toxic effects would not be expected for PAHs but for TBT, which represents a serious environmental threat for the benthic community. Benthos surveys revealed a deterioration of the benthic community throughout the harbour, especially in the inner port. - A possible correlation exists between TBT concentration in sediments and ecological effects on benthos in Barcelona harbour

  15. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve Program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Randall, R.E. (eds.)

    1980-12-01

    The purpose of this report is to describe the environmental conditions found by the principal investigators during the predisposal study conducted from September 1977 through February 1980 prior to the start of brine discharge in March 1980. The major areas of investigation are physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, phytoplankton, zooplankton, and data management. Volume 1 describes the results of the predisposal study, and it is divided into eight chapters entitled: Physical Oceanography, Analsyis of the Discharge Plume, Water and Sediment Quality, Nekton, Benthos, Zooplankton, Phytoplankton, and Data Management. Volume 2 consists of appendices which contain additional supporting data in the form of figures and tables.

  16. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve Program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Randall, R.E. (eds.)

    1980-12-01

    The purpose of this report is to describe the environmental conditions found by the principal investigators during the predisposal study conducted from September 1977 through February 1980 prior to the start of brine discharge in March 1980. The major areas of investigation are physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, phytoplankton, zooplankton, and data management. Volume 1 describes the results of the predisposal study, and it is divided into eight chapters entitled: Physical Oceanography, Analysis of the Discharge Plume, Water and Sediment Quality, Nekton, Benthos, Zooplankton, Phytoplankton, and Data Management. Volume 2 consists of appendices which contain additional supporting data in the form of figures and tables.

  17. Browse Title Index

    African Journals Online (AJOL)

    Items 1 - 50 of 175 ... Vol 18, No 2 (2009), A mesocosm analytical study on the ecological interactions of certain benthos in response to the biodeposition and bioturbation activities of the freshwater mussel Lamellidens marginalis (Lamarck), Abstract. VI Paul, P Jayakumar, N Jothivel, N Susithra. Vol 17, No 1 (2008), A Rapid ...

  18. Author Details

    African Journals Online (AJOL)

    Susithra, N. Vol 18, No 2 (2009) - Articles A mesocosm analytical study on the ecological interactions of certain benthos in response to the biodeposition and bioturbation activities of the freshwater mussel Lamellidens marginalis (Lamarck) Abstract. ISSN: 0795-0101. AJOL African Journals Online. HOW TO USE AJOL.

  19. Western Indian Ocean Journal of Marine Science - Vol 15, No 1 (2016)

    African Journals Online (AJOL)

    Sandeep Shivram Beepat, Chandani Appadoo, Daniel Edgard Pierre Marie, Shamimtaz Bibi Sadally, Jose Pavao Mendes Paula, Kannan Sivakumar, Rashmi ... The benthos and ichthyofauna of Baixo São João, Ponta do Ouro Partial Marine Reserve, southern Mozambique · EMAIL FREE FULL TEXT EMAIL FREE FULL ...

  20. Coral reef fish biomass and benthic cover data from Timor-Leste in June 2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral reef fish and benthos were surveyed at 150 shallow-water coral reef sites across the north coast of Timor-Leste and around Atauro Island in June 2013 during a...

  1. Natural history of coral-algae competition across a gradient of human activity in the Line Islands

    NARCIS (Netherlands)

    Barott, K.L.; Williams, G.J.; Vermeij, M.J.A.; Harris, J.; Smith, J.E.; Rohwer, F.L.; Sandin, S.A.

    2012-01-01

    Competition between corals and benthic algae is prevalent on coral reefs worldwide and has the potential to influence the structure of the reef benthos. Human activities may influence the outcome of these interactions by favoring algae to become the superior competitor, and this type of change in

  2. A depth-adjusted ambient distribution approach for setting ...

    Science.gov (United States)

    We compiled and modelled macroinvertebrate assemblage data from samples collected in 1995-2014 from the estuarine portion of the St. Louis River Area of Concern (AOC) of western Lake Superior. Our objective to create depth-adjusted cutoff values for benthos condition classes (poor, fair, reference) that can be used to plan remediation and restoration actions, and to assess progress toward achieving removal targets for the degraded benthos beneficial use impairment. The relationship between depth and benthos metrics was wedge-shaped. We therefore used 90th percentile quantile regression to define the limiting effect of depth on selected benthos metrics, including taxa richness, percent non-oligochaete individuals, percent Ephemeroptera, Trichoptera, and Odonata individuals, and density of ephemerid mayfly larvae (e.g., Hexagenia). We also created a scaled trimetric index from the first three metrics. We examined gear type (standard vs. petite Ponar sampler), exposure class (derived from fetch), geographic zone of the AOC, and substrate type for confounding effects on the limiting depth. The effect of gear type was minimal. Metric values were generally higher at more exposed locations, but we judged the exposure effect less important for model application than variation among three geographic zones, so we combined data across exposure classes and created separate models for each geographic zone of the AOC. Based on qualitative substrate data for most samples, we

  3. Further Studies of Plutonium and Americium at Thule, Greenland

    DEFF Research Database (Denmark)

    Aarkrog, Asker; Dahlgaard, Henning; Nilsson, Karen Kristina

    1984-01-01

    further away from the impact point and at some locations the vertical distribution indicated a downward displacement of Pu in the sediment column since 1974. Seawater and seaplants showed no evidence of the presence of Pu from sources other than fallout; but Pu in benthos varied nearly proportionally...

  4. New York Bight Study: Report 5, NY Bight Biological Review Program

    Science.gov (United States)

    1994-05-01

    bottom Benthos ..................... 30 Table 5. Common and Scientific Names of Common Species from the NY Bight that Exhibit Thigmotropic and...crustaceans are attracted to structures ( thigmotropism ) or cunrents (rheotropism) for a variety of reasons (e.g., protection from predators, mini- mized...1992). Many fish are naturally attracted to borrow pits due to thigmotropism , rheotropism, higher food abundance, ame- liorated environmental

  5. Plectolyngbya hodgsonii: a novel filamentous cyanobacterium from Antarctic lakes

    Czech Academy of Sciences Publication Activity Database

    Taton, A.; Wilmotte, A.; Šmarda, J.; Elster, Josef; Komárek, Jiří

    2011-01-01

    Roč. 34, č. 2 (2011), 181-191 ISSN 0722-4060 R&D Projects: GA ČR GA206/05/0253 Institutional research plan: CEZ:AV0Z60050516 Keywords : Antarctica * benthos of lake * cyanobacteria Subject RIV: EF - Botanics Impact factor: 1.659, year: 2011

  6. Large-scale spatial patterns within soft-bottom epibenthic ...

    African Journals Online (AJOL)

    Knowledge of benthic invertebrate biodiversity and distribution patterns over the continental shelf of South Africa is poor and this is hampering efforts to design a network of marine protected areas aimed at conserving regional benthic biota. We analysed invertebrate biodiversity patterns within the offshore benthos along the ...

  7. Invertebrates of Meadow Creek, Union County, Oregon, and their use as food by trout.

    Science.gov (United States)

    Carl E. McLemore; William R. Meehan

    1988-01-01

    From 1976 to 1980, invertebrates were collected three times each year from several reaches of Meadow Creek in eastern Oregon. Five sampling methods were used: benthos, drift, sticky traps, water traps, and fish stomachs. A total of 372 taxa were identified, of which 239 were used as food by rainbow trout (steelhead; Salmo gairdneri Richardson). Of...

  8. The first cyanobacterial infection of crustose coralline algae discovered on the reefs of Pohnpei, Micronesia

    Science.gov (United States)

    Aeby, Greta S.; Work, Thierry M.; Hughen, Konrad A.

    2014-01-01

    Crustose coralline algae (CCA) can cover substantial areas on living reef benthos (Adey et al. 1982, Keats et al. 1997), are important to reef integrity by acting to cement reefs together (Littler and Littler 1984), and serve as recruitment sites for coral larvae (Lasker and Kim 1996, Harrington et al. 2004, Price 2010).

  9. Oconee Nuclear Station, Units 1, 2, and 3. Annual operating report for 1976, volume 1: nonradiological environmental surveillance report; II: summary of operations

    International Nuclear Information System (INIS)

    1977-01-01

    The non-radiological environmental surveillance program including thermal and chemical effluents, water quality, fish populations, benthos, fish impingement, gas-bubble disease, and plankton, fish larvae and fish egg entrainment is described. Information is also presented concerning operations, personnel radiation exposures, and fuel examinations

  10. Environmental Impacts—Marine Ecosystems

    DEFF Research Database (Denmark)

    Brander, Keith; Ottersen, Geir; Bakker, J.P.

    2016-01-01

    This chapter presents a review of what is known about the impacts of climate change on the biota (plankton, benthos, fish, seabirds and marine mammals) of the North Sea. Examples show how the changing North Sea environment is affecting biological processes and organisation at all scales, includin...

  11. The impact of Dictyota spp. on Halimeda populations of Conch Reef, Florida Keys

    NARCIS (Netherlands)

    Beach, K; Walters, L; Borgeas, H; Coyer, J; Vroom, P

    2003-01-01

    Species of the brown alga Dictyota dominate the reef tract in the Florida Keys. In surveys during summer and fall months between 1994 and 2001, Dictyota occupied as much as 70% of the benthos on Conch Reef Dictyota spp. were found growing epiphytically on Halimeda tuna, Halimeda opuntia, Lobophora

  12. Variation in the decomposition of Phragmites australis litter in a monomictic lake: the role of gammarids.

    NARCIS (Netherlands)

    van Dokkum, H.P.; Slijkerman, D.M.E.; Rossi, L.; Constantini, M.L.

    2002-01-01

    A decomposition study has been carried out in Lake Geestmerambacht, a moderately deep (max. ca. 22 m), monomictic slightly brackish lake in The Netherlands. To assess the relative importance of biotic (benthos) and physico-chemical factors, the mass loss rate (K) of reed leaf litter was measured at

  13. Tropical Freshwater Biology - Vol 18, No 2 (2009)

    African Journals Online (AJOL)

    Organic fertilizer decomposition and nutrient loads in water reservoir with changing temperature, Wakiso – Ug · EMAIL FULL TEXT EMAIL FULL TEXT ... benthos in response to the biodeposition and bioturbation activities of the freshwater mussel Lamellidens marginalis (Lamarck) · EMAIL FULL TEXT EMAIL FULL TEXT

  14. Camparison of benthic bacterial community composition in nine streams

    Science.gov (United States)

    Xuqing Gao; Ola A. Olapade; Laura G. Leff

    2005-01-01

    In this study, the abundance of major bacterial taxa (based on fluorescent in situ hybridization, FISH) and the structure of the bacterial community (based on denaturing gradient gel electrophoresis, DGGE) were determined in the benthos of 9 streams in the southeastern and midwestern United States and related to differences in environmental conditions. Taxa examined...

  15. Comparison of benthic bacterial community composition in nine streams

    Science.gov (United States)

    Xueqing Gao; Ola A. Olapade; Laura G. Leff

    2005-01-01

    In this study, the abundance of major bacterial taxa (based on fluorescent in situ hybridization, FISH) and the structure of the bacterial community (based on denaturing gradient gel electrophoresis, DGGE) were determined in the benthos of 9 streams in the southeastern and midwestern United States and related to differences in environmental...

  16. Ecological assessment of a coastal shallow lagoon in Lagos, Nigeria

    African Journals Online (AJOL)

    Michael Horsfall

    insects such as stonefly and mayfly nymphs. These organisms form a major link in the food chain as most estuarine and marine fishes, birds and mammals depend directly or indirectly on the benthos for their food supply (Barnes and Hughes, 1988). Benthic macro-invertebrates can be used as indicators of water quality.

  17. Coral reef fish biomass and benthic cover data from Timor-Leste in June 2013 (NCEI Accession 0165354)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Coral reef fish and benthos were surveyed at 150 shallow-water coral reef sites across the north coast of Timor-Leste and around Atauro Island in June 2013 during a...

  18. Untitled

    African Journals Online (AJOL)

    rotifers, cladocerans such 'as Daphnia magna and copepods such as. Mesocyclops og'unnus (Defaye, 1988; Green and Seyoum Mengistou, 1991). The benthos is dominated by oligochaetes, chironomids and gastropods. (T udorancea et al., 1989), all of which are important food items for B. docmak in Lake Chamo.

  19. Ecology of benthic macroinvertebrates in the depositional biotope of ...

    African Journals Online (AJOL)

    The ecology of benthic macroinvertebrates was studied in the depositional biotope of a river in southern Nigeria in two contrasting tidally influenced fresh and brackish water stations. Forty five taxa in nineteen families representing seven major groups of benthos were recorded. The molluscan families, dominated by ...

  20. Population ecology and community structure of sub-tidal soft sediment dwelling macro-invertebrates of Konkan, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Vizakat, L.; Harkantra, S.N.; Parulekar, A.H.

    Population density of benthos varied from 350 to 29,975 m super(-2) (X = 4325, SD = + or - 5939) in the study area. The fauna was mainly composed of Polychaeta (76.96%), Crustacea (4.93%), Echinodermata (4.36%) and other groups, viz. Echiurida...

  1. MAKROAVERTEBRATA BENTOS SEBAGAI BIOINDIKATOR KUALITAS AIR SUNGAI NIMBAI MANOKWARI, PAPUA BARAT

    Directory of Open Access Journals (Sweden)

    Simon Petrus Oktovianus Leatemia

    2017-04-01

    Full Text Available Benthos macroinvertebrates have been used as bioindicators to assess the waters quality of the stream, but still are very rarely to applied in West Papua streams. Benthos macroinvertebrates can describe the stream water quality so that very well be used as bioindicators, due to each species has a different tolerance to interference organic pollutants in waters. This study aimed to assess the water quality of Nimbai stream using benthos macroinvertebrates tolerance level and several water quality parameters. Data retrieval was conducted in JuneJuly and SeptemberOctober 2012 in seven stations (L1L7 from Nimbai upstream to downstream that connected to Prafi river. The water macroinvertebrates were taken using surber with mesh size 200 μm and then was identified at the family level. At L5 station near the oil palm waste disposal installations was contains oil and fat (<1-3 mg/l, which resulted in dissolved oxygen (DO and pH is lower than the other stations. Similarly the value of H' is low (0.83, however, the value of C (0.79 was high that dominated by Oligochaeta. Famili biotic index (FBI value obtained showed that water quality in the L1L4 stations was in good to excellent condition, but the quality at L5 station is classified as very poor. As the distance far away from the sources of pollution in the L5 station, water quality tends to improve as shown in the L6 and L7 stations. The result of this study shows the important benefits of benthos macroinvertebrates as bioindicators for assessing the quality of stream waters, and can be described aquatic environments disturbance to the benthos macroinvertebrates habitats in Nimbai stream.

  2. The Chukchi Sea zoobenthos: contemporary conditions and trends in anthropogenic influence.

    Directory of Open Access Journals (Sweden)

    Kirievskaya Dubrava

    2017-06-01

    Full Text Available The Chukchi Sea is a key region where rapid changes of the Arctic environment have been observed recently. Benthos of the Chukchi Sea is a sensitive indicator of these changes. In addition, the benthos can be used as an indicator of the anthropogenic load on the marine environment. A lot of researches have been conducted in the different parts of the Chukchi Sea. In this paper we summarized all the data collected for the last 30 years to evaluate contemporary conditions of the Chukchi Sea benthos as well as to discuss a potential response of the benthic ecosystem to the anthropogenic load. The Chukchi Sea zoobenthos is characterized by relatively high biodiversity compared to the seas of the western Arctic Ocean. The spatial distribution of zoobenthos is non-uniform. It is caused by a lot of factors: depth, bottom and sediment temperature, geochemical structure of the sediments, hydrodynamics, etc. Present environmental conditions of the Chukchi Sea biota can be considered to be close to the average long-term norms. By the reason of climate change scientists started to observe northing displacement of subarctic and temperate species of the benthic ecosystem. The Chukchi Sea is still included into the area with low anthropogenic pressure. The main potential threat for the Chukchi sea benthos results from continued oil and gas exploration and sea transport. For example, benthos around oil-wells (the Burger and the Klondike contains pollutants at a high concentration. The risk of rising anthropogenic load on the Chukchi Sea ecosystem poses the problem to additionally identify vulnerable areas of increased ecological significance for later receiving conservation status.

  3. Evaluating the effect of fishery closures: lessons learnt from the Plaice Box

    DEFF Research Database (Denmark)

    Beare, Doug; Rijnsdorp, Adriaan D.; Blæsbjerg, Mette

    2013-01-01

    to the fact that fishing had never been completely prohibited in the area. To evaluate whether the PB has been an effective management measure, the changes in the ecosystem (plaice, demersal fish, benthos) and fisheries are analysed to test whether the observed changes are due to the PB or to changes...... and an appropriate evaluation framework including both ecological and socio-economic indicators when implementing closed areas. Key words: Marine Protected Area, MPA, spatial management, fisheries management, discards, climate change, trawling impact, North Sea, benthos, ecosystem change, stakeholder perception....... It is concluded that the observed changes are most likely related to changes in the North Sea ecosystem, which may be related to changes in eutrophication and temperature. It is less likely that they are related to the change in fishing. This case study highlights the importance setting testable objectives...

  4. Some features of the quantitative distribution of sipunculan worms (Sipuncula in the central and southern Barents Sea

    Directory of Open Access Journals (Sweden)

    Evgeny A. Garbul

    2012-02-01

    Full Text Available The article reports on the current state of the sipunculan fauna of the central and southern parts of the Barents Sea. The main quantitative parameters (biomass and abundance of the sipunculan populations are obtained, and the contribution of sipunculids to the total benthos biomass is assessed. The major factors causing long-term variations in Sipunculidae distribution and abundance are evaluated for the area in question.      The investigations show that the most commonly encountered sipunculan species are Nephasoma diaphanes diaphanes,N. abyssorum abyssorum and Phascolion strombus strombus. The main contribution to the total benthos biomass comes from the two species most typical of the Barents Sea benthic fauna: Golfingia margaritacea margaritacea and G. vulgaris vulgaris. It is possible that the reductionin Golfingia biomass between the 1970s and 1990s, described in the article, is due to changes in the sampling methodology.

  5. Anti-inflammatory activity in selected Antarctic benthic organisms

    OpenAIRE

    Moles, Juan; Torrent, Anna; Alcaraz, M. José; Ruhí, Ramon; Avila, Conxita

    2014-01-01

    Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to obtain extracts that were soluble at an innocuous ethanol concentration (0.2%) for cell culture, and further test them for anti-inflammatory activity. From t...

  6. Distribution and abundance of macrobenthic polychaetes along the South Indian coast

    Digital Repository Service at National Institute of Oceanography (India)

    Musale, A.S.; Desai, D.V.

    and distribution. Keywords Polychaete • Macrobenthos • Indian coast • Pollution indicator • Organic carbon 1 Introduction Soft bottom macrobenthic communities are key components in the functioning of coastal and marine ecosystems (Lu 2005... of benthos on the South-west coast of India. In: Fertility of the sea. Vol. I, J. D. Costlow Jr. (Ed.) Gordon and Breach Scientific Publication, New York: 225-239. Lu, L. (2005). The relationship between soft bottom macrobenthic communities...

  7. Abundance and composition of benthic fauna in Penaeus monodon Fabricius culture pond on the west coast of Malaysia peninsular

    OpenAIRE

    Abu Hena, M.K.; Hishamuddin, O.; Misri, K.

    2006-01-01

    This paper reports a study on the benthic faunal abundance and diversity of tiger shrimp P. monodon culture ponds in Perak, west coast of Malaysia Peninsular. Sampling was carried out at three weeks interval throughout the 116 days culture period. In addition, water temperature, dissolved oxygen, salinity, transparency, pH and organic matter of soil were also measured. Results showed that the major groups of macro-benthos comprised of gastropod, foraminifera, polychaetes, bivalve and insects;...

  8. Thermal responses of marine animals with reference to Kalpakkam Coast (South East Coast of India)

    International Nuclear Information System (INIS)

    Shahul Hameed, P.; Syed Mohamed, H.E.; Krishnamoorthy, R.

    2008-01-01

    Kalpakkam has been chosen as model coastal site to study the impact of thermal discharges on water qualities, benthic animals and fishes. The results of this study are expected to be valid for any given open coastal location on the east and west coast of India. The present study investigates, the impact of the elevated temperature due to thermal discharge on two groups of marine animals viz. Benthos (non-swimming bottom dwellers) and fishes

  9. Marine biology, biodiversity and conservation: foreword to the SIEBM 2010 Conference

    Directory of Open Access Journals (Sweden)

    Sánchez Lizaso, J. L.

    2011-06-01

    Full Text Available The SIEBM (Iberian Symposium of Studies on Marine Biology has a long tradition. The conference was first convened in 1979 and it has since been held approximately biannually. It was originally focused on marine benthos, but two editions ago it was decided to widen its objectives to include other related subjects. The 15th edition was held at the University of Alicante from 6th to 10th September 2010.

  10. Diversity of Bacterial Photosymbionts in Lubomirskiidae Sponges from Lake Baikal

    OpenAIRE

    Kulakova, Nina V.; Denikina, Natalia N.; Belikov, Sergei I.

    2014-01-01

    Sponges are permanent benthos residents which establish complex associations with a variety of microorganisms that raise interest in the nature of sponge-symbionts interactions. A molecular approach, based on the identification of the 16S rRNA and ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit genes, was applied to investigate diversity and phylogeny of bacterial phototrophs associated with four species of Lubomirskiidae in Lake Baikal. The phylogeny inferred from both genes sh...

  11. The Influence of Coral Reef Benthic Condition on Associated Fish Assemblages

    OpenAIRE

    Chong-Seng, Karen M.; Mannering, Thomas D.; Pratchett, Morgan S.; Bellwood, David R.; Graham, Nicholas A. J.

    2012-01-01

    Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs ar...

  12. West Hackberry Strategic Petroleum Reserve site brine-disposal monitoring, Year I report. Volume III. Biological oceanography. Final report

    Energy Technology Data Exchange (ETDEWEB)

    DeRouen, L.R.; Hann, R.W.; Casserly, D.M.; Giammona, C.; Lascara, V.J. (eds.)

    1983-02-01

    The Department of Energy's Strategic Petroleum Reserve Program began discharging brine into the Gulf of Mexico from its West Hackberry site near Cameron, Louisiana in May 1981. The brine originates from underground salt domes being leached with water from the Intracoastal Waterway, making available vast underground storage caverns for crude oil. The effects of brine discharge on aquatic organisms are presented in this volume. The topics covered are: benthos; nekton; phytoplankton; zooplankton; and data management.

  13. Numerical analyses of soft bottom macroinvertebrates to diagnose the pollution in tropical coastal waters

    Digital Repository Service at National Institute of Oceanography (India)

    Harkantra, S.N.; Rodrigues, N.R.

    among the sites. Effectiveness and applicability of some of the above techniques are highlighted and discussed with the present set of data for environmental impact assessment studies. Keywords: benthos, coastal zone of India, diagnosis of industrial... Publishers. Printed in the Netherlands. 252 S. N. HARKANTRA AND N. R. RODRIGUES states that high organic carbon enrichment will result in a decrease in species richness and increase in abundance by few opportunistic species, reduction of biomass except for a...

  14. Impacts of different rice-fish-prawn culture systems on yield of rice, fish and prawn and limnological conditions

    OpenAIRE

    Nahar, Ashfaqun

    2010-01-01

    An experiment was conducted to determine the impact of fish and prawn culture on some physicochemical parameters of water, weeds, benthos, and rice yield under simultaneous method for a period of 5 months from July to November 2007. The experiment was comprised of five individual treatments having three replicates for each. The treatments were: rice combined with fish and regular urea fertilization (treatment І, T1), rice combined with prawn and regular urea fertilization (treatment ІI, T2), ...

  15. Horns Rev offshore wind farm. Introducing hard bottom substrate sea bottom and marine biology. Data report 2001

    International Nuclear Information System (INIS)

    Leonhard, S.B.; Pedersen, John

    2002-08-01

    The Ministry of Environment and Energy requested ELSAM and ELTRA to establish an offshore wind farm with an output of 150 MW in the waters of Horns Rev, approximately 15 km off Blaevandshuk, which is the most westerly point of Denmark. The first phase of construction of the wind farm have started in spring 2002. Before the construction activities take place, a baseline description of the benthos has been conducted as a part of an environmental monitoring programme for the introduction of hard bottom substrates in the North Sea. The establishment of a monitoring programme is required according to some environmental guidelines for offshore wind farms prepared by the Danish Energy Agency. The monitoring programme established for the benthic infauna was performed in spring 2001. In addition to a proposed fish investigation programme concerning the stomach contents of fish a comparative programme on benthos was established as part of the monitoring programme. The benthos sampling in connection with the fish programme was conducted in autumn 2001. This benthic survey includes sampling in a proposed reference area for the fish surveys north east of the wind farm. This report presents the data of the baseline environmental survey of the seabed in the wind farm site and in the proposed reference site and a brief description of the weather conditions at the time of sampling. (au)

  16. Decline in the deepwater benthic communities abundance in the Onego Lake under multifactor influence

    Directory of Open Access Journals (Sweden)

    Kalinkina Nataliya Michailovna

    2016-06-01

    Full Text Available The dynamics of deepwater benthic communities state between 1988 and 2015 was analyzed. In the last decade the decline in the deepwater benthic communities development indicators is observed in Petrozavodskaya Bay and contiguous central area of the Lake Onego. The abundance of benthos decreased by 6-7 times, biomass dropped in 2-4 times. At the same time the changes in sedimentation processes of organic matter, nutrients, iron and manganese are observed in the water ecosystem. This has resulted in an increase in the concentrations of Fe and Mn in the sediment surface layers; in pore waters up to 13 mg Fe/l and 7 mg Mn/l. The sharp increase in the content of iron and manganese in the bottom sediment can be considered as a possible factor of benthos oppression. Another reason of the benthos decrease is the reduction of anthropogenic load. Now Petrozavodskaya bay receives 3 times less light organic substances than 10 years ago. The third possible reason for the reduction of benthic communities is invasion of baikalian amphipods Gmelinoides fasciatus, resulting in the redistribution of organic matter flow from the littoral zone to the pelagic zone and depletion of deepwater benthic food resources.

  17. Horns Rev offshore wind farm. Introducing hard bottom substrate sea bottom and marine biology. Data report 2001

    Energy Technology Data Exchange (ETDEWEB)

    Leonhard, S.B.; Pedersen, John

    2002-08-15

    The Ministry of Environment and Energy requested ELSAM and ELTRA to establish an offshore wind farm with an output of 150 MW in the waters of Horns Rev, approximately 15 km off Blaevandshuk, which is the most westerly point of Denmark. The first phase of construction of the wind farm have started in spring 2002. Before the construction activities take place, a baseline description of the benthos has been conducted as a part of an environmental monitoring programme for the introduction of hard bottom substrates in the North Sea. The establishment of a monitoring programme is required according to some environmental guidelines for offshore wind farms prepared by the Danish Energy Agency. The monitoring programme established for the benthic infauna was performed in spring 2001. In addition to a proposed fish investigation programme concerning the stomach contents of fish a comparative programme on benthos was established as part of the monitoring programme. The benthos sampling in connection with the fish programme was conducted in autumn 2001. This benthic survey includes sampling in a proposed reference area for the fish surveys north east of the wind farm. This report presents the data of the baseline environmental survey of the seabed in the wind farm site and in the proposed reference site and a brief description of the weather conditions at the time of sampling. (au)

  18. Assessment of the environmental status in Hellenic coastal waters (Eastern Mediterranean: from the Water Framework Directive to the Marine Strategy Water Framework Directive.

    Directory of Open Access Journals (Sweden)

    N. SIMBOURA

    2014-11-01

    Full Text Available A  methodology is presented to assess the environmental status sensu the Marine Strategy Water Framework Directive (MSFD based on data obtained from the monitoring of water quality in the Hellenic coastal waters within the Water Framework Directive (WFD.   An adapted decision tree used for integrating the results of the WFD in the Basque country was applied. Modifications lie to the evaluation of the physicochemical status based on a eutrophication index developed for Eastern Mediterranean waters. Results on hydromorphological, physicochemical and biological elements are presented. The chemical status was evaluated based on measurements of heavy metals in water. The evaluation of the biological quality was based on the use of metrics developed for phytoplankton biomass, benthic macroinvertebrates and macroalgae updated to accommodate MSFD needs. Results on the integrative status of the water bodies were validated by correlating classification results with a pressure index and environmental indicators in water column and sediment. Following this decision tree the majority of stations expected to be at risk of achieving the good status were found in moderate status. Benthos was found to be the element with the closest agreement with the integrated final status having an increased weighting in the decision tree. The quality of benthos and in some  limited cases  the eutrophication index determined largely the final status. The highest disagreement with the integrative classification was produced by macroalgae. All indicators used correlated with water and sediment parameters but benthos correlated better with sediment factors while phytoplankton and eutrophication index with water column parameters.

  19. Sun Glint Correction of High and Low Spatial Resolution Images of Aquatic Scenes: a Review of Methods for Visible and Near-Infrared Wavelengths

    Directory of Open Access Journals (Sweden)

    Susan Kay

    2009-10-01

    Full Text Available Sun glint, the specular reflection of light from water surfaces, is a serious confounding factor for remote sensing of water column properties and benthos. This paper reviews current techniques to estimate and remove the glint radiance component from imagery. Methods for processing of ocean color images use statistical sea surface models to predict the glint from the sun and sensor positions and wind data. Methods for higher resolution imaging, used in coastal and shallow water mapping, estimate the glint radiance from the near-infrared signal. The effects of some current methods are demonstrated and possibilities for future techniques are briefly addressed.

  20. Are macroinvertebrates in high altitude streams affected by oxygen deficiency?

    DEFF Research Database (Denmark)

    Jacobsen, Dean; Rostgaard, S.; Vásconez, J. J.

    2003-01-01

    1. The solubility of oxygen in water increases with decreasing temperature. This has led to a general perception of cold, high mountain streams as more oxygen rich than warmer lowland streams, and that macroinvertebrates inhabiting high altitude streams have had no need to adapt to critical oxygen...... conditions. However, this fails to take into account that oxygen solubility declines with decreasing atmospheric pressure, which may be of importance at high altitudes. 2. Based on samples of macroinvertebrate benthos and in situ measurements of respiratory oxygen demand of macroinvertebrates in small...

  1. Assessment of dreissenid biodeposits as a potential food resource for invasive Asian carp

    Science.gov (United States)

    Anderson, Karl R.; Chapman, Duane C.; Hayer, Cari-Ann

    2016-01-01

    Silver carp (Hypophthalmichthys molitrix) and bighead carp (H. nobilis) are poised to invade the Laurentian Great Lakes. Zebra mussels (Dreissena polymorpha) and quagga mussels (D. rostriformis bugensis) have shifted nutrient pathways towards the benthos, partly through deposition of feces and rejected food particles called biodeposits. When biodeposit material was fed to bighead and silver carp, they fed on the material, but on average lost weight. Energy density between fed and unfed fish did not differ, but a few individual fish did gain weight on the biodeposits diet. Our results demonstrate that biodeposits might be considered a supplemental food for bigheaded carps.

  2. Impacts of pollution on freshwater communities in the border region between Russia and Norway. Results of the 1990-96 monitoring programme

    International Nuclear Information System (INIS)

    Noest, Terje; Lukin, Anatoli; Schartau, Ann Kristin Lien; Kashulin, Nikolai; Berger, Hans Mack; Yakovlev, Valeri; Sharov, Andrey; Dauvalter, Vladimir

    1997-05-01

    This report summarises the results and conclusions of the investigations in the border region between Russia and Norway, primary in selected monitoring lakes during 1990-96. The results of the 1996 investigations are given a more thorough presentation. Results on species composition, abundances and biomasses of phytoplankton, zooplankton, benthos and fish communities, as well as population parameters (length and age distribution) for different fish species are presented. Pathological state and trace metal accumulation in fish are analysed. The biological results are related to analyses of chemical parameters in lake sediments and water. 46 refs., 12 figs., 6 tabs

  3. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve program. Final report of 18 month postdisposal studies

    Energy Technology Data Exchange (ETDEWEB)

    Chittenden, M.E. Jr.; Cummings, J.A.; Harper, D.E. Jr.

    1982-03-01

    The Department of Energy's Strategic Petroleum Reserve Program began leaching the Bryan Mound salt dome and discharging brine into the coastal waters of Freeport, Texas on March 10, 1980. This report describes the findings of a team of Texas A and M University scientists and engineers who have conducted an eighteen-month environmental study to evaluate the effects of the Bryan Mound brine discharge. The study addresses the areas of physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, phytoplankton, zooplankton, and data management.

  4. EFEKTIFITAS PENGELOLAAN DAERAH PERLINDUNGAN LAUT (STUDI KASUS DESA MATTIRO LABANGENG KABUPATEN PANGKEP

    Directory of Open Access Journals (Sweden)

    Dafiuddin Salim

    2014-10-01

    Full Text Available Makalah ini menilai efektivitas manajemen di Marine Sanctuary (Daerah Perlindungan Laut atau DPL dari Mattiro Labangeng Kabupaten Village-Pangkep. Hal ini menunjukkan bahwa dampak dan efektivitas proses manajemen dinilai menggunakan indikator, termasuk indikator biofisik, sosial ekonomi dan institusi. Hasil penelitian menunjukkan bahwa ada dampak positif dalam beberapa indikator ekologi (karang, ikan dan benthos, sosio-ekonomi dan institusi. The increasion total persen tutupan karang diikuti oleh kelompok meningkatkan ikan karang (indikator, target dan jurusan dan benthos organisme di DPL. Dari sudut ekonomi ini pandangan, nilai-nilai ekonomi terumbu karang sumber daya dari kegiatan perikanan sebelum dan sesudah DPL adalah Rp 42,635,910.51/ha/tahun dan Rp 52,084,390.18/ha/tahun, masing-masing. Efektivitas DPL ini ditunjukkan oleh grafik teknik Amoeba dan hasil yang disajikan nilai-nilai positif. Ringkasan adalah nilai indikator saat ini lebih besar dari nilai ambang batas kritis / CTV.Kata Kunci: CTV, efektivitas, indikator, perlindungan laut, teknik amubaTHE EFFECTIVITY OF MARINE SANCTUARY MANAGEMENT (CASE STUDY OF MATTIRO VILLAGE OF LABANGENG PANGKEP DISTRICTABSTRAKThis paper is assessing management effectiveness in Marine Sanctuary (Daerah Perlindungan Laut or DPL of Mattiro Labangeng Village-Pangkep Regency. It is showed that impacts and effectiveness of the management process was assessed using indicators, includes biophysical, socio-economic and institution indicators. The results showed that there are positive impacts in some indicators of ecology (corals, fish and benthos, socio-economic and institution. The increasion in percent total of coral cover was followed by the increasing groups of reef fish (indicators, targets, and majors and benthos organisms in DPL. From economic’s point of views, the economic values of coral reefs resource from fisheries activities before and after DPL were Rp 42,635,910.51/ha/year and Rp 52,084,390.18/ha

  5. [The marine coastal water monitoring program of the Italian Ministry of the Environment].

    Science.gov (United States)

    Di Girolamo, Irene

    2003-01-01

    The Ministry of the Environment carries out marine and coastal monitoring programs with the collaboration of the coastal Regions. The program in progress (2001-2003), on the basis of results of the previous one, has identified 73 particulary significant areas (57 critical areas and 16 control areas). The program investigates several parameters on water, plancton, sediments, mollusks and benthos with analyses fortnightly, six-monthly and annual. The main aim of these three year monitoring programs is to assess the quality of national marine ecosystem.

  6. Biodiversity and species-environment relationships of the demersal fish assemblage at the Great Meteor Seamount (subtropical NE Atlantic), sampled by different trawls

    DEFF Research Database (Denmark)

    Fock, H.; Uiblein, F.; Köster, Fritz

    2002-01-01

    information, a grand total of 46 species was found associated with the Great Meteor Seamount. Diversity was higher in 1967 and 1970 (Shannon's diversity: H'=2.5 and 1.6) than in 1998 (H'=0.9). Species-environment relationships are discussed in terms of a sound-scattering layer-interception hypothesis, i.......e. utilisation of prey from a diurnally moving sound-scattering layer for the bentho-pelagic community. This is probably augmented by concentration effects in a circular current around the seamount (Taylor-column). Long-term changes are discussed with respect to a decrease in biodiversity due to considerable...

  7. Ocean Wave Energy Harvesting Devices

    Science.gov (United States)

    2008-01-01

    Conmiow W re Tif d. b §n P edo W ScUAe BM BMW- Nbat# PwVdnO 250- 300 P 2 ryin 1.7-4sec 573 15.1 2D 5 264o 851 0.05BO/o X-Od 1GCD AM 1 tr 2-4smc 198 11.87 4...o Teledyne Benthos is developing a low power surface "Gateway" communications buoy for use in underwater acoustic to satellite and/or RF

  8. Some ecological studies of the lower Cape Fear River Estuary, ocean outfall, and Dutchman Creek, 1971

    International Nuclear Information System (INIS)

    Copeland, B.J.; Birkhead, W.S.

    1972-01-01

    A survey of the hydrography and biological components of the Cape Fear River Estuary and nearshore ocean off Oak Island was conducted. Species diversity indices were computed from nekton samples and phytoplankton, zooplankton, and benthos samples are being analysed. A computer program was developed whereby data were alphabetized by species, sorted by location, station, and date, and printed. Experiments were conducted to determine the Critical Thermal Maximum of shrimp. Measurements were made on water temperature, salinity, and dissolved oxygen from June through October. (U.S.)

  9. A three-dimensional radiative transfer model for shallow water environments.

    Science.gov (United States)

    Hedley, John

    2008-12-22

    A geometric optical model for three-dimensional radiative transfer capable of handling arbitrary arrangements of surfaces within anisotropic scattering media is described. The model operates by discretizing surfaces and volumes into patches and voxels and establishing the radiative transfer relationship between every pair of elements. In a plane-parallel configuration results for directional radiance agree closely with the numerical integration invariant imbedded method. Model accuracy for two examples incorporating surface water waves and complex benthic structures were assessed by conservation of energy, errors were less than 1%. Potential applications in remote sensing or photobiological studies of structurally complex benthos in shallow water environments are illustrated.

  10. Taxonomy of Ophiuroidea (Echinonermata) from the continental shelf and slope of the southern and southeastern Brazilian coast

    OpenAIRE

    Borges, Michela; Monteiro, Ana Maria Gouveia [UNESP; Amaral, Antonia Cecília Zacagnini

    2002-01-01

    This study focuses on the ophiuroids collected during the Programme of Evaluation of the Living Resources of the Exclusive Economic Zone for the Brazilian coast (REVIZEE), South Score/Benthos, in the states of Rio de Janeiro (Ilha Grande Bay), São Paulo, Paraná, Santa Catarina and Rio Grande do Sul (Tramandaí) (24° 07,113' S and 29° 48,500' S; and 43° 46,759' W and 49° 06,800' W). Samples were collected on the continental shelf and slope (60-810 m) using the following equipment: van Veen, box...

  11. Geohimicheskaja harakteristika donnyh otlozhenij v zone pokmarkov v vostochnoj chasti Finskogo zaliva [The geochemical characteristics of the bottom sediment in the pockmark area of the eastern part of the Gulf of Finland

    Directory of Open Access Journals (Sweden)

    Ivanova Varvara

    2011-01-01

    Full Text Available It is the first time pockmark-like structures have been detected in the south-eastern part of the Gulf of Finland with the help of a side-scan sonar and a profile recorder. The analysis of the distribution of microcomponents in the bottom sediment indicates that the pockmark area is located in the geochemical barrier border zone where the reducing medium of the incoming mineralized solution meets the highly oxidizing sea water medium. The hydrodynamic and geochemical processes in the pockmark zone create focal areas of anomalous microenvironment and affect the composition and development of benthos.

  12. The geochemical characteristics of the bottom sediment in the pockmark area of the eastern part of the Gulf of Finland

    Directory of Open Access Journals (Sweden)

    Ivanova Varvara

    2011-03-01

    Full Text Available It is the first time pockmark-like structures have been detected in the south-eastern part of the Gulf of Finland with the help of a side-scan sonar and a profile recorder. The analysis of the distribution of microcomponents in the bottom sediment indicates that the pockmark area is located in the geochemical barrier border zone where the reducing medium of the incoming mineralized solution meets the highly oxidizing sea water medium. The hydrodynamic and geochemical processes in the pockmark zone create focal areas of anomalous microenvironment and affect the composition and development of benthos.

  13. Impacts of pollution on freshwater communities in the border region between Russia and Norway. Results of the 1990-96 monitoring programme

    Energy Technology Data Exchange (ETDEWEB)

    Noest, Terje; Lukin, Anatoli; Schartau, Ann Kristin Lien; Kashulin, Nikolai; Berger, Hans Mack; Yakovlev, Valeri; Sharov, Andrey; Dauvalter, Vladimir

    1997-05-01

    This report summarises the results and conclusions of the investigations in the border region between Russia and Norway, primary in selected monitoring lakes during 1990-96. The results of the 1996 investigations are given a more thorough presentation. Results on species composition, abundances and biomasses of phytoplankton, zooplankton, benthos and fish communities, as well as population parameters (length and age distribution) for different fish species are presented. Pathological state and trace metal accumulation in fish are analysed. The biological results are related to analyses of chemical parameters in lake sediments and water. 46 refs., 12 figs., 6 tabs.

  14. Marine resources in the tropics

    Digital Repository Service at National Institute of Oceanography (India)

    Qasim, S.Z.; Wafar, M.V.M.

    rc.aurces: ~upwelling areas, estuaries, coral reds, shelfW3h::~.margro .... es and open OC:C:ln. ID \\he Mandovi-2um oSlumnesYSl~m.a prediclion of fish yield. based cn tM production r..te> of phyloplani:ton. I>"'\\'l.nl.loo and benthos compares well... IN THE TROPICS S.2. QASIM Department of Ocean Development, 'Mahasagar Bhavan' Lodi Road, New Delhi-l10003 and MVM. WAFAR Nalionallnstitute of Oceanography, Dona Paula, Goa 4C3 004 CONTENTS I. INTHODUCfION.... . . 2. ESTUARIES. BACKWATERS AND LAGOONS... 2...

  15. Diatoms from a peat bog on the Pešter plateau (southwestern Serbia: New records for diatom flora of Serbia

    Directory of Open Access Journals (Sweden)

    Vidaković Danijela

    2016-01-01

    Full Text Available The distribution of diatoms was studied in three types of diatom communities (epiphytes, benthos and plankton of a peat bog on the Pešter plateau. The observed diatom flora inhabited all investigated communities, comprising in total 250 taxa in 53 genera. Among them, 45 taxa were new records for the Serbian diatom flora. Identified taxa belonged to different groups of algae, however alkaliphile diatoms were dominant. New ecological data for Encyonopsis minuta, Pinnularia isostauron and P. marchica are presented here. All the diatoms were documented by light micrographs, and brief notes on their morphology, distribution and ecology are provided. [Projekat Ministarstva nauke Republike Srbije, br. TR 037009

  16. Distribution patterns of Recent planktonic foraminifera in surface sediments of the western continental margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Naidu, P.D.

    derived from organisms living as benthos on the seafloor, and shells of organisms which once had lived as plankton in the surface waters (Diester-Haass et al., 1973). Thus the sedi- ments of continental margins show features typical 0025... surface waters contrast sharply with low salinity waters along the south Indian coast and in the Bay of Bengal (Fig. 3A). The North Equato- rial Current sets-in during the northeastern mon- soon period and it penetrates into the southern Arabian Sea...

  17. Influence d'une fine sédimentation dans un canal expérimental sur la densité du macrobenthos, sa composition et sa consommation par les salmonidés

    Directory of Open Access Journals (Sweden)

    NEVEU A.

    1980-01-01

    Full Text Available Les relations entre la qualité du substrat, la densité benthique et la nourriture de Salmonides ont été étudiées dans un ruisseau expérimental pour déterminer les effets d'un apport limoneux. L'eau était captée dans une rivière dont le bassin subit une forte érosion. Au début la composition du benthos était la même dans les deux systèmes, mais avec des stocks plus élevés dans le ruisseau artificiel, en relation avec l'absence de poisson et la régulation du débit. La sédimentation commença avec les crues de la rivière, les cailloux furent progressivement colmatés par la boue. La diversité et la biomasse du benthos sont alors réduites par ce changement de la qualité du substrat. La consommation du poisson, liée à la densité benthique, est plus basse dans les zones colmatées. Ces changements fauniques affectent aussi le choix, les contenus stomacaux sont plus diversifiés lorsque la nourriture est rare.

  18. Indigenous people's detection of rapid ecological change.

    Science.gov (United States)

    Aswani, Shankar; Lauer, Matthew

    2014-06-01

    When sudden catastrophic events occur, it becomes critical for coastal communities to detect and respond to environmental transformations because failure to do so may undermine overall ecosystem resilience and threaten people's livelihoods. We therefore asked how capable of detecting rapid ecological change following massive environmental disruptions local, indigenous people are. We assessed the direction and periodicity of experimental learning of people in the Western Solomon Islands after a tsunami in 2007. We compared the results of marine science surveys with local ecological knowledge of the benthos across 3 affected villages and 3 periods before and after the tsunami. We sought to determine how people recognize biophysical changes in the environment before and after catastrophic events such as earthquakes and tsunamis and whether people have the ability to detect ecological changes over short time scales or need longer time scales to recognize changes. Indigenous people were able to detect changes in the benthos over time. Detection levels differed between marine science surveys and local ecological knowledge sources over time, but overall patterns of statistically significant detection of change were evident for various habitats. Our findings have implications for marine conservation, coastal management policies, and disaster-relief efforts because when people are able to detect ecological changes, this, in turn, affects how they exploit and manage their marine resources. © 2014 Society for Conservation Biology.

  19. How will fisheries management measures contribute towards the attainment of Good Environmental Status for the North Sea ecosystem?

    Directory of Open Access Journals (Sweden)

    Christopher Philip Lynam

    2015-07-01

    Full Text Available European fisheries management have adopted maximum sustainable yield (MSY targets for fishing mortality on commercial species to maximise the provision of food. EU member states are also committed to reach Good Environmental Status by 2020 through the Marine Strategy Framework Directive which aims to protect all ecosystem services. So, how will fisheries management measures contribute to ecosystem functioning and the attainment of environmental objectives as measured by improvements in indicators of biodiversity and food webs? We model ecosystem effects of fishing in the North Sea using food web model projections incorporating fishing effort strategies consistent with MSY targets. Correlations between modelled indicators and survey data were significant (p≤0.02. Reduced fishing effort led to increases in size-based indicators and biomasses of benthivores, planktivores and piscivores. However, predation by piscivores depressed bentho-piscivore biomass. Climate warming may also decrease biomasses of bentho-piscivores and piscivores, while planktivores, benthivores and state indicators of size and trophic level may increase. Fisheries management measures will benefit the biodiversity of the fish community in terms of size structure, but not necessarily the food web since decreases in relative biomass of some trophic guilds are expected.

  20. Use of psamobenthos in the marine ecotoxicology in Brazil: bibliographical revision with petroleum substances emphasis; Uso de psamobentos em estudos de ecotoxicologia marinha no Brasil: revisao bibliografica com enfase em substancias de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Brendolan, Rodrigo A.; Gomes, Abilio Soares [Universidade Federal Fluminense, Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Marinha]. E-mail: 1gbmrabpg@vm.uff.br; abiliosg@vm.uff.br

    2003-07-01

    This study aims to make a bibliographical revision on studies about marine ecotoxicology in Brazil. The emphasis is on psamobenthos species used as test-organisms and petroleum substances as toxicants. Sediments are important repositories of pollutants in the sea. Compared to the overlaying water, pollutants become highly enriched in sediments, the reasons for this are physical adsorption and chemical bonding that occurs between the pollutants and sediment constituents. Among marine habitats, the benthos shows the highest biodiversity, and their components are important as living resources themselves or as food for economically exploited pelagic species. These contaminants could potentially cause damages to local fishing production, among other environmental consequences. These review shows that ecotoxicological tests carried out with psamobenthos are still scarce in Brazil. The current Brazilian research groups on ecotoxicology have tested only five psamobenthic species, and none of them is a standard species adopted by local environmental agencies. The search for other relevant psamobenthic species for use in ecotoxicological tests is urgent. A larger number of species could be more representative of the natural diversity of benthos, in way that testing more species, one could get a better assessment of the actual impact of pollutants on the structure and function of ecosystems. (author)

  1. Ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae

    Directory of Open Access Journals (Sweden)

    Pedro H.C. Pereira

    2016-10-01

    Full Text Available Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM with similar values for juveniles (86.6%, initial phase (88.1% and terminal phase (88.6% individuals. The second preferred benthos for juveniles was sponge (11.6% compared with initial (4.5% and terminal life phases (1.3%. Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev’s electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean.

  2. Characteristics of radionuclide accumulation in benthic organisms and fish of the Barents and Kara Seas

    International Nuclear Information System (INIS)

    Matishov, G.G.; Matishov, D.G.; Rissanen, C.

    1995-01-01

    Artificial radionuclides play a specific role in the hydrochemical, geochemical, and hydrobiological processes that are currently occurring in the western Arctic. The existing data on radioactive contamination of different plant and animal species inhabiting the sea shelf are fragmentary. Hence, it was difficult to follow the transformation of radionuclides during their transmission along food chains, from phyto- and zoo-plankton to benthos, fish, birds, and marine mammals. In 1990-1994, the Murmansk Institute of Marine Biology organized expeditions to collect samples of residues on the sea floor and also of benthos, benthic fish, macrophytes, and other organisms inhabiting the shelf of the Barents and Kara Seas. These samples were tested for cesium-137, cesium-134, strontium-90, plutonium-239, plutonium-240, americium-241, and cobalt-60 in Rovaniemi (Finland) by the regional radiation administration of the Finnish Centre for Radiation and Nuclear Safety. Over 1000 tests were made. Their results provided new data on the content and distribution of these radionuclides among different components of marine ecosystems. 7 refs

  3. Ecological effects of nuclear steam electric station operations on estuarine systems. Final report

    International Nuclear Information System (INIS)

    Mihursky, J.A.

    1983-01-01

    This report summarizes the findings of studies of the impact of the Calvert Cliffs Nuclear Power Plant on the aquatic biota of Chesapeake Bay. Physical findings show that the typical radial extent of influence of the discharge on the physical and chemical environment of the Bay is rather limited (< 2 km). This suggestion is bolstered by findings of phytoplankton and zooplankton studies: when effects were noted at all, they only appeared at sampling stations nearest (within 2 km of) the discharge. Also, direct entrainment effects on these groups were either small (in the case of phytoplankton) or species-specific (in the case of zooplankton). Benthos showed mixed responses to plant operations - the populations of some species were enhanced, one species was adversely affected, and others were unaffected. The major plant effect on the benthos was due to habitat resource enrichment, and the consequence was higher standing stocks (e.g., more food for fish) in the affected area. Direct plant effects on finfish are dominated by impingement. Mortality as a result of impingement, for many species, tends to be moderate to slight. Effects as a result of entrainment of eggs and larvae are limited because the Calvert Cliffs area is not a major spawning location for any species. In sum, the Calvert Cliffs plant appears to have a limited effect on the Chesapeake Bay ecosystem. 180 references, 6 figures, 18 tables

  4. Assessing condition of macroinvertebrate communities and bed sediment toxicity in the Rochester Embayment Area of Concern, New York, USA

    Science.gov (United States)

    Duffy, Brian; George, Scott D.; Baldigo, Barry P.; Smith, Alexander J.

    2017-01-01

    The United States and Canada agreed to restore the chemical, physical, and biological integrity of the Great Lakes ecosystem under the first Great Lakes Water Quality Agreement in 1972. The lowest reach of the Genesee River and the Rochester Embayment on Lake Ontario between Bogus Point and Nine Mile Point, including Braddock Bay, were designated as an Area of Concern (AOC) due to effects of contaminated sediments and physical disturbance on several beneficial uses. Following sediment remedial efforts and with conditions improving in the AOC, the present study was conducted to reevaluate the status of the benthic macroinvertebrate (benthos) beneficial use impairment (BUI). Benthic macroinvertebrate community assessments and 10-day Chironomus dilutus bioassays were used to test the hypotheses that sediments within the AOC were no more toxic than sediments from surrounding reference areas. The study was separated into three discrete systems (Genesee River, Lake Ontario, and Braddock Bay) and non-parametric analyses determined that a multimetric index of benthic macroinvertebrate community integrity was significantly higher at AOC sites compared to reference sites on the Genesee River and in Braddock Bay while AOC and reference sites on Lake Ontario did not differ significantly. Survival and growth of C. dilutus were also similar between AOC and reference sites for each system with the exception of significantly higher growth at reference sites on Lake Ontario. Results generally indicated that the condition of benthos and toxicity of sediment of the Rochester Embayment AOC are similar to or better than that in the surrounding area.

  5. Diel resource partitioning among juvenile Atlantic Salmon, Brown Trout, and Rainbow Trout during summer

    Science.gov (United States)

    Johnson, James H.; McKenna, James E.

    2015-01-01

    Interspecific partitioning of food and habitat resources has been widely studied in stream salmonids. Most studies have examined resource partitioning between two native species or between a native species and one that has been introduced. In this study we examine the diel feeding ecology and habitat use of three species of juvenile salmonids (i.e., Atlantic Salmon Salmo salar, Brown Trout Salmo trutta, and Rainbow Trout Oncorhynchus mykiss) in a tributary of Skaneateles Lake, New York. Subyearling Brown Trout and Rainbow Trout fed more heavily from the drift than the benthos, whereas subyearling Atlantic Salmon fed more from the benthos than either species of trout. Feeding activity of Atlantic Salmon and Rainbow Trout was similar, with both species increasing feeding at dusk, whereas Brown Trout had no discernable feeding peak or trough. Habitat availability was important in determining site-specific habitat use by juvenile salmonids. Habitat selection was greater during the day than at night. The intrastream, diel, intraspecific, and interspecific variation we observed in salmonid habitat use in Grout Brook illustrates the difficulty of acquiring habitat use information for widespread management applications.

  6. Abyssal near-bottom dispersal stages of benthic invertebrates in the Clarion-Clipperton polymetallic nodule province

    Science.gov (United States)

    Kersten, Oliver; Smith, Craig R.; Vetter, Eric W.

    2017-09-01

    Growing interest in polymetallic nodule mining has intensified the need to characterize the abundance, community structure and vertical flux of meroplankton in the Clarion-Clipperton Zone (CCZ) to facilitate the estimation of larval supply and potential connectivity of benthic populations. These ecological parameters are essential to predict recolonization processes following the expected large-scale, high intensity disturbances associated with nodule extraction. Here, we present the first description of the composition, abundance, temporal variability, and mesoscale distribution of dispersing stages of the benthos in two study areas in the eastern CCZ. Samples from free-vehicle plankton pumps showed little variation in meroplankton diversity and abundance over scales of 30-100 km for time scales of days to weeks. However, sediment-trap samples revealed high temporal variability in vertical flux over weeks to months. Larval abundances and fluxes measured in the abyssal CCZ are 1-2 orders of magnitude lower than observed at deep-sea ridge and hydrothermal-vent habitats. We found significantly higher downward larval fluxes at 11 m above the bottom (mab) than at 146 mab, indicating accumulation or retention of meroplankton within the Benthic Boundary Layer (BBL). The high abundance of meroplankton in the BBL emphasizes its importance to dispersing stages and suggests that the creation of large sediment plumes in the BBL during nodule mining could compromise the dispersal and recruitment abilities of the abyssal benthos, potentially slowing rates and altering patterns of benthic community recovery following mining disturbance.

  7. Ophiomusium acuferum (Ophiolepididae and Ophiomisidium pulchellum (Ophiuridae (Ophiuroidea: Echinodermata, redescription based on the Brazilian specimens

    Directory of Open Access Journals (Sweden)

    Michela Borges

    2011-04-01

    Full Text Available Ophiomusium (Ophiolepididae and Ophiomisidium (Ophiuridae are similar, but differ in features such as size of the adult, number of disc dorsal plates, length of the arms, shape of the first ventral arm plates and number of the tentacle. In this contribution, a large number of specimens of Ophiomusium acuferum Lyman, 1869 and Ophiomisidium pulchellum (Wyville Thomson, 1878 were sampled from southeastern and southern Brazilian at depths ranging from 46 to 1300 m. A close analysis has shown that specimens identified as Ophiomisidium pulchellum (C.W. Thomson, 1877 in several Brazilian museums are actually Ophiomusium acuferum Lyman, 1875. A total of 2330 individuals were examined: 2046 specimens of Ophiomusium acuferum ('Evaluation of the sustainable potential of living resources from the Brazilian Economic Exclusive Zone/Score South - Benthos' - REVIZEE; 'Rational usage of coastal ecosystems from the Brazilian Tropical Region: São Paulo State - Integrated Project/Subproject Benthos' - INTEGRADO; and the MD55/Brazil and 284 of Ophiomisidium pulchellum (MD55/Brazil. The disc diameter of each individual was measured and the specimens were digitally photographed. The samples studied are deposited in the Museum of Zoology of the University of Campinas and Institute of Biology at the Federal University of Rio de Janeiro. The specimens from the MD55 are deposited at the Paris Museum National d'Histoire Naturelle. An identification key to these species is provided here. A detailed morphological analysis and redescription of both species, comparisons, and their geographic distribution in Brazil are discussed.

  8. Late Permian marine ecosystem collapse began in deeper waters: evidence from brachiopod diversity and body size changes.

    Science.gov (United States)

    He, W-H; Shi, G R; Twitchett, R J; Zhang, Y; Zhang, K-X; Song, H-J; Yue, M-L; Wu, S-B; Wu, H-T; Yang, T-L; Xiao, Y-F

    2015-03-01

    Analysis of Permian-Triassic brachiopod diversity and body size changes from different water depths spanning the continental shelf to basinal facies in South China provides insights into the process of environmental deterioration. Comparison of the temporal changes of brachiopod diversity between deepwater and shallow-water facies demonstrates that deepwater brachiopods disappeared earlier than shallow-water brachiopods. This indicates that high environmental stress commenced first in deepwater settings and later extended to shallow waters. This environmental stress is attributed to major volcanic eruptions, which first led to formation of a stratified ocean and a chemocline in the outer shelf and deeper water environments, causing the disappearance of deep marine benthos including brachiopods. The chemocline then rapidly migrated upward and extended to shallow waters, causing widespread mass extinction of shallow marine benthos. We predict that the spatial and temporal patterns of earlier onset of disappearance/extinction and ecological crisis in deeper water ecosystems will be recorded during other episodes of rapid global warming. © 2014 John Wiley & Sons Ltd.

  9. SOIL AND WATER MICROORGANISM DIVERSITY OF MANGROVE FOREST OF TELUK KELUMPANG, SELAT LAUT AND SELAT SEBUKU NATURAL RESERVE

    Directory of Open Access Journals (Sweden)

    Wawan Halwany

    2015-12-01

    Full Text Available Mangrove is a unique ecosystem that has complex biotic and abiotic components. Soil and water microorganisms have function as decomposer in mangrove forest ecosystem. This paper studies the soil and water microorganisms' diversity, their potential, function in ecosystem and their role as environmental parameters in mangrove area of Teluk Kelumpang, Selat Laut and Selat Sebuku Natural Reserve (Kelautku Natural Reserve. Data of soil and water microorganisms were recorded from soil and water samplings then analyzed in the laboratory. Results show that benthos in Selat Sebuku figure the highest diversity index. Anadara granosa is one of the common benthos found in Selat Sebuku. In contrary the phytoplankton in Selat Sebuku is the lowest value compared to the other two locations, due to the settlements in the locations and it was suspected that Selat Sebuku has a relatively larger wave exposure than the two other locations. In addition, input of organic matters from the settlements in Teluk Kelumpang and Selat Laut is also effected by the growth of phytoplankton. Cyanophyta found in Teluk Kelumpang and Selat Laut was genera of Oscillatoria that showed high tolerance genera to the environment conditions.

  10. Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines

    Science.gov (United States)

    Kilpatrick, Robert; Ewing, Graeme; Lamb, Tim; Welsford, Dirk; Constable, Andrew

    2011-04-01

    Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill ( Euphausia superba).

  11. Characterization of biocenosis in the storage-reservoirs of liquid radioactive wastes of 'Mayak' PA

    Energy Technology Data Exchange (ETDEWEB)

    Pryakhin, E.; Tryapitsina, G.; Andreyev, S.; Akleyev, A. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation); Mokrov, Y.; Ivanov, I. [Mayak PA (Russian Federation)

    2014-07-01

    A number of storage-reservoirs of liquid radioactive wastes of 'Mayak' Production Association ('Mayak' PA) with different levels of radioactive contamination: reservoir R-17 ('Staroye Boloto'), reservoir R-9 (Lake Karachay), reservoirs of the Techa Cascade R-3 (Koksharov pond), R-4 (Metlinsky pond), R-10 and R-11 is located in Chelyabinsk Oblast (Russia). The operation of these reservoirs began in 1949-1964. Full-scale hydro-biological studies of these reservoirs were started in 2007. The research into the status of biocenosis of these storage reservoirs of liquid radioactive wastes of 'Mayak' PA was performed in 2007 - 2011. The status of biocenosis was evaluated in accordance with the status of following communities: bacterio-plankton, phytoplankton, zooplankton, zoo-benthos, macrophytes and ichthyofauna. The status of ecosystems was determined by radioactive and chemical contamination of water bodies. The results of hydro-biological investigations showed that no changes in the status of biota in reservoir R-11 were revealed as compared to the biological parameters of the water bodies of this geographical zone. In terms of biological parameters the status of the ecosystem of the reservoir R-11 is characterized by a sufficient biological diversity, and can be considered acceptable. The ecosystem of the reservoir R-10 maintains its functional integrity, although there were registered negative effects in the zoo-benthos community associated with the decrease in the parameters of the development of pelophylic mollusks that live at the bottom of the water body throughout the entire life cycle. In reservoir R-4 the parameters of the development of phytoplankton did not differ from those in Reservoirs R-11 and R-10; however, a significant reduction in the quantity of Cladocera and Copepoda was registered in the zooplankton community, while in the zoo-benthos there were no small mollusks that live aground throughout the entire life

  12. Ophiuroidea (Echinodermata: quatro novas ocorrências para o Brasil Ophiuroidea (Echinodermata: four new records for Brazil

    Directory of Open Access Journals (Sweden)

    Michela Borges

    2007-12-01

    Full Text Available Os ofiuróides aqui analisados são procedentes dos programas "Biodiversidade Bêntica Marinha no Estado de São Paulo" - BIOTA/FAPESP-Bentos Marinhos, "Avaliação do Potencial Sustentável dos Recursos Vivos da Zona Econômica Exclusiva" - REVIZEE/Score Sul-Bentos e "Utilização Racional dos Ecossistemas Costeiros da Região Tropical Brasileira: Estado de São Paulo" - INTEGRADO/Subprojeto Bentos. As amostras analisadas foram coletadas nas regiões da plataforma e talude continental do Sudeste e Sul brasileiros, em profundidades entre 10 e 800 m. São aqui descritas e ilustradas quatro espécies de Ophiuroidea, as quais representam novos registros de ocorrência para o Brasil, duas da família Ophiuridae, uma de Amphiuridae e uma de Ophiochitonidae. Este é também o primeiro registro desta última família para o Brasil. Somente Amphiodia trychna (Amphiuridae foi amostrada na região da plataforma interna (profundidade The ophiuroids were collected during the Programs "Biodiversidade Bêntica Marinha no Estado de São Paulo" - BIOTA/FAPESP-Marine Benthos, "Avaliação do Potencial Sustentável dos Recursos Vivos da Zona Econômica Exclusiva" - REVIZEE/Score South - Benthos and "Utilização Racional dos Ecossistemas Costeiros da Região Tropical Brasileira: Estado de São Paulo" - INTEGRADO/Subproject Benthos. Samples were obtained from the continental shelf and slope off southeast and south Brazil, between 10 and 800 m. Four species of the Ophiuroidea are described and they are new records for Brazil. Two species belong to the family Ophiuridae, and the others belong to Amphiuridae and Ophiochitonidae. The family Ophiochitonidae is recorded for the first time in Brazil. Amphiodia trychna (Amphiuridae was sampled in the inner continental shelf (depth < 50 m. The other three species were collected deeper (between 314 and 808 m.

  13. Accumulation of polychlorinated organic contaminants from sediment by three benthic marine species

    Energy Technology Data Exchange (ETDEWEB)

    Pruell, R.J.; Rubinstein, N.I.; Taplin, B.K.; LiVolsi, J.A.; Bowen, R.D.

    1993-01-01

    A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. Sandworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sediment collected from the Passaic River, New Jersey. All three species accumulated 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF) and polychlorinated biphenyls (PCBs) from the sediment. In addition, a recently identified sulfur containing analog of tetrachlorinated dibenzofurans. The objectives of the study were to determine the relative bioavailability of 2,3,7,8-TCDD, 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-TCDF) and selected PCB congeners from bottom sediments as well as to examine the relationship between contaminant concentrations in sediments and biota.

  14. Gross morphology and histology of the olfactory organ of the Greenland shark Somniosus microcephalus

    DEFF Research Database (Denmark)

    Ferrando, S.; Gallus, L.; Ghigliotti, L.

    2016-01-01

    The Greenland shark (Somniosus microcephalus) is the largest predatory fish in Arctic waters. Knowledge of the fundamental biology and ecological role of the Greenland shark is limited, and the sensory biology of the Greenland shark has been poorly studied. Given the potential relevant contribution...... of chemoreception to the sensory capability of the Greenland shark to forage and navigate in low-light environments, we examined the architecture of the peripheral olfactory organ (the olfactory rosette) through morphological, histological and immunohistochemical assays. We found that each olfactory rosette...... neurons, presence of unusually large cells along the olfactory fiber bundles) deserve further investigation. Overall, the structure of the olfactory rosette suggests a well-developed olfactory capability for the Greenland shark coherent with a bentho-pelagic lifestyle....

  15. Significance of microcystin production by benthic communities in water treatment systems of arid zones.

    Science.gov (United States)

    Hurtado, I; Aboal, M; Zafra, E; Campillo, D

    2008-02-01

    The study of the dynamics of phytobenthic and phytoplankton communities was undertaken, during a year, in the regulation reservoir associated with a water treatment plant (WTP), which provides the city of Murcia (Spain) with drinking water. Water samples were collected in different stages of the treatment. In the reservoir, the presence of dissolved and intracellular microcystins is constant, both in benthos and in plankton. The collected samples show a positive correlation between the dissolved microcystins and the benthic ones in the reservoir itself, as well as in an upstream reservoir (Ojós Reservoir). The treatment process (ozone+clarification+ozone+activated carbon) is very effective in the removal of toxins, and the drinking water produced is totally free of microcystins. The incorporation of the benthic communities in the routine check for the presence of microcystins is recommended, since it is not compulsory according to the current legislation.

  16. Observation of radionuclides in marine biota off the coast of Fukushima prefecture after TEPCO's Fukushima Daiichi Nuclear Power Plant accident

    International Nuclear Information System (INIS)

    Aono, Tatsuo; Ito, Yukari; Kanda, Jyota; Ishimaru, Takashi; Saotome, Tadahiro; Mizuno, Takuji; Igarashi, Satoshi

    2012-01-01

    Monitoring and surveying radioactivity in seawater and biota in the marine environment off the coast of Fukushima prefecture in the Pacific are important for understanding the dispersion of artificial radionuclides after TEPCO's Fukushima Daiichi Nuclear Power Plant (F1NPP) accident. Marine biota were collected in the coastal area of Fukushima prefecture after this accident due to investigate the activities of 134 Cs, 137 Cs, and 110m Ag in marine biota, including not only fish and shellfish but also benthos. It is well known that 108m Ag, one of the radioactive isotopes of Ag, was observed in some kinds of squid and octopus before this accident. As the results, 110m Ag was observed in many kinds of marine biota off the coastal area of Fukushima. It is suggested that rapid change in the radioactivities in seawater, resuspension of particles from sediments and food chain effects led to high radionuclide activities in marine biota after this accident. (author)

  17. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve Program. Annual report, September 1981-August 1982. Volume II

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Randall, R.E. (eds.)

    1983-06-01

    The Department of Energy's Strategic Petroleum Reserve Program began leaching the Bryan Mound salt dome and discharging brine into the coastal waters offshore of Freeport, Texas on March 10, 1980. This report describes the findings of a team of Texas A and M University scientists and engineers who have conducted a study to evaluate the effects of the Bryan Mound brine discharge on the marine environment. The study addresses the areas of physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, and data management. It focuses on the period from September 1981 through August 1982. Volume II contains appendices for: (1) supporting data for physical oceanography; (2) supporting data for analysis of the discharge plume; (3) supporting data for water and sediment quality; (4) supporting data for nekton studies; and (5) Bryan Mound discharge data.

  18. Strategic Petroleum Reserve: brine-disposal studies in the Gulf of Mexico. Field and laboratory procedures manual

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Giammona, C.P.; Randall, R.E. (eds.)

    1983-09-01

    The purpose of this manual is to describe the field and laboratory procedures which have been developed over the past five years and those currently in use for monitoring the effects of brine discharge on the marine environment in the Gulf of Mexico. Using such a manual provides a mechanism for updating procedures as changes occur, such as those for a monitoring plan change or the inclusion of the Big Hill site. The manual is divided into chapters which generally correspond to areas of responsibility of the principal investigators on the project team. These chapters are entitled Introduction (Chapter 1), Project Organization (Chapter 2), Objectives/Project Plan (Chapter 3), Field Operations (Chapter 4), Physical Oceanography (Chapter 5), CTD/DO and Brine Plume Tracking (Chapter 6), Water and Sediment Quality (Chapter 7), Special Pollutant Survey (Chapter 8), Phytoplankton (Chapter 9), Zooplankton (Chapter 10), Benthos (Chapter 11), Nekton (Chapter 12), and Data Management (Chapter 13). 65 references, 144 figures, 34 tables.

  19. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve program. Vol. III. Annual report, September 1981-August 1982

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Randall, R.E. (eds.)

    1983-06-01

    The purpose of this report is to describe the findings of the project team during the 12 months of postdisposal study conducted from September 1981 through August 1982. The areas of investigation are benthos, analysis of the discharge plume, data management, nekton, physical oceanography, and water and sediment quality. The specific objectives of this report are: (1) to describe the physical oceanographic and meteorological conditions which have been measured at the offshore diffuser site and in the surrounding waters; (2) to describe the effect of brine discharge on the benthic community in the diffuser site area; (3) to discuss the effect of the brine discharge on the quality of the water and sediment in the vicinity of the diffuser site; (4) to describe the measurement of the areal and vertical extent of the brine plume; and (5) to characterize the effect of brine discharge on the nekton community in the vicinity of the diffuser.

  20. Increasing levels and biomagnification of persistent organic pollutants (POPs) in Antarctic biota

    Energy Technology Data Exchange (ETDEWEB)

    Goerke, Helmut; Weber, Kurt; Bornemann, Horst; Ramdohr, Sven; Ploetz, Joachim

    2004-02-01

    Representatives of the Antarctic food web (krill, cephalopod, fish, penguin, seal) of the area around Elephant Island and from the Weddell Sea were analysed for the most recalcitrant organochlorine compounds. Due to sorption of the compounds to sinking particles and accumulation in sediments, two benthic fish species (Gobionotothen gibberifrons, Chaenocephalus aceratus) feeding on benthos invertebrates and fish reflected significantly increasing concentrations within a decade (1987-1996), while a benthopelagic species (Champsocephalus gunnari) feeding on krill did not. In the pelagic food chain, lipid normalised concentrations of all compounds increased from Antarctic krill to fish proving that biomagnification of highly lipophilic pollutants (log octanol-water partition coefficient > 5) occurs in water-breathing animals. As top predators Weddell and southern elephant seals (Leptonychotes weddellii, Mirounga leonina) biomagnified the persistent organic pollutants relative to krill 30-160 fold with the exception of hexachlorobenzene, the levels of which were lower than in fish indicating its intense specific elimination.

  1. Effects of light pollution on the emergent fauna of shallow marine ecosystems: Amphipods as a case study.

    Science.gov (United States)

    Navarro-Barranco, Carlos; Hughes, Lauren Elizabeth

    2015-05-15

    Light pollution from coastal urban development is a widespread and increasing threat to biodiversity. Many amphipod species migrate between the benthos and the pelagic environment and light seems is a main ecological factor which regulates migration. We explore the effect of artificial lighting on amphipod assemblages using two kind of lights, LED and halogen, and control traps in shallow waters of the Great Barrier Reef. Both types of artificial light traps showed a significantly higher abundance of individuals for all species in comparison to control traps. LED lights showed a stronger effect over the amphipod assemblages, with these traps collecting a higher number of individuals and differing species composition, with some species showing a specific attraction to LED light. As emergent amphipods are a key ecological group in the shallow water environment, the impact of artificial light can affect the broader functioning of the ecosystem. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Platforms of the Nicaraguan Rise: Examples of the sensitivity of carbonate sedimentation to excess trophic resources

    Science.gov (United States)

    Hallock, Pamela; Hine, Albert C.; Vargo, Gabriel A.; Elrod, Jane A.; Jaap, Walter C.

    1988-12-01

    The Nicaraguan Rise is an active tectonic structure in the western Caribbean. Carbonate accumulation on its platforms has not kept pace with relative Holocene sea-level rise, despite a tropical location remote from terrigenous sedimentation. Trophic resources apparently exceed levels favoring coral-reef development because sponge-algal communities dominate the drowning western platforms, in contrast to mixed coral-algal benthos on Pedro Bank and well- developed coral reefs along the north coast of Jamaica. Concentrations of biotic pigments in sea-surface waters show a corresponding west-east gradient; oceanic waters flowing over the western banks carry nearly twice as much biotic pigment as oceanic waters north of Jamaica. Sources enriching the western Caribbean are terrestrial runoff, upwelling off northern South America, and topographic upwelling over the Nicaraguan Rise. That relatively modest levels of trophic resources can suppress coral-reef development holds important implications for understanding carbonate platform drownings in the geologic record.

  3. A trophic framework for animal origins

    DEFF Research Database (Denmark)

    Mills, D. B.; Canfield, D. E.

    2017-01-01

    Metazoans emerged in a microbial world and play a unique role in the biosphere as the only complex multicellular eukaryotes capable of phagocytosis. While the bodyplan and feeding mode of the last common metazoan ancestor remain unresolved, the earliest multicellular stem-metazoans likely subsisted...... on picoplankton (planktonic microbes 0.2–2 μm in diameter) and dissolved organic matter (DOM), similarly to modern sponges. Once multicellular stem-metazoans emerged, they conceivably modulated both the local availability of picoplankton, which they preferentially removed from the water column for feeding......, and detrital particles 2–100 μm in diameter, which they expelled and deposited into the benthos as waste products. By influencing the availability of these heterotrophic food sources, the earliest multicellular stem-metazoans would have acted as ecosystem engineers, helping create the ecological conditions...

  4. Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

    DEFF Research Database (Denmark)

    Stief, P.

    2013-01-01

    on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies reveal that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly......-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen...... (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release...

  5. Benthic Macroinvertebrate Communities in the Northern Tributaries of the “Iron Gates” Gorge (Danube River

    Directory of Open Access Journals (Sweden)

    Curtean-Bănăduc Angela

    2014-12-01

    Full Text Available The paper presents the structure of the benthonic macro-invertebrates communities in the Berzasca, Sirinia, Liubcova, and Mraconia rivers. The results are based on quantitative benthos samples (95 samples, collected in July 2014 from 19 sampling stations within the study area. In longitudinal profile, the benthonic macro-invertebrate communities of the Sirinia, Liubcova and Berzasca rivers displays relatively large structural variability, while the communities of the Mraconia River displays smaller structural variability. The structure of the benthonic macro-invertebrate communities correlated with the biotope characteristics indicates the good ecological status of the analysed rivers, with the exception of the Berzasca River sector downstream of the town of Berzasca and immediately upstream of the Danube junction, a sector with moderate ecological status due to negative effects from man-made modifications in the lotic biotope of the sector.

  6. Diversity of Bacterial Photosymbionts in Lubomirskiidae Sponges from Lake Baikal

    Directory of Open Access Journals (Sweden)

    Nina V. Kulakova

    2014-01-01

    Full Text Available Sponges are permanent benthos residents which establish complex associations with a variety of microorganisms that raise interest in the nature of sponge-symbionts interactions. A molecular approach, based on the identification of the 16S rRNA and ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit genes, was applied to investigate diversity and phylogeny of bacterial phototrophs associated with four species of Lubomirskiidae in Lake Baikal. The phylogeny inferred from both genes showed three main clusters of Synechococcus associated with Baikalian sponges. One of the clusters belonged to the cosmopolitan Synechococcus rubescens group and the two other were not related to any of the assigned phylogenetic groups but placed as sister clusters to S. rubescens. These results expanded the understanding of freshwater sponge-associated photoautotroph diversity and suggested that the three phylogenetic groups of Synechococcus are common photosynthetic symbionts in Lubomirskiidae sponges.

  7. Subsurface phytoplankton blooms fuel pelagic production in the North Sea

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    relatively quickly from the water column and a large proportion of the material sedimenting to the bottom following the spring bloom is often comprised of intact phytoplankton cells. Thus, it is easy to argue that the spring bloom is fueling the energy demands of the benthos, but more difficult to argue......The seasonal phytoplankton biomass distribution pattern in stratified temperate marine waters is traditionally depicted as consisting of spring and autumn blooms. The energy source supporting pelagic summer production is believed to be the spring bloom. However, the spring bloom disappears...... convincingly that energy fixed during the spring bloom is fueling the pelagic production occurring during summer months. We argue here that periodic phytoplankton blooms are occurring during the summer in the North Sea at depths of >25 m and that the accumulated new production [sensu (Dugdale and Goering...

  8. OIL DECONTAMINATION OF BOTTOM SEDIMENTS EXPERIMENTAL WORK RESULTS

    Directory of Open Access Journals (Sweden)

    Lushnikov Sergey V.

    2006-08-01

    Full Text Available This article presents the results of experimental work during 2004-2005 on oil decontamination of bottom sediments of Lake Schuchye, situated in the Komi Republic (Northern Russia. The cause of thecontamination were huge oil spills occurred after a series of accidental ruptures on the Harjaga-Usinsk and Vozej-Usinsk oil-pipe lines in 1994. Flotation technology was used for the cleaning of bottom sediments.157 tons of crude oil were removed during the course of 2-year experimental work from an area of 4,1 ha.The content of aliphatic and alicyclic oil hydrocarbons was reduced from 53,3 g/kg to 2,2 g/kg, on average.Hydrobiological investigations revealed that bottom sediments started to be inhabited by benthos organisms, dominantly Oligochaeta. Besides Oligochaeta, Chironomidae maggots and Bivalvia were detected. Theappearance of Macrozoobenthos organisms can serve as a bioindicator of water quality.

  9. The Extinction of the Conulariids

    Directory of Open Access Journals (Sweden)

    Spencer G. Lucas

    2012-03-01

    Full Text Available Conulariids are unusual extinct metazoans most often considered to be a group of scyphozoan cnidarians or close relatives. Generally, the temporal range of conulariid fossils is perceived to be late Precambrian or Cambrian to Triassic, though a supposed Cretaceous conulariid from Peru was published 46 years ago. A re-evaluation of this fossil indicates it is not a conulariid, but instead a pinnacean bivalve (Pinna sp., confirming that the geologically youngest conulariids are of Late Triassic age. However, a review of the Triassic conulariid fossil record indicates it is very sparse, with only eight published records. It does not provide a reliable basis for analyzing the structure of conulariid extinction. Nevertheless, conulariid extinction still appears to have taken place very close to the end of the Triassic. The cause of conulariid extinction may have been the onset of the Mesozoic marine revolution, in which durivorous predators developed new mechanisms for preying on the epifaunal benthos, including the conulariids.

  10. The structure and functioning of the benthic macrofauna of the Bristol Channel and Severn Estuary, with predicted effects of a tidal barrage.

    Science.gov (United States)

    Warwick, R M; Somerfield, P J

    2010-01-01

    The severity of the physical regime in the hypertidal Severn Estuary and Bristol Channel decreases in intensity in the seaward direction. As a result, the diversity of benthic macrofaunal species is very low in the Estuary and Inner Channel, but is still relatively low in the Outer Channel compared with more benign conditions elsewhere in the UK. Nevertheless, the taxonomic spread of species (taxonomic distinctness) throughout the area is no lower than expected. Barrage construction would result in an increase in the area of soft sediment relative to hard bottom benthic assemblages and the disappearance of reduced communities seaward of the barrage, although the time-scale of such a change is not known. Above the barrage the overall species richness, density and biomass of the benthos are likely to increase, factors that will ameliorate the loss of inter-tidal area. (c) 2010 Elsevier Ltd. All rights reserved.

  11. A deep sea community at the Kebrit brine pool in the Red Sea

    KAUST Repository

    Vestheim, Hege

    2015-02-26

    Approximately 25 deep sea brine pools occur along the mid axis of the Red Sea. These hypersaline, anoxic, and acidic environments have previously been reported to host diverse microbial communities. We visited the Kebrit brine pool in April 2013 and found macrofauna present just above the brine–seawater interface (~1465 m). In particular, inactive sulfur chimneys had associated epifauna of sea anemones, sabellid type polychaetes, and hydroids, and infauna consisting of capitellid polychaetes, gastropods of the genus Laeviphitus (fam. Elachisinidae), and top snails of the family Cocculinidae. The deep Red Sea generally is regarded as extremely poor in benthos. We hypothesize that the periphery along the Kebrit holds increased biomass and biodiversity that are sustained by prokaryotes associated with the brine pool or co-occurring seeps.

  12. Hanna Shoal: An integrative study of a High Arctic marine ecosystem in the Chukchi Sea

    Science.gov (United States)

    Dunton, Kenneth H.; Grebmeier, Jacqueline M.; Trefry, John H.

    2017-10-01

    This second special issue on the ecosystem under the COMIDA (Chukchi Sea Offshore Monitoring in the Drilling Area) Project focuses on the productive region around Hanna Shoal, the northernmost shoal on the Chukchi shelf. Our first issue (Dunton et al., 2014) emphasized the chemical and biological characteristics of the northeastern Chukchi Sea benthos. This effort expands our studies on the unique physical oceanography of Hanna Shoal, which lies at the interface between northward flowing Pacific Water and the Arctic Ocean, to include its influence on zooplankton dynamics and higher trophic level biota. Between both studies, conducted over a 5-year period (2009-2013) and four summer cruises, COMIDA scientists from seven institutions occupied some 85 stations (Fig. 1).

  13. Effect of closed areas on distribution of fish and epibenthos

    DEFF Research Database (Denmark)

    Hoffmann, Erik; Dolmer, Per

    2000-01-01

    The high blue mussel catches in a fjord system in Denmark, the visible effects of dredging by resuspension of bottom sediment and the possible destruction of benthic flora and fauna have all raised concerns about the impact on the ecosystem. As a consequence, a formerly lucrative blue mussel...... fishing area in the fjord was closed on dredging in 1988. This made it possible to investigate changes in the distribution of fish and benthos based on experimental fishing with trawl, set net and traps, and scuba diving during 1981-1998. The investigations showed no long-term effects of mussel dredging...... on the distribution of fish and epibenthic invertebrates, and the closed area appeared to have had no influence on the demersal fish and epibenthic fauna. Factors other than mussel dredging appear to determine the observed spatial and temporal variability in the ecosystem. (C) 2000 International Council...

  14. Relations entre les types de dépôts évaporitiques et la présence de couches riches en matière organique (roches-mères potentielles) Relationship Between Different Types of Evaporitic Deposits and the Occurrence of Organic-Rich Layers (Potential Source Rocks)

    OpenAIRE

    Busson G.

    2006-01-01

    La fertilité exceptionnelle des eaux salées est confirmée par des études récentes sur l'Actuel (marais salants de Méditerranée occidentale). Le benthos est représenté par des mollusques, foraminifères, ostracodes et surtout des cyanophycées et des populations bactériennes ; le plancton par le microphytoplancton (Dunaliella, diatomées, etc), par le zooplancton (flagellés, Arternia salina) et par de très nombreuses bactéries hétérotrophes. Si les espèces sont d'autant plus rares que la salinité...

  15. Natural diet of three species of shrimp in a tropical coastal lagoon

    Directory of Open Access Journals (Sweden)

    Albertoni Edélti Faria

    2003-01-01

    Full Text Available The gut content of 495 specimens of Farfantepenaeus brasiliensis, 131 of F. paulensis (Penaeidae and 102 of Macrobrachium acanthurus (Palaemonidae were analyzed to establish the composition of their diets F. brasiliensis had as the most important feeding items in its diet larvae of Chironomidae, Polychaeta and Heleobia australis (Mollusca. For F. paulensis, the most important items were the same as for F. brasiliensis, but the order of importance of H. australis and Polychaeta was inverted. M. acanthurus had detritus as the most important item, followed by Chironomidae larvae, Odonata nymphs, and fragments of the macroalgae Chara. The results showed that the three species were omnivorous, with a varied diet including both components of macrofauna of benthos and associated to the macroalgae Chara and plant fragments and detritus.

  16. Comparison Between Water Quality Index (WQI) and Biological Water Quality Index (BWQI) for Water Quality Assessment: Case Study of Melana River, Johor

    International Nuclear Information System (INIS)

    Nor Zaiha Arman; Mohd Ismid Mohd Said; Shamila Azman; Muhammad Hazim Mat Hussin

    2013-01-01

    A study of water quality in Melana River, Johor was carried out in three consecutive months (March - May 2012). This study aims to determine the comparative results through biological monitoring as well as conventional method (physical and chemical analysis). Assessment is carried out through collection and identification of the biological indicator which comprises of macro benthos based on Biological Water Quality Index (BWQI). Comparison was done based on two methods namely invertebrate analysis and also laboratory analysis. For invertebrate analysis, Melana River consist of three types of Family groups namely Nymphs, Larvae and Molluscs. The result for Water Quality Index (WQI) and also Biological Water Quality Index (BWQI) analysis showed that the level of Melana River is polluted and classified in Class III. This study shows that even though different methods were used, the similar results were obtained for both rivers and can be applied to any river to identify their level of cleanliness. (author)

  17. Sometimes two arms are enough--an unusual life-stage in brittle stars (Echinodermata: Ophiuroidea).

    Science.gov (United States)

    Stöhr, Sabine; Alme, Øydis

    2015-08-03

    Off West Africa (Angola-Morocco), benthos samples were collected in the years 2005-2012. These contained 124 specimens of brittle stars with two long arms and three extremely short or absent arms and an elongated, narrow disc. These unusual brittle stars, as well as 33 specimens with five fully developed arms, were identified as Amphiura ungulata. The specimens with unequal arms were juvenile stages, whereas adults had five equal arms. The large number of specimens with unequal arms suggests that this condition is not the result of damage and regeneration, but a normal growth pattern in this species. This study documents the morphology by SEM, amends the species description, and discusses possible explanations for the evolution of this condition. Although brittle star species with unequal arm growth have been reported, this is an extreme case that was unknown before this study.

  18. Freshwater lakes--a potential source for aquaculture activities--a model study on Perumal Lake, Cuddalore, Tamil Nadu.

    Science.gov (United States)

    Usha, R; Ramalingam, K; Bharathi Rajan, U D

    2006-10-01

    The freshwater Perumal lake located at Cuddalore was assessed for its suitability and potential for aquaculture practices. Various hydrobiological parameters determined reveals that the various physicochemical characteristics are with in normal range of values. The DO level, BOD and COD values determined in the lake revealed the consequences of community activities and pollution possibilities. The primary productivity data revealed maximum productivity during March which infer that the lake is unaffected by anthropogenic disturbance and community contamination. The bacterial count remained higher during the monsoon periods, which characterize profuse rainfall and storm water discharge into the lake. The microfauna includes zooplankter such as cladocerans, copepods, rotifers and ostracods. Benthos include carps, catfishes, mullets and prawns. The above study revealed that the various parameters in the lake conform to the levels suited for freshwater fish culture and represents a resource for scientific management.

  19. West Hackberry Brine Disposal Project pre-discharge characterization. Final report

    Energy Technology Data Exchange (ETDEWEB)

    DeRouen, L.R.; Hann, R.W.; Casserly, D.M.; Giammona, C. (eds.)

    1982-01-01

    The physical, chemical and biological attributes are described for: (1) a coastal marine environment centered about a Department of Energy Strategic Petroleum Reserve (SPR) brine disposal site 11.4 km off the southwest coast of Louisiana; and (2) the lower Calcasieu and Sabine estuarine systems that provide leach waters for the SPR project. A three month sampling effort, February through April 1981, and previous investigations from the study area are integrated to establish baseline information for evaluation of impacts from brine disposal in the nearshore marine waters and from freshwater withdrawal from the coastal marsh of the Chenier Plain. January data are included for some tasks that sampled while testing and mobilizing their instruments prior to the February field effort. The study addresses the areas of physical oceanography, estuarine hydrology and hydrography, water and sediment quality, benthos, nekton, phytoplankton, zooplankton, and data management.

  20. Spreading of sediment due to underwater blasting and dredging

    DEFF Research Database (Denmark)

    Nielsen, Morten Holtegaard; Bach, Lis; Bollwerk, Sandra

    2015-01-01

    leads to a wider spreading of the organic part of the sediment. Almost all material less than 2 μm, including surficial clay minerals and much organic material, was transported away from the construction site and its vicinity, which could imply mobilization and export of pollutants. Environmental...... impacts of suspended sediment from underwater blasting, which could include coverage of the benthos or increased turbidity, can be managed by timing the blast favourably relative to currents, waves and stratification. It is argued that the environmental impact of blasting can be minimized by decreasing...... out in connection with the construction of a new quay at the existing harbour of Sisimiut, Greenland. Subsequent to the largest of a series of underwater blasts, the distribution of suspended sediment in the water column at and around the construction site was observed using a CTD (Conductivity...

  1. Moorea producens gen. nov., sp. nov. and Moorea bouillonii comb. nov., tropical marine cyanobacteria rich in bioactive secondary metabolites.

    Science.gov (United States)

    Engene, Niclas; Rottacker, Erin C; Kaštovský, Jan; Byrum, Tara; Choi, Hyukjae; Ellisman, Mark H; Komárek, Jiří; Gerwick, William H

    2012-05-01

    The filamentous cyanobacterial genus Moorea gen. nov., described here under the provisions of the International Code of Botanical Nomenclature, is a cosmopolitan pan-tropical group abundant in the marine benthos. Members of the genus Moorea are photosynthetic (containing phycocyanin, phycoerythrin, allophycocyanin and chlorophyll a), but non-diazotrophic (lack heterocysts and nitrogenase reductase genes). The cells (discoid and 25-80 µm wide) are arranged in long filaments (algae blooms and, due to morphological resemblance to the genus Lyngbya, this group has often been incorrectly cited in the literature. We here describe two species of the genus Moorea: Moorea producens sp. nov. (type species of the genus) with 3L(T) as the nomenclature type, and Moorea bouillonii comb. nov. with PNG5-198(R) as the nomenclature type.

  2. Intertidal ecology of the sea shore near Tarapur Atomic Power Station

    International Nuclear Information System (INIS)

    Balani, M.C.

    1975-01-01

    Surveys were carried out between March 1969 and August 1970 to study the fauna and flora in the littoral zone of the sea shore near the Tarapur Atomic Power Station. The beach adjacent to the Station is rocky with a number of tidal pools inhabited by a variety of organisms whereas the beach to the south is mostly sandy and barren except for a small rocky stretch. The tidal range is 6 m and over a mile of beach is exposed during low tide. The near shore currents are very strong and have a clear northsouth oscillation with the changing tides. Less Atherina sp. fry were available near the Power Station in March 1970 than during the previous year. Possible reasons for these differences are discussed, including the effect of heated discharges on biota. The need is also emphasized to monitor the biota (Plankton, Nekton and Benthos) systematically for content of fission products released by the Power Station. (auth.)

  3. Effect of radioactive pollution on the biodiversity of marine benthic ecosystems of the Russian Arctic shelf

    Science.gov (United States)

    Alexeev, Denis K.; Galtsova, Valentina V.

    2012-07-01

    This study is the result of many years of research on the ecology of the marine benthos of Russian Arctic seas. We used samples collected at various locations from the Russian continental shelf during 1993-2009 as the basis of our study. Our main aim was to analyze the spatial distribution of taxonomic and quantitative characteristics of the meiobenthos (small bottom-dwelling animals, 0.1-3.0 mm in size). Statistical analysis of the data revealed that the factors determining the spatial distribution of meiobenthic organisms under natural conditions, and conditions impacted upon by human activity, were salinity, water depth, hydrocarbons, heavy metals and radiocaesium volumetric activity. The possible use of the meiobenthos as a tool for environmental impact assessment is proposed and discussed on the level of higher taxa.

  4. Spatio-temporal patterns in the coral reef communities of the Spermonde Archipelago, 2012–2014, II: Fish assemblages display structured variation related to benthic condition

    DEFF Research Database (Denmark)

    Plass-Johnson, Jeremiah Grahm; Teichberg, Mirta; Bednarz, Vanessa N.

    2018-01-01

    The Spermonde Archipelago is a complex of ~70 mostly populated islands off Southwest Sulawesi, Indonesia, in the center of the Coral Triangle. The reefs in this area are exposed to a high level of anthropogenic disturbances. Previous studies have shown that variation in the benthos is strongly...... with distance, while few species were present across the entire range of sites. Relating fish communities to benthic composition using a multivariate generalized linear model confirmed that fish groups relate to structural complexity (rugosity) or differing benthic groups; either algae, reef builders (coral...... and crustose coralline algae) or invertebrates and rubble. From these relationships we can identify sets of fish species that may be lost given continued degradation of the Spermonde reefs. Lastly, the incorporation of water quality, benthic and fish indices indicates that local coral reefs responded...

  5. Feeding periodicity, diet composition, and food consumption of subyearling rainbow trout in winter

    Science.gov (United States)

    Johnson, James H.; Chalupnicki, Marc; Abbett, Ross

    2016-01-01

    Although winter is a critically important period for stream salmonids, aspects of the ecology of several species are poorly understood. Consequently, we examined the diel feeding ecology of subyearling rainbow trout (Oncorhynchus mykiss) during winter in a central New York stream. Rainbow trout diet was significantly different during each 4-h interval and also differed from the drift and benthos. Feeding was significantly greater during darkness (i.e. 20:00 h – 04:00 h) than during daylight hours (i.e. 08:00 h – 16:00 h), peaking at 20:00 h. Daily food consumption (1.9 mg) and daily ration (3.4 %) during winter were substantially lower than previously reported for subyearling rainbow trout in the same stream during summer. These findings provide important new insights into the winter feeding ecology of juvenile rainbow trout in streams.

  6. Evaluation of brine disposal from the Bryan Mound site of the Strategic Petroleum Reserve Program. Annual report, September 1981-August 1982. Volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Hann, R.W. Jr.; Randall, R.E. (eds.)

    1983-06-01

    The Department of Energy's Strategic Petroleum Reserve Program began leaching the Bryan Mound salt dome and discharging brine into the coastal waters offshore of Freeport, Texas on March 10, 1980. This report describes the findings of a team of Texas A and M University scientists and engieers who have conducted a study to evaluate the effects of the Bryan Mound brine discharge on the marine environment. The study addresses the areas of physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, and data management. It focuses on the period from September 1981 through August 1982. The physical oceanography studies include the analysis of data from continuous recording in situ current/conductivity/temperature meters and synoptic hydrographic data. The quarterly water and sediment quality data show a slight increase in sodium and chloride ions occur in the sediment pore waters at the diffuser and that this increase is reflected in the ion ratios of Na/K and SO/sub 4//Cl. Increases in the ion levels with time appears to be a trend, but the extent cannot be determined as yet. Plume measurements indicate the higher brine exit velocity has increased the areal and vertical extent and decreased the above ambient salinity values. The quarterly nekton sampling indicate there has been no dramatic lethal effects at any station within any cruise nor any unusual behavior in captured specimens. In general, the only change in the benthos has been the persistent ring effect. There have been fluctuations in population densities, but they have fallen within naturally occurring extremes over the period of brine disposal.

  7. Influence of calcium on the distribution of the pheasant in North America

    Science.gov (United States)

    Dale, F.H.

    2000-01-01

    Rapid Bioassessment Protocols (RBP) and the Sediment Quality Triad (SQT) were used to evaluate the biological effects of a municipal waste-water treatment facility (WWTF) on a small southern stream. During major storm events, raw sewage from the WWTF is released directly into the stream. The headwaters of the stream also receive non-point surface runoff from urban areas. RBP analyses, which included benthos, fish and habitat evaluations, and SQT, including the benthos (from the RBP), contaminant analyses (metals, organochlorine pesticides, PCBs and PAHs) andl toxicity tests of depositional sediment (exposures of Hyalella azteca to solid-phase sediment and pore water) were conducted at five sites on the stream (two upstream of the WWTF and three downstream). The stream has been channelized throughout its entire length, resulting in high, unstable banks, degraded stream channel, and unstable substratum. RBP analyses indicated that the two stations upstream of the WWTF were degraded due to poor physical habitat quality (unstable benthic substratum and lack of fish habitat). The SQT also showed reduced habitat quality at the two stations above the WWTF, but the cause was attributed to high concentrations of PAHs and metals in the sediments. The increased discharge and stabilized base flow provided by the WWTF improved habitat quality downnstream, although conditions were still impaired due to the habitat alteration. Though the causes of degradation were attributed to different factors (physical habitat vs. contamination), there was close concordance between the RBP and SQT in identifying the degraded sites in this stream. The combination of these two procedures provides a robust examination of environmental quality utilizing the weight of evidence approach.

  8. Spatial and overwinter changes in clam populations of San Pablo Bay, a semiarid estuary with highly variable freshwater inflow

    Science.gov (United States)

    Poulton, V.K.; Lovvorn, J.R.; Takekawa, John Y.

    2004-01-01

    In many estuaries worldwide, climate trends together with human diversion of fresh water have dramatically impacted the benthos. Such impacts have sometimes been complicated by exotic species, whose invasion and persistence can be mediated by wide variations in freshwater inflow. Monitoring such changes usually involves periodic samples at a few sites; but sampling that does not recognize variation at a range of spatial and seasonal scales may not reveal important benthic trends. San Pablo Bay, in northern San Francisco Bay, has extreme fluctuations in freshwater inflow. This bay also experienced a major benthic change with introduction of the Asian clam (Potamocorbula amurensis) in 1986. This species initially displaced the former community, but later appeared to vary in abundance depending on site and freshwater inflow. To investigate such patterns and provide guidelines for research and monitoring, we took 1746 core samples at six sites around San Pablo Bay from 19 October to 17 December 1999 and from 6 March to 19 April 2000. Most biomass consisted of the clams P. amurensis,Macoma balthica and Mya arenaria. Potamocorbula amurensis dominated the benthos at most sites in the fall and recruited a new cohort during winter, while there was weak recruitment in M. balthica and none in M. arenaria. At most but not all sites, densities of P. amurensis and M. arenaria declined dramatically over winter while M. balthica declined only slightly. The dominant clams had patch diameters >5 m at most but not all sites, and some showed inconsistent patch structure at scales of 100–1400 m. In this semiarid estuary with highly variable freshwater inflow, samples for research and monitoring should include multiple sites and seasons, and samples within sites should be ≥5 m apart to account for between-patch variation. Species abundance in winter 1999–2000 appeared to be affected by high freshwater inflows in 1997–1999, while spatial patterns were probably most affected by

  9. Short-term ecological effects of an offshore wind farm in the Dutch coastal zone. A compilation

    Energy Technology Data Exchange (ETDEWEB)

    Lindeboom, H.J.; Brasseur, S.; Leopold, M.; Scheidat, M. [IMARES, PO Box 167, 1790 AD Den Burg (Netherlands); Kouwenhoven, H.J. [NoordzeeWind, 2e Havenstraat 5b, 1976 CE IJmuiden (Netherlands); Bergman, M.J.N.; Daan, R. [Royal NIOZ, PO Box 59, 1790 AB Den Burg (Netherlands); Bouma, S.; Fijn, R.C.; Dirksen, S.; Krijgsveld, K.L. [Bureau Waardenburg, PO Box 365, 4100 AJ Culemborg (Netherlands); De Haan, D.; Van Hal, R.; Hille Ris Lambers, R.; Ter Hofstede, R. [IMARES, PO Box 68, 1970 AB IJmuiden (Netherlands)

    2011-07-15

    The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.

  10. Short-term ecological effects of an offshore wind farm in the Dutch coastal zone; a compilation

    Energy Technology Data Exchange (ETDEWEB)

    Lindeboom, H J; Brasseur, S; Leopold, M; Scheidat, M [IMARES, PO Box 167, 1790 AD Den Burg (Netherlands); Kouwenhoven, H J [NoordzeeWind, 2e Havenstraat 5b, 1976 CE IJmuiden (Netherlands); Bergman, M J N; Daan, R [Royal NIOZ, PO Box 59, 1790 AB Den Burg (Netherlands); Bouma, S; Fijn, R C; Dirksen, S; Krijgsveld, K L [Bureau Waardenburg, PO Box 365, 4100 AJ Culemborg (Netherlands); De Haan, D; Van Hal, R; Hille Ris Lambers, R; Ter Hofstede, R, E-mail: han.lindeboom@wur.nl [IMARES, PO Box 68, 1970 AB IJmuiden (Netherlands)

    2011-07-15

    The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.

  11. Application of solidified sea bottom sediments into environmental bioremediation materials

    Directory of Open Access Journals (Sweden)

    Ahmed H.A. Dabwan

    2017-05-01

    Full Text Available Since dredged sea bottom sediments normally give off a horrible smell, the limitation of disposal places has become a serious problem in Japan. Hence, development of an alternative system to readily treat dredged sea bottom sediments is therefore needed. The development of “value-added” reused products from these sediments offers particular benefits both in terms of resource recovery and protection of the environment. We developed an in situ solidification system for the treatment of sea bottom sediments, the “Hi-Biah-System (HBS”. Firstly, this review deals with solidified sea bottom sediments for the construction of an artificial tidal flat in Ago Bay, Japan. The environmental conditions (pH, oxidation–reduction potential (ORP, acid volatile sulphide (AVS, loss on ignition (LOI, water content (WC, chemical oxygen demand (COD, total organic carbon (TOC, total nitrogen (T-N, chlorophyll a and particle size were then monitored in the constructed tidal flat. The number of benthos individuals and growth of short-necked clams (Ruditapes philippinarum in the artificial tidal flat were also evaluated. The environmental conditions, number of benthos individuals and growth of short-necked clams in the artificial tidal flat were shown to be similar to those observed in a natural tidal flat. Next, the potential use of solidified sea bottom sediments as soil parent material in the germination/growth of seagrass is presented. The soil parent material consisting of solidified sediments obtained using HBS plus soil conditioner and hardener seems to be effective for the germination of Zostera marina. The best growth after six months was observed in plants grown in soil parent material consisting of a mixture of solidified sediments and the sand by weight ration 70:30. The present study may suggest the possible application of solidified sea bottom sediments into growth of other plants.

  12. Short-term ecological effects of an offshore wind farm in the Dutch coastal zone. A compilation

    International Nuclear Information System (INIS)

    Lindeboom, H.J.; Brasseur, S.; Leopold, M.; Scheidat, M.; Kouwenhoven, H.J.; Bergman, M.J.N.; Daan, R.; Bouma, S.; Fijn, R.C.; Dirksen, S.; Krijgsveld, K.L.; De Haan, D.; Van Hal, R.; Hille Ris Lambers, R.; Ter Hofstede, R.

    2011-01-01

    The number of offshore wind farms is increasing rapidly, leading to questions about the environmental impact of such farms. In the Netherlands, an extensive monitoring programme is being executed at the first offshore wind farm (Offshore Windfarm Egmond aan Zee, OWEZ). This letter compiles the short-term (two years) results on a large number of faunal groups obtained so far. Impacts were expected from the new hard substratum, the moving rotor blades, possible underwater noise and the exclusion of fisheries. The results indicate no short-term effects on the benthos in the sandy area between the generators, while the new hard substratum of the monopiles and the scouring protection led to the establishment of new species and new fauna communities. Bivalve recruitment was not impacted by the OWEZ wind farm. Species composition of recruits in OWEZ and the surrounding reference areas is correlated with mud content of the sediment and water depth irrespective the presence of OWEZ. Recruit abundances in OWEZ were correlated with mud content, most likely to be attributed not to the presence of the farm but to the absence of fisheries. The fish community was highly dynamic both in time and space. So far, only minor effects upon fish assemblages especially near the monopiles have been observed. Some fish species, such as cod, seem to find shelter inside the farm. More porpoise clicks were recorded inside the farm than in the reference areas outside the farm. Several bird species seem to avoid the park while others are indifferent or are even attracted. The effects of the wind farm on a highly variable ecosystem are described. Overall, the OWEZ wind farm acts as a new type of habitat with a higher biodiversity of benthic organisms, a possibly increased use of the area by the benthos, fish, marine mammals and some bird species and a decreased use by several other bird species.

  13. Horns Rev offshore wind farm. Introducing hard bottom substrate sea bottom and marine biology. Status report 2001

    Energy Technology Data Exchange (ETDEWEB)

    Leonhard, S.B.; Pedersen, John

    2002-08-15

    A baseline description of the benthos was carried out in spring and autumn 2001 prior to the construction of an offshore wind farm at Horns Rev, situated approximately 15 km off Blaevands Huk, which is Denmark's most westerly point. The surveys have been conducted as part of an environmental monitoring programme for the introduction of hard bottom substrates in the North Sea. The establishment of a monitoring programme is required according to some environmental guidelines set up by the Danish Energy Agency for offshore wind farms. Because no environmental criteria existed for benthic communities in connection with the construction activities, no power analysis was made prior to the design of the monitoring programme. The monitoring programme established for the benthic infauna is thus somewhat limited and only major changes in the community structure are expected to be detectable. The baseline description for the benthic infauna can also be used for comparison of the stomach contents of fish in a comparative programme. A newly defined reference area may be introduced for the fish programme why sampling in this area was carried out in the autumn 2001. Samples were recovered at a total of 18 stations at 6 wind turbine locations in the wind farm area in June 2001 and at a total of 9 stations at 3 wind turbine locations in September 2001. In September additional sampling was carried out at 5 stations in a designated reference area. At the wind turbine locations sampling was carried out at 3 stations located 5, 25 and 100 m from the edge of the planned scour protection. Samples were analysed for sediment characteristics and for benthic infauna. Only the benthos relating to the macrofauna was investigated during the surveys. (au)

  14. Limited grounding-line advance onto the West Antarctic continental shelf in the easternmost Amundsen Sea Embayment during the last glacial period.

    Science.gov (United States)

    Klages, Johann P; Kuhn, Gerhard; Hillenbrand, Claus-Dieter; Smith, James A; Graham, Alastair G C; Nitsche, Frank O; Frederichs, Thomas; Jernas, Patrycja E; Gohl, Karsten; Wacker, Lukas

    2017-01-01

    Precise knowledge about the extent of the West Antarctic Ice Sheet (WAIS) at the Last Glacial Maximum (LGM; c. 26.5-19 cal. ka BP) is important in order to 1) improve paleo-ice sheet reconstructions, 2) provide a robust empirical framework for calibrating paleo-ice sheet models, and 3) locate potential shelf refugia for Antarctic benthos during the last glacial period. However, reliable reconstructions are still lacking for many WAIS sectors, particularly for key areas on the outer continental shelf, where the LGM-ice sheet is assumed to have terminated. In many areas of the outer continental shelf around Antarctica, direct geological data for the presence or absence of grounded ice during the LGM is lacking because of post-LGM iceberg scouring. This also applies to most of the outer continental shelf in the Amundsen Sea. Here we present detailed marine geophysical and new geological data documenting a sequence of glaciomarine sediments up to ~12 m thick within the deep outer portion of Abbot Trough, a palaeo-ice stream trough on the outer shelf of the Amundsen Sea Embayment. The upper 2-3 meters of this sediment drape contain calcareous foraminifera of Holocene and (pre-)LGM age and, in combination with palaeomagnetic age constraints, indicate that continuous glaciomarine deposition persisted here since well before the LGM, possibly even since the last interglacial period. Our data therefore indicate that the LGM grounding line, whose exact location was previously uncertain, did not reach the shelf edge everywhere in the Amundsen Sea. The LGM grounding line position coincides with the crest of a distinct grounding-zone wedge ~100 km inland from the continental shelf edge. Thus, an area of ≥6000 km2 remained free of grounded ice through the last glacial cycle, requiring the LGM grounding line position to be re-located in this sector, and suggesting a new site at which Antarctic shelf benthos may have survived the last glacial period.

  15. Coexistence of macro-zoobenthic species on the Antarctic shelf: An attempt to link ecological theory and results

    Science.gov (United States)

    Gutt, Julian

    2006-04-01

    The coexistence of species within a community generally can be explained by niche differentiation, mechanisms that control competitive displacement, and by chance. This review is an attempt to link ecological conceptual models with results from field research. A verification of different theoretically developed mechanisms shows that niche differentiation plays a major role in the Antarctic. This is particularly true if a broad niche definition is applied that includes alternating phases of competitive strength and weakness that allow populations to persist in a community. Such specific adaptation to the environment also seems to be an important mechanism among animals, which, to date, have been assumed to have broadly overlapping ecological demands. Nevertheless, disturbances due to glaciation history, ice impact, and predation, as well as a high dispersal capacity and low resource limitation contribute to the coexistence or, locally, to the reduction of potential competitors. Chance, reflecting extremely complex or otherwise indecipherable processes, also shapes diversity, e.g., during recolonization after habitat devastation due to iceberg scouring. The slow rates of ecological processes in the Antarctic benthos are shown not necessarily to reduce, but perhaps, to increase the potential for evolutionary radiation in some systematic groups. The fundamental question of how ecosystems continue to develop in the presence or absence of anthropogenic impacts can only be answered if such system-specific ecological and evolutionary mechanisms can be better identified and verified. Studies of the Antarctic benthos can contribute to a corresponding global approach if more comparable information on the life histories of representative species becomes available and if ecological models are developed to decipher complex processes, that shape biodiversity patterns.

  16. Impact Of Coral Structures On Wave Directional Spreading Across A Shallow Reef Flat - Lizard Island, Northern Great Barrier Reef

    Science.gov (United States)

    Leon, J. X.; Baldock, T.; Callaghan, D. P.; Hoegh-guldberg, O.; Mumby, P.; Phinn, S. R.; Roelfsema, C. M.; Saunders, M. I.

    2013-12-01

    Coral reef hydrodynamics operate at several and overlapping spatial-temporal scales. Waves have the most important forcing function on shallow (stress, directly mixing water (temperature and nutrients) and transporting sediments, nutrients and plankton. Reef flats are very effective at dissipating wave energy and providing an important ecosystem service by protecting highly valued shorelines. The effectiveness of reef flats to dissipate wave energy is related to the extreme hydraulic roughness of the benthos and substrate composition. Hydraulic roughness is usually obtained empirically from frictional-dissipation calculations, as detailed field measurements of bottom roughness (e.g. chain-method or profile gauges) is a very labour and time-consuming task. In this study we measured the impact of coral structures on wave directional spreading. Field data was collected during October 2012 across a reef flat on Lizard Island, northern Great Barrier Reef. Wave surface levels were measured using an array of self-logging pressure sensors. A rapid in situ close-range photogrammetric method was used to create a high-resolution (0.5 cm) image mosaic and digital elevation model. Individual coral heads were extracted from these datasets using geo-morphometric and object-based image analysis techniques. Wave propagation was modelled using a modified version of the SWAN model which includes the measured coral structures in 2m by 1m cells across the reef. The approach followed a cylinder drag approach, neglecting skin friction and inertial components. Testing against field data included bed skin friction. Our results show, for the first time, how the variability of the reef benthos structures affects wave dissipation across a shallow reef flat. This has important implications globally for coral reefs, due to the large extent of their area occupied by reef flats, particularly, as global-scale degradation in coral reef health is causing a lowering of reef carbonate production that

  17. Use of imploding spheres: An alternative to explosives as acoustic sources at mid-latitude SOFAR channel depths

    International Nuclear Information System (INIS)

    Harben, P.E.; Boro, C.; Dorman, L.; Pulli, J.

    2000-05-01

    The hydroacoustic nuclear explosion monitoring regime, like its counterpart in seismic monitoring, requires ground truth calibration. Model predictions of traveltimes, blockages, reflections, diffractions, and waveform envelopes need to be verified with ground truth experiments, particularly in the high latitudes where models often fail. Although pressure detonated explosives are a simple, reliable, and flexible method to generate an impulsive hydroacoustic calibration source at a desired depth; safety procedures, specialized training, and local regulations often preclude their use. This leaves few alternatives since airgun and other seismic marine sources are designed for use only at shallow depths and hence do not effectively couple into the SOFAR channel, a necessary requirement for long range propagation. Imploding spheres could be an effective source at mid-ocean depths and below but development of a method to reliably break such spheres has been elusive. We designed and tested a prototype system to initiate catastrophic glass sphere failure at a prescribed depth. The system firmly holds a glass sphere in contact with a piston-ram assembly. The end cap on the cylinder confining the piston and opposing the ram has a rupture disk sealed to it. The rupture disk is calibrated to fail within 5% of the calibrated failure pressure, 1000 psi in our tests. Failure of the rupture disk results in a sudden inrush of high pressure water into the air-filled piston chamber, driving the piston - and attached ram - towards the glass sphere. The spherecracker was first tested on Benthos Corp. flotation spheres. The spherecracker mechanism successfully punched a hole in the Benthos sphere at the nominal pressure of 1000 psi or at about 700 meters depth in each of four tests. Despite the violent inrush of high pressure water the spheres did not otherwise fail. We concluded that the Benthos spheres were too thick-walled to be used as an imploding source at nominal SOFAR channel

  18. Geomorphological, trophic and human influences on the bamboo coral Isidella elongata assemblages in the deep Mediterranean: To what extent does Isidella form habitat for fish and invertebrates?

    Science.gov (United States)

    Cartes, J. E.; LoIacono, C.; Mamouridis, V.; López-Pérez, C.; Rodríguez, P.

    2013-06-01

    We analyzed what are the best ecological conditions for megafauna associated with the bamboo coral Isidella elongata based on the geomorphological, physical and trophic information taken in 3 stations (St1, St2, St3) off the southern Catalonian coasts at 620 m depth in June 2011. Results were compared with assemblage compositions recorded in past cruises (May 1992, 1994) at the same 3 stations. St1 was in a fishing ground exploited since the 1940s over a relatively wide slope at ca. 22 km from the nearest canyon head; St2 and St3 were on a narrower slope closer to canyon heads and to the Ebro river mouth than St1. I. elongata had formed (to May 1994, at least) a dense coral forest at St2-St3 (to ca. 255 colonies/ha at St3), and some isolated colonies (to ca. 0.9 colonies/ha) were still collected in 2011. Fish and invertebrate communities significantly differed between St1 and St2/St3, with two macrourid fishes (Trachrhynchus trachyrhynchus and Nezumia aequalis) and two decapods (Plesionika martia and Plesionika acanthonotus) more abundant at St2/St3. The following ecological indicators imply better food conditions for megafauna at St2-St3 and for I. elongata itself: (i) greater density of zooplankton (copepods, euphausiids, and others) as potential prey for planktivores (including I. elongata); (ii) greater biomass and mean weight of epifaunal and infaunal deposit feeders; (iii) higher feeding intensity, F, at St3 for benthos feeders (Phycis blennoides, N. aequalis and Aristeus antennatus). Also, at St2-St3 we found higher near-bottom turbidity (indicating particle resuspension: food for suspension feeders) and finer and more reduced (Eh) sediments. The results let us suggest that corals and accompanying fauna preferently found optimal ecological conditions in the same habitat, while habitat-forming capacity by I. elongata seemed weak to generate these conditions. Coral forests may enhance detritus accumulations around them, improving habitat conditions for benthos

  19. Defining winter trophic habitat of juvenile Gulf Sturgeon in the Suwannee and Apalachicola rivermouth estuaries, acoustic telemetry investigations

    Science.gov (United States)

    Sulak, K.J.; Randall, M.T.; Edwards, R.E.; Summers, T.M.; Luke, K.E.; Smith, W.T.; Norem, A.D.; Harden, William M.; Lukens, R.H.; Parauka, F.; Bolden, S.; Lehnert, R.

    2009-01-01

    Three automated listening post-telemetry studies were undertaken in the Suwannee and Apalachicola estuaries to gain knowledge of habitats use by juvenile Gulf Sturgeons (Acipenser oxyrinchus desotoi) on winter feeding grounds. A simple and reliable method for external attachment of small acoustic tags to the dorsal fin base was developed using shrink-tubing. Suspending receivers on masts below anchored buoys improved reception and facilitated downloading; a detection range of 500–2500 m was realized. In the Apalachicola estuary, juvenile GS stayed in shallow water (< 2 m) within the estuarine transition zone all winter in the vicinity of the Apalachicola River mouth. Juvenile GS high-use areas did not coincide with high density benthic macrofauna areas from the most recent (1999) benthos survey. In the Suwannee estuary, juveniles ranged widely and individually throughout oligohaline to mesohaline subareas of the estuary, preferentially using mesohaline subareas seaward of Suwannee Reef (52% of acoustic detections). The river mouth subarea was important only in early and late winter, during the times of adult Gulf Sturgeon migrations (41% of detections). Preferred winter feeding subareas coincided spatially with known areas of dense macrofaunal benthos concentrations. Following a dramatic drop in air and water temperatures, juvenile GS left the river mouth and estuary, subsequently being detected 8 km offshore in polyhaline open Gulf of Mexico waters, before returning to the estuary. Cold-event offshore excursions demonstrate that they can tolerate full-salinity polyhaline waters in the open Gulf of Mexico, for at least several days at a time. For juvenile sturgeons, the stress and metabolic cost of enduring high salinity (Jarvis et al., 2001; McKenzie et al., 2001; Singer and Ballantyne, 2002) for short periods in deep offshore waters seems adaptively advantageous relative to the risk of cold-event mortality in shallow inshore waters of lower salinity. Thus

  20. Global warming enhances sulphide stress in a key seagrass species (NW Mediterranean).

    Science.gov (United States)

    García, Rosa; Holmer, Marianne; Duarte, Carlos M; Marbà, Núria

    2013-12-01

    The build-up of sulphide concentrations in sediments, resulting from high inputs of organic matter and the mineralization through sulphate reduction, can be lethal to the benthos. Sulphate reduction is temperature dependent, thus global warming may contribute to even higher sulphide concentrations and benthos mortality. The seagrass Posidonia oceanica is very sensitive to sulphide stress. Hence, if concentrations build up with global warming, this key Mediterranean species could be seriously endangered. An 8-year monitoring of daily seawater temperature, the sulphur isotopic signatures of water (δ(34)S(water)), sediment (δ(34)SCRS ) and P. oceanica leaf tissue (δ(34)S(leaves)), along with total sulphur in leaves (TS(leaves)) and annual net population growth along the coast of the Balearic archipelago (Western Mediterranean) allowed us to determine if warming triggers P. oceanica sulphide stress and constrains seagrass survival. From the isotopic S signatures, we estimated sulphide intrusion into the leaves (F(sulphide)) and sulphur incorporation into the leaves from sedimentary sulphides (SS(leaves)). We observed lower δ(34)S(leaves), higher F(sulphide) and SS(leaves) coinciding with a 6-year period when two heat waves were recorded. Warming triggered sulphide stress as evidenced by the negative temperature dependence of δ(34)S(leaves) and the positive one of F(sulphide), TS(leaves) and SS(leaves). Lower P. oceanica net population growth rates were directly related to higher contents of TS(leaves). At equivalent annual maximum sea surface water temperature (SST(max)), deep meadows were less affected by sulphide intrusion than shallow ones. Thus, water depth acts as a protecting mechanism against sulphide intrusion. However, water depth would be insufficient to buffer seagrass sulphide stress triggered by Mediterranean seawater summer temperatures projected for the end of the 21st century even under scenarios of moderate greenhouse gas emissions, A1B

  1. Environmentally associated spatial changes of a macrozoobenthic community in the Saemangeum tidal flat, Korea

    Science.gov (United States)

    Ryu, Jongseong; Khim, Jong Seong; Choi, Jin-Woo; Shin, Hyun Chool; An, Soonmo; Park, Jinsoon; Kang, Daeseok; Lee, Chang-Hee; Koh, Chul-Hwan

    2011-05-01

    Estuarine tidal flats are both ecologically and economically important, hence developing methods to reliably measure ecosystem health is essential. Because benthic fauna play a central role in the food web of tidal flats, in this study we set out to quantitatively describe the intertidal zonation of macro-invertebrates and their associations with specific environmental parameters along three transects in the Saemangeum tidal flat, Korea. The abundance and biomass of intertidal fauna with respect to five environmental parameters (i.e., shore level, mud content, coarse sand content, water content, and organic content) were measured, to identify environmental factors that influence macrofaunal distribution in intertidal soft bottom habitats. A total of 75 species were identified, with dominant species showing distinct zones of distribution along all transects. The number of species recorded in each transect was found to be dependent on sediment characteristics and salinity. Cluster analysis classified the entire study area into three faunal assemblages (i.e., location groups), which were delineated by characteristic species, including (A) ' Periserrula-Macrophthalmus', (B) ' Umbonium-Meretrix', and (C) ' Prionospio-Potamocorbula'. Four environmental variables (i.e., shore level, water content, mud content, and organic content) appeared to determine factors that distinguished the three faunal assemblages, based on the discriminant analysis. The faunal assemblage types of the sampled locations were accurately predicted from environmental variables in two discriminant functions, with a prediction accuracy of 98%. It should be noted that the zonation of benthos in the lower section (C) of Sandong had been affected by the construction of a nearby dike, while this parameter had remained essentially unchanged at the other two location groups (A-B). Overall, the zonation of benthos from the Saemangeum tidal flat was explained adequately by the measured environmental variables

  2. Exceptional vertebrate biotas from the Triassic of China, and the expansion of marine ecosystems after the Permo-Triassic mass extinction

    Science.gov (United States)

    Benton, Michael J.; Zhang, Qiyue; Hu, Shixue; Chen, Zhong-Qiang; Wen, Wen; Liu, Jun; Huang, Jinyuan; Zhou, Changyong; Xie, Tao; Tong, Jinnan; Choo, Brian

    2013-10-01

    The Triassic was a time of turmoil, as life recovered from the most devastating of all mass extinctions, the Permo-Triassic event 252 million years ago. The Triassic marine rock succession of southwest China provides unique documentation of the recovery of marine life through a series of well dated, exceptionally preserved fossil assemblages in the Daye, Guanling, Zhuganpo, and Xiaowa formations. New work shows the richness of the faunas of fishes and reptiles, and that recovery of vertebrate faunas was delayed by harsh environmental conditions and then occurred rapidly in the Anisian. The key faunas of fishes and reptiles come from a limited area in eastern Yunnan and western Guizhou provinces, and these may be dated relative to shared stratigraphic units, and their palaeoenvironments reconstructed. The Luoping and Panxian biotas, both from the Guanling Formation, are dated as Anisian (Pelsonian) on the basis of conodonts and radiometric dates, the former being slightly older than the latter. The Xingyi biota is from the Zhuganpo Formation, and is Ladinian or early Carnian, while the Guanling biota is from the overlying Xiaowa Formation, dated as Carnian. The first three biotas include extensive benthos and burrowing in the sediments, and they were located in restricted basins close to shore. Further, even though the Luoping and Panxian biotas are of similar age, their faunas differ significantly, reflecting perhaps palaeogeographically isolated basins. Between the time of the Xingyi and Guanling biotas, there was a major transgression, and the Guanling biota is entirely different in character from the other three, being dominated by pelagic forms such as large floating crinoids attached to logs, very large ichthyosaurs and thalattosaurs, and pseudoplanktonic bivalves, with no benthos and no burrowing. Phylogenetic study of the fishes and marine reptiles shows apparently explosive diversification among 20 actinopterygian lineages very early in the Early Triassic

  3. Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs.

    Directory of Open Access Journals (Sweden)

    Bernardo Vargas-Ángel

    Full Text Available This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm(-2 yr(-1 of early successional recruitment communities on Calcification Accretion Unit (CAU plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons

  4. Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs.

    Science.gov (United States)

    Vargas-Ángel, Bernardo; Richards, Cristi L; Vroom, Peter S; Price, Nichole N; Schils, Tom; Young, Charles W; Smith, Jennifer; Johnson, Maggie D; Brainard, Russell E

    2015-01-01

    This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm(-2) yr(-1)) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years) of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA) percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons makes CCA

  5. Prediction, scenarios and insight: The uses of an end-to-end model

    Science.gov (United States)

    Steele, John H.

    2012-09-01

    A major function of ecosystem models is to provide extrapolations from observed data in terms of predictions or scenarios or insight. These models can be at various levels of taxonomic resolution such as total community production, abundance of functional groups, or species composition, depending on the data input as drivers. A 40-year dynamic simulation of end-to-end processes in the Georges Bank food web is used to illustrate the input/output relations and the insights gained at the three levels of food web aggregation. The focus is on the intermediate level and the longer term changes in three functional fish guilds - planktivores, benthivores and piscivores - in terms of three ecosystem-based metrics - nutrient input, relative productivity of plankton and benthos, and food intake by juvenile fish. These simulations can describe the long term constraints imposed on guild structure and productivity by energy fluxes over the 40 years but cannot explain concurrent switches in abundance of individual species within guilds. Comparing time series data for individual species with model output provides insights; but including the data in the model would confer only limited extra information. The advantages and limitations of the three levels of resolution of models in relation to ecosystem-based management are: The correlations between primary production and total yield of fish imply a “bottom-up” constraint on end-to-end energy flow through the food web that can provide predictions of such yields. Functionally defined metrics such as nutrient input, relative productivity of plankton and benthos and food intake by juvenile fish, represent bottom-up, mid-level and top-down forcing of the food web. Model scenarios using these metrics can demonstrate constraints on the productivity of these functionally defined guilds within the limits set by (1). Comparisons of guild simulations with time series of fish species provide insight into the switches in species dominance

  6. Influence of seabird colonies and other environmental variables on benthic community structure, Lancaster Sound Region, Canadian Arctic

    Science.gov (United States)

    Bouchard Marmen, Mariève; Kenchington, Ellen; Ardyna, Mathieu; Archambault, Philippe

    2017-03-01

    The Canadian Arctic shelters millions of seabirds each year during the breeding season. By the excretion of important quantities of guano, seabirds locally concentrate nutrient-rich organic matter in the marine areas surrounding colonies. Seabirds, acting as biological vectors of nutrients, can markedly affect terrestrial ecosystems, but their influence on the structure of marine benthic communities is still under-studied. Sessile and long-lived megabenthic species can integrate environmental variation into marine food webs over long time frames. The objectives of this study were (1) to characterize the epifaunal and infaunal communities of the Lancaster Sound Region (LSR) and (2) to test the influence of the presence of seabird colonies and other environmental parameters on the structure of those benthic communities. Our prediction was that benthic diversity, number of taxa, total biomass of infauna and total density of epifauna and infauna, would be higher in areas with colonies present. Photos of the seafloor (data on epifauna) and grab samples (data on infauna) were taken at three control areas and at five areas near seabird colonies, within a depth range of 122 to 442 m. A database of 26 environmental parameters was built to study the environment-benthos relationships. Infauna, which was relatively uniform across the LSR, was numerically dominated by Annelida. Epifauna was much patchier, with each study area having unique epibenthic assemblages. Brittle stars were highly abundant in epifaunal communities, reaching 600 individuals per square meter. The presence of seabird colonies was not a major driver of benthic community structure in the LSR at the depths studied. Negative effects of colonies were detected on the density and number of taxa of infauna, perhaps due to top-down effects transmitted by the seabirds which feed in the water column and can directly reduce the quantity of food reaching the seabed. Sediment concentration of pigment, percent cover of

  7. Iceberg killing fields limit huge potential for benthic blue carbon in Antarctic shallows.

    Science.gov (United States)

    Barnes, David K A

    2017-07-01

    Climate-forced ice losses are increasing potential for iceberg-seabed collisions, termed ice scour. At Ryder Bay, West Antarctic Peninsula (WAP) sea ice, oceanography, phytoplankton and encrusting zoobenthos have been monitored since 1998. In 2003, grids of seabed markers, covering 225 m 2 , were established, surveyed and replaced annually to measure ice scour frequency. Disturbance history has been recorded for each m 2 of seabed monitored at 5-25 m for ~13 years. Encrusting fauna, collected from impacted and nonimpacted metres each year, show coincident benthos responses in growth, mortality and mass of benthic immobilized carbon. Encrusting benthic growth was mainly determined by microalgal bloom duration; each day, nanophytoplankton exceeded 200 μg L -1 produced ~0.05 mm radial growth of bryozoans, and sea temperature >0 °C added 0.002 mm day -1 . Mortality and persistence of growth, as benthic carbon immobilization, were mainly influenced by ice scour. Nearly 30% of monitored seabed was hit each year, and just 7% of shallows were not hit. Hits in deeper water were more deadly, but less frequent, so mortality decreased with depth. Five-year recovery time doubled benthic carbon stocks. Scour-driven mortality varied annually, with two-thirds of all monitored fauna killed in a single year (2009). Reduced fast ice after 2006 ramped iceberg scouring, killing half the encrusting benthos each year in following years. Ice scour coupled with low phytoplankton biomass drove a phase shift to high mortality and depressed zoobenthic immobilized carbon stocks, which has persevered for 10 years since. Stocks of immobilized benthic carbon averaged nearly 15 g m -2 . WAP ice scouring may be recycling 80 000 tonnes of carbon yr -1 . Without scouring, such carbon would remain immobilized and the 2.3% of shelf which are shallows could be as productive as all the remaining continental shelf. The region's future, when glaciers reach grounding lines and iceberg

  8. Effects of late-cenozoic glaciation on habitat availability in Antarctic benthic shrimps (Crustacea: Decapoda: Caridea.

    Directory of Open Access Journals (Sweden)

    Johannes Dambach

    Full Text Available Marine invertebrates inhabiting the high Antarctic continental shelves are challenged by disturbance of the seafloor by grounded ice, low but stable water temperatures and variable food availability in response to seasonal sea-ice cover. Though a high diversity of life has successfully adapted to such conditions, it is generally agreed that during the Last Glacial Maximum (LGM the large-scale cover of the Southern Ocean by multi-annual sea ice and the advance of the continental ice sheets across the shelf faced life with conditions, exceeding those seen today by an order of magnitude. Conditions prevailing at the LGM may have therefore acted as a bottleneck event to both the ecology as well as genetic diversity of today's fauna. Here, we use for the first time specific Species Distribution Models (SDMs for marine arthropods of the Southern Ocean to assess effects of habitat contraction during the LGM on the three most common benthic caridean shrimp species that exhibit a strong depth zonation on the Antarctic continental shelf. While the shallow-water species Chorismus antarcticus and Notocrangon antarcticus were limited to a drastically reduced habitat during the LGM, the deep-water shrimp Nematocarcinus lanceopes found refuge in the Southern Ocean deep sea. The modeling results are in accordance with genetic diversity patterns available for C. antarcticus and N. lanceopes and support the hypothesis that habitat contraction at the LGM resulted in a loss of genetic diversity in shallow water benthos.

  9. Precise and economical dredging model of sediments and its field application: case study of a river heavily polluted by organic matter, nitrogen, and phosphorus.

    Science.gov (United States)

    Zhang, Rui; Zeng, Fan-Xin; Liu, Wu-Jun; Zeng, Raymond J; Jiang, Hong

    2014-06-01

    Environmental dredging is an efficient means to counteract the eutrophication of water bodies caused by endogenous release of nitrogen and/or phosphorus from polluted sediments. The huge operational cost and subsequent disposal cost of the dredged polluted sediments, as well as the adverse effect on the benthic environment caused by excessive dredging, make the currently adopted dredging methods unfavorable. Precise dredging, i.e., determining the dredging depth based on the pollution level, not only significantly decreases the costs but also leaves a uniform favorable environment for benthos. However, there is still no feasible process to make this promising method executable. Taking a river heavily polluted by organic compounds as an example, we proposed an executable precise dredging process, including sediment survey, model establishment, data interpolation, and calculation of dredging amount. Compared with the traditional dredging method, the precise one would save 16 to 45% of cost according to different pollutant removal demands. This precise dredging method was adopted by the National Water Project of China to treat the endogenous pollution of Nanfei River in 2010. This research provides a universal scientific and engineering basis for sediment dredging projects.

  10. Biophysical research requirements for Beaufort Sea hydrocarbon development

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2008-08-15

    This review identified biophysical research requirements and data gaps for the development of hydrocarbon resources in the Beaufort Sea. The potential major effects of critical activities during each phase of the offshore oil and gas development cycle were identified in order to assess the impacts on local communities and traditional harvesting methods. Baseline environmental conditions were established. Information needs were ranked using 3 criteria: (1) the current understanding of the biophysical component in terms of present status and long-term sustainability, (2) the potential impact of the oil and gas development on the long-term sustainability of the biophysical component, and (3) the timeline for completion of the research relative to the expected development for the Beaufort Sea region. Mitigation and environmental management plans were outlined, and key research, data collection, and data analyses required to address data gaps were identified. Previous gap analyses for the region were reviewed. Data from a series of workshops conducted with various stakeholders were also included in the study. High research priorities include the assessment of the effects of climatic change on the physical oceanography of the region, studies on deepwater plankton, benthos, and fish. It was concluded that studies are needed to determine the effects of development on marine mammals, avifauna, and macroalgae. 207 refs., 49 tabs., 4 figs.

  11. Effects of sea lamprey substrate modification and carcass nutrients on macroinvertebrate assemblages in a small Atlantic coastal stream

    Science.gov (United States)

    Weaver, Daniel M.; Coghlan, Stephen M.; Zydlewski, Joseph D.

    2018-01-01

    Aquatic macroinvertebrates respond to patch dynamics arising from interactions of physical and chemical disturbances across space and time. Anadromous fish, such as sea lamprey, Petromyzon marinus, migrate from the ocean and alter physical and chemical properties of recipient spawning streams. Sea lamprey disturb stream benthos physically through nest construction and spawning, and enrich food webs through nutrient deposition from decomposing carcasses. Sea lamprey spawning nests support greater macroinvertebrate abundance than adjacent reference areas, but concurrent effects of stream bed modification and nutrient supplementation have not been examined sequentially. We added carcasses and cleared substrate experimentally to mimic the physical disturbance and nutrient enrichment associated with lamprey spawning, and characterized effects on macroinvertebrate assemblage structure. We found that areas receiving cleared substrate and carcass nutrients were colonized largely by Simuliidae compared to upstream and downstream control areas that were colonized largely by Hydropsychidae, Philopotamidae, and Chironomidae. Environmental factors such as stream flow likely shape assemblages by physically constraining macroinvertebrate establishment and feeding. Our results indicate potential changes in macroinvertebrate assemblages from the physical and chemical changes to streams brought by spawning populations of sea lamprey.

  12. Risk assessment for produced water discharges to Louisiana Open Bays

    Energy Technology Data Exchange (ETDEWEB)

    Meinhold, A.F.; DePhillips, M.P.; Holtzman, S.

    1995-06-23

    Data were collected prior to termination of discharge at three sites (including two open bay sites at Delacroix Island and Bay De Chene) for the risk assessments. The Delacroix Island Oil and Gas Field has been in production since the first well drilling in 1940; the Bay De Chene Field, since 1942. Concentrations of 226Ra, 228Ra, 210Po, and 228Th were measured in discharges. Radium conc. were measured in fish and shellfish tissues. Sediment PAH and metal conc. were also available. Benthos sampling was conducted. A survey of fishermen was conducted. The tiered risk assessment showed that human health risks from radium in produced water appear to be small; ecological risk from radium and other radionuclides in produced water also appear small. Many of the chemical contaminants discharged to open Louisiana bays appear to present little human health or ecological risk. A conservative screening analysis suggested potential risks to human health from Hg and Pb and a potential risk to ecological receptors from total effluent, Sb, Cd, Cu, Pb, Ni, Ag, Zn, and phenol in the water column and PAHs in sediment; quantitiative risk assessments are being done for these contaminants.

  13. Toxicity of sediments from a mangrove forest patch in an urban area in Pernambuco (Brazil).

    Science.gov (United States)

    Oliveira, D D; Souza-Santos, L P; Silva, H K P; Macedo, S J

    2014-06-01

    Industrial and urban residues are discharged every day to the rivers and may arrive at the mangrove forest and prejudice the quality of the environment and the organisms present there. The mangrove forest patch studied is encircled by an urban area of the city of Recife (Brazil) that has approximate 1.5 million inhabitants and is one of the most industrialized centers in Northeast Brazil. The aim of this study was to assess the quality of the sediments of this mangrove patch in terms of metal contamination and ecotoxicology. Samples of surface sediment were collected in six stations for toxicological tests and trace metal determination (Cr, Zn, Mn, Fe, Cu, Pb, Co and Ni), in July and August, 2006 (rainy season); and in January and February 2007 (dry season). Toxicity tests with solid-phase sediments were carried out with the copepod Tisbe biminiensis in order to observe lethal and sub-lethal endpoints and correlate them with chemical data. In June, there were no observed lethal effect, but two stations presented sub-lethal effects. In January, lethal effect occurred in three stations and sub-lethal in one station. The levels for Zn and Cr were at higher levels than international proposed guidelines (NOAA). There was a negative significant correlation between the copepods׳ fecundity, and Zn and Cr concentrations. Therefore, the studied sediments can be considered to have potential toxic to benthos due to the high content of Zn and Cr. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Radio-active waste disposal and deep-sea biology

    International Nuclear Information System (INIS)

    Rice, A.L.

    1978-01-01

    The deep-sea has been widely thought of as a remote, sparsely populated, and biologically inactive environment, well suited to receive the noxious products of nuclear fission processes. Much of what is known of abyssal biology tends to support this view, but there are a few disquieting contra-indications. The realisation, in recent years, that many animal groups show a previously unsuspected high species diversity in the deep-sea emphasized the paucity of our knowledge of this environment. More dramatically, the discovery of a large, active, and highly mobile abysso-bentho-pelagic fauna changed the whole concept of abyssal life. Finally, while there is little evidence for the existence of vertical migration patterns linking the deep-sea bottom communities with those of the overlying water layers, there are similarly too few negative results for the possibility of such transport mechanisms to be dismissed. In summary, biological knowledge of the abyss is insufficient to answer the questions raised in connection with deep-sea dumping, but in the absence of adequate answers it might be dangerous to ignore the questions

  15. Cunea n. g. (Amoebozoa, Dactylopodida) with two cryptic species isolated from different areas of the ocean

    KAUST Repository

    Kudryavtsev, Alexander

    2015-06-01

    © 2015 Elsevier GmbH. This paper describes a new genus, Cunea n. g., of marine naked amoebae with two cryptic species, Cunea profundata and Cunea thuwala, isolated from distant localities in the ocean and different depths (Brazilian abyssal plain, Western Atlantic Ocean, depth >5. km and the Red Sea off the Saudi Arabian coast, depth ca. 58.7. m). Both species are very similar to each other in the set of light microscopic and ultrastructural characters and might be described as a single species, yet their genetic divergence based on 3 molecular markers (small-subunit ribosomal RNA, actin and cytochrome c oxidase subunit 1) corresponds to the level of variation typically observed between different morphospecies of Amoebozoa. In addition, the studied strains differ strongly in their temperature tolerance ranges, C. profundata isolated from the cold Atlantic deep-sea habitat being able to reproduce under lower temperatures than C. thuwala isolated from the warm Red Sea benthos. Molecular phylogenetic analysis based on SSU rRNA gene shows that the new genus robustly branches within the Dactylopodida, but forms an independent clade within this order that does not group with any of its known genera.

  16. Bioaccumulation of metals in constructed wetlands used to treat acid drainage

    International Nuclear Information System (INIS)

    Edwards, G.S.; Mays, P.A.

    1994-01-01

    Constructed wetlands are being used extensively as a potential mitigation for acid drainage. However, removal of metals to meet compliance requirements has varied among wetlands, ranging from partial to total success. In addition, wetlands are sinks for contaminants found in acid drainage, and bioaccumulation of these contaminants to levels that would adversely affect the food web is of growing concern. The primary objective of this project was to determine whether bioaccumulation of metals occurs in wetlands constructed for treatment of acid drainage. Water, sediment, plant and benthos samples were collected from two wetlands constructed by the Tennessee Valley Authority and a natural wetland in the spring and fall of 1992, and metal concentrations were determined. One of the constructed wetlands, Impoundment 1, has generally been in compliance for NPDES; the other, Widow's Creek, has never been in compliance. Preliminary results indicate similarities in sediment and plant metal concentrations between Impoundment 1 and the natural wetland and greater metal concentrations in the sediment and plants at Widow's Creek. Data also indicate that Mn, Zn, Cu, Ni, and Cr are being accumulated in the plants at each wetland. However, accumulation of metals by these plants probably accounts for only a small percentage of the removal of the annual metal load supplied to each wetland. Bioaccumulation of metals in the benthic organisms at each wetland is currently being investigated

  17. Interactions between sediment chemistry and frenulate pogonophores (Annelida) in the north-east Atlantic

    Science.gov (United States)

    Dando, P. R.; Southward, A. J.; Southward, E. C.; Lamont, P.; Harvey, R.

    2008-08-01

    The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit muddy sediments on the continental slope, although a few species occur near hydrothermal vents and cold seeps. We present data on the distribution and habitat characteristics of several species on the European continental shelf and slope from 48°N to 75°N and show how the animals interact with the chemistry of the sediments. The environments inhabited include: shallow (30 m), organic-rich, fjord sediments; slope sediments (1000-2200 m) and methane seeps at 330 m depth. All the species studied obtain nutrition from endosymbiotic bacteria. They take up reduced sulphur species, or in one case, methane, through the posterior parts of their tubes buried in the anoxic sediment. We conclude that most species undertake sulphide 'mining', a mechanism previously demonstrated in the bivalves Lucinoma borealis and Thyasira sarsi. These pogonophores participate in the sulphur cycle and effectively lower the sulphide content of the sediments. Our results show that the abundance of frenulate pogonophores increases with increasing sedimentation and with decreasing abundance of other benthos, particularly bioturbating organisms. The maximum sustainable carrying capacity of non-seep sediments for frenulate pogonophores is limited by the rate of sulphate reduction.

  18. Evaluation of potential relationships between benthic community structure and toxic metals in Laizhou Bay.

    Science.gov (United States)

    Wu, Bin; Song, Jinming; Li, Xuegang

    2014-10-15

    The objective of the present study was to examine the relationships between benthic community structure and toxic metals using bivariate/multivariate techniques at 17 sediment locations in Laizhou Bay, North China. Sediment chemical data were evaluated against geochemical background values and sediment quality guidelines, which identified Cu and As as contaminants of concern with a moderate potential for adverse effects. Benthic community data were subjected to non-metric multidimensional scaling, which generated four groups of stations. Spearman rank correlation was then employed to explore the relationships between the major axes of heavy metals and benthic community structure. However, weak and insignificant correlations were found between these axes, indicating that contaminants of concern may not be the primary explanatory factors. Polychaeta were abundant in southern Laizhou Bay, serving as a warning regarding the health status of the ecosystem. Integrated sediment quality assessment showed sediments from northern central locations were impaired, displaying less diverse benthos and higher metal contamination. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Observations of cocooned Hydrobaenus (Diptera: Chironomidae) larvae in Lake Michigan

    Science.gov (United States)

    Tucker, Taaja R.; Hudson, Patrick L.; Riley, Stephen

    2016-01-01

    Larvae of the family Chironomidae have developed a variety of ways to tolerate environmental stress, including the formation of cocoons, which allows larvae to avoid unfavorable temperature conditions, drought, or competition with other chironomids. Summer cocoon formation by younger instars of the genus Hydrobaenus Fries allows persistence through increased temperatures and/or intermittent dry periods in arid regions or temporary habitats, but this behavior was not observed in the Great Lakes until the current study. Cocoon-aestivating Hydrobaenus sp. larvae were found in benthic grab samples collected in 2010–2013 near Sleeping Bear Dunes National Lakeshore in northern Lake Michigan with densities up to 7329/m2. The aestivating species was identified as Hydrobaenus johannseni (Sublette, 1967), and the associated chironomid community was typical for an oligotrophic nearshore system. Hydrobaenus cocoon formation in the Great Lakes was likely previously unnoticed due to the discrepancies between the genus' life history and typical benthos sampling procedures which has consequences for describing chironomid communities where Hydrobaenus is present.

  20. Selective extinction and survival across the Cretaceous/Tertiary boundary in the northern Atlantic Coastal Plain

    Science.gov (United States)

    Gallagher, William B.

    1991-10-01

    The inner Atlantic Coastal Plain in New Jersey and the Delmarva Peninsula is underlain by an Upper Cretaceous-lower Tertiary sequence of marine and paralic sand, clay, and glauconitic beds. Campanian, Maastrichtian, Danian, and Thanetian deposits are especially fossiliferous and yield a succession of marine faunas that reveal a pattern of selective extinction and survival across the Cretaceous/Tertiary (K/T) boundary in this area. Cretaceous benthic invertebrate communities are dominated by oysters and other semi-infaunal and infaunal molluscs with planktotrophic larval stages. These are replaced in the Danian by brachiopod-dominated communities that are composed of epifaunal benthos with a variety of nonplanktotrophic reproductive strategies. A similar pattern is observable in the nektonic cephalopod populations in this sequence; the typical ammonites of the Cretaceous became extinct at the K/T boundary, whereas the nautilids survived. Ammonites are thought to have had a planktotrophic larval stage, whereas nautilids are known to lay large lecithotrophic eggs. This pattern of differential survival is attributed to the planktonic population crash at the K/T boundary which placed planktotrophically reproducing species at a disadvantage while favoring the varied groups that practiced alternative reproductive strategies.

  1. Gametogenic cycle of Ophioderma januarii, a common Ophiodermatidae (Echinodermata: Ophiuroidea in southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Michela Borges

    2009-03-01

    Full Text Available This study describes the gametogenic cycle of Ophioderma januarii Lütken, 1856, a common species of ophiuroid in Southeastern Brazil. The specimens were collected during the project "Biodiversidade Bêntica Marinha no Estado de São Paulo-BIOTA/FAPESP-Bentos Marinho" (Marine benthic biodiversity in the State of São Paulo-BIOTA/ Fapesp-Marine Benthos which was conducted off the northern coast of the state of São Paulo. Specimens were captured monthly between February 2001 and December 2002. Due to the low number of individuals the monthly data was grouped in seasons (spring to winter. A total of 101 specimens were obtained: 33 in spring, 10 in summer, 23 in autumn, and 35 in winter. The gonads of eighty-eight individuals (45 females, 42 males, and one hermaphrodite were analyzed histologically. The male and female gametogenic cycles were classified into five different gonadal stages, which were analyzed separately. The reproductive pattern could be defined through histological analyses of male and female gonads, together with oocyte diameter frequency. Some general conclusions could also be reached: this is a gonochoric species that reproduces year-round but increases its gonadal activity during summer; based on the size of its mature oocytes, it has lecithotrophic development. Apparently, its recruitment is enhanced in late summer, and smaller individuals are more frequent during autumn and winter.

  2. Cunea n. g. (Amoebozoa, Dactylopodida) with two cryptic species isolated from different areas of the ocean.

    Science.gov (United States)

    Kudryavtsev, Alexander; Pawlowski, Jan

    2015-06-01

    This paper describes a new genus, Cunea n. g., of marine naked amoebae with two cryptic species, Cunea profundata and Cunea thuwala, isolated from distant localities in the ocean and different depths (Brazilian abyssal plain, Western Atlantic Ocean, depth >5km and the Red Sea off the Saudi Arabian coast, depth ca. 58.7m). Both species are very similar to each other in the set of light microscopic and ultrastructural characters and might be described as a single species, yet their genetic divergence based on 3 molecular markers (small-subunit ribosomal RNA, actin and cytochrome c oxidase subunit 1) corresponds to the level of variation typically observed between different morphospecies of Amoebozoa. In addition, the studied strains differ strongly in their temperature tolerance ranges, C. profundata isolated from the cold Atlantic deep-sea habitat being able to reproduce under lower temperatures than C. thuwala isolated from the warm Red Sea benthos. Molecular phylogenetic analysis based on SSU rRNA gene shows that the new genus robustly branches within the Dactylopodida, but forms an independent clade within this order that does not group with any of its known genera. Copyright © 2015 Elsevier GmbH. All rights reserved.

  3. Diet selectivity of juvenile blue crabs (Callinectes sapidus) in Chesapeake Bay.

    Science.gov (United States)

    Seitz, Rochelle D; Knick, Kathleen E; Westphal, Miranda

    2011-10-01

    Shallow coves in Chesapeake Bay have abundant food and serve as nursery grounds for juvenile blue crabs. In this study, we examined the relationships between the diet of very small (4-40 mm CW) juvenile blue crabs and the benthic infauna in shallow, unvegetated nursery coves. We compared infauna in benthic samples with gut contents of juvenile blue crabs from six shallow coves in each of two sub-estuaries (Rappahannock and York Rivers) in Chesapeake Bay, Virginia, USA. Benthic communities differed depending on river and location, with abundant clams in upriver regions and abundant polychaetes in downriver regions. Juvenile crabs, like adults, appeared to be opportunistic feeders, with gut contents including clams, amphipods, polychaetes, small crustaceans, plant matter, and detritus. There was a positive relationship between polychaetes in the benthic samples and in crab guts, suggesting that juvenile crabs are opportunistic feeders on polychaetes in the benthos. Moreover, Ivlev's electivity index and foraging ratio showed that clams and polychaetes were selectively eaten at all locations. Alternatively, crabs selectively rejected amphipods. Crab densities corresponded positively with polychaete densities, which suggests that there may be bottom-up control of crab distributions and that food resources are important in nursery habitats.

  4. Scaling up Ecological Measurements of Coral Reefs Using Semi-Automated Field Image Collection and Analysis

    Directory of Open Access Journals (Sweden)

    Manuel González-Rivero

    2016-01-01

    Full Text Available Ecological measurements in marine settings are often constrained in space and time, with spatial heterogeneity obscuring broader generalisations. While advances in remote sensing, integrative modelling and meta-analysis enable generalisations from field observations, there is an underlying need for high-resolution, standardised and geo-referenced field data. Here, we evaluate a new approach aimed at optimising data collection and analysis to assess broad-scale patterns of coral reef community composition using automatically annotated underwater imagery, captured along 2 km transects. We validate this approach by investigating its ability to detect spatial (e.g., across regions and temporal (e.g., over years change, and by comparing automated annotation errors to those of multiple human annotators. Our results indicate that change of coral reef benthos can be captured at high resolution both spatially and temporally, with an average error below 5%, among key benthic groups. Cover estimation errors using automated annotation varied between 2% and 12%, slightly larger than human errors (which varied between 1% and 7%, but small enough to detect significant changes among dominant groups. Overall, this approach allows a rapid collection of in-situ observations at larger spatial scales (km than previously possible, and provides a pathway to link, calibrate, and validate broader analyses across even larger spatial scales (10–10,000 km2.

  5. West Hackberry Strategic Petroleum Reserve site brine-disposal monitoring, year 1 report. Volume 1. Executive summary. Final report

    Energy Technology Data Exchange (ETDEWEB)

    DeRouen, L.R.; Hann, R.W.; Casserly, D.M.; Giammona, C.; Lascara, V.J. (eds.)

    1983-02-01

    The physical, chemical and biological attributes are described for: (1) a coastal marine environment centered about a Department of Energy Strategic Petroleum Reserve (SPR) brine disposal site located 11.4 km off the southwest coast of Louisiana; and (2) the lower Calcasieu and Sabine estuarine systems that provide leach waters for the SPR project. During the study period, the daily discharge averaged 529,000 barrels of 216 0/00 brine, representing a loading of 18,000 metric tons of salt per day. The objective of this study are: (1) characterize the environment in terms of physical, chemical and biological attributes; (2) determine if significant adverse changes in ecosystem productivity and stability of the biological community are occurring as a result of brine discharge; and (3) determine the magnitude of any change observed. This report describes the methodology and significant results of the first year's monitoring effort of the West Hackberry brine disposal site. The investigative tasks, presented as separate sections, are: Physical Oceanography, Estuarine Hydrology and Hydrography, Analysis of Discharge Plume, Water and Sediment Quality, Special Pollutant Surveys, Benthos, Nekton, Phytoplankton, Zooplankton and Data Management.

  6. Impact of disposal of dredged material on sediment quality in the Kaohsiung Ocean Dredged Material Disposal Site, Taiwan.

    Science.gov (United States)

    Chen, Chih-Feng; Chen, Chiu-Wen; Ju, Yun-Ru; Kao, Chih-Ming; Dong, Cheng-Di

    2018-01-01

    Kaohsiung Ocean Dredged Material Disposal Site (KODMDS) that located in the southwest offshore of Taiwan, has been annually disposed about 500,000 ton dredged sediments of Kaohsiung Harbor from 2003 to 2012. Five sediment cores collected from KODMDS and three from nearby reference sites were analyzed to evaluate their sedimentation rates, vertical profiles of heavy metal, and heavy metal pollution indices to assess the impact of dumping harbor dredged sediments into the ocean on the sediment quality in KODMDS. The sedimentation rate of 0.24 cm/y was estimated by the 210 Pb method, which means that the effected depth of the top layer of a core of D1 was affected in the period of dumping dredging sediments. The vertical distribution of heavy metals in the sediment cores from KODMDS showed the concentrations of most heavy metals were slightly elevated in the top layers of the sediment cores, which may be affected by the dumping of harbor dredged sediments. According to the analyzed results of the heavy metal pollution indices, the level of heavy metal pollution, the potential eco-toxicity and the potential ecological risk of the sediments in KODMDS exhibited only a slight increase, which indicated that the increase in concentration of heavy metals may potentially pose the insignificant impact on benthos inhabiting the disposal site. Copyright © 2017. Published by Elsevier Ltd.

  7. Peritidal carbonate cycles induced by carbonate productivity variations: A conceptual model for an isolated Early Triassic greenhouse platform in South China

    Directory of Open Access Journals (Sweden)

    Wan Yang

    2014-04-01

    Full Text Available Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is difficult to explain cycles formed in a greenhouse climate when eustasy is minimal. We propose that peritidal cycles on an Early Triassic isolated carbonate platform in Guizhou, South China, were formed by hierarchical carbonate productivity variations. Most of the 149 shallowing-upward cycles are typically terminated by flooding over intertidal facies and contain rare supratidal facies and no prolonged subaerial exposure. Low-diversity benthos in the platform interior during the post-end-Permian biotic recovery were sensitive to environmental perturbations, which caused variations in benthic sediment productivity in the subtidal carbonate factory. The perturbations may be driven by changes in salinity and degree of eutrophication, or repeated platform mini-drowning by anoxic and/or CO2-charged deep water upwelled onto the banktop. They were modulated by Milankovitch orbitally-driven climatic and oceanographic factors as suggested by the hierarchical stacking pattern and spectral signals of these cycles. A one-dimensional conceptual model shows that hierarchical productivity variations alone may generate hierarchical peritidal carbonate cycles under conditions of constant subsidence and no sea-level fluctuation.

  8. The Southern Ocean ecosystem under multiple climate change stresses--an integrated circumpolar assessment.

    Science.gov (United States)

    Gutt, Julian; Bertler, Nancy; Bracegirdle, Thomas J; Buschmann, Alexander; Comiso, Josefino; Hosie, Graham; Isla, Enrique; Schloss, Irene R; Smith, Craig R; Tournadre, Jean; Xavier, José C

    2015-04-01

    A quantitative assessment of observed and projected environmental changes in the Southern Ocean (SO) with a potential impact on the marine ecosystem shows: (i) large proportions of the SO are and will be affected by one or more climate change processes; areas projected to be affected in the future are larger than areas that are already under environmental stress, (ii) areas affected by changes in sea-ice in the past and likely in the future are much larger than areas affected by ocean warming. The smallest areas (Changes in iceberg impact resulting from further collapse of ice-shelves can potentially affect large parts of shelf and ephemerally in the off-shore regions. However, aragonite undersaturation (acidification) might become one of the biggest problems for the Antarctic marine ecosystem by affecting almost the entire SO. Direct and indirect impacts of various environmental changes to the three major habitats, sea-ice, pelagic and benthos and their biota are complex. The areas affected by environmental stressors range from 33% of the SO for a single stressor, 11% for two and 2% for three, to changes, and together cover almost 86% of the SO ecosystem. © 2014 John Wiley & Sons Ltd.

  9. Inter-annual variability and potential for selectivity in the diets of deep-water Antarctic echinoderms

    Science.gov (United States)

    Wigham, B. D.; Galley, E. A.; Smith, C. R.; Tyler, P. A.

    2008-11-01

    The continental shelf of the West Antarctic Peninsula (WAP) is a highly productive region but also unusually deep as a result of isostatic depression by the polar ice cap. The close coupling of surface processes with those of the benthos would be expected in such a seasonally variable environment; however, the cold, deep conditions of the WAP shelf may allow for the persistence of organic material in the sediments as a "food bank". Chlorophyll and carotenoid pigments were determined from the gut contents of seven species of echinoderm and from the surficial sediment on the bathyal continental shelf. Samples were collected as part of the FOODBANCS programme during successive cruises in austral spring (October 2000) and austral autumn (March 2001). Pigments were identified and quantified using reverse-phase high-performance liquid chromatography (HPLC). A lack of qualitative selectivity was observed among species, compared to that observed for deep-water assemblages at temperate latitudes, supporting the theory of a persistent "food bank". However, significant quantitative differences were observed among species and between years and sampling location on the shelf. Species differences were marked between those we classified as "true" deposit feeders and those species whose diet also may be supplemented by scavenging and/or grazing.

  10. A meta-analysis approach to the effects of fish farming on soft bottom polychaeta assemblages in temperate regions

    International Nuclear Information System (INIS)

    Martinez-Garcia, Elena; Sanchez-Jerez, Pablo; Aguado-Giménez, Felipe; Ávila, Pablo; Guerrero, Alejandro; Sánchez-Lizaso, Jose Luis; Fernandez-Gonzalez, Victoria; González, Nieves; Gairin, Joan Ignasi; Carballeira, Carlos; García-García, Benjamín; Carreras, Jordi

    2013-01-01

    Highlights: ► This study was carried out in ten fish farms along the Spanish coast. ► Fish farm caused a decline in abundance and family richness in polychaete assemblages. ► There are two main groups of polychaeta, sensitive families and tolerant families. ► The main influence is associated to percentage of silt and clays. ► Total free sulfides, silt and clays and 15 N, have influence on polychaete populations. -- Abstract: Marine fish farms could cause environmental disturbances on the sediment due to uneaten food and fish faeces that impact the marine benthos. Polychaete assemblages are considered good indicators of environmental perturbations. The present study aimed to establish groups of polychaetes as potential indicators of fish farm pollution. This study was carried out in ten fish farms along the Spanish coast. Changes in polychaete assemblage were analyzed with meta-analysis and multivariate techniques. Abundance, richness and diversity showed significant decreases under fish farm conditions. Distribution patterns of polychaetes responded to combinations of physicochemical variables. The main ones are sulfide concentration, silt and clays percentage, and stable nitrogen isotope ratio. The results showed that some families are tolerant, Capitellidae, Dorvilleidae, Glyceridae, Nereididae, Oweniidae and Spionidae; while others are sensitive to fish farm pollution, Magelonidae, Maldanidae, Nephtyidae, Onuphidae, Paralacydoniidae, Paraonide, Sabellidae and also Cirratulidae in spite of being reported as a tolerant family

  11. Marine biology

    International Nuclear Information System (INIS)

    Thurman, H.V.; Webber, H.H.

    1984-01-01

    This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index

  12. [Cryptobenthic coral reef fishes in Los Roques National Park, Caribbean of Venezuela].

    Science.gov (United States)

    Rodríguez-Quintal, José G

    2010-03-01

    A significant portion of coral reef fish assemblages are composed of small cryptobenthic fishes, but these are poorly represented in regional fish characterization works. We characterized the cryptobenthic reef fish community associated with coral reef in Los Roques National Park during six week surveys. The study included 11 locations in which these fish were registered in transects of 10 x 2 m. Specimens were collected using the suction method and a fine-mesh net. A total of 31 species of six families were collected (four Blenniidae, six Chaenopsidae, one Gobiesocidae, 12 Gobiidae, seven Labrisomidae and one Tripterygiidae). Six represented new records to the park, and Coralliozetus cardonae (Chaenopsidae) was a new record for Venezuela. The most important families were Gobiidae, Chaenopsidae and Labrisomidae. Cryptic fish assemblages changed with the reef environments, with a clear distribution pattern: some species were only observed in shallow areas of less than 5 m depth, while in fringing and barrier reef areas, other species were present and differentially distributed between the reef crest and the seaward slope. These patterns probably are related to the close association that these small fish maintain with the benthos.

  13. The influence of coral reef benthic condition on associated fish assemblages.

    Science.gov (United States)

    Chong-Seng, Karen M; Mannering, Thomas D; Pratchett, Morgan S; Bellwood, David R; Graham, Nicholas A J

    2012-01-01

    Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

  14. QUANTITATIVE AND QUALITATIVE EVALUATION OF ZOOBENTHOS IN THE ROSCI0066 DANUBE DELTA - THE MARIN AREA SITE – A CASE STUDY IN VERNAL SEASON 2012

    Directory of Open Access Journals (Sweden)

    Carmen Georgeta Nicolae

    2014-06-01

    Full Text Available Zoobenthos plays an important role in the proper functioning of aquatic ecosystems. Benthic animal organisms may have a role in filtering water, remineralisation of the organic matter but also can be used as feed for fish or human food. To assess the qualitative and quantitative structure of zoobenthos in ROSCI0066 site, in vernal season 2012, benthos sampled were taken on sedimentary substrate at depths between 8 m and 18 m, with Van Veen bodengreif. The species were identified up to species level or group and for quantitative analysis the individuals were counted simultaneously with the sorting and their identification. Density was expressed in individuals per m2 and biomass in g m-2. In vernal season 2012, in ROSCI0066 site have been identified 20 species of benthic invertebrates, mostly polychaetes (50%, followed by mollusks (bivalves and gastropods (40%, crustaceans (5% and other groups (5%. In quantitative terms, the values of zoobenthos density and biomass showed variations ranging from a minimum density of 50 individuals m-2 (Mila 9 and a maximum of 2575 individuals m-2 (Periboina or a minimum biomass below 1 g m-2 (Sulina, Mila 9 Perisor and maximum of 530 g m-2 (Periboina. Compared with the previous year, in the ROSCI0066 Danube Delta - the Marin Area site is recorded a decrease of the number of zoobenthos species from 36 to 20 species.

  15. Relationships between ecosystem metabolism, benthic macroinvertebrate densities, and environmental variables in a sub-arctic Alaskan river

    Science.gov (United States)

    Benson, Emily R.; Wipfli, Mark S.; Clapcott, Joanne E.; Hughes, Nicholas F.

    2013-01-01

    Relationships between environmental variables, ecosystem metabolism, and benthos are not well understood in sub-arctic ecosystems. The goal of this study was to investigate environmental drivers of river ecosystem metabolism and macroinvertebrate density in a sub-arctic river. We estimated primary production and respiration rates, sampled benthic macroinvertebrates, and monitored light intensity, discharge rate, and nutrient concentrations in the Chena River, interior Alaska, over two summers. We employed Random Forests models to identify predictor variables for metabolism rates and benthic macroinvertebrate density and biomass, and calculated Spearman correlations between in-stream nutrient levels and metabolism rates. Models indicated that discharge and length of time between high water events were the most important factors measured for predicting metabolism rates. Discharge was the most important variable for predicting benthic macroinvertebrate density and biomass. Primary production rate peaked at intermediate discharge, respiration rate was lowest at the greatest time since last high water event, and benthic macroinvertebrate density was lowest at high discharge rates. The ratio of dissolved inorganic nitrogen to soluble reactive phosphorus ranged from 27:1 to 172:1. We found that discharge plays a key role in regulating stream ecosystem metabolism, but that low phosphorous levels also likely limit primary production in this sub-arctic stream.

  16. Controls on methane concentrations and fluxes in streams draining human-dominated landscapes

    Science.gov (United States)

    Crawford, John T.; Stanley, Emily H.

    2016-01-01

    Streams and rivers are active processors of carbon, leading to significant emissions of CO2 and possibly CH4 to the atmosphere. Patterns and controls of CH4 in fluvial ecosystems remain relatively poorly understood. Furthermore, little is known regarding how major human impacts to fluvial ecosystems may be transforming their role as CH4 producers and emitters. Here, we examine the consequences of two distinct ecosystem changes as a result of human land use: increased nutrient loading (primarily as nitrate), and increased sediment loading and deposition of fine particles in the benthic zone. We did not find support for the hypothesis that enhanced nitrate loading down-regulates methane production via thermodynamic or toxic effects. We did find strong evidence that increased sedimentation and enhanced organic matter content of the benthos lead to greater methane production (diffusive + ebullitive flux) relative to pristine fluvial systems in northern Wisconsin (upper Midwest, USA). Overall, streams in a human-dominated landscape of southern Wisconsin were major regional sources of CH4 to the atmosphere, equivalent to ~20% of dairy cattle emissions, or ~50% of a landfill’s annual emissions. We suggest that restoration of the benthic environment (reduced fine deposits) could lead to reduced CH4 emissions, while decreasing nutrient loading is likely to have limited impacts to this ecosystem process.

  17. Two new stygobiotic copepod species from the Tibesti area (Northern Chad) and a re-description of Pilocamptus schroederi (van Douwe, 1915).

    Science.gov (United States)

    Brancelj, Anton

    2015-08-04

    Between 4th and 18th March 2014, an international group of biologists carried out a hydrobiological expedition to the Ounianga-Tibesti area of northern Chad (Africa). The Tibesti is a desert volcanic area, intersected by the beds of ancient rivers which were active in the Tertiary. In deep canyons there are small water bodies (gueltas/aguelmans), fed by rain and spring water. They are rich in zooplankton, benthos, and even fish, but their groundwater fauna has previously been unknown. Groundwater samples collected in the vicinity of one guelta contained Syncarida, Isopoda, and Copepoda. Among the latter, two new species were recognised, Haplocyclops (H.) henrii sp. nov. and Parastenocaris joi sp. nov., together with a third species, Pilocamptus schroederi (van Douwe, 1915), previously known only from the littoral zone and wet mosses of Lake Victoria. The Tibesti area is thus the third known location of P. schroederi. All these species have a Gondwanaland distribution and are probably relicts of the Tertiary fauna, formerly widespread in the Sahara. Together with descriptions of two new species, a detailed re-description of P. schroederi is presented, along with remarks on their ecology.

  18. On Branchiostoma californiense (Cephalochordata from the Gulf of Nicoya estuary, Costa Rica

    Directory of Open Access Journals (Sweden)

    José A Vargas

    2010-12-01

    Full Text Available The cephalochordates are represented by the lancelets, of which species of the genus Branchiostoma are the best known. In recent years, these organisms have been the center of activity of studies focusing on the phylogenetic relationships of the chordates. In 1980, a survey of the benthos at 48 stations in the Gulf of Nicoya estuary, Pacific coast of Costa Rica, yielded 265 specimens of the lancelet Branchiostoma californiense. A total of 48 specimens was also collected at an intertidal flat in the mid upper estuary. Of the 48 subtidal stations, only eight had B. californiense, and these sites all had a sand fraction above 72%. The remaining stations ranged in their sand content from as low as 1% to as high as 92%, with an average of 25.9%, with 29 stations having a sand content lower than 72%. Lower salinities and muddy sediments may limit the distribution of the lancelet further upstream. This information is useful when changes over decades in the ecology of the estuary need to be evaluated against the background of local, regional, and global dynamics. Rev. Biol. Trop. 58 (4: 1143-1148. Epub 2010 December 01.

  19. Bomb-cratered coral reefs in Puerto Rico, the untold story about a novel habitat: from reef destruction to community-based ecological rehabilitation

    Directory of Open Access Journals (Sweden)

    Edwin A. Hernández-Delgado

    2014-09-01

    Full Text Available Ecological impacts of military bombing activities in Puerto Rico have often been described as minimal, with recurrent allegations of confounding effects by hurricanes, coral diseases and local anthropogenic stressors. Reef craters, though isolated, are associated with major colony fragmentation and framework pulverization, with a net permanent loss of reef bio-construction. In contrast, adjacent non-bombarded reef sections have significantly higher benthic spatial relief and biodiversity. We compared benthic communities on 35-50 year-old bomb-cratered coral reefs at Culebra and Vieques Islands, with adjacent non-impacted sites; 2 coral recruit density and fish community structure within and outside craters; and 3 early effects of a rehabilitation effort using low-tech Staghorn coral Acropora cervicornis farming. Reef craters ranged in size from approximately 50 to 400m² and were largely dominated by heavily fragmented, flattened benthos, with coral cover usually below 2% and dominance by non-reef building taxa (i.e., filamentous algal turfs, macroalgae. Benthic spatial heterogeneity was lower within craters which also resulted in a lowered functional value as fish nursery ground. Fish species richness, abundance and biomass, and coral recruit density were lower within craters. Low-tech, community-based approaches to culture, harvest and transplant A. cervicornis into formerly bombarded grounds have proved successful in increasing percent coral cover, benthic spatial heterogeneity, and helping rehabilitate nursery ground functions.

  20. Deforestation and sedimentation in Uraba Gulf mangroves; a synthesis of the impacts on macrobenthos and fishes in the Turbo River Delta

    International Nuclear Information System (INIS)

    Blanco Libreros, Juan Felipe; Taborda Marin, Alexander; Amortegui Torres, Viviana; Arroyave Rincon, Andrea; Sandoval, Alejandro; Estrada, Edgar Andres; Leal Florez, Jenny; Vasquez Arango, Jairo Guillermo; Vivas Narvaez, Alberto

    2013-01-01

    This synthesis relates deforestation and land use change in coastal plain of the Turbo River watershed and impacts upon estuarine fauna in its delta. This watershed is shown within the context of hidroclimatological (rainfall and discharge) variability across the eastern margin of Uraba Gulf. Coastal-plain forest conversion rate to crops were quantified, as a possible explanation of increased sediment transport to the river and the near shore. Despite of the expansion of the delta, mangrove area was reduced as a consequence of conversion to crops and pastures. The dominant mangrove snail Neritina virginea was reduced in density in anthropogenic forest gaps and edges, as well as in pastures, due to altered microhabitats, and can be therefore used as a bio-indicator. The high sedimentation rates seem to be responsible for the faunistic poverty of the benthos, but do not seem responsible of deleterious effects on the dominant species. The diversity and abundance of fishes was greatly altered by high sedimentation near the river mouth. Finally, social features of the human communities were related to landscape changes. Herewith, we reported on the current ecosystem status, as the baseline for proposing management and conservation guidelines in order to prevent and restore impacts on mangroves and the coastal zone in this region.

  1. Variability of kokanee and rainbow trout food habits, distribution, and population dynamics, in an ultraoligotrophic lake with no manipulative management

    Science.gov (United States)

    Buktenica, M.W.; Girdner, S.F.; Larson, G.L.; McIntire, C.D.

    2007-01-01

    Crater Lake is a unique environment to evaluate the ecology of introduced kokanee and rainbow trout because of its otherwise pristine state, low productivity, absence of manipulative management, and lack of lotic systems for fish spawning. Between 1986 and 2004, kokanee displayed a great deal of variation in population demographics with a pattern that reoccurred in about 10 years. We believe that the reoccurring pattern resulted from density dependent growth, and associated changes in reproduction and abundance, driven by prey resource limitation that resulted from low lake productivity exacerbated by prey consumption when kokanee were abundant. Kokanee fed primarily on small-bodied prey from the mid-water column; whereas rainbow trout fed on large-bodied prey from the benthos and lake surface. Cladoceran zooplankton abundance may be regulated by kokanee. And kokanee growth and reproductive success may be influenced by the availability of Daphnia pulicaria, which was absent in zooplankton samples collected annually from 1990 to 1995, and after 1999. Distribution and diel migration of kokanee varied over the duration of the study and appeared to be most closely associated with prey availability, maximization of bioenergetic efficiency, and fish density. Rainbow trout were less abundant than were kokanee and exhibited less variation in population demographics, distribution, and food habits. There is some evidence that the population dynamics of rainbow trout were in-part related to the availability of kokanee as prey. ?? 2007 Springer Science+Business Media B.V.

  2. Effects of growth and change of food on the δ15N in marine fishes

    International Nuclear Information System (INIS)

    Kasamatsu, Fujio; Sato, Rie; Park, Kwang Lai

    1998-01-01

    Information is limited concerning variation of the δ 15 N with growth in marine organisms and consequently the effect of growth of marine biota on the δ 15 N is not yet well understood. The δ 15 N in 26 species of marine fishes taken from Japanese coastal waters together with 4664 stomach contents of these fishes were examined to investigate the effects of food habits and growth on the δ 15 N. The mean δ 15 N for two species that fed mainly on large-size fishes and six species that fed mainly on small-size fishes were 14.5±1.0per mille and 12.8±0.7per mille, respectively. For five species that fed mainly on decapod crustaceans, two species that fed mainly on zooplankton, and three species that fed mainly on benthos (mainly Polychaeta), the δ 15 N were 13.0±0.7, 9.7±0.9, and 12.2±1.2per mille, respectively. The mean δ 15 N in the species whose prey were mainly fish or decapod crustaceans was about 3-5per mille higher than the species whose prey was mainly zooplankton. Within the four species that shift their food habits with growth to higher trophic level, the δ 15 N significantly increased with growth in one species (Pacific cod), while not significant increase in the δ 15 N with growth in the remaining species. (author)

  3. Environmental assessment of exploration drilling off Nova Scotia: executive summary

    International Nuclear Information System (INIS)

    2000-01-01

    The environmental assessment project of drilling offshore Nova Scotia covers year-around drilling conducted from jackup rigs, semi-submersible rigs, and drill ships that use the methods described in the project description on the Scotian Shelf, the Laurentian Channel and St, Pierre Bank. The assessment was sponsored by all the oil companies active in the area, namely Mobil Oil Canada, Shell Canada, Imperial Oil Resources, Gulf Canada Resources, Chevron Canada Resources, PanCanadian Petroleum, Murphy Oil Company and Norsk Hydro Canada Oil and Gas. This summary describes the impact assessment methodology used, provides a description of the project, reviews the cumulative impact, and the impacts of discrete activities such as noise and disturbances, operational discharges of oil, disruption of the benthos, garbage and waste disposal, and accidental oil spills, and outlines mitigation and monitoring activities to deal with the impacts. Mitigation measures encompass routine discharges, accidental oil spills, spill response, monitoring activities, contingency plans and an overall environmental protection plan. In addition to this generic assessment, the consultants recommend that individual exploration drilling programs that fall outside of the parameters outlined in the generic environmental assessment document, be required to undergo a program-specific assessment that focuses on those aspects of the proposed program that differ from the parameters prescribed in the present document. 9 refs

  4. A seascape approach to investigating fish spillover across a marine protected area boundary in Hawai'i

    Science.gov (United States)

    Stamoulis, Kostantinos A.; Friedlander, Alan M.

    2013-01-01

    Marine protected areas (MPAs) can benefit fisheries through export of pelagic eggs and larvae and the net emigration of adults and juveniles (spillover). Spillover was investigated for a marine protected area on the north shore of Oahu, Hawai‘i utilizing a seascape approach. This study incorporated habitat variables and underwater visual surveys of fishes and benthos measured at two distinct scales (125 m2 and 1000 m2) inside and outside the protected area at varying distance from the boundary. The relationship between fish biomass from fine-scale surveys and key habitat variables was found to account for a large portion of the variability for both resource (targeted) fish species (15%) and non-resource fish (28%). The remaining variation in resource fish biomass was significantly correlated with distance from the MPA boundary showing a decreasing gradient from inside to outside (r2 = 0.46, p = 0.001), indicating fish spillover at a local scale (p = 0.45). The evidence of spillover based on the fine-scale surveys was corroborated by results from broad-scale surveys, which also showed a significant relationship (r2 = 0.19, p positive effect on the attitudes of fishers toward marine reserves and marine protected areas.

  5. Behavior and Potential Impacts of Metal-Based Engineered Nanoparticles in Aquatic Environments

    Directory of Open Access Journals (Sweden)

    Cheng Peng

    2017-01-01

    Full Text Available The specific properties of metal-based nanoparticles (NPs have not only led to rapidly increasing applications in various industrial and commercial products, but also caused environmental concerns due to the inevitable release of NPs and their unpredictable biological/ecological impacts. This review discusses the environmental behavior of metal-based NPs with an in-depth analysis of the mechanisms and kinetics. The focus is on knowledge gaps in the interaction of NPs with aquatic organisms, which can influence the fate, transport and toxicity of NPs in the aquatic environment. Aggregation transforms NPs into micrometer-sized clusters in the aqueous environment, whereas dissolution also alters the size distribution and surface reactivity of metal-based NPs. A unique toxicity mechanism of metal-based NPs is related to the generation of reactive oxygen species (ROS and the subsequent ROS-induced oxidative stress. Furthermore, aggregation, dissolution and ROS generation could influence each other and also be influenced by many factors, including the sizes, shapes and surface charge of NPs, as well as the pH, ionic strength, natural organic matter and experimental conditions. Bioaccumulation of NPs in single organism species, such as aquatic plants, zooplankton, fish and benthos, is summarized and compared. Moreover, the trophic transfer and/or biomagnification of metal-based NPs in an aquatic ecosystem are discussed. In addition, genetic effects could result from direct or indirect interactions between DNA and NPs. Finally, several challenges facing us are put forward in the review.

  6. Evaluating long-term trends in littoral benthic macroinvertebrate communities of lakes recovering from acid deposition.

    Science.gov (United States)

    Lento, Jennifer; Dillon, Peter J; Somers, Keith M

    2012-12-01

    The Mann-Kendall test has been proposed as a nonparametric method to evaluate trends in long-term water quality datasets with missing values, serial correlation, and non-normality. However, this test has rarely been used to evaluate long-term trends in biological data. In this study, we used the Mann-Kendall test to evaluate trends in 15 years of data on benthic macroinvertebrate communities from 17 Precambrian Shield lakes. We also used the van Belle and Hughes test of trend homogeneity to assess whether common among-lake temporal trends existed. We assumed that evidence of a common regional trend among lakes would support the hypothesis of long-term biological recovery from past acidification. We found decreasing proportions of Chironomidae and increasing proportions of Ephemeroptera, Plecoptera, and Trichoptera (EPT) in both single-lake and multi-lake trend analysis. Moreover, six of the nine lakes with significant trends in more than one benthos metric displayed a significant decrease in Chironomidae and increase in EPT concurrently, indicating a shift towards more acid-sensitive taxa. Weak trends in several of the biological metrics indicated that recovery in these lakes has been impeded. Results of this study indicate that the Mann-Kendall and van Belle and Hughes trend tests are useful statistical tools to evaluate long-term patterns in biological data.

  7. Particle Image Velocimetry (PIV) Measurements of Suspension-Feeding Velocities

    Science.gov (United States)

    Du Clos, K.; Jones, I. T.; Carrier, T. J.; Jumars, P. A.

    2016-02-01

    Active suspension feeders, such as bivalves and tunicates, connect benthic and pelagic ecosystems by packaging suspended matter into larger fecal and pseudofecal particles, greatly enhancing the flux of carbon and nutrients from the water column to the benthos. The volume of water processed by a population of suspension feeders is commonly estimated by scaling up results from experiments that measure the clearance rate (the volume of water cleared of particles per time) of one or a few individual suspension feeders. Clearance rates vary, however, between species, within a species, and over time for a single individual; and the velocity fields produced by suspension feeders are likely to interact in complex ways. We measured the water velocity fields produced by two species of bivalve, Mya arenaria and Mercenaria mercenaria, and the tunicate Ciona intestinalis, using particle image velocimetry (PIV). We used these measurements to calculate flow rates and Reynolds numbers of inhalant and exhalant siphons. We also observed strong entrainment of water by M. arenaria's exhalant siphon jet that may help to explain how the clam avoids depleting the water around it of particles and oxygen as it feeds. We are using these measurements to inform computational fluid mechanics (CFD) models of suspension feeding, allowing us to examine the interactions of flow fields produced by multiple suspension feeders and other effects not quantified by clearance-rate measurements.

  8. Changing chain: past, present and future of the Scotia Arc's and Antarctica's shallow benthic communities

    Directory of Open Access Journals (Sweden)

    David K.A. Barnes

    2005-12-01

    Full Text Available The Scotia Arc links Patagonia to the Antarctic Peninsula. This island chain has changed considerably since Antarctica’s geographic and thermal isolation from other land and water masses. Now its rates of air, land and fresh-water climate change are among the highest measured. This review examines work on the shallow water benthos of this region in the context of climate change. In summer, primary productivity is as intense as anywhere, whilst in winter the water reaches unprecedented clarity. Suspension feeders may eat for just a few months but others feed all year. Growth and reproduction are up to 50x slower than non-polar rates. Life here is in the slow lane. There is intense summer disturbance from ice-scour and wave action. This has erased shore zonation and created it below the surface. In contrast to summer disturbance, the winter is among the calmest and most thermally stable environments, when the area is overlain by fast ice. Whilst few animal phyla or species are represented on land, phyletic richness—and in some groups species richness—rivals that of tropical regions. Data showing clines in benthic richness at several taxonomic levels across the Patagonia-South Georgia-Signy Is.-Adelaide Is. chain and 50 years of ice-sheet retreat are presented.

  9. A proposed biogeography of the deep ocean floor

    Science.gov (United States)

    Watling, Les; Guinotte, John; Clark, Malcolm R.; Smith, Craig R.

    2013-04-01

    While there are many generalized schemes representing the biogeographic distribution of life in the deep sea, reviewed here, a comprehensive analysis has not been undertaken since Vinogradova (1979, 1997) for the abyssal and Belyaev (1989) for the hadal. The purpose of this paper is to propose global biogeographic provinces for the lower bathyal and abyssal benthos (>800 m depths) in order to aid high seas management efforts. Biological samples from these depths are sparse so delineation of biogeographic provinces was initially hypothesized using oceanographic proxies, and examined with documented locations of select benthic marine species. These biogeographic provinces were first developed in 2009 via an expert consultation workshop to delineate biogeographic provinces in offshore regions - the Global Open Ocean and Deep Sea (GOODS) classification. We have refined the GOODS deep-sea classification by incorporating additional high-resolution hydrographic and organic-matter flux data for the seafloor. Water mass characteristics (temperature and salinity) and particulate organic flux to the seafloor were the strongest determinants in the final delineation of provincial boundaries. This process resulted in the delineation of 14 lower bathyal and 14 abyssal provinces. The bathyal and abyssal classifications presented here should be used with other management tools and analyses (e.g., predictive habitat modeling, seamount classifications, etc.) to help determine where marine protected areas should be placed and to minimize the negative impacts of commercial activities in the high seas.

  10. Seamount ecology and dynamics: A multidisciplinary data set from repeated surveys at different seamounts in the Northeast Atlantic and Mediterranean (2003 - 2013).

    Science.gov (United States)

    Mohn, C.; Christiansen, B.; Denda, A.; George, K. H.; Kaufmann, M.; Maranhão, M.; Martin, B.; Metzger, T.; Peine, F.; Schuster, A.; Springer, B.; Stefanowitsch, B.; Turnewitsch, R.; Wehrmann, H.

    2016-02-01

    Seamounts are amongst the most common physiographic open ocean systems, but remoteness and geographic complexity have limited the number of integrated and multidisciplinary seamount surveys in the past. As a consequence, important aspects of seamount ecology and dynamics remain poorly studied. Here we present a multi-parameter data set from individual and repeated seamount surveys conducted at different sites in the Northeast Atlantic and Eastern Mediterranean between 2003 and 2013. The main objective of these surveys was to establish a collection of ecosystem relevant descriptors and to develop a better understanding of seamount ecosystem composition and variability in different dynamical and bio-geographic environments. Measurements were conducted at four seamounts in the Northeast Atlantic (Ampère, Sedlo, Seine, Senghor) and two seamounts in the Eastern Mediterranean (Anaximenes, Eratosthenes). The data set comprises records from a total number of 11 cruises including physical oceanography (temperature, salinity, pressure, currents), biology (phytoplankton, zooplankton, fish, benthos) and biogeochemistry (sedimentary particle dynamics, carbon flux). The resulting multi-disciplinary data collection provides a unique opportunity for comparative studies of seamount ecosystem structure and dynamics between different physical, biological and biogeochemical regimes

  11. Coastal hypoxia and sediment biogeochemistry

    Directory of Open Access Journals (Sweden)

    J. J. Middelburg

    2009-07-01

    Full Text Available The intensity, duration and frequency of coastal hypoxia (oxygen concentration <63 μM are increasing due to human alteration of coastal ecosystems and changes in oceanographic conditions due to global warming. Here we provide a concise review of the consequences of coastal hypoxia for sediment biogeochemistry. Changes in bottom-water oxygen levels have consequences for early diagenetic pathways (more anaerobic at expense of aerobic pathways, the efficiency of re-oxidation of reduced metabolites and the nature, direction and magnitude of sediment-water exchange fluxes. Hypoxia may also lead to more organic matter accumulation and burial and the organic matter eventually buried is also of higher quality, i.e. less degraded. Bottom-water oxygen levels also affect the organisms involved in organic matter processing with the contribution of metazoans decreasing as oxygen levels drop. Hypoxia has a significant effect on benthic animals with the consequences that ecosystem functions related to macrofauna such as bio-irrigation and bioturbation are significantly affected by hypoxia as well. Since many microbes and microbial-mediated biogeochemical processes depend on animal-induced transport processes (e.g. re-oxidation of particulate reduced sulphur and denitrification, there are indirect hypoxia effects on biogeochemistry via the benthos. Severe long-lasting hypoxia and anoxia may result in the accumulation of reduced compounds in sediments and elimination of macrobenthic communities with the consequences that biogeochemical properties during trajectories of decreasing and increasing oxygen may be different (hysteresis with consequences for coastal ecosystem dynamics.

  12. Spatial and temporal variations in silver contamination and toxicity in San Francisco Bay

    Science.gov (United States)

    Flegal, A.R.; Brown, C.L.; Squire, S.; Ross, J.R.M.; Scelfo, G.M.; Hibdon, S.

    2007-01-01

    Although San Francisco Bay has a "Golden Gate", it may be argued that it is the "Silver Estuary". For at one time the Bay was reported to have the highest levels of silver in its sediments and biota, along with the only accurately measured values of silver in solution, of any estuarine system. Since then others have argued that silver contamination is higher elsewhere (e.g., New York Bight, Florida Bay, Galveston Bay) in a peculiar form of pollution machismo, while silver contamination has measurably declined in sediments, biota, and surface waters of the Bay over the past two to three decades. Documentation of those systemic temporal declines has been possible because of long-term, ongoing monitoring programs, using rigorous trace metal clean sampling and analytical techniques, of the United States Geological Survey and San Francisco Bay Regional Monitoring Program that are summarized in this report. However, recent toxicity studies with macro-invertebrates in the Bay have indicated that silver may still be adversely affecting the health of the estuarine system, and other studies have indicated that silver concentrations in the Bay may be increasing due to new industrial inputs and/or the diagenetic remobilization of silver from historically contaminated sediments being re-exposed to overlying surface waters and benthos. Consequently, the Bay may not be ready to relinquish its title as the "Silver Estuary". ?? 2007 Elsevier Inc. All rights reserved.

  13. SCARDINIUS GENUS IN MOLECULAR STUDIES – A REVIEW

    Directory of Open Access Journals (Sweden)

    Ovidiu Popescul

    2015-12-01

    Full Text Available Scardinius is a genus of ray-finned fish in the Cyprinidae family commonly called rudds. The common rudd(Scardinius erithrophthalmus is a bentho-pelagic freshwater fish that occurs mainly in nutrient-rich, well vegetatedlowland rivers, backwaters, oxbows, ponds and lakes and it is widespread in Europe and middle Asia. It has a mediumlength of 20-30 cm, but it can reach 50 cm. The classification of cyprinids has always been controversial the morphologicaltraits have an unclear homology this led to the idea that the recognized monophyletic groups are surely misinterpreted. Thispaper aims to assess the current level of molecular data regarding Scardinius genera. Some of the molecular data obtainedfor Scardinius genus is from DNA barcoding studies on fresh water fishes, but studies regarding this genus and Cyprinidaefamily used mitochondrial genes like cytochrome b (cyt b and cytochrome oxidase (CO, but nuclear genes or nuclearmicrosatellites were also used. We found that molecular data exists for both nuclear and mitochondrial genes, but this genuswasn’t studied separately and as many of the researchers suggest more taxonomic studies are required in order to solve theuncertainties within it.

  14. Assessing condition of macroinvertebrate communities and sediment toxicity in the St. Lawrence River at Massena Area-of-Concern

    Science.gov (United States)

    Duffy, Brian T.; Baldigo, Barry P.; Smith, Alexander J.; George, Scott D.; David, Anthony M.

    2016-01-01

    In 1972, the USA and Canada agreed to restore the chemical, physical, and biological integrity of the Great Lakes ecosystem under the first Great Lakes Water Quality Agreement. In subsequent amendments, part of the St. Lawrence River at Massena, New York and segments of three tributaries, were designated as an Area of Concern (AOC) due to the effects of polychlorinated biphenyls (PCBs), lead and copper contamination, and habitat degradation and resulting impairment to several beneficial uses. Because sediments have been largely remediated, the present study was initiated to evaluate the current status of the benthic macroinvertebrate (benthos) beneficial use impairment (BUI). Benthic macroinvertebrate communities and sediment toxicity tests using Chironomus dilutus were used to test the hypotheses that community condition and sediment toxicity at AOC sites were not significantly different from those of adjacent reference sites. Grain size was found to be the main driver of community composition and macroinvertebrate assemblages, and bioassessment metrics did not differ significantly between AOC and reference sites of the same sediment class. Median growth of C. dilutus and its survival in three of the four river systems did not differ significantly in sediments from AOC and reference sites. Comparable macroinvertebrate assemblages and general lack of toxicity across most AOC and reference sites suggest that the quality of sediments should not significantly impair benthic macroinvertebrate communities in most sites in the St. Lawrence River AOC.

  15. Chemical Munitions Search & Assessment-An evaluation of the dumped munitions problem in the Baltic Sea

    Science.gov (United States)

    Bełdowski, Jacek; Klusek, Zygmunt; Szubska, Marta; Turja, Raisa; Bulczak, Anna I.; Rak, Daniel; Brenner, Matthias; Lang, Thomas; Kotwicki, Lech; Grzelak, Katarzyna; Jakacki, Jaromir; Fricke, Nicolai; Östin, Anders; Olsson, Ulf; Fabisiak, Jacek; Garnaga, Galina; Nyholm, Jenny Rattfelt; Majewski, Piotr; Broeg, Katja; Söderström, Martin; Vanninen, Paula; Popiel, Stanisław; Nawała, Jakub; Lehtonen, Kari; Berglind, Rune; Schmidt, Beata

    2016-06-01

    Chemical Munitions Search & Assessment (CHEMSEA) project has performed studies on chemical weapon (CW) detection, sediment pollution and spreading as well as biological effects of chemical warfare agents (CWAs) dumped in the Baltic Sea. Results suggest that munitions containing CWAs are more scattered on the seafloor than suspected, and previously undocumented dumpsite was discovered in Gdansk Deep. Pollution of sediments with CWA degradation products was local and close to the detected objects; however the pollution range was larger than predicted with theoretical models. Bottom currents observed in the dumpsites were strong enough for sediment re-suspension, and contributed to the transport of polluted sediments. Diversity and density of the faunal communities were poor at the dumping sites in comparison to the reference area, although the direct effects of CWA on benthos organisms were difficult to determine due to hypoxic or even anoxic conditions near the bottom. Equally, the low oxygen might have affected the biological effects assessed in cod and caged blue mussels. Nonetheless, both species showed significantly elevated molecular and cellular level responses at contaminated sites compared to reference sites.

  16. Microbial diversity associated with four functional groups of benthic reef algae and the reef-building coral Montastraea annularis.

    Science.gov (United States)

    Barott, Katie L; Rodriguez-Brito, Beltran; Janouškovec, Jan; Marhaver, Kristen L; Smith, Jennifer E; Keeling, Patrick; Rohwer, Forest L

    2011-05-01

    The coral reef benthos is primarily colonized by corals and algae, which are often in direct competition with one another for space. Numerous studies have shown that coral-associated Bacteria are different from the surrounding seawater and are at least partially species specific (i.e. the same bacterial species on the same coral species). Here we extend these microbial studies to four of the major ecological functional groups of algae found on coral reefs: upright and encrusting calcifying algae, fleshy algae, and turf algae, and compare the results to the communities found on the reef-building coral Montastraea annularis. It was found using 16S rDNA tag pyrosequencing that the different algal genera harbour characteristic bacterial communities, and these communities were generally more diverse than those found on corals. While the majority of coral-associated Bacteria were related to known heterotrophs, primarily consuming carbon-rich coral mucus, algal-associated communities harboured a high percentage of autotrophs. The majority of algal-associated autotrophic Bacteria were Cyanobacteria and may be important for nitrogen cycling on the algae. There was also a rich diversity of photosynthetic eukaryotes associated with the algae, including protists, diatoms, and other groups of microalgae. Together, these observations support the hypothesis that coral reefs are a vast landscape of distinctive microbial communities and extend the holobiont concept to benthic algae. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  17. The influence of coral reef benthic condition on associated fish assemblages.

    Directory of Open Access Journals (Sweden)

    Karen M Chong-Seng

    Full Text Available Accumulative disturbances can erode a coral reef's resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58% and high structural complexity to high macroalgae cover (up to 95% and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae.

  18. First laboratory insight on the behavioral rhythms of the bathyal crab Geryon longipes

    Science.gov (United States)

    Nuñez, J. D.; Sbragaglia, V.; García, J. A.; Company, J. B.; Aguzzi, J.

    2016-10-01

    The deep sea is the largest and at the same time least explored biome on Earth, but quantitative studies on the behavior of bathyal organisms are scarce because of the intrinsic difficulties related to in situ observations and maintaining animals in aquaria. In this study, we reported, for the first time, laboratory observations on locomotor rhythms and other behavioral observations (i.e. feeding, exploring and self-grooming) for the bathyal crab Geryon longipes. Crabs were collected on the middle-lower slope (720-1750 m) off the coast of Blanes (Spain). Inertial (18 h) water currents and monochromatic blue (i.e. 470 nm) light-darkness (24 h) cycles were simulated in two different experiments in flume tanks endowed with burrows. Both cycles were simulated in order to investigate activity rhythms regulation in Mediterranean deep-sea benthos. Crabs showed rhythmic locomotor activity synchronized to both water currents and light-darkness cycles. In general terms, feeding and exploring behaviors also followed the same pattern. Results presented here indicate the importance of local inertial (18 h) periodicity of water currents at the seabed as a temporal cue regulating the behavior of bathyal benthic fauna in all continental margin areas where the effects of tides is negligible.

  19. Effects of a chronic lower range of triclosan exposure to a stream mesocosm community

    Science.gov (United States)

    Nietch, C.T.; Quinlan, E.L.; Lazorchak, J.; Impellitteri, C.; Raikow, D.; Walters, David M.

    2013-01-01

    Triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) is an antimicrobial found in consumer soaps and toothpaste. It is in treated wastewater effluents at low part per billion concentrations, representing a potentially chronic exposure condition for biota inhabiting receiving streams. A naturally colonized benthos was created using flow-through indoor mesocosms. Then the benthic communities were dosed to achieve different in-stream triclosan concentrations (Control, 0.1, 0.5, 1.0, 5.0, and 10 µg/L) for 56 days. Water quality parameters and endpoints from bacteria to macroinvertebrates plus interacting abiotic components were measured. Effects of triclosan on specific microbial endpoints were observed at all doses, including an effect on litter decomposition dynamics at doses 1.0 µg/L and higher. Resistance of periphytic bacteria to triclosan significantly increased in doses 0.5 µg/L and above. By the end of dosing, the antimicrobial appeared to stimulate the stream periphyton at the three lowest doses while the two highest doses exhibited decreased stocks of periphyton, including significantly lower bacteria cell densities, and cyanobacteria abundance compared to the control. Beside an effect on benthic ostracods, the changes that occurred in the periphyton did not translate to significant change in the colonizing nematodes, the macroinvertebrate community as a whole, or other measurements of stream function. The results shed light on the role a low, chronic exposure to triclosan may play in effluent dominated streams.

  20. Chemical composition of Lake Orta sediments

    Directory of Open Access Journals (Sweden)

    Monica BELTRAMI

    2001-08-01

    Full Text Available Lake Orta (18.2 km2, 1.3 km3, 143 m max. depth has been severely polluted since industrialisation of its watershed began in 1926, at which time the lake began to receive industrial effluents containing high concentrations of copper and ammonia. Chromium-, nickel-, and zinc-rich effluents from plating factories have also contributed to pollution levels, and pH -levels dropped below 4.0 as a result of the oxidation of ammonia to nitrates. More than 60 papers have documented the evolution of the chemical characteristics of both water and sediment, and the sudden decline of plankton, as well as benthos and fish. As a remedial action the lake was limed from May 1989 to June 1990 with 10,900 tons of CaCO3. The treatment was immediately effective in raising the pH and decreasing the metal concentrations in the water column, and plankton and fish communities quickly rebounded. However, the chemical characteristics of sediments were influenced by the liming to a much lesser extent. Since 900 tons of copper and the same amount of chromium were contained in the top 10 cm of sediment, it appears likely that the sediment could potentially act as a current and future source of these metals to the water column. This observation has resulted in the implementation of a vigorous monitoring regime to track the post-liming recovery of Lake Orta.

  1. Investigational research on CO2 isolation technology in fiscal 1995; 1995 nendo nisanka tanso no kakuri gijutsu ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    The paper studied present technical subjects and future study subjects of the CO2 isolation technology in order to clarify technical and social problems and the developmental subjects of the CO2 isolation technology and related technologies for separating/concentrating CO2 emitted in relation to quantity consumption of fossil fuel and storing it in ocean or underground. Main items for the study were: (1) investigational study of the technology of CO2 ocean storage, (2) investigational study of environmental effect assessment in storing CO2 in ocean, (3) investigational study of the technology of CO2 ocean storage, etc. Technologies required for the ocean isolation were arranged such as CO2 storage, injection, dispersion technique, CO2 behavior simulation, and the developmental subjects were extracted. Further, in the deep-sea bottom storage method, a simulation to calculate the range of PH effects was conducted presuming the specified amount of CO2 and applying known physical values, and evaluation of the CO2 ocean discharge/solution method was made. A method was also studied for experiments on water bacteria and benthos. 127 refs., 102 figs., 81 tabs.

  2. The "island rule" and deep-sea gastropods: re-examining the evidence.

    Directory of Open Access Journals (Sweden)

    John J Welch

    2010-01-01

    Full Text Available One of the most intriguing patterns in mammalian biogeography is the "island rule", which states that colonising species have a tendency to converge in body size, with larger species evolving decreased sizes and smaller species increased sizes. It has recently been suggested that an analogous pattern holds for the colonisation of the deep-sea benthos by marine Gastropoda. In particular, a pioneering study showed that gastropods from the Western Atlantic showed the same graded trend from dwarfism to gigantism that is evident in island endemic mammals. However, subsequent to the publication of the gastropod study, the standard tests of the island rule have been shown to yield false positives at a very high rate, leaving the result open to doubt.The evolution of gastropod body size in the deep sea is reexamined. Using an extended and updated data set, and improved statistical methods, it is shown that some results of the previous study may have been artifactual, but that its central conclusion is robust. It is further shown that the effect is not restricted to a single gastropod clade, that its strength increases markedly with depth, but that it applies even in the mesopelagic zone.The replication of the island rule in a distant taxonomic group and a partially analogous ecological situation could help to uncover the causes of the patterns observed--which are currently much disputed. The gastropod pattern is evident at intermediate depths, and so cannot be attributed to the unique features of abyssal ecology.

  3. Chlorophyll and zooplankton in microbasins along the Strait of Magellan - Beagle Channel passage

    Directory of Open Access Journals (Sweden)

    Madeleine Hamamé

    1999-12-01

    Full Text Available Distributions of chlorophyll and zooplankton were compared to temperature and salinity distributions along previously defined microbasins. Results were consistent for chlorophyll: 1.- Paso Ancho-Seno Magdalena showed a shallow chlorophyll maximum (ca. 5 mg m-3 at 0 - 20 m in a vertically homogeneous cold and brackish water column, 2.- Canal Magdalena-Canal Cockburn-Canal Brecknock had relatively lower chlorophyll concentrations (2-3 mg m-3 at 0-50 m, minor stratification of salinity and a surface lens of warmer water, 3.- Canal Ballenero-Brazo Noroeste had a subsurface layer of high chlorophyll concentration (> 4 mg m-3 in a vertically stratified water column of 2 salinity layers and 3 temperature layers, 4.- Canal Beagle presented a subsurface chlorophyll maximum (> 4 mg m-3 extending to the bottom, and vertically homogeneous salinity and temperature distribution. Chaetoceros spp.-dominated phytoplankton was a common feature in the entire area. Zooplankton distributions did not match the above mentioned subdivision of microbasins despite some trends along the passage. High relative abundance of invertebrate larvae in the zooplankton was associated with a matching response to the spring bloom and implies a strong bentho-pelagic coupling.

  4. Effects of drilling fluids on marine organisms

    International Nuclear Information System (INIS)

    Parrish, P.R.; Duke, T.W.

    1990-01-01

    This paper reports on drilling fluids, also called drilling muds, which are essential to drilling processes in the exploration and production of oil and gas from the U.S. Outer Continental Shelf (OCS). These fluids are usually discharged from drilling platforms into surrounding waters of the OCS and are regulated by the U.S. Environmental Protection Agency (EPA). In a program carried out by the EPA Environmental research Laboratory at Gulf Breeze, Florida, diverse marine species as well as microbiotic and macrobiotic communities were studied. Drilling fluids were toxic to marine organisms in certain concentrations and exposure regimes. Furthermore, the fluids adversely affected the benthos physically by burying them or by altering the substrates. Toxicity of the drilling-fluid components, used drilling fluids from active Gulf of Mexico sites, and laboratory-prepared drilling fluids varied considerably. for example 96-h LC 50 s were from 25 μ liter -1 to > 1500 μl liter -1 for clams, larval lobsters, mysids, and grass shrimp. In most instances, mortality was significantly (α = 0.05) correlated with the diesel-oil content of the fluids collected from the Gulf of Mexico. Data and model simulations suggest a rapid dilution of drilling fluids released into OCS waters, resulting in concentrations below the acute-effect concentration for the water column organisms tested

  5. Foraminiferal assemblages from a transitional tropical upwelling zone in the Golfe d'Arguin, Mauritania

    Science.gov (United States)

    Reymond, Claire E.; Mateu-Vicens, Guillem; Westphal, Hildegard

    2014-07-01

    With the growing pressure of eutrophication in tropical regions, the Mauritian shelf provides a natural situation to understand the variability in mesotrophic assemblages. Site-specific dynamics occur throughout the 1200 m depth gradient. The shallow assemblages divide into three types of warm-water mesotrophic foraminiferal assemblages, which is not only a consequence of high primary productivity restricting light to the benthos but due to low pore water oxygenation, shelf geomorphology, and sediment partitioning. In the intermediate depth (approx. 500 m), the increase in foraminiferal diversity is due to the cold-water coral habitat providing a greater range of micro niches. Planktonic species characterise the lower bathyal zone, which emphasizes the reduced benthic carbonate production at depth. Although, due to the strong hydrodynamics within the Golf, planktonic species occur in notable abundances through out the whole depth gradient. Overall, this study can easily be compared to other tropical marine settings investigating the long-term effects of tropical eutrophication and the biogeographic distribution of carbonate producing organisms.

  6. The Seasonal Contribution of Different Celtic Sea Shelf Sediments to Benthic Carbon Cycling

    Science.gov (United States)

    Hicks, N.; Stahl, H.; Ubbara, G.; Marshall, L.; Hatton, A.

    2016-02-01

    Continental shelf sediments are responsible for sequestering significant amounts of organic carbon annually, and this usually occurs in cohesive sediments. It is still unclear how much variation there is in organic carbon sequestration between different sediment types (cohesive, permeable), and the relative spatial and temporal variability of these measurements. Here we present initial findings on community respiration rates (diffusive and total oxygen uptake rates) from whole core incubations experiments run on three cruises in the Celtic Sea. Sampling covered four different benthic sites (mud, sand, muddy sand and sandy mud), representing a gradient between cohesive and permeable sediments. Sediment cores were collected pre-, during- and post-phytoplankton bloom, to encompass the different organic matter inputs reaching the benthos over an annual cycle. There are clear differences in oxygen uptake rates between sediment type, and a trend according to season, which links directly to organic matter input. This demonstrates the relative contribution of the micro and meiofauna to community respiration, and the organic carbon turnover rates for different shelf sea sediments in the Celtic Sea.

  7. A novel resource polymorphism in fish, driven by differential bottom environments: an example from an ancient lake in Japan.

    Directory of Open Access Journals (Sweden)

    Takefumi Komiya

    2011-02-01

    Full Text Available Divergent natural selection rooted in differential resource use can generate and maintain intraspecific eco-morphological divergence (i.e., resource polymorphism, ultimately leading to population splitting and speciation. Differing bottom environments create lake habitats with different benthos communities, which may cause selection in benthivorous fishes. Here, we document the nature of eco-morphological and genetic divergence among local populations of the Japanese gudgeon Sarcocheilichthys (Cyprinidae, which inhabits contrasting habitats in the littoral zones (rocky vs. pebbly habitats in Lake Biwa, a representative ancient lake in East Asia. Eco-morphological analyses revealed that Sarcocheilichthys variegatus microoculus from rocky and pebbly zones differed in morphology and diet, and that populations from rocky environments had longer heads and deeper bodies, which are expected to be advantageous for capturing cryptic and/or attached prey in structurally complex, rocky habitats. Sarcocheilichthys biwaensis, a rock-dwelling specialist, exhibited similar morphologies to the sympatric congener, S. v. microoculus, except for body/fin coloration. Genetic analyses based on mitochondrial and nuclear microsatellite DNA data revealed no clear genetic differentiation among local populations within/between the gudgeon species. Although the morphogenetic factors that contribute to morphological divergence remain unclear, our results suggest that the gudgeon populations in Lake Biwa show a state of resource polymorphism associated with differences in the bottom environment. This is a novel example of resource polymorphism in fish within an Asian ancient lake, emphasizing the importance and generality of feeding adaptation as an evolutionary mechanism that generates morphological diversification.

  8. Eocene spiculites and spongolites in southwestern Australia: Not deep, not polar, but shallow and warm

    Science.gov (United States)

    Gammon, Paul R.; James, Noel P.; Pisera, Andrjez

    2000-09-01

    Siliceous spongolite and spiculite are generally interpreted as deep- and/or cold-water deposits, largely because modern analogs are found mostly in cold- and/or deep-water environments. However, extensive shallow-water, biosiliceous accumulations are present in late Eocene age deposits of southern Western Australia. The attributes and paleoenvironmental setting of these accumulations frame the specific climatic and/or oceanographic constraints that allow such shallow neritic sediments to form. The generally fine grained siliciclastic-biosiliceous sediments accumulated in a nearshore, shallow-water setting, around numerous islands, and offshore from a warm-temperate, rainforest-covered upland. Sponges compose a lithistid-hexactinellid assemblage of Mesozoic Tethyan affinity, confined to deep water in the modern ocean, that migrated into neritic paleoenvironments during late Eocene time. Lithistids dominated shoreface environments and were reworked into sponge-conglomerate beaches, while hexactinellids flourished offshore in muddy subshoreface environments. These deposits also contain common soft demosponge spicules, and a rare but otherwise normal marine calcareous biota. The biosiliceous sediments grade offshore into bryozoan-rich marls and limestones. Sponges outcompeted the calcareous benthos in these inner shelf environments because of elevated amounts of land-derived nutrients that included high dissolved silica and a calm hydrodynamic setting. These deposits suggest that neither temperature nor water depth are critical factors for prolific sponge colonization. The rarity of such deposits in the rock record likely reflects the necessity for the coincidence of all of these factors, or they are misinterpreted.

  9. Selective uptake of prokaryotic picoplankton by a marine sponge ( Callyspongia sp.) within an oligotrophic coastal system

    Science.gov (United States)

    Hanson, Christine E.; McLaughlin, M. James; Hyndes, Glenn A.; Strzelecki, Joanna

    2009-09-01

    Marine sponges are key players in the transfer of carbon from the pelagic microbial food web into the benthos. Selective uptake of prokaryotic picoplankton (time in the oligotrophic coastal waters of southwestern Australia, where sponge abundance and biodiversity ranks among the highest in the world. Water sampling and flow rate measurements were conducted over five sampling occasions following the InEx method of Yahel et al. (2005), with heterotrophic bacteria and autotrophic Synechococcus cyanobacteria identified and enumerated by flow cytometry. Callyspongia sp. demonstrated high filtration efficiencies, particularly for high DNA (HDNA) bacteria (up to 85.3% in summer 2008) and Synechococcus (up to 91.1% in autumn 2007), however efficiency varied non-uniformly with time and food type ( p food types, Callyspongia sp. exhibited consistently negative selectivity for LDNA bacteria and positive selectivity for Synechococcus, while HDNA bacteria was generally a neutral or positive selection. The total carbon removal rate (sum of all prokaryotic picoplankton cells), calculated on a per unit area basis, varied significantly with time ( p food webs of southwestern Australia, and support the conclusion that sponges actively select food particles that optimise their nutritional intake.

  10. Decoupling of body-plan diversification and ecological structuring during the Ediacaran–Cambrian transition: evolutionary and geobiological feedbacks

    Science.gov (United States)

    Mángano, M. Gabriela; Buatois, Luis A.

    2014-01-01

    The rapid appearance of bilaterian clades at the beginning of the Phanerozoic is one of the most intriguing topics in macroevolution. However, the complex feedbacks between diversification and ecological interactions are still poorly understood. Here, we show that a systematic and comprehensive analysis of the trace-fossil record of the Ediacaran–Cambrian transition indicates that body-plan diversification and ecological structuring were decoupled. The appearance of a wide repertoire of behavioural strategies and body plans occurred by the Fortunian. However, a major shift in benthic ecological structure, recording the establishment of a suspension-feeder infauna, increased complexity of the trophic web, and coupling of benthos and plankton took place during Cambrian Stage 2. Both phases were accompanied by different styles of ecosystem engineering, but only the second one resulted in the establishment of the Phanerozoic-style ecology. In turn, the suspension-feeding infauna may have been the ecological drivers of a further diversification of deposit-feeding strategies by Cambrian Stage 3, favouring an ecological spillover scenario. Trace-fossil information strongly supports the Cambrian explosion, but allows for a short time of phylogenetic fuse during the terminal Ediacaran–Fortunian. PMID:24523279

  11. Decoupling of body-plan diversification and ecological structuring during the Ediacaran-Cambrian transition: evolutionary and geobiological feedbacks.

    Science.gov (United States)

    Mángano, M Gabriela; Buatois, Luis A

    2014-04-07

    The rapid appearance of bilaterian clades at the beginning of the Phanerozoic is one of the most intriguing topics in macroevolution. However, the complex feedbacks between diversification and ecological interactions are still poorly understood. Here, we show that a systematic and comprehensive analysis of the trace-fossil record of the Ediacaran-Cambrian transition indicates that body-plan diversification and ecological structuring were decoupled. The appearance of a wide repertoire of behavioural strategies and body plans occurred by the Fortunian. However, a major shift in benthic ecological structure, recording the establishment of a suspension-feeder infauna, increased complexity of the trophic web, and coupling of benthos and plankton took place during Cambrian Stage 2. Both phases were accompanied by different styles of ecosystem engineering, but only the second one resulted in the establishment of the Phanerozoic-style ecology. In turn, the suspension-feeding infauna may have been the ecological drivers of a further diversification of deposit-feeding strategies by Cambrian Stage 3, favouring an ecological spillover scenario. Trace-fossil information strongly supports the Cambrian explosion, but allows for a short time of phylogenetic fuse during the terminal Ediacaran-Fortunian.

  12. Environmental impact of bleufin tuna aquaculture on benthic assemblages in the western coast of Baja California, Mexico

    Science.gov (United States)

    Diaz-Castaneda, V.

    2013-05-01

    Sea-cage farming results in a constant rain of organic waste onto the surrounding benthos. In Baja California there is growing concern over the effects of sea-cages on the local environment: sediment chemistry and benthic communities. Samples were taken in 18 stations using a Van veen grab (0.1 m2) in Bahía Salsipuedes, Baja California in 2003, 2004, 2006 and 2008. Organisms belonging to 7 Phyla were collected: Polychaeta, Mollusca, Crustacea, Echinodermata, Cnidaria, Sipuncula and Bryozoa. Polychaetes were the dominant group followed by crustaceans and mollusks. Polychaetes were represented by 37 families and 157 species. Best represented families were Paraonidae, Cirratulidae, Spionidae, Glyceridae and Maldanidae. This study shows that in the NW area of the bay organic carbon (2.54%) and organic nitrogen (0.95%) are being accumulated (higher concentrations and lower Eh values) and smaller opportunistic species are increasing rapidly near the tuna pens. It is crucial to maintain "healthy" macrofaunal populations in order to enhance decomposition of organic matter and to prevent its excessive accumulation. The most abundant polychaete species were Aphelochaeta multifinis, Mediomastus ambiseta, Prionospio steenstrupi Spiophanes bombyx, Apoprionospio pygnaea, Paraonella sp, Monticellina sp, Aricidea (Allia) ramosa, Spiophanes bombyx and Levinsenia gracilis. The dominant trophic groups were deposit-feeders and carnivores. The buildup of organic matter on the seafloor has attracted scavenger species particularly peracarid crustaceans. Non-metric multidimensional scaling (MDS) separated stations depending of the distance to the tuna pens.

  13. Deep-sea faunal communities associated with a lost intermodal shipping container in the Monterey Bay National Marine Sanctuary, CA.

    Science.gov (United States)

    Taylor, Josi R; DeVogelaere, Andrew P; Burton, Erica J; Frey, Oren; Lundsten, Lonny; Kuhnz, Linda A; Whaling, P J; Lovera, Christopher; Buck, Kurt R; Barry, James P

    2014-06-15

    Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281 m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the container's exterior and the seabed within 10 m of the container differed significantly from those up to 500 m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10 m. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Environmental Parameters Affecting the Algal Diversity in a Sewage Water Treatment Plant

    International Nuclear Information System (INIS)

    Hammad, D.M.; Tawfik, T.A.; Ismail, G.A.; Abou El-Khair, W.S.; Abou El-Nour, F.

    2008-01-01

    The present investigation was carried out at a tertiary sewage water treatment plant located at El-Kattameya city, Cairo, Egypt, for a duration period of 12 months during 2004. The present work aimed to study the algal diversity (phyto benthos and phytoplankton) of the different tanks (collector, oxidation, settling and effluent) included in the tertiary sewage treatment system with respect to changes in physico-chemical characteristics of sewage water during the different seasons to be used for golf course irrigation. The treatment system is of the physico-biological type. Representing data of the physico-chemical parameters are air and water temperatures, ph, electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD), total suspended salts (TSS), total alkalinity, nutrients (nitrate, ammonia, phosphate, ortho-phosphorus, phosphorus and silicate), as well as major ions (calcium, potassium, sodium, magnesium, sulfate and chloride). In addition, the treatment efficiency of the system was evaluated and the suitability of using the effluent in irrigation purposes was discussed

  15. Diverse communities of active Bacteria and Archaea along oxygen gradients in coral reef sediments

    Science.gov (United States)

    Rusch, A.; Hannides, A. K.; Gaidos, E.

    2009-03-01

    Microbial communities inhabiting highly permeable sediments of Checker Reef in Kaneohe Bay, Hawaii, were characterized in relation to porewater geochemistry (O2, NO3 -, NO2 -, NH4 +, phosphate). The physiologically active part of the population, assessed by sequencing cDNA libraries of 16S rRNA amplicons, was very diverse, with an estimated ribotype richness ≥1,380 in anoxic sediment. Quantitative analysis of community structure by rRNA-targeted fluorescence in situ hybridization (FISH) indicated that the archaeal population (9-18%) was dominated by marine Crenarchaeota (5-9%). Planctomycetales were the most abundant group in the oxic and interfacial habitat (17-19%) but were a minority (<5%) in anoxic reef sediment, where γ-Proteobacteria were numerically dominant (18%). Another 9-14% of the microbial benthos belonged to β-Proteobacteria, predominantly within the order Nitrosomonadales, many cultured representatives of which are NH4 + oxidizers. The results of this study contribute to the phylogenetic characterization of benthic microbial communities that are important in organic matter degradation and nutrient recycling in coral reef ecosystems.

  16. Status of biodiversity in the Baltic Sea.

    Science.gov (United States)

    Ojaveer, Henn; Jaanus, Andres; Mackenzie, Brian R; Martin, Georg; Olenin, Sergej; Radziejewska, Teresa; Telesh, Irena; Zettler, Michael L; Zaiko, Anastasija

    2010-09-01

    The brackish Baltic Sea hosts species of various origins and environmental tolerances. These immigrated to the sea 10,000 to 15,000 years ago or have been introduced to the area over the relatively recent history of the system. The Baltic Sea has only one known endemic species. While information on some abiotic parameters extends back as long as five centuries and first quantitative snapshot data on biota (on exploited fish populations) originate generally from the same time, international coordination of research began in the early twentieth century. Continuous, annual Baltic Sea-wide long-term datasets on several organism groups (plankton, benthos, fish) are generally available since the mid-1950s. Based on a variety of available data sources (published papers, reports, grey literature, unpublished data), the Baltic Sea, incl. Kattegat, hosts altogether at least 6,065 species, including at least 1,700 phytoplankton, 442 phytobenthos, at least 1,199 zooplankton, at least 569 meiozoobenthos, 1,476 macrozoobenthos, at least 380 vertebrate parasites, about 200 fish, 3 seal, and 83 bird species. In general, but not in all organism groups, high sub-regional total species richness is associated with elevated salinity. Although in comparison with fully marine areas the Baltic Sea supports fewer species, several facets of the system's diversity remain underexplored to this day, such as micro-organisms, foraminiferans, meiobenthos and parasites. In the future, climate change and its interactions with multiple anthropogenic forcings are likely to have major impacts on the Baltic biodiversity.

  17. Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest

    Directory of Open Access Journals (Sweden)

    Hawkins Lawrence E

    2003-01-01

    Full Text Available Abstract Background The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. Results The taxonomic composition (at family to genus level of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. Conclusion The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described of the group. However, nematode ecology is in dire need of further study.

  18. Anti-inflammatory activity in selected Antarctic benthic organisms

    Directory of Open Access Journals (Sweden)

    Juan eMoles

    2014-07-01

    Full Text Available Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to test them for anti-inflammatory activity. From these, ethanol extracts of ten species from five different phyla resulted suitable to be studied in cell macrophage cultures (RAW 264.7. Cytotoxicity (MTT method and production of inflammatory mediators (prostaglandin E2, leukotriene B4, interleukin-1 were determined at three extract concentrations (50, 125, 250 g/mL. Bioassays resulted in four different species showing anti-inflammatory activity corresponding to three sponges: Mycale (Oxymycale acerata, Isodictya erinacea, and I. toxophila; and one hemichordate: Cephalodiscus sp. These results show that Antarctic sessile invertebrates may have great value as a source of lead compounds with potential pharmaceutical applications.

  19. Evaluation of brine disposal from the Bryan Mound site of the strategic petroleum reserve program. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Case, Robert J.; Chittenden, Jr, Mark E.; Harper, Jr, Donald E.; Kelly, Jr, Francis J.; Loeblich, Laurel A.; McKinney, Larry D.; Minello, Thomas J.; Park, E. Taisoo; Randall, Robert E.; Slowey, J. Frank

    1981-01-01

    On March 10, 1980, the Department of Energy's Strategic Petroleum Reserve Program began leaching the Bryan Mound salt dome and discharging the resulting brine into the coastal waters off Freeport, Texas. During the months of March and April, a team of scientists and engineers from Texas A and M University conducted an intensive environmental study of the area surrounding the diffuser site. A pipeline has been laid from the Bryan Mound site to a location 12.5 statute miles (20 km) offshore. The last 3060 ft (933 m) of this pipeline is a 52-port diffuser through which brine can be discharged at a maximum rate of 680,000 barrels per day. Initially, 16 ports were open which permitted a maximum discharge rate of 350,000 barrels per day and a continuous brine discharge was achieved on March 13, 1980. The purpose of this report is to describe the findings of the project team during the intensive postdisposal study period of March and April, 1980. The major areas of investigation are physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos, phytoplankton, zooplankton, and data management.

  20. Brominated diphenyl ethers in the sediments, porewater, and biota of the Chesapeake Bay, USA

    Energy Technology Data Exchange (ETDEWEB)

    Baker, K.; Klosterhaus, S.; Liebert, D.; Stapleton, H. [Maryland Univ., Solomons, MD (United States)

    2004-09-15

    Levels of brominated diphenyl ethers (BDEs) are rapidly increasing in the environment, and in a short time these chemicals have evolved from 'emerging contaminants' to globally-distributed organic pollutants. Recent research demonstrates BDEs are sufficiently stable to be transported long distances in the environment and to accumulate in higher trophic levels. Photolysis and metabolism appear to be dominant loss processes for the parent compounds, generating a variety of lower brominated diphenyl ethers, hydroxylated metabolites, and other products. BDEs are hydrophobic, and therefore their transport in aquatic systems is likely controlled by sorption to sediments and perhaps exchange across the air-water interface. To date, few studies have examined the geochemistry of BDEs in natural waters. In this paper, we review our recent measurements of BDEs in the Chesapeake Bay, a shallow, productive estuary in eastern North America. We focus on the distribution of BDE congeners sediment, porewater, and in faunal benthos along a contamination gradient downstream from a wastewater treatment plant and on the spatial distribution of BDEs in bottom-feeding and pelagic fish species.

  1. Stable isotopes reveal the effect of trawl fisheries on the diet of commercially exploited species.

    Science.gov (United States)

    Hinz, Hilmar; Moranta, Joan; Balestrini, Stephen; Sciberras, Marija; Pantin, Julia R; Monnington, James; Zalewski, Alex; Kaiser, Michel J; Sköld, Mattias; Jonsson, Patrik; Bastardie, Francois; Hiddink, Jan Geert

    2017-07-24

    Bottom trawling can change food availability for benthivorous demersal species by (i) changing benthic prey composition through physical seabed impacts and (ii) by removing overall benthic consumer biomass increasing the net availability of benthic prey for remaining individuals. Thus trawling may both negatively and positively influence the quantity and quality of food available. Using δ 13 C and δ 15 N we investigated potential diet changes of three commercially exploited species across trawling gradients in the Kattegat (plaice, dab and Norway lobster (Nephrops)) and the Irish Sea (Nephrops). In the Kattegat, trawling affected primarily the biomass of benthic consumers, lowering competition. Nephrops showed significant positive relationships for δ 13 C and a domed relationship for δ 15 N with trawling. In the Irish Sea, intense trawling had a negative effect on benthic prey. δ 13 C and δ 15 N thus showed the inverse relationships to those observed in the Kattegat. Plaice from the Kattegat, showed a significant relationship with trawling intensity for δ 13 C, but not for δ 15 N. No relationship was found for dab. Changes of δ 13 C and δ 15 N correlated with changes in condition of species. The results show that the removal of demersal competitors and benthos by trawling can change the diets of commercial species, ultimately affecting their body condition.

  2. Marine ostracod provinciality in the Late Ordovician of palaeocontinental Laurentia and its environmental and geographical expression.

    Directory of Open Access Journals (Sweden)

    Mohibullah Mohibullah

    Full Text Available BACKGROUND: We examine the environmental, climatic and geographical controls on tropical ostracod distribution in the marine Ordovician of North America. METHODOLOGY/PRINCIPAL FINDINGS: Analysis of the inter-regional distribution patterns of Ordovician Laurentian ostracods, focussing particularly on the diverse Late Ordovician Sandbian (ca 461 to 456 Ma faunas, demonstrates strong endemicity at the species-level. Local endemism is very pronounced, ranging from 25% (e.g. Foxe basin to 75% (e.g. Michigan basin in each basin, a pattern that is also reflected in other benthic faunas such as brachiopods. Multivariate (ordination analyses of the ostracod faunas allow demarcation of a Midcontinent Province and a southern Marginal Province in Laurentia. While these are most clearly differentiated at the stratigraphical level of the bicornis graptolite biozone, analyses of the entire dataset suggest that these provinces remain distinct throughout the Sandbian interval. Differences in species composition between the provinces appear to have been controlled by changes in physical parameters (e.g. temperature and salinity related to water depth and latitude and a possible regional geographic barrier, and these differences persist into the Katian and possibly the Hirnantian. Local environmental parameters, perhaps operating at the microhabitat scale, may have been significant in driving local speciation events from ancestor species in each region. CONCLUSIONS/SIGNIFICANCE: Our work establishes a refined methodology for assessing marine benthic arthropod micro-benthos provinciality for the Early Palaeozoic.

  3. Delta13C and delta15N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica.

    Science.gov (United States)

    Conlan, Kathleen E; Rau, Greg H; Kvitek, Rikk G

    2006-12-01

    In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic.

  4. δ13C and δ15N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica

    International Nuclear Information System (INIS)

    Conlan, Kathleen E. . E-mail kconlan@mus-nature.ca; Rau, Greg H.; Kvitek, Rikk G.

    2006-01-01

    In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic

  5. {delta}{sup 13}C and {delta}{sup 15}N shifts in benthic invertebrates exposed to sewage from McMurdo Station, Antarctica

    Energy Technology Data Exchange (ETDEWEB)

    Conlan, Kathleen E. [Canadian Musem of Nature, P.O. Box 3443 Station D, Ottawa, Ont., K1P 6P4 (Canada)]. E-mail kconlan@mus-nature.ca; Rau, Greg H. [Institute of Marine Sciences, University of California, Santa Cruz, CA 95064 (United States); Kvitek, Rikk G. [Earth Systems Science and Policy, California State University Monterey Bay, 100 Campus Center, Seaside, CA 93955 (United States)

    2006-12-15

    In an effort to identify biomonitors for contamination of Antarctic marine benthos by sewage, this study determines whether the US Antarctic Program's McMurdo Station produces a benthic sewage footprint and whether resident megafauna are assimilating sewage-derived material. We identified strong C and N isotopic gradients in benthic sediment as a function of downstream distance from McMurdo Station's point-source sewage addition. Sediment C and N isotope ratios approached marine background levels at the sampling end-point 612 m downcurrent. Based on isotope abundances in their tissues, at least some sewage C and N were assimilated by the sedentary, suspension feeding soft coral Alcyonium antarcticum, ascidian Cnemidocarpa verrucosa and bivalve Laternula elliptica. However, as inferred by tissue-sediment differences in downstream isotope trends, such assimilation was not in proportion to sewage exposure and input, therefore implying non-generalist feeding behavior by these species. In contrast, the motile, generalist feeding sea urchin Sterechinus neumayeri, sea star Odontaster validus and ribbon worm Parborlasia corrugatus showed isotopic evidence of sewage C and N assimilation roughly in proportion to sewage input. We recommend these generalist feeders for further use as biomonitors at this site now that sewage treatment has been implemented. As these species are circumpolar in distribution, they may also prove useful elsewhere in the Antarctic.

  6. The impact of heavy metal pollution gradients in sediments on benthic macrofauna at population and community levels

    International Nuclear Information System (INIS)

    Ryu, Jongseong; Khim, Jong Seong; Kang, Seong-Gil; Kang, Daeseok; Lee, Chang-hee; Koh, Chul-hwan

    2011-01-01

    The effect of sediment pollution on benthos was investigated in the vicinity of a large sewage treatment outflow at Incheon North Harbor, Korea. Animal size, vertical distribution and standard community parameters were analyzed along a 3 km transect line (n = 7). Univariate parameters showed a general trend of increasing species diversity with increasing distance from the pollution source. Multi-dimensional scaling analysis led to the clear separation of 3 locational groups, supporting gradient-dependent faunal composition. The innermost location was dominated by small sub-surface dwellers while the outer locations by large mid to deep burrowers. Looking for the size-frequency distribution, most abundance species (Heteromastus filiformis) showed the presence of larger size animals with increasing proximity to the pollution source. Meanwhile, species-specific vertical distributions, regardless of the pollution gradient, indicated that such shifts were due to species replacement resulting from a higher tolerance to pollutants over some species. - Highlights: → Hypotheses on benthic responses to sediment pollution were tested. → Decrease of species diversity with the proximity to the pollution source. → Shift of vertical distribution along the transect line attributes to species replacement. → Larger-size species occurred distant from the pollution source. → Larger individuals of Heteromastus filiformis occurred closer to the pollution source. - Community and population level response to the polluted environment of the harbor reflected an integration effect, together with biological interactions.

  7. Plankton of Southern Chilean fjords: trends and linkages

    Directory of Open Access Journals (Sweden)

    Tarcisio Antezana

    1999-12-01

    Full Text Available The present paper compiles and reviews past and recent results from Magellan and Fuegian fjords for an overview of the planktonic assemblage there. It first examines linkages to local, adjacent and remote environments. The plankton assemblage presents deviations from the biota of the Magellan biogeographic Province, where the occasional presence of Antarctic species is related to oceanographic phenomena at the Polar Front. Complex bathymetric and hydrographic features within the fjords suggest that the plankton is rather isolated. Adaptations and constraints for population survival, and the role of diel migrators and gregarious zooplankters with regard to bentho-pelagic coupling are discussed. Results on seasonal differences in the plankton of the largest and most isolated basin of the Strait of Magellan are compiled. In spring the plankton was dominated by large diatoms suggesting a short food chain where most of the phytoplankton bloom goes to the bottom, to the meroplankton and to a few dominant holoplankters. In summer, the phytoplankton was dominated by pico- and nanophytoplankton suggesting a more complex food web mediated by a bacterial loop. High abundance of holo- and meroplanktonic larvae coincided with spring blooming conditions.

  8. Structure-forming corals and sponges and their use as fish habitat in Bering Sea submarine canyons.

    Directory of Open Access Journals (Sweden)

    Robert J Miller

    Full Text Available Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide.

  9. Exobiology site selection for future Mars missions: Martian paleolake sediments and terrestrial analogs

    Science.gov (United States)

    Wharton, Robert A., Jr.

    1989-11-01

    This research was conducted to establish the scientific framework for the exobiological study of sediments on Mars and to encourage the selection of these sedimentary deposits as sampling sites for future Mars missions. A study was completed on the Antarctic Dry Valley Lakes (terrestrial analogs of the purported Martian paleolakes) and their sediments that allowed the development of quantitative models relating environmental factors to the nature of the biological community and sediment forming processes. The publications presented include: (1) Diversity of micro-fungi isolated in an Antarctic dry valley; (2) Lake Hoare, Antarctica--sedimentation through a thick perennial ice cover; (3) The possibility of life on Mars during a water-rich past; (4) An Antarctic research outpost as a model for planetary exploration; (5) Early Martian environments--the Antarctic and other terrestrial analogs; (6) Lipophilic pigments from the benthos of a perennially ice-covered Antarctic lake; and (7) Perennially ice-covered Lake Hoare, Antarctica--physical environment, biology, and sedimentation.

  10. High frequency sampling of the 1984 spring bloom within the mid-Atlantic Bight: Synoptic shipboard, aircraft, and in situ perspectives of the SEEP-I experiment

    Science.gov (United States)

    Walsh, J. J.; Wirick, C. D.; Pietrafesa, L. J.; Whitledge, T. E.; Hoge, F. E.; Swift, R. N.

    1986-01-01

    Moorings of current meters, thermistors, transmissometers, and fluorometers on the mid-Atlantic shelf, south of Long Island, suggest a cumulative seaward export of perhaps 0.35 g C/sq m/day between the 80 and 120 m isobaths during February-April 1984. Such a horizontal loss of algal carbon over the lower third of the water column would be 23 to 78% of the March-April 1984 primary production. This physical carbon loss is similar to daily grazing losses from zooplankton of 32-40% of the algal fixation of carbon. Metabolic demands of the benthos could be met by just the estimated fecal pellet flux, without direct consumption of algal carbon, while bacterioplankton needs could be served by excretory release of dissolved organic matter during photosynthesis. Sediment traps tethered 10 m off the bottom at the 120 m isobath and 50 m above the 500 m isobath caught as much as 0.16 to 0.26 g C /sq m/day during March-April 1984, in reasonable agreement with the flux estimated from the other moored instruments.

  11. Different Oceanographic Regimes in the Vicinity of the Antarctic Peninsula Reflected in Benthic Nematode Communities.

    Directory of Open Access Journals (Sweden)

    Freija Hauquier

    Full Text Available Marine free-living nematode communities were studied at similar depths (~500 m at two sides of the Antarctic Peninsula, characterised by different environmental and oceanographic conditions. At the Weddell Sea side, benthic communities are influenced by cold deep-water formation and seasonal sea-ice conditions, whereas the Drake Passage side experiences milder oceanic conditions and strong dynamics of the Antarctic Circumpolar Current. This resulted in different surface primary productivity, which contrasted with observed benthic pigment patterns and varied according to the area studied: chlorophyll a concentrations (as a proxy for primary production were high in the Weddell Sea sediments, but low in the surface waters above; this pattern was reversed in the Drake Passage. Differences between areas were largely mirrored by the nematode communities: nematode densities peaked in Weddell stations and showed deeper vertical occurrence in the sediment, associated with deeper penetration of chlorophyll a and indicative of a strong bentho-pelagic coupling. Generic composition showed some similarities across both areas, though differences in the relative contribution of certain genera were noted, together with distinct community shifts with depth in the sediment at all locations.

  12. Managing an invasive corallimorph at Palmyra Atoll National Wildlife Refuge, Line Islands, Central Pacific

    Science.gov (United States)

    Work, Thierry M.; Aeby, Greta S.; Neal, Benjamin P.; Price, Nichole N.; Conklin, Eric; Pollock, Amanda

    2018-01-01

    In 2007, a phase shift from corals to corallimorpharians (CM) centered around a shipwreck was documented at Palmyra Atoll, Line Islands. Subsequent surveys revealed CM to be overgrowing the reef benthos, including corals and coralline algae, potentially placing coral ecosystems in the atoll at risk. This prompted the U.S. Fish and Wildlife Service, the lead management agency of the atoll, to remove the shipwreck. Subsequent surveys showed reductions in CM around the ship impact site. We explain patterns of spread of the CM in terms of both life history and local currents and show with a pilot study that pulverized bleach may be an effective tool to eradicate CM on a local scale. If applied strategically, particularly in heavily infested (> 66% cover) areas, active intervention such as this could be an effective management tool to reduce CM impact on localized areas and decrease colonization rate of remaining reefs. This is the first documentation of the response of an invasive cnidarian to shipwreck removal. While this was a singular event in Palmyra, the spatial and temporal patterns of this invasion and the eradications lessons described herein, are useful for anticipating and controlling similar situations elsewhere.

  13. Alimentación de Microthrissa congica (Osteichthyes: Clupeidae en la cuenca alta del río Congo (África

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    Godefroid Mambyanga Mokoma

    1999-12-01

    Full Text Available Mensualmente durante un año, se estudió la alimentación de Microthrissa congica en la cuenca alta del Río Congo, mediante el análisis de contenidos estomacales de ejemplares adultos. De acuerdo con la frecuencia de aparición, las ninfas de quironómidos constituyen la base de su alimentación durante todo el año. La importancia de los insectos de origen terrestre aumenta durante la época de lluvias, momento en que aumenta la amplitud del nicho. Estos resultados demuestran que este clupeido es una especie insectívora pelágica, utilizando muy poco el bentos como fuente de alimento.The feeding habits of the fish Microthrissa congica were studied for a year in the upper Congo river basin, by monthly analysis of stomach contents of adult specimens (N= 460. The nymphs of chironomid midges represented the bulk of the diet throughout most of the year, although terrestrial insects became more abundant in the rainy season. Niche breadth also increased in the wet season. This species feeds mainly in the water column and benthos is not an important food source.

  14. Effects of fish removal in the Furnas Lake, Azores

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    Bio, A.

    2008-01-01

    Full Text Available The Furnas Lake is a small volcanic, monomitic and increasingly eutrophised water body. Next to agricultural nutrient inputs, high densities of herbivorous fish are thought to contribute to high levels of turbidity in the lake, through zooplankton consumption and re suspension of the nutrients accumulated in the sediment. According to the alternative state hypothesis a shift from turbid to clear water conditions is favoured by reduction of nutrient concentrations, increased light availability and reduction of planktivorous and benthos-feeding fish stock. To improve water quality in the Furnas Lake, a substantial part of the bottom-feeding fish population (62% of the estimated common carp population, Cyprinus carpio, and 5% of the estimated roach population, Rutilus rutilus was removed. Effects of fish removal on turbidity and associated trophic state were analysed next to post-manipulation chlorophyll a concentration, zooplankton and macrophytes densities. Results suggest that fish removal was not enough to change lake conditions towards a lasting clear state dominated by macrophytes. Excessive nutrient load, in water and sediments, nutrient input from the lake basin and fish recruitment causing enhanced zooplankton grazing are appointed causes. Any further biomanipulation efforts should be associated to nutrient reduction; and continued monitoring of water quality, fish stock, macrophytes and zooplankton is needed.

  15. Bioassay of Lake Onego bottom sediments toxicity based on their chemical composition and deepwater macrozoobenthos state

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    Kalinkina Nataliya Michailovna

    2017-03-01

    Full Text Available The bioassay of the toxicity of bottom sediments sampled in different areas of Lake Onega was carried out by crustaceans biotesting (Ceriodaphnia affinis Lillijeborg. It was shown that in the most areas of Lake Onega there are non-toxic bottom sediments. Toxic bottom sediments were found in Kondopogskaya Bay, intensively polluted with pulp-and-paper mill wastewaters. For the first time in the deep central part of Lake Onega the area was revealed where the toxic bottom sediments contain a high content of iron, manganese and other trace elements typical for the central areas of the lake. The mapping of the bottom of Lake Onega was accomplished, and three zones were identified based on the analysis of the data concerning the chemical composition of bottom sediments, bioassay toxicity data and the results of the deepwater macrozoobenthos assessment. For each zone the parameters of the main groups of benthos (Amphipoda, Oligochaeta, Chironomidae were defined. The first zone is located in the area of intensive anthropogenic influence (Kondopogskaya Bay, Petrozavodskaya Bay, Povenets Bay, Kizhi Skerries. The second zone is located mostly in the deep part of Petrozavodskaya Bay, where the most intensive development of amphipods is observed. The third area is identified for the first time: it is located in the central deep part of Lake Onega, where the communities of macrozoobenthos are limited by a natural toxic factor.

  16. Comparison of passive sampling and biota for monitoring of tonalide in aquatic environment.

    Science.gov (United States)

    Tumova, Jitka; Grabicova, Katerina; Golovko, Oksana; Koba, Olga; Kodes, Vit; Fedorova, Ganna; Grabic, Roman; Kroupova, Hana Kocour

    2017-10-01

    Synthetic musk compounds are extensively used in personal care and cosmetic products all over the world. Afterwards, they are discharged into the environment mainly because they are not completely removed in wastewater treatment plants. The aim of this study was to investigate if a passive sampler is applicable for the monitoring of tonalide, a polycyclic musk compound, in the aquatic environment and to compare the levels of tonalide in pesticide-polar organic chemical integrative sampler (POCIS) and biota. For this purpose, four sampling localities on the three biggest rivers in the Czech Republic were selected. Tonalide was determined in POCIS at all sampling sites in the concentration ranging from 9 ng/POCIS (Labe River, Hradec Králové) to 25 ng/POCIS (Morava River, Blatec). The locality with the most frequent occurrence of tonalide in biota samples was the Morava River which well corresponded with the highest tonalide concentration in POCIS among sampling sites. The highest number of positive tonalide detections among all studied biota samples was found in fish plasma. To the best of our knowledge, this is the first evidence that tonalide bioaccumulates in fish blood. Tonalide levels were below the limit of quantification in benthos samples at all sampling sites.

  17. Modelling benthic biophysical drivers of ecosystem structure and biogeochemical response

    Science.gov (United States)

    Stephens, Nicholas; Bruggeman, Jorn; Lessin, Gennadi; Allen, Icarus

    2016-04-01

    The fate of carbon deposited at the sea floor is ultimately decided by biophysical drivers that control the efficiency of remineralisation and timescale of carbon burial in sediments. Specifically, these drivers include bioturbation through ingestion and movement, burrow-flushing and sediment reworking, which enhance vertical particulate transport and solute diffusion. Unfortunately, these processes are rarely satisfactorily resolved in models. To address this, a benthic model that explicitly describes the vertical position of biology (e.g., habitats) and biogeochemical processes is presented that includes biological functionality and biogeochemical response capturing changes in ecosystem structure, benthic-pelagic fluxes and biodiversity on inter-annual timescales. This is demonstrated by the model's ability to reproduce temporal variability in benthic infauna, vertical pore water nutrients and pelagic-benthic solute fluxes compared to in-situ data. A key advance is the replacement of bulk parameterisation of bioturbation by explicit description of the bio-physical processes responsible. This permits direct comparison with observations and determination of key parameters in experiments. Crucially, the model resolves the two-way interaction between sediment biogeochemistry and ecology, allowing exploration of the benthic response to changing environmental conditions, the importance of infaunal functional traits in shaping benthic ecological structure and the feedback the resulting bio-physical processes exert on pore water nutrient profiles. The model is actively being used to understand shelf sea carbon cycling, the response of the benthos to climatic change, food provision and other societal benefits.

  18. Biodiversity of nematode assemblages from the region of the Clarion-Clipperton Fracture Zone, an area of commercial mining interest.

    Science.gov (United States)

    Lambshead, P John D; Brown, Caroline J; Ferrero, Timothy J; Hawkins, Lawrence E; Smith, Craig R; Mitchell, Nicola J

    2003-01-09

    The possibility for commercial mining of deep-sea manganese nodules is currently under exploration in the abyssal Clarion-Clipperton Fracture Zone. Nematodes have potential for biomonitoring of the impact of commercial activity but the natural biodiversity is unknown. We investigate the feasibility of nematodes as biomonitoring organisms and give information about their natural biodiversity. The taxonomic composition (at family to genus level) of the nematode fauna in the abyssal Pacific is similar, but not identical to, the North Atlantic. Given the immature state of marine nematode taxonomy, it is not possible to comment on the commonality or otherwise of species between oceans. The between basin differences do not appear to be directly linked to current ecological factors. The abyssal Pacific region (including the Fracture Zone) could be divided into two biodiversity subregions that conform to variations in the linked factors of flux to the benthos and of sedimentary characteristics. Richer biodiversity is associated with areas of known phytodetritus input and higher organic-carbon flux. Despite high reported sample diversity, estimated regional diversity is less than 400 species. The estimated regional diversity of the CCFZ is a tractable figure for biomonitoring of commercial activities in this region using marine nematodes, despite the immature taxonomy (i.e. most marine species have not been described) of the group. However, nematode ecology is in dire need of further study.

  19. Evaluation of body weight of sea cucumber Apostichopus japonicus by computer vision

    Science.gov (United States)

    Liu, Hui; Xu, Qiang; Liu, Shilin; Zhang, Libin; Yang, Hongsheng

    2015-01-01

    A postichopus japonicus (Holothuroidea, Echinodermata) is an ecological and economic species in East Asia. Conventional biometric monitoring method includes diving for samples and weighing above water, with highly variable in weight measurement due to variation in the quantity of water in the respiratory tree and intestinal content of this species. Recently, video survey method has been applied widely in biometric detection on underwater benthos. However, because of the high flexibility of A. japonicus body, video survey method of monitoring is less used in sea cucumber. In this study, we designed a model to evaluate the wet weight of A. japonicus, using machine vision technology combined with a support vector machine (SVM) that can be used in field surveys on the A. japonicus population. Continuous dorsal images of free-moving A. japonicus individuals in seawater were captured, which also allows for the development of images of the core body edge as well as thorn segmentation. Parameters that include body length, body breadth, perimeter and area, were extracted from the core body edge images and used in SVM regression, to predict the weight of A. japonicus and for comparison with a power model. Results indicate that the use of SVM for predicting the weight of 33 A. japonicus individuals is accurate ( R 2=0.99) and compatible with the power model ( R 2 =0.96). The image-based analysis and size-weight regression models in this study may be useful in body weight evaluation of A. japonicus in lab and field study.

  20. New technology reveals the role of giant larvaceans in oceanic carbon cycling.

    Science.gov (United States)

    Katija, Kakani; Sherlock, Rob E; Sherman, Alana D; Robison, Bruce H

    2017-05-01

    To accurately assess the impacts of climate change on our planet, modeling of oceanic systems and understanding how atmospheric carbon is transported from surface waters to the deep benthos are required. The biological pump drives the transport of carbon through the ocean's depths, and the rates at which carbon is removed and sequestered are often dependent on the grazing abilities of surface and midwater organisms. Some of the most effective and abundant midwater grazers are filter-feeding invertebrates. Although the impact of smaller, near-surface filter feeders is generally known, efforts to quantify the impact of deeper filter feeders, such as giant larvaceans, have been unsuccessful. Giant larvaceans occupy the upper 400 m of the water column, where they build complex mucus filtering structures that reach diameters greater than 1 m. Because of the fragility of these structures, direct measurements of filtration rates require in situ methods. Hence, we developed DeepPIV, an instrument deployed from a remotely operated vehicle that enables the direct measurement of in situ filtration rates. The rates measured for giant larvaceans exceed those of any other zooplankton filter feeder. Given these filtration rates and abundance data from a 22-year time series, the grazing impact of giant larvaceans far exceeds previous estimates, with the potential for processing their 200-m principal depth range in Monterey Bay in as little as 13 days. Technologies such as DeepPIV will enable more accurate assessments of the long-term removal of atmospheric carbon by deep-water biota.

  1. Ecological Status of a Patagonian Mountain River: Usefulness of Environmental and Biotic Metrics for Rehabilitation Assessment

    Science.gov (United States)

    Laura, Miserendino M.; Adriana, M. Kutschker; Cecilia, Brand; La Ludmila, Manna; Cecilia, Prinzio Y. Di; Gabriela, Papazian; José, Bava

    2016-06-01

    This work evaluates the consequences of anthropogenic pressures at different sections of a Patagonian mountain river using a set of environmental and biological measures. A map of risk of soil erosion at a basin scale was also produced. The study was conducted at 12 sites along the Percy River system, where physicochemical parameters, riparian ecosystem quality, habitat condition, plants, and macroinvertebrates were investigated. While livestock and wood collection, the dominant activities at upper and mean basin sites resulted in an important loss of the forest cover still the riparian ecosystem remains in a relatively good status of conservation, as do the in-stream habitat conditions and physicochemical features. Besides, most indicators based on macroinvertebrates revealed that both upper and middle basin sections supported similar assemblages, richness, density, and most functional feeding group attributes. Instead, the lower urbanized basin showed increases in conductivity and nutrient values, poor quality in the riparian ecosystem, and habitat condition. According to the multivariate analysis, ammonia level, elevation, current velocity, and habitat conditions had explanatory power on benthos assemblages. Discharge, naturalness of the river channel, flood plain morphology, conservation status, and percent of urban areas were important moderators of plant composition. Finally, although the present land use in the basin would not produce a significant risk of soil erosion, unsustainable practices that promotes the substitution of the forest for shrubs would lead to severe consequences. Mitigation efforts should be directed to protect headwater forest, restore altered riparian ecosystem, and to control the incipient eutrophication process.

  2. Structure-Forming Corals and Sponges and Their Use as Fish Habitat in Bering Sea Submarine Canyons

    Science.gov (United States)

    Miller, Robert J.; Hocevar, John; Stone, Robert P.; Fedorov, Dmitry V.

    2012-01-01

    Continental margins are dynamic, heterogeneous settings that can include canyons, seamounts, and banks. Two of the largest canyons in the world, Zhemchug and Pribilof, cut into the edge of the continental shelf in the southeastern Bering Sea. Here currents and upwelling interact to produce a highly productive area, termed the Green Belt, that supports an abundance of fishes and squids as well as birds and marine mammals. We show that in some areas the floor of these canyons harbors high densities of gorgonian and pennatulacean corals and sponges, likely due to enhanced surface productivity, benthic currents and seafloor topography. Rockfishes, including the commercially important Pacific ocean perch, Sebastes alutus, were associated with corals and sponges as well as with isolated boulders. Sculpins, poachers and pleuronectid flounders were also associated with corals in Pribilof Canyon, where corals were most abundant. Fishes likely use corals and sponges as sources of vertical relief, which may harbor prey as well as provide shelter from predators. Boulders may be equivalent habitat in this regard, but are sparse in the canyons, strongly suggesting that biogenic structure is important fish habitat. Evidence of disturbance to the benthos from fishing activities was observed in these remote canyons. Bottom trawling and other benthic fishing gear has been shown to damage corals and sponges that may be very slow to recover from such disturbance. Regulation of these destructive practices is key to conservation of benthic habitats in these canyons and the ecosystem services they provide. PMID:22470486

  3. Trophic Dynamics of Deep-Sea Megabenthos Are Mediated by Surface Productivity

    Science.gov (United States)

    Tecchio, Samuele; van Oevelen, Dick; Soetaert, Karline; Navarro, Joan; Ramírez-Llodra, Eva

    2013-01-01

    Most deep-sea benthic ecosystems are food limited and, in the majority of cases, are driven by the organic matter falling from the surface or advected downslope. Species may adapt to this scarceness by applying a wide variety of responses, such as feeding specialisation, niche width variation, and reduction in metabolic rates. The Mediterranean Sea hosts a gradient of food availability at the deep seafloor over its wide longitudinal transect. In the Mediterranean, broad regional studies on trophic habits are almost absent, and the response of deep-sea benthos to different trophic conditions is still speculative. Here, we show that both primary and secondary production processes taking place at surface layers are key drivers of deep-sea food web structuring. By employing an innovative statistical tool, we interpreted bulk-tissue δ13C and δ15N isotope ratios in benthic megafauna, and associated surface and mesopelagic components from the 3 basins of the Mediterranean Sea at 3 different depths (1200, 2000, and 3000 m). The trophic niche width and the amplitude of primary carbon sources were positively correlated with both primary and secondary surface production indicators. Moreover, mesopelagic organic matter utilization processes showed an intermediate position between surface and deep benthic components. These results shed light on the understanding of deep-sea ecosystems functioning and, at the same time, they demand further investigation. PMID:23691098

  4. Notes on some sertulariid hydroids (Cnidaria: Hydrozoa from the tropical western Pacific, with descriptions of nine new species

    Directory of Open Access Journals (Sweden)

    Horia R. Galea

    2016-08-01

    Full Text Available Forty-three species of sertulariid hydroids (Cnidaria: Hydrozoa: Sertulariidae, collected from the tropical western Pacific (Taiwan, Philippines, New Caledonia, French Polynesia, Vanuatu, Fiji, Tonga, Solomon Islands during various expeditions of the French Tropical Deep-Sea Benthos program, are discussed. Of these, nine are new to science: Gonaxia nova sp. nov., G. plumularioides sp. nov., Sertularella folliformis sp. nov., Se. plicata sp. nov., Se. pseudocatena sp. nov., Se. splendida sp. nov., Se. tronconica sp. nov., Se. tubulosa sp. nov., and Symplectoscyphus paucicatillus sp. nov. The subspecies Symplectoscyphus johnstoni (Gray, 1843 tropicus Vervoort, 1993 is raised to species but, in order to avoid the secondary homonymy with Sy. tropicus (Hartlaub, 1901, the replacement name, Sy. fasciculatus nom. nov., is introduced. The male and female gonothecae of Diphasia cristata Billard, 1920, the male gonothecae of Gonaxia elegans Vervoort, 1993, as well as the female gonothecae of Salacia macer Vervoort & Watson, 2003, are described for the first time. Additional notes on the morphology of several other species are provided. All taxa are illustrated, in most cases using figures drawn at the same scale, so as to highlight the differences between related species.

  5. Behaviour of fish by-catch in the mouth of a crustacean trawl.

    Science.gov (United States)

    Queirolo, D; Gaete, E; Montenegro, I; Soriguer, M C; Erzini, K

    2012-06-01

    The behaviour of fish by-catch was recorded and characterized by in situ observations in the mouth of a crustacean trawl using an underwater camera system with artificial light, at depths between 106 and 461 m, along the central coast of Chile. The groups or species studied were rattails (family Macrouridae), Chilean hake Merluccius gayi gayi, sharks (orders Carcharhiniformes and Squaliformes), skates (family Rajidae), flatfishes (genus Hippoglossina) and small benthopelagic and demersal fishes (orders Osmeriformes, Stomiiformes, Gadiformes, Ophidiiformes and Perciformes). The fish behaviour was categorized in terms of (1) position in the water column, (2) initial orientation with respect to the trawl, (3) locomotion and (4) swimming speed with respect to the trawl. Rattails, sharks, skates and flatfishes were passive in response to the trawl and showed similar behavioural patterns, with most fishes observed sitting or touching the bottom with no swimming or other activity. Merluccius gayi gayi was the most active species, displaying a wide combination of behavioural responses when the trawl approached. This species showed several behavioural patterns, mainly characterized by swimming forward at variable speed. A fraction of small bentho-pelagic and demersal fishes also showed an active behaviour but always at lower speed than the trawl. The species-specific differences in behaviour in the mouth of the trawl suggest that improvements at the level of the footrope can be made to reduce by-catch, especially of passive species. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

  6. Re-evaluating the health of coral reef communities: baselines and evidence for human impacts across the central Pacific.

    Science.gov (United States)

    Smith, Jennifer E; Brainard, Rusty; Carter, Amanda; Grillo, Saray; Edwards, Clinton; Harris, Jill; Lewis, Levi; Obura, David; Rohwer, Forest; Sala, Enric; Vroom, Peter S; Sandin, Stuart

    2016-01-13

    Numerous studies have documented declines in the abundance of reef-building corals over the last several decades and in some but not all cases, phase shifts to dominance by macroalgae have occurred. These assessments, however, often ignore the remainder of the benthos and thus provide limited information on the present-day structure and function of coral reef communities. Here, using an unprecedentedly large dataset collected within the last 10 years across 56 islands spanning five archipelagos in the central Pacific, we examine how benthic reef communities differ in the presence and absence of human populations. Using islands as replicates, we examine whether benthic community structure is associated with human habitation within and among archipelagos and across latitude. While there was no evidence for coral to macroalgal phase shifts across our dataset we did find that the majority of reefs on inhabited islands were dominated by fleshy non-reef-building organisms (turf algae, fleshy macroalgae and non-calcifying invertebrates). By contrast, benthic communities from uninhabited islands were more variable but in general supported more calcifiers and active reef builders (stony corals and crustose coralline algae). Our results suggest that cumulative human impacts across the central Pacific may be causing a reduction in the abundance of reef builders resulting in island scale phase shifts to dominance by fleshy organisms. © 2016 The Author(s).

  7. Drowned reefs and carbonate platforms: reef-community disruption by nutrients provides a clue to the paradox

    Energy Technology Data Exchange (ETDEWEB)

    Hallock, P.

    1985-01-01

    Growth rates of corals on Holocene reefs indicate that carbonate platforms should easily keep pace with long-term subsidence and sea-level changes, yet drowned reefs and platforms are common in the geologic record. Recognition of the influence of nutrients in reef communities provides a clue to that paradox. Coral reefs are ecosystems adapted to nutrient-deficient environments. Input of nitrates and phosphates stimulates growth of plankton and, in the benthos, of fleshy algae and suspension-feeding animals such as bryozoans, barnacles, boring bivalves, sponges and tunicates. These fast-growing organisms not only displace the hermatypic algae and corals that produce most of the carbonate, but many are bioeroders that actively destroy the reefal structure. Nutrient enrichment can result from either runoff or upwelling. Thus, not only are terrigenous sediments detrimental to reefs, but suppression of reef development by nutrients carried in runoff from land can extend well beyond the range of sediment influx. Understanding that increased organic productivity disrupts reefal communities and curtails carbonate production provides important new insights for paleoenvironmental interpretations. Carbonate platforms that have succumbed to upwelled nutrients may include those whose drownings coincide with times of increasing deep-ocean circulation.

  8. Diel feeding ecology of Slimy Sculpin in a tributary to Skaneateles Lake, New York

    Science.gov (United States)

    Chalupnicki, Marc A.; Johnson, James H.

    2016-01-01

    Interactions among the benthic community are typically overlooked but play an important role in fish community dynamics. We examined the diel feeding ecology of Slimy Sculpin (Cottus cognatus) from Grout Brook, a tributary to Skaneateles Lake. Of the six time periods examined, Slimy Sculpin consumed the least during the nighttime (2400 h and 0400 h). Chironomids were the major prey consumed during all time periods except for 2400 h when ephemeropterans were the major prey consumed. There was a moderate preference by Slimy Sculpin for food from the benthos (0.59 ± 0.06) with Diptera (Chironomids), Ephemeroptera (Baetidae), and Trichoptera (Brachycentridae) representing the major taxa. Slimy Sculpin appear to be opportunistic feeders selecting what is most available in the brook. Index of fullness was variable and averaged 1.15% across the diel cycle. Daily ration was measured as a function of fish dry body weight and ranged from 0.12 to 0.22. Estimates of daily consumption ranged from 0.007% to 4.0% of body weight, which corresponds to reports for other species. These findings have application in gauging the relative importance of Slimy Sculpin in streams where highly valued salmonid species also occur.

  9. Endemic Lake Baikal sponges from deep water. 1: Potential cryptic speciation and discovery of living species known only from fossils.

    Science.gov (United States)

    Itskovich, Valeria B; Kaluzhnaya, Oxana V; Veynberg, Elena; Erpenbeck, Dirk

    2015-07-23

    We revealed new deep-water species and cryptic speciation within freshwater sponges of the endemic family Lubomirskiidae (Porifera; Demospongiae; Spongillina) based on molecular and spicule morphology analyses of ITS and CO1 mtDNA. Lubomirskiidae contains a group of closely related species which are a dominant component of the benthos in Lake Baikal, the world's deepest and most ancient lake. Spicule morphology was similar between two Recent samples and species only known previously from fossils in Late Pliocene (3.2-2.8 mya) sediments. Despite the morphological similarity with the cosmopolitan family Spongillidae, molecular analysis of ITS sequences has reliably assigned these species to Lubomirskiidae. This not only indicates that species identification of freshwater fossil sponge spicules should be made with caution, but also suggests that the structure of megascleres may not be a reliable character for interpretations of paleoclimatic reconstructions for the Baikal region. Our results do not support the current classification of Lubomirskiidae into its morphologically defined genera and species, suggesting a strong discrepancy between molecular and morphological variation in Baikalian sponges. This present contribution is the first part of a study on the phylogenetic relationships of the Lake Baikal deep water sponge fauna.

  10. Bioassessment of Choghakhor Wetland using Benthic Macroinvertebrates

    Directory of Open Access Journals (Sweden)

    P. Fathi

    2016-05-01

    Full Text Available In present study, besides investigating benthic communities and their demographics in Choghakhor wetland, the water quality has been evaluated and classified. Then, 10 stations were selected and sampling of benthos was done every 45 days since April 2010 to March 2011, with 3 replications at each station. Samples were obtained by Ekman grab Sampler (surface 400 cm2. The collected samples were separated and fixed by formalin (4%. The Macroinvertebrates samples were identified and counted in laboratory. Generally 25 families of benthic macroinvertebrates belonging to 5 classes and 12 orders were identified. The results were calculated as community measures, including total richness, Shannon - Wiener diversity index and Hilsenhoff Biological index at family level. The results obtained from temporal and spatial changes of data (Statgeraphics software and water qualitative classification using Shannon diversity index conformed to biological Hilsenhoff index. And finally, water quality of wetland was assessed to be polluted in average to high level. According to this study findings, it seems that, these indicators could be used as useful tools for evaluating water supplies quality.

  11. Response of stream benthic macroinvertebrates to current water management in Alpine catchments massively developed for hydropower.

    Science.gov (United States)

    Quadroni, Silvia; Crosa, Giuseppe; Gentili, Gaetano; Espa, Paolo

    2017-12-31

    The present work focuses on evaluating the ecological effects of hydropower-induced streamflow alteration within four catchments in the central Italian Alps. Downstream from the water diversions, minimum flows are released as an environmental protection measure, ranging approximately from 5 to 10% of the mean annual natural flow estimated at the intake section. Benthic macroinvertebrates as well as daily averaged streamflow were monitored for five years at twenty regulated stream reaches, and possible relationships between benthos-based stream quality metrics and environmental variables were investigated. Despite the non-negligible inter-site differences in basic streamflow metrics, benthic macroinvertebrate communities were generally dominated by few highly resilient taxa. The highest level of diversity was detected at sites where upstream minimum flow exceedance is higher and further anthropogenic pressures (other than hydropower) are lower. However, according to the current Italian normative index, the ecological quality was good/high on average at all of the investigated reaches, thus complying the Water Framework Directive standards. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Factors Effecting Adsorption of 137 Cs in Marine Sediment Samples in Marine Sediment Samples from the Upper Gulf of Thailand

    International Nuclear Information System (INIS)

    Saengkul, C.; Sawangwong, P.; Pakkong, P.

    2014-01-01

    Contamination of 137 Cs in sediment is a far more serious problem than in water because sediment is a main transport factor of 137 Cs to the aquatic environmental. Most of 137 Cs in water could be accumulated in sediment which has direct effect to benthos. This study focused on factors effecting the adsorption of 137Cs in marine sediment samples collected from four different estuary sites to assess the transfer direction of 137 Cs from water to sediment that the study method by treat 137 Cs into seawater and mixed with different sediment samples for 4 days. The result indicated that properties of marine sediment (cation exchange capacity (CEC), organic matter, clay content, texture, type of clay mineral and size of soil particle) had effects on 137 Cs adsorption. CEC and clay content correlated positively with the accumulation of 137 Cs in the marine sediment samples. On the other hand, organic matter in sediment correlated negatively with the accumulation of 137 Cs in samples. The study of environmental effects (pH and potassium) found that the 137 Cs adsorption decreased when concentration of potassium increased. The pH effect is still unclear in this study because the differentiation of pH levels (6, 7, 8.3) did not have effects on 137 Cs adsorption in the samples.

  13. Modelling and forecasting long-term dynamics of Western Baltic macrobenthic fauna in relation to climate signals and environmental change

    Science.gov (United States)

    Gröger, Joachim; Rumohr, Heye

    2006-05-01

    Long-term macrobenthos data from Kiel Bight in the Western Baltic collected between 1968 and 2000 have been correlated with the winter NAO index (North Atlantic Oscillation Index) and other environmental data such as temperature, salinity and oxygen content in the bottom water in order to detect systematic patterns related to so far unexplained abiotic signals in the dynamics of zoobenthic species assemblages. The benthos data come from a cluster of five stations (Süderfahrt/ Millionenviertel) in Kiel Bay. Our investigations concentrated on the macrobenthic dynamics with a focus on the number of species m - 2 (species richness). Using logarithms and the time series analysis approach of Box/Jenkins (ARIMA modelling, transfer function modelling) it was shown that species richness was strongly influenced by the winter NAO (adjusted for a linear time trend within the 1968-2000 period) and salinity (with a shift/lag of four years). Bootstrapping experiments (i.e. sampling from the error process) and analysis of prediction power (by means of the one- or more-years leaving-out method) showed that the parameter estimates behaved in a stable way, leading to a relatively robust model.

  14. Determination of heavy metals in macrozoobenthos from the rivers Tisza and Szamos by total reflection X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Woelfl, S. [Universidad Austral de Chile, Instituto de Zoologia, Casilla 567, Valdivia (Chile)]. E-mail: swoelfl@uach.cl; Mages, M. [Helmhotz Centre for Environmental Research (UFZ), Department of River Ecology, Brueckstrasse 3a, D-39114, Magdeburg (Germany); Ovari, M. [Ovari, M. Eoetvoes University, Department of Organic Chemistry, H-1117, Budapest, Pazmany P. stny. 1/a (Hungary); Geller, W. [Helmhotz Centre for Environmental Research (UFZ), Department of River Ecology, Brueckstrasse 3a, D-39114, Magdeburg (Germany)

    2006-11-15

    In 2000, accidents in the Romanian mining industry in key catchment areas led to heavy metal contamination of the Hungarian rivers Tisza and Szamos resulting in substantial heavy metal loads in several sediments of the upper river basins. This enhanced metal content might have been bioaccumulated in benthic organisms during the following years. Therefore, the aim of this study was to test, whether the zoobenthic fauna showed an enhanced metal content 3 years after the industrial accident. Macrozoobenthic insect larvae (chironomids) were sampled 100 m below and above the confluent site of the rivers Tisza and Szamos during summer 2003 and for comparison purpose also in the river Maros, a tributary of the Tisza river, during 2005. In order to determine their heavy metal content, single specimens were prepared and analysed by Total Reflection X-ray Fluorescence Spectrometry (TRXF) according to the modified dry method. Fe was much lower and Mn and Zn much higher concentrated in benthos from the more contaminated Szamos river compared to the Tisza and Maros rivers. In this sense, the benthic organisms reflected very well the enhanced metal concentrations in the contaminated rivers being suitable as bioindicators of metal contamination. However, the sediment bioaccumulation factor was low at all sampling sites indicating a low bioavailability of trace metals for benthic organisms.

  15. Determination of heavy metals in macrozoobenthos from the rivers Tisza and Szamos by total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Woelfl, S.; Mages, M.; Óvári, M.; Geller, W.

    2006-11-01

    In 2000, accidents in the Romanian mining industry in key catchment areas led to heavy metal contamination of the Hungarian rivers Tisza and Szamos resulting in substantial heavy metal loads in several sediments of the upper river basins. This enhanced metal content might have been bioaccumulated in benthic organisms during the following years. Therefore, the aim of this study was to test, whether the zoobenthic fauna showed an enhanced metal content 3 years after the industrial accident. Macrozoobenthic insect larvae (chironomids) were sampled 100 m below and above the confluent site of the rivers Tisza and Szamos during summer 2003 and for comparison purpose also in the river Maros, a tributary of the Tisza river, during 2005. In order to determine their heavy metal content, single specimens were prepared and analysed by Total Reflection X-ray Fluorescence Spectrometry (TRXF) according to the modified dry method. Fe was much lower and Mn and Zn much higher concentrated in benthos from the more contaminated Szamos river compared to the Tisza and Maros rivers. In this sense, the benthic organisms reflected very well the enhanced metal concentrations in the contaminated rivers being suitable as bioindicators of metal contamination. However, the sediment bioaccumulation factor was low at all sampling sites indicating a low bioavailability of trace metals for benthic organisms.

  16. Long-term effects of mechanical harvesting of lugworms Arenicola marina on the zoobenthic community of a tidal flat in the Wadden Sea

    Science.gov (United States)

    Beukema, J. J.

    More than half of the annual catch of about 30 million lugworms Arenicola marina from the Dutch Wadden Sea originates from digging machines which make 40-cm deep guilles in a few restricted tidal-flat areas (Texel, Balgzand) in the westernmost part of the Wadden Sea. Four successive years (1978-1982) of frequent disturbance by a lugworm dredge of one of the 15 sampling stations involved in a long-term study of the dynamics of the macrozoobenthos on Balgzand allowed a study of long-term effects of mechanical lugworm digging. Within an area of about 1 km 2, a near-doubling of the annual lugworm mortality rate resulted in a gradual and substantial decline of the local lugworm stock from more than twice the overall Balgzand mean at the start of the 4-year digging period to a value close to this mean at the end of the period (when the dredge moved to a richer area). Simultaneously, total zoobenthic biomass declined even more by the almost complete extinction of the population of larger gaper clams Mya arenaria that initially comprised half of the total biomass. Of the other, mostly short-lived, species only Heteromastus filiformis showed a clear reduction during the dredging period. Recovery of the biomass of the benthos took several years, particularly by the slow re-establishment of a Mya population with a normal size and age structure.

  17. Pollution-induced community tolerance in benthic macroinvertebrates of a mildly lead-contaminated lake.

    Science.gov (United States)

    Oguma, Andrew Y; Klerks, Paul L

    2017-08-01

    Pollution-induced community tolerance (PICT) has been used to demonstrate effects of sediment contamination on microbes and meiofauna. Our study explored the potential to detect PICT in benthic macroinvertebrates of a lake with long-term mild lead (Pb) contamination. We collected macrobenthos from two areas in Caddo Lake, Texas, a control area (CO) with a mean sediment Pb level of 11 μg/g and Goose Prairie (GP) where sediment Pb levels averaged 74 μg/g. Upon return to the laboratory, we exposed macroinvertebrates to a lethal lead concentration and assessed 48-h mortality. Mortality of CO macrobenthos was significantly higher than that of GP macrobenthos, providing evidence that these communities differed in their tolerance to lead. A comparison of macrobenthos community composition between the areas showed that the GP macrobenthos lacked metal-sensitive taxa such as gastropods and amphipods (which were present at CO). Similarly, a higher proportion of the GP benthos belonged to metal-tolerant taxa such as isopods and chironomids. Thus, changes in community composition appeared to be at least partly responsible for differences in community tolerance. Our results showed that a sediment Pb concentration below effect-based sediment quality guidelines had a measurable impact on macrobenthos, thus demonstrating that results from single-species toxicity tests may underestimate impacts on communities. This study also confirms that the PICT approach with macroinvertebrates is a feasible and potentially powerful approach for detecting contaminant impacts.

  18. Benthic macroinvertebrate and fish communities in Lake Huron are linked to submerged groundwater vents

    Science.gov (United States)

    Garrison, Sanders T.; Biddanda, B.A.; Stricker, C.A.; Nold, S.C.

    2011-01-01

    Groundwater can be an important source of nutrients and energy to aquatic ecosystems, but quantifying the inputs and biogeochemical importance remains challenging. A series of submerged groundwater vents in northern Lake Huron were examined to determine the linkage between groundwater nutrients and aquatic food webs. We collected samples of key food-web components from groundwater vent and reference habitats and analyzed them for 13C, 15N, and 34S isotopes. Dissolved inorganic carbon (DIC) in the groundwater was depleted in 13C, while aqueous sulfate was enriched in 34S (mean differences between groundwater and reference sites were -3.9% and +12.0%, respectively). Benthic primary producers, macroinvertebrates, and benthivorous fish had significantly lower ??13C values in groundwater environments, and benthivorous fish were somewhat depleted (-2.5%) in ??34S at groundwater sites compared to reference sites. However, ??15N values were not different between groundwater and reference sites, and pelagic components of the ecosystems (plankton and planktivorous and piscivorous fish) were similar in both ??13C and ??15N. These data suggest benthic metazoan communities surrounding groundwater vents are partially linked to groundwater-derived benthic primary production, while planktivorous and piscivorous communities not directly associated with the benthos do not rely on groundwater nutrients. ?? Inter-Research 2011.

  19. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    International Nuclear Information System (INIS)

    Fu, Jie; Zhao, Changpo; Luo, Yupeng; Liu, Chunsheng; Kyzas, George Z.; Luo, Yin; Zhao, Dongye; An, Shuqing; Zhu, Hailiang

    2014-01-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD Mn in water drove heavy metals to deposit in sediments. • B-IBI was sensitive to the adverse effect of heavy metals in sediments. - Abstract: This work investigated heavy metal pollution in surface sediments of the Jialu River, China. Sediment samples were collected at 19 sites along the river in connection with field surveys and the total concentrations were determined using atomic fluorescence spectrometer and inductively coupled plasma optical emission spectrometer. Sediment samples with higher metal concentrations were collected from the upper reach of the river, while sediments in the middle and lower reaches had relatively lower metal concentrations. Multivariate techniques including Pearson correlation, hierarchical cluster and principal components analysis were used to evaluate the metal sources. The ecological risk associated with the heavy metals in sediments was rated as moderate based on the assessments using methods of consensus-based Sediment Quality Guidelines, Potential Ecological Risk Index and Geo-accumulation Index. The relations between heavy metals and various environmental factors (i.e., chemical properties of sediments, water quality indices and aquatic organism indices) were also studied. Nitrate nitrogen, total nitrogen, and total polycyclic aromatic hydrocarbons concentrations in sediments showed a co-release behavior with heavy metals. Ammonia nitrogen, total nitrogen, orthophosphate, total phosphate and permanganate index in water were found to be related to metal sedimentation. Heavy metals in sediments posed a potential impact on the benthos community

  20. Pseudodiarrhoea in zebra mussels Dreissena polymorpha (Pallas) exposed to microcystins.

    Science.gov (United States)

    Juhel, Guillaume; Davenport, John; O'Halloran, John; Culloty, Sarah; Ramsay, Ruth; James, Kevin; Furey, Ambrose; Allis, Orla

    2006-03-01

    Microcystins are produced by bloom-forming cyanobacteria and pose significant health and ecological problems. In this study we show that zebra mussels respond differently to different strains of Microcystis aeruginosa, and that a highly toxic strain causes zebra mussels to produce large quantities of mucous pseudofaeces, 'pseudodiarrhoea', that are periodically expelled hydraulically through the pedal gape by shell valve adductions rather than by the normal ciliary tracts. Analysis of the pseudofaecal ejecta showed that the proportion of Microcystis aeruginosa relative to Asterionella formosa was high in the pseudofaeces and even higher in the 'pseudodiarrhoea' when a mixed diet was given to the mussels. This confirms that very toxic Microcystis aeruginosa were preferentially being rejected by comparison with the non-toxic diatom in the pseudofaeces and even more so in the 'pseudodiarrhoea'. Such selective rejection was not observed with low or non-toxic strains and would therefore tend to enhance the presence of toxic Microcystis aeruginosa in mixed Microcystis aeruginosa cyanobacterial blooms, as well as transferring toxins from the water column to the benthos. The observed acute irritant response to the toxin represents the first demonstration of an adverse sublethal effect of microcystins on invertebrate ecophysiology. Our results also suggest that it could be a specific response to microcystin-LF, a little studied toxin variant.

  1. Polycyclic aromatic hydrocarbon (PAH) contamination of surface sediments and oysters from the inter-tidal areas of Dar es Salaam, Tanzania

    International Nuclear Information System (INIS)

    Gaspare, Lydia; Machiwa, John F.; Mdachi, S.J.M.; Streck, Georg; Brack, Werner

    2009-01-01

    Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low. - PAH contamination may pose hazards to benthos but limited risks to humans

  2. The Effects of Sediments Burdened by Sewerage Water Originating in Car Batteries Production in the Klenice River (CZ

    Directory of Open Access Journals (Sweden)

    Petra Beránková

    2009-01-01

    Full Text Available The aim of this work was to perform tests of genotoxicity and toxicity on samples of riverine sediments from a location subject to motor industry load (car battery production. Together with sediment samples we also collected benthos, biofilm and juvenile fish. Concentration of lead was established in all the samples since the sewage waters discharged from the car battery production plant are heavily polluted with lead. Genotoxicity was tested with two tests of genotoxicity: the SOS chromotest and the Escherichia coli WP2 test. The toxicity of sediments was tested with a test of toxicity performed on a water crustacean Daphnia magna. A profound toxic influence upon benthic organisms was found; a consequence of the river pollution with waste water and flush water from the car battery production plant. This toxic effect was also proven by an aqueous leach from the test performed with Daphnia magna. Both tests of genotoxicity proved a significant genotoxic potential of the sediment samples linked with the growth of the concentration of lead in the sediments (up to 647 mg kg-1. The content of lead also increased in the biofilm (up to 3.37 mg kg-1 of dry mass as well as in the fish bodies (up to 804.5 mg kg-1 of dry mass. This thesis is the first study of the load imposed on this river as a consequence of the waste water and flush water discharge from the motor industry production plant (car battery production.

  3. The effects of a winter upwelling on biogeochemical and planktonic components in an area close to the Galician Upwelling Core: The Sound of Corcubión (NW Spain)

    Science.gov (United States)

    Varela, Manuel; Álvarez-Ossorio, Ma Teresa; Bode, Antonio; Prego, Ricardo; Bernárdez, Patricia; Garcia-Soto, Carlos

    2010-10-01

    To study the biogeochemical response and the coupling plankton-benthos to an unusual winter upwelling event a cruise was carried out in February 2005 in the Sound of Corcubión, near Cape Finisterre (NW Iberian Peninsula), the Galician upwelling core. This area represents the northern boundary of the Eastern North Atlantic Upwelling System (ENAUS). The spatial distribution of plankton assemblages (phytoplankton and zooplankton), chlorophyll, physical and chemical parameters as well as diatom distribution in surface sediments, were studied in a total of 17 stations in the Sound. The upwelling processes caused an important accumulation of water in the inner Sound and near the Cape. This accumulation zone must be persistent through the upwelling events in the area, including those of summer, as indicated by the diatoms' distribution in the sediment. Unlike the summer upwelling events, the main effect of winter upwelling in the area is the increase in solar radiation due to the persistent clear skies. In this season nutrient supply is not critical due to water column mixing. The meteorological conditions were equivalent to those of early spring. As a result, both phyto- and zooplankton species assemblages were typical of spring blooms in Galician coasts. The bloom lasted for up to 6 days, as estimated from the availability and uptake of nitrogen forms. Winter blooms represented ca. 20% of total annual phytoplankton biomass, and 30% of the average biomass during summer upwelling, in the period 1997-2007, as estimated from the analysis of both, in situ and satellite derived chlorophyll.

  4. Marine Sciences: from natural history to ecology and back, on Darwin's shoulders

    Directory of Open Access Journals (Sweden)

    Ferdinando Boero

    2010-12-01

    Full Text Available The naturalist Charles Darwin founded modern ecology, considering in a single conceptual framework the manifold aspects regarding the organization of life at various levels of complexity and its relationship with the physical world. The development of powerful analytical tools led to abandon Darwin's natural history and to transform naturalists, as Darwin labelled himself, into the practitioners of more focused disciplines, aimed at tackling specific problems that considered the various aspects of the organization of life in great detail but, also, in isolation from each other. Among the various disciplines that stemmed from the Darwinian method, ecology was further split into many branches, and marine ecology was no exception. The compartmentalization of the marine realm into several sub-domains (e.g., plankton, benthos, nekton led to neglect of the connections linking the various parts that were separated for the ease of analyses that, in this way, prevented synthetic visions. The way marine sciences were studied also led to separate visions depending on the employed tools, so that ship-based biological oceanography developed almost separately from marine station-based marine biology. The necessity of putting together such concepts as biodiversity and ecosystem functioning is rapidly leading to synthetic approaches that re-discover the historical nature of ecology, leading to the dawn of a new natural history.

  5. Bioeconomic analysis of the environmental impact of a marine fish farm.

    Science.gov (United States)

    Rabassó, Miguel; Hernández, Juan M

    2015-08-01

    The evaluation of the environmental impact of aquaculture installations is nowadays a common social demand in many countries. The usual scientific approach to this question has been to assess the outcome from an ecological perspective, focussing on the effects produced on benthos or the water column and interactions with marine flora and fauna. In this paper, a bioeconomic model is developed to extend this traditional approach, to determine both the amount of total settled matter, its dispersion on the ocean floor and impacts on the marine ecosystem, while also taking into account other social considerations such as discounted net profits and investment returns. The model was applied to the case of off-shore gilthead seabream production in a coastal area of the Canary Isles archipelago, where the tidal current is predominant. Cage emissions and the degree of degradation of seagrass meadows on the seabed were taken as ecological impact indicators, while the net present value (NPV) for a specific time period was used as an economic indicator. By analysing the simulation results obtained by the bioeconomic model, we were able to determine the combination of production volume and harvest quantity which yields the greatest economic efficiency for different levels of degraded area. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Nutrients, Recycling, and Biological Populations in Upwelling Ecosystems

    Energy Technology Data Exchange (ETDEWEB)

    Whitledge, T. E.

    1980-01-01

    Nutrient recycling has been studied in the upwelling areas of Baja California, Northwest Africa, and Peru. Regeneration by biological populations in these areas contributes significant quantities of recycled nitrogen which is utilized in productivity processes. Each area has a different combination of organisms which leads to differences in the relative contributions of zooplankton, nekton, or benthos to the nutrient cycles. Comparisons of ammonium regeneration rates of zooplankton and nekton-micronekton populations in the three upwelling areas show that zooplankton recycle relatively less nitrogen in the Baja California and Peru systems than nekton. In the Northwest Africa upwelling region, however, zooplankton, fish, and benthic inputs are all substantial. In recent years the Peruvian upwelling system has been altered with the decline of the anchoveta population and an increase in the importance of zooplankton in nutrient recycling. The distribution of recycled nitrogen (ammonium and urea) in transects across the shelf at 10°S and 15°S indicates that regeneration is relatively more important at 10°S in the region of the wide shelf. In both areas the distribution of ammonium and urea are not entirely coincident thereby indicating differences in their production and/or utilization.

  7. NW Black Sea ecosystems recovery from former severe seasonal hypoxia and effect on macrofauna

    Science.gov (United States)

    Gomoiu, Marian-Traian; Begun, Tatiana; Teaca, Adrian

    2013-04-01

    The benthos researches carried out in the last decade on the NW Black Sea shelf established the transitional process of the bottom communities, from the severe disturbed state resulted from seasonal hypoxia of high eutrophication from 1970-2000 period towards a new state. The authors, with their expertise achieved in the framework of several national and EU FP6&7 projects (SESAME, HYPOX, PERSEUS), analyzing more than 600 quantitative samples, consider the benthic associations influenced mainly by the Danube River discharge being characterized as follows: • decrease in the specific diversity (e.g. Mollusca - from 170 species in the 1960s - 1970s to 70 species in the present in NW Black Sea); • loss or diminishing of some habitat areas (typical habitat with Zostera, Phyllophora, Cystoseira, Barnea, Donacilla etc.); • increase in the numeric abundance and biomass of some specific benthic populations (Melinna, Alitta, Dipolydora etc.); • loss or reduction of some specific populations (Abra prismatica, Spisula subtruncata, Chamelia gallina etc.); • replacement of some strong and quite large benthic populations by metapopulation of small extension; • diminution of the biofilter strength by reduction of the filter - feeder populations; • qualitative and quantitative worsening of benthic biological resources, especially molluscs - forms playing an important ecological part and with great economic importance (mussel Mytilus galloprovincialis, soft-shell clam Mya arenaria, veined rapa whelk Rapana venosa); • thriving of opportunistic forms (especially worms populations causing sediment bioturbation - Melinna palmata, Heteromastus filiformis) and, temporarily, some exotic species recently pervading Black Sea (Mya, Anadara, Rapana etc.); • great quantitative fluctuations of all benthic populations; • occurrence of some weak sing of ecosystem recovery. However, recovery of the benthic ecosystem appears to be less certain although an improvement on

  8. Comparative analysis of the mobility of uranium and artificial radionuclides in the ecosystem of the Yenisei River

    Energy Technology Data Exchange (ETDEWEB)

    Bolsunovsky, Alexander; Medvedeva, Marina [Institute of Biophysics SB Russian Academy of Sciences, 660036, Krasnoyarsk (Russian Federation)

    2014-07-01

    The Yenisei River is one of the largest rivers in the world, which had been subjected to radioactive contamination for over 50 years, due to operation of the Mining-and-Chemical Combine (MCC) of Rosatom at Zheleznogorsk, which had been producing weapons-grade plutonium. Bottom sediments and flood plain of the Yenisei River are contaminated by artificial radionuclides, including transuranium ones, both close to the MCC and at a considerable distance downstream. The MCC is also a source of uranium isotopes in the Yenisei. Thus, the Yenisei River basin is a unique environment for studying the mobility of both uranium isotopes and artificial radionuclides in all components of the aquatic ecosystem. The purpose of this study was to compare the mobility of uranium and artificial radionuclides in the ecosystem of the Yenisei River. Samples of water, sediments, and aquatic organisms were used as study material. Aquatic organisms were represented by submerged plants, benthic-feeding fish, and zoo-benthos. The submerged plants (macrophytes) analyzed were of five species: Fontinalis antipyretica, Potamogeton lucens, Ceratophyllum demersum, Myriophyllum spicatum, and Elodea canadensis. Grayling (Timalus arcticus) represented benthic-feeding fish, and zoo-benthos species were represented by Philolimnogammarus viridis, which forms the major part of the grayling's diet. Samples were collected at positions in the vicinity of the MCC discharge point, at a distance of 110 km downstream of Krasnoyarsk, and upstream of the MCC, during sampling campaigns in 2008-2012. Radionuclide measurements were performed using a wide range of instrumental methods: gamma-spectrometry with a 'Canberra' spectrometer (U.S.), mass spectrometry with an 'Agilent' spectrometer (U.S.), neutron activation analysis, and beta-alpha radiometry. The results obtained in this study suggest that the part of the Yenisei River ecosystem contaminated due to MCC radioactive discharges contains

  9. Distribution and size of benthic marine habitats in Dominica, Lesser Antilles

    Directory of Open Access Journals (Sweden)

    Sascha Claus Christoff Steiner

    2010-06-01

    total of 755ha of benthos were surveyed in October and November of 2007. The benthic habitat composition of an additional 1 059.7ha was inferred with the help of unpublished data and satellite imagery. Seagrass beds were the most widespread organism-built habitat type with 265ha. Coral reefs covered 72.2ha. Both of these habitats were predominantly established along the West and North coasts, which included the island’s most habitatdiverse regions. Rocky environments (911.5ha dominated the East and South coast and together with sandy areas (566ha constituted 81% of the island’s marine benthos. It is apparent that seagrass beds, which include four native and one invasive seagrass species, had not been surveyed as previous distribution reports could not be confirmed. Similarly, the benthic cover of Dominica’s coral reefs is evidently far below the previously reported 7 000ha. Such discrepancies highlight the advantage of environmental assessments based on field surveys and systematic data compilation, particularly in cases like Dominica where a narrow island shelf stages marginal marine resources in spatial proximity to each other and human settlements. This study has demonstrated how low-tech field methods can be applied on an island-wide scale to build an inventory of marine resources in the form of habitat maps and data repositories publicly accessible for future use. In the absence of such efforts, the development of conservation measures and status reports will remain ill founded. Rev. Biol. Trop. 58 (2: 589- 602. Epub 2010 June 02.

  10. Marine Biodiversity in Juan Fernández and Desventuradas Islands, Chile: Global Endemism Hotspots.

    Directory of Open Access Journals (Sweden)

    Alan M Friedlander

    Full Text Available The Juan Fernández and Desventuradas islands are among the few oceanic islands belonging to Chile. They possess a unique mix of tropical, subtropical, and temperate marine species, and although close to continental South America, elements of the biota have greater affinities with the central and south Pacific owing to the Humboldt Current, which creates a strong biogeographic barrier between these islands and the continent. The Juan Fernández Archipelago has ~700 people, with the major industry being the fishery for the endemic lobster, Jasus frontalis. The Desventuradas Islands are uninhabited except for a small Chilean military garrison on San Félix Island. We compared the marine biodiversity of these islands across multiple taxonomic groups. At San Ambrosio Island (SA, in Desventuradas, the laminarian kelp (Eisenia cokeri, which is limited to Desventuradas in Chile, accounted for >50% of the benthic cover at wave exposed areas, while more sheltered sites were dominated by sea urchin barrens. The benthos at Robinson Crusoe Island (RC, in the Juan Fernández Archipelago, comprised a diverse mix of macroalgae and invertebrates, a number of which are endemic to the region. The biomass of commercially targeted fishes was >2 times higher in remote sites around RC compared to sheltered locations closest to port, and overall biomass was 35% higher around SA compared to RC, likely reflecting fishing effects around RC. The number of endemic fish species was extremely high at both islands, with 87.5% of the species surveyed at RC and 72% at SA consisting of regional endemics. Remarkably, endemics accounted for 99% of the numerical abundance of fishes surveyed at RC and 96% at SA, which is the highest assemblage-level endemism known for any individual marine ecosystem on earth. Our results highlight the uniqueness and global significance of these biodiversity hotspots exposed to very different fishing pressures.

  11. Marine Biodiversity in Juan Fernández and Desventuradas Islands, Chile: Global Endemism Hotspots.

    Science.gov (United States)

    Friedlander, Alan M; Ballesteros, Enric; Caselle, Jennifer E; Gaymer, Carlos F; Palma, Alvaro T; Petit, Ignacio; Varas, Eduardo; Muñoz Wilson, Alex; Sala, Enric

    2016-01-01

    The Juan Fernández and Desventuradas islands are among the few oceanic islands belonging to Chile. They possess a unique mix of tropical, subtropical, and temperate marine species, and although close to continental South America, elements of the biota have greater affinities with the central and south Pacific owing to the Humboldt Current, which creates a strong biogeographic barrier between these islands and the continent. The Juan Fernández Archipelago has ~700 people, with the major industry being the fishery for the endemic lobster, Jasus frontalis. The Desventuradas Islands are uninhabited except for a small Chilean military garrison on San Félix Island. We compared the marine biodiversity of these islands across multiple taxonomic groups. At San Ambrosio Island (SA), in Desventuradas, the laminarian kelp (Eisenia cokeri), which is limited to Desventuradas in Chile, accounted for >50% of the benthic cover at wave exposed areas, while more sheltered sites were dominated by sea urchin barrens. The benthos at Robinson Crusoe Island (RC), in the Juan Fernández Archipelago, comprised a diverse mix of macroalgae and invertebrates, a number of which are endemic to the region. The biomass of commercially targeted fishes was >2 times higher in remote sites around RC compared to sheltered locations closest to port, and overall biomass was 35% higher around SA compared to RC, likely reflecting fishing effects around RC. The number of endemic fish species was extremely high at both islands, with 87.5% of the species surveyed at RC and 72% at SA consisting of regional endemics. Remarkably, endemics accounted for 99% of the numerical abundance of fishes surveyed at RC and 96% at SA, which is the highest assemblage-level endemism known for any individual marine ecosystem on earth. Our results highlight the uniqueness and global significance of these biodiversity hotspots exposed to very different fishing pressures.

  12. Consequences of ecological, evolutionary and biogeochemical uncertainty for coral reef responses to climatic stress.

    Science.gov (United States)

    Mumby, Peter J; van Woesik, Robert

    2014-05-19

    Coral reefs are highly sensitive to the stress associated with greenhouse gas emissions, in particular ocean warming and acidification. While experiments show negative responses of most reef organisms to ocean warming, some autotrophs benefit from ocean acidification. Yet, we are uncertain of the response of coral reefs as systems. We begin by reviewing sources of uncertainty and complexity including the translation of physiological effects into demographic processes, indirect ecological interactions among species, the ability of coral reefs to modify their own chemistry, adaptation and trans-generational plasticity. We then incorporate these uncertainties into two simple qualitative models of a coral reef system under climate change. Some sources of uncertainty are far more problematic than others. Climate change is predicted to have an unambiguous negative effect on corals that is robust to several sources of uncertainty but sensitive to the degree of biogeochemical coupling between benthos and seawater. Macroalgal, zoanthid, and herbivorous fish populations are generally predicted to increase, but the ambiguity (confidence) of such predictions are sensitive to the source of uncertainty. For example, reversing the effect of climate-related stress on macroalgae from being positive to negative had no influence on system behaviour. By contrast, the system was highly sensitive to a change in the stress upon herbivorous fishes. Minor changes in competitive interactions had profound impacts on system behaviour, implying that the outcomes of mesocosm studies could be highly sensitive to the choice of taxa. We use our analysis to identify new hypotheses and suggest that the effects of climatic stress on coral reefs provide an exceptional opportunity to test emerging theories of ecological inheritance. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Bioactivity of Benthic and Picoplanktonic Estuarine Cyanobacteria on Growth of Photoautotrophs: Inhibition versus Stimulation

    Directory of Open Access Journals (Sweden)

    Viviana R. Lopes

    2011-05-01

    Full Text Available Understanding potential biochemical interactions and effects among cyanobacteria and other organisms is one of the main keys to a better knowledge of microbial population structuring and dynamics. In this study, the effects of cyanobacteria from benthos and plankton of estuaries on other cyanobacteria and green algae growth were evaluated. To understand how the estuarine cyanobacteria might influence the dynamics of phytoplankton, experiments were carried out with the freshwater species Microcystis aeruginosa and Chlorella sp., and the marine Synechocystis salina and Nannochloropsis sp. exposed to aqueous and organic (70% methanol crude extracts of cyanobacteria for 96 h. The most pronounced effect observed was the growth stimulation. Growth inhibition was also observed for S. salina and M. aeruginosa target-species at the highest and lowest concentrations of cyanobacterial extracts. The methanolic crude extract of Phormidium cf. chalybeum LEGE06078 was effective against S. salina growth in a concentration-dependent manner after 96 h-exposure. All of the cyanobacterial isolates showed some bioactivity on the target-species growth, i.e., inhibitory or stimulating effects. These results indicate that the analyzed cyanobacterial isolates can potentially contribute to blooms’ proliferation of other cyanobacteria and to the abnormal growth of green algae disturbing the dynamic of estuarine phytoplankton communities. Since estuaries are transitional ecosystems, the benthic and picoplanktonic estuarine cyanobacteria can change both freshwater and marine phytoplankton succession, competition and bloom formation. Furthermore, a potential biotechnological application of these isolates as a tool to control cyanobacteria and microalgae proliferation can be feasible. This work is the first on the subject of growth responses of photoautotrophs to cyanobacteria from Atlantic estuarine environments.

  14. Preliminary evaluation of an in vivo fluorometer to quantify algal periphyton biomass and community composition

    Science.gov (United States)

    Harris, Theodore D.; Graham, Jennifer L.

    2015-01-01

    The bbe-Moldaenke BenthoTorch (BT) is an in vivo fluorometer designed to quantify algal biomass and community composition in benthic environments. The BT quantifies total algal biomass via chlorophyll a (Chl-a) concentration and may differentiate among cyanobacteria, green algae, and diatoms based on pigment fluorescence. To evaluate how BT measurements of periphytic algal biomass (as Chl-a) compared with an ethanol extraction laboratory analysis, we collected BT- and laboratory-measured Chl-a data from 6 stream sites in the Indian Creek basin, Johnson County, Kansas, during August and September 2012. BT-measured Chl-a concentrations were positively related to laboratory-measured concentrations (R2 = 0.47); sites with abundant filamentous algae had weaker relations (R2 = 0.27). Additionally, on a single sample date, we used the BT to determine periphyton biomass and community composition upstream and downstream from 2 wastewater treatment facilities (WWTF) that discharge into Indian Creek. We found that algal biomass increased immediately downstream from the WWTF discharge then slowly decreased as distance from the WWTF increased. Changes in periphyton community structure also occurred; however, there were discrepancies between BT- and laboratory-measured community composition data. Most notably, cyanobacteria were present at all sites based on BT measurements but were present at only one site based on laboratory-analyzed samples. Overall, we found that the BT compared reasonably well with laboratory methods for relative patterns in Chl-a but not as well with absolute Chl-aconcentrations. Future studies need to test the BT over a wider range of Chl-aconcentrations, in colored waters, and across various periphyton assemblages.

  15. Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata).

    Science.gov (United States)

    Wells-Berlin, Alicia M; Perry, Matthew C; Kohn, Richard A; Paynter, Kennedy T; Ottinger, Mary Ann

    2015-01-01

    Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

  16. Microturbellarians (Platyhelminthes and Acoelomorpha) in Brazil: invisible organisms?

    Science.gov (United States)

    Braccini, J A L; Amaral, S V; Leal-Zanchet, A M

    2016-06-01

    Microturbellarians typically belong to the benthos and may occur in a wide variety of environments. They are abundant in freshwater and marine ecosystems and may occur in moist terrestrial habitats. However, turbellarians are seldom taken into account in studies of biodiversity. Most studies on Brazilian microturbellarians had taxonomical purposes and were done in the years 1940-1950. Thus, information on their occurrence and ecological aspects are dispersed throughout several papers. We intend here to summarize the biogeographical distribution and ecological aspects of microturbellarians recorded for Brazil, indicating the main gaps in their knowledge and possible actions to enhance studies on this group. There are 239 species of microturbellarians registered for Brazil, with records distributed in 12 states. However, just three states located in southern Brazil have records of 94% of microturbellarian species. Thus, knowledge on the systematics and geographical distribution of Brazilian microturbellarians clearly reflect the scientific activity over many years or decades in two states of southeastern and southern Brazil. Considering the scant information on this group in Brazil, which is also the situation of the Neotropical microturbellarians in general, some actions should be proposed. First, it would be necessary to sample in the diverse biomes, as well as in the various river and sea basins, based on standardized sampling protocols. Second, it would be necessary to encourage diverse research groups to include microturbellarians and/or turbellarians in general into biodiversity inventories and studies on community structure of invertebrates. Third, it is necessary to increase the number of research groups on microturbellarians, in order to augment the studies on their morphology, systematics, and ecology. Considering their abundance, species richness and ecological importance in aquatic environments, despite some peculiarities regarding their sampling, sorting

  17. Microturbellarians (Platyhelminthes and Acoelomorpha in Brazil: invisible organisms?

    Directory of Open Access Journals (Sweden)

    J. A. L. Braccini

    Full Text Available Abstract Microturbellarians typically belong to the benthos and may occur in a wide variety of environments. They are abundant in freshwater and marine ecosystems and may occur in moist terrestrial habitats. However, turbellarians are seldom taken into account in studies of biodiversity. Most studies on Brazilian microturbellarians had taxonomical purposes and were done in the years 1940-1950. Thus, information on their occurrence and ecological aspects are dispersed throughout several papers. We intend here to summarize the biogeographical distribution and ecological aspects of microturbellarians recorded for Brazil, indicating the main gaps in their knowledge and possible actions to enhance studies on this group. There are 239 species of microturbellarians registered for Brazil, with records distributed in 12 states. However, just three states located in southern Brazil have records of 94% of microturbellarian species. Thus, knowledge on the systematics and geographical distribution of Brazilian microturbellarians clearly reflect the scientific activity over many years or decades in two states of southeastern and southern Brazil. Considering the scant information on this group in Brazil, which is also the situation of the Neotropical microturbellarians in general, some actions should be proposed. First, it would be necessary to sample in the diverse biomes, as well as in the various river and sea basins, based on standardized sampling protocols. Second, it would be necessary to encourage diverse research groups to include microturbellarians and/or turbellarians in general into biodiversity inventories and studies on community structure of invertebrates. Third, it is necessary to increase the number of research groups on microturbellarians, in order to augment the studies on their morphology, systematics, and ecology. Considering their abundance, species richness and ecological importance in aquatic environments, despite some peculiarities

  18. Stable-isotope analysis of canvasback winter diet in upper Chesapeake Bay

    Science.gov (United States)

    Haramis, G.M.; Jorde, Dennis G.; Macko, S.A.; Walker, J.L.

    2001-01-01

    A major decline in submerged aquatic vegetation (SAV) in Chesapeake Bay has altered the diet of wintering Canvasbacks (Aythya valisineria) from historically plant to a combination of benthic animal foods, especially the ubiquitous Baltic clam (Macoma balthica), supplemented with anthropogenic corn (Zea mays). Because the isotopic signature of corn is readily discriminated from bay benthos, but not SAV, we used stable-isotope methodology to investigate the corn–SAV component of the winter diet of Canvasbacks. Feeding trials with penned Canvasbacks were conducted to establish turnover rates and fractionation end-point loci of δ13C and δ15N signatures of whole blood for individual ducks fed ad libitum diets of (1) Baltic clams, (2) Baltic clams and corn, and (3) tubers of wild celery (Vallisneria americana). Turnover time constants averaged 4.5 weeks, indicating that signatures of wild ducks would be representative of bay diets by late February. Isotopic signatures of wild Canvasbacks sampled in February fell on a continuum between end-point loci for the Baltic clam and the combination Baltic clam and corn diet. Although that finding verifies a clear dependence on corn–SAV for wintering Canvasbacks, it also reveals that not enough corn–SAV is available to establish ad libitum consumption for the 15,000+ Canvasbacks wintering in the upper bay. On the basis of mean δ13C signature of bay Canvasbacks (n = 59) and ingestion rates from feeding trials, we estimated that 258 kg corn per day would account for the observed δ13C enrichment and supply 18% of daily energetic needs for 15,000 Canvasbacks. That level of corn availability is so realistic that we conclude that SAV is likely of little dietary importance to Canvasbacks in that portion of the bay.

  19. Offshore oceanographic and environmental monitoring services for the Strategic Petroleum Reserve. Volume I. Appendices. Annual report for the Bryan Mound Site, September 1982-August 1983

    Energy Technology Data Exchange (ETDEWEB)

    None

    1984-03-01

    The Department of Energy's Strategic Petroleum Reserve Program began leaching the Bryan Mound salt dome and discharging brine into the coastal waters offshore of Freeport, Texas on March 10, 1980. This report describes the findings of a team of Texas A and M University scientists and engineers who have conducted a study to evaluate the effects of the Bryan Mound brine discharge on the marine environment. The study addresses the areas of physical oceanography, analysis of the discharge plume, water and sediment quality, nekton, benthos and data management. It focuses on the period from September 1982 through August 1983. The ambient physical environment and its temporal and spatial variability were studied by means of continuously recording in situ current/conductivitiy/temperature meters and twelve, one-day synoptic hydrographic cruises. The quarterly water and sediment quality data show a small increase in salinity, sodium and chloride ions occurs in the bottom waters and sediment pore waters near the diffuser relative to those values measured at stations farther away. Data from the brine plume study for this reporting study show the largest areal extent within the +1 o/oo above ambient salinity contour was 40.0 km/sup 2/ which occurred on August 11, 1983. It appears that brine disposal at Bryan Mound has had neglible if any influence on the nekton community surrounding the diffuser. The benthic quarterly data from 26 stations, including 7 collections made after the diffuser outflow rate was increased to 1,000,000 barrels/day, show the total numbers of species at the diffuser station were higher than most other nearfield stations as well as many farfield stations in both the pre- and post-1,000,000 barrels/day brine flow periods. 138 references, 175 figures, 53 tables.

  20. Rapid sea-level change in the Late Guadalupian (Permian) on the Tethyan side of South China: litho- and biostratigraphy of the Chaotian section in Sichuan.

    Science.gov (United States)

    Isozaki, Yukio; Yao, Jianxin; Ji, Zhangshen; Saitoh, Masafumi; Kobayashi, Noritada; Sakai, Harutaka

    2008-01-01

    The Capitanian (Late Guadalupian) Maokou Formation at Chaotian in northern Sichuan, South China, is composed mainly of shallow marine shelf carbonates deposited on the Tethyan side of South China. By detailed field mapping and scientific drilling, we newly found out unique fossil assemblages and a sharp lithologic change in the upper part of the Maokou Formation. The main part of the Maokou Formation (over 130 m thick) is composed of algal packstone with Wordian-Capitanian large-tested fusulines, rugose corals and other sessile benthos, whereas the Uppermost Member (13 m thick) is composed of black limy mudstone/chert with Capitanian offshore biota (ammonoids, radiolarians, and conodonts). The topmost Capitanian conodont zones are missing; however, the Maokou Formation is disconformably overlain by 260+/-4 Ma volcanic ash (Wangpo bed) and the Early Lopingian Wujiaping Formation with plant-bearing coaly mudstone and shallow marine carbonates (packstone). The newly identified facies change indicates that northern Sichuan has experienced rapid sea-level changes in the late Guadalupian, i.e., first a transgression in the mid-Capitanian and then a regression across the Guadalupian-Lopingian boundary. As the end-Guadalupian is characterized by a global regression, such a volatile sea-level fluctuation, in particular the sea-level rise, is unique to the Tethyan side of South China. The newly recognized relatively deep-water late Guadalupian sequence adds new paleo-environmental information and further provides a paleotectonic interpretation of the low-latitude eastern Tethyan margin immediately before the end-Guadalupian mass extinction.

  1. Environmental influences on the at-sea behaviour of a major consumer, Mirounga leonina, in a rapidly changing environment

    Directory of Open Access Journals (Sweden)

    Trevor McIntyre

    2014-11-01

    Full Text Available Understanding the distribution and foraging ecology of major consumers within pelagic systems, specifically in relation to physical parameters, can be important for the management of bentho-pelagic systems undergoing rapid change associated with global climate change and other anthropogenic disturbances such as fishing (i.e., the Antarctic Peninsula and Scotia Sea. We tracked 11 adult male southern elephant seals (Mirounga leonina, during their five-month post-moult foraging migrations from King George Island (Isla 25 de Mayo, northern Antarctic Peninsula, using tags capable of recording and transmitting behavioural data and in situ temperature and salinity data. Seals foraged mostly within the Weddell–Scotia Confluence, while a few foraged along the western Antarctic Peninsula shelf of the Bellingshausen Sea. Mixed model outputs suggest that the at-sea behaviour of seals was associated with a number of environmental parameters, especially seafloor depth, sea-ice concentrations and the temperature structure of the water column. Seals increased dive bottom times and travelled at slower speeds in shallower areas and areas with increased sea-ice concentrations. Changes in dive depth and durations, as well as relative amount of time spent during the bottom phases of dives, were observed in relation to differences in overall temperature gradient, likely as a response to vertical changes in prey distribution associated with temperature stratification in the water column. Our results illustrate the likely complex influences of bathymetry, hydrography and sea ice on the behaviour of male southern elephant seals in a changing environment and highlight the need for region-specific approaches to studying environmental influences on behaviour.

  2. Linking benthic community structure to terrestrial runoff and upwelling in the coral reefs of northeastern Hainan Island

    Science.gov (United States)

    Li, Xiubao; Wang, Daoru; Huang, Hui; Zhang, Jing; Lian, Jiansheng; Yuan, Xiangcheng; Yang, Jianhui; Zhang, Guoseng

    2015-04-01

    Near-shore coral reefs in northeastern Hainan Island are close to river mouths and aquaculture ponds, and also located at the center of the Qiongdong Upwelling (QDU). However, it is still unclear how terrestrial runoff and upwelling influence the community composition and spatial distribution of the benthos. During three cruises in 2010 and 2011 in Wenchang, northeastern Hainan Island, we determined a subset of environmental parameters in seawater (e.g. temperature, salinity, DO, dissolved inorganic nutrient (DIN), turbidity and transparency) and macroalgal δ15N and investigated the benthic communities (e.g. live coral cover, coral species richness, juvenile coral density, macroalgal cover and coverage of calcified algae) by video transect and visual census techniques at 10 stations (i.e. 1S-6D). The results showed that the QDU has influenced the reef waters in Wenchang. In 2011, the upwelling started in early May, peaked in July and disappeared in September and most upwelling events lasted for 1-2 weeks between May and July. The results also demonstrated that the reef water was nutrient enriched. Stations close to the river mouth and aquaculture ponds had higher levels of DIN and a higher percentage of ammonia in DIN, and there was consistently lower live coral cover, juvenile coral density and higher macroalgal cover. At some stations in this study, live coral cover was negatively correlated with macroalgal cover (i.e. 2S-6D). Live coral cover, species richness, and juvenile coral density all increased with the distance away from the river outlet and decreased with the rise of DIN. These results suggest that terrestrial runoff and upwelling stimulate nutrient enrichment, and that overgrowing macroalgae has an important influence on the coral communities in northeastern Hainan Island.

  3. Evaluation of hydropeaking impacts on the food web in alpine streams based on modelling of fish- and macroinvertebrate habitats.

    Science.gov (United States)

    Holzapfel, P; Leitner, P; Habersack, H; Graf, W; Hauer, C

    2017-01-01

    Hydropeaking as a result of peak-load electricity production has been identified as one of the most significant pressures in alpine streams. Scouring of macroinvertebrates leads to downstream transport of aquatic organisms (catastrophic drift). Additionally, invertebrates are affected by periodic drying of wetted area during the dewatering of gravel bars and exposed areas along the banks. Even though fish are physiologically better adapted to switch to suitable habitats, artificial flow fluctuations may be followed by lethal stranding and quick alteration in habitat quantity and quality. Nevertheless, the interactions between pressures on fish and macroinvertebrates in terms of hydropeaking have not been investigated so far. The aim of this paper is to evaluate effects of flow fluctuations on potential epibenthic feeding grounds. Therefore, we evaluated changes in habitat distribution resulting from rapid flow fluctuations in river reaches with different river morphological characteristics, for five different macroinvertebrate taxa. Additionally, microhabitats for brown trout at two different life stages were calculated using representative peaking events (seasonal analysis) based on mid- to long term times series. Moreover, GIS-analysis allowed the evaluation of hydropeaking impacts (interaction) on both, macroinvertebrates and fish. In this study, it could be documented that feeding from the benthos for juvenile and subadult brown trout is inhibited during peak flow and is therefore reduced to times of base flow. Moreover, potential benthic feeding areas occurring at base flow have been found to increase with the level of morphological heterogeneity within analyzed river reaches. Likewise, hydrological sensitivity testing in terms of reducing ∆Q at different levels was performed and revealed that possible positive effects required heterogeneous river morphology as a precondition. However, this approach might be applied for estimating the impacts of hydrological

  4. Environmental effects monitoring for exploration drilling

    International Nuclear Information System (INIS)

    Buchanan, R.A.; Cook, J.A.; Mathieu, A.

    2003-01-01

    Strategies for monitoring the environmental effects of single exploratory offshore wells on the east coast of Canada were evaluated. The report was compiled from consultations with scientists, regulators and stakeholders as well as a review of regulatory regimes and toxicity results. The aim of the report was to develop a decision tree for determining when to conduct environmental effects monitoring (EEM). Respondents evinced lower levels of concern for single exploratory wells than for production developments. A number of scientists argued for full statistical treatment of all data, and many people argued that more assurance was needed that the marine environment was not being unduly harmed. Respondents also considered that biological effects should be a primary focus, rather than the occurrence of trace chemical signals, and that seabirds and mammals should be monitored. Concern was expressed over the value of data collected from monitoring the effects of exploratory drilling activities. It was suggested that local and site-specific issues should be considered in the design of EEM programs. Respondents expressed strong concern about potential cumulative effects with other industrial activities, and suggested that test cases should be established and monitored to develop a scientific rationale for the inclusion or exclusion of specific variables in future EEM programs. A decision tree was developed based on 3 scenarios: (1) compliance monitoring only in well known areas with no sensitive issues; opportunistic EEM surveys of sediments, benthos, seabirds and marine mammals in shallow or deep areas with no known sensitive issues; and (3) custom EEM surveys for sensitive areas. Currently, there are EEM requirements for drilling exploratory wells offshore Canada's east coast. 58 refs., 2 tabs., 7 figs

  5. Evaluation of the Modern State of Water Ecosystems and the Issues with Protecting Biological Resources During Development of the Kruzenshternskoye Gas Condensate Field

    Directory of Open Access Journals (Sweden)

    Vladimir Dmitrievich Bogdanov

    2015-09-01

    Full Text Available In the article, the results of the studies of the present state of freshwater ecosystems and their biotic components in the western part of the Yamal Peninsula are presented. Based on the evaluation of the structure of the communities of phytoplankton, zooplankton, benthos and whitefishes, the range of the problems related to the protection of biological resources at the development of the Kruzenshternskoye gas field is defined. Data on species composition and quantitative indicators of hydrobionts of different types of waterbodies and watercourses in the lower reaches of the Mordyyakha and Naduyyakha rivers basins are the basis for environmental monitoring of water objects at development and exploitation of the Kruzenshternskoye gas field. According to the monitoring program, evaluation of the fish fauna state and their food base on the territory of the Kruzenshternskoye gas condensate field (GCF, is present. The zones of rivers deltas are the most important areas of the salmonid and whitefishes valuable fish species feeding at the territory of Kruzenshternskoye GCF. In the cases where complete demolish of waterbodies and watercourses for construction of facilities for GCF does not occur, changes of quantitative and qualitative characteristics of communities of hydrobionts after cease of works are reversible. River ecosystems are restored within a more short period of time in comparison to lacustrine ones. On the basis of conducted comprehensive studies, the proposals for the protection of fisheries resources and monitoring of aquatic ecosystems are reported. Recommendations for reducing the anthropogenic impact on aquatic ecosystems in the development period are presented. The results of the investigation were used in the designing the environmental protection part of the Kruzenshternskoye deposit project. At present, the disturbances in the territory of Kruzenshternskoye deposit of gas does not impact the aquatic ecosystems

  6. Development of radionuclide transport model in the ecosystem of brackish lake Obuchi

    International Nuclear Information System (INIS)

    Ueda, Shinji; Kondo, Kunio; Chikuchi, Yuki; Inaba, Jiro

    2003-01-01

    The purpose of this study is to develop a computer code for a radionuclide transport model in Lake Obuchi which is adjacent to nuclear fuel cycle facilities including a nuclear spent-fuel reprocessing plant under construction in Rokkasho-mura. The lake is brackish and this fact makes the entry mode of radionuclides into the lake and its ecosystem very characteristic. For the construction of the code, it is important to incorporate the characteristics of the ecosystem as well as the hydraulic movements into the model. In the present study we report the biological parameters related to the transport model obtained from field observations and a laboratory experiment. We also give results from development of an advective-diffusion model. Monthly field observations revealed that 18 to 47 species of phytoplankton, 9 to 20 species of zooplankton and 0 to 21 species of benthos were present in the lake. A marked seasonal change was observed in the dominant species for both planktons. Mean carbon masses of DOC, POC, phytoplankton and zooplankton in the lake were 16 x 10 4 , 5.9 x 10 4 , 3.7 x 10 4 and 0.20 x 10 4 kg-C, respectively. Phytoplanktons of 10 species in 8 genera were isolated and maintained in a bacteria-free medium in the laboratory. Some physiological and metabolic characteristics of the planktons were studied under those conditions. An advective-diffusion model was developed for particles in the lake. Field observations showed that the model could simulate formation and elimination of the water current. (author)

  7. Climate change and Southern Ocean ecosystems I: how changes in physical habitats directly affect marine biota.

    Science.gov (United States)

    Constable, Andrew J; Melbourne-Thomas, Jessica; Corney, Stuart P; Arrigo, Kevin R; Barbraud, Christophe; Barnes, David K A; Bindoff, Nathaniel L; Boyd, Philip W; Brandt, Angelika; Costa, Daniel P; Davidson, Andrew T; Ducklow, Hugh W; Emmerson, Louise; Fukuchi, Mitsuo; Gutt, Julian; Hindell, Mark A; Hofmann, Eileen E; Hosie, Graham W; Iida, Takahiro; Jacob, Sarah; Johnston, Nadine M; Kawaguchi, So; Kokubun, Nobuo; Koubbi, Philippe; Lea, Mary-Anne; Makhado, Azwianewi; Massom, Rob A; Meiners, Klaus; Meredith, Michael P; Murphy, Eugene J; Nicol, Stephen; Reid, Keith; Richerson, Kate; Riddle, Martin J; Rintoul, Stephen R; Smith, Walker O; Southwell, Colin; Stark, Jonathon S; Sumner, Michael; Swadling, Kerrie M; Takahashi, Kunio T; Trathan, Phil N; Welsford, Dirk C; Weimerskirch, Henri; Westwood, Karen J; Wienecke, Barbara C; Wolf-Gladrow, Dieter; Wright, Simon W; Xavier, Jose C; Ziegler, Philippe

    2014-10-01

    Antarctic and Southern Ocean (ASO) marine ecosystems have been changing for at least the last 30 years, including in response to increasing ocean temperatures and changes in the extent and seasonality of sea ice; the magnitude and direction of these changes differ between regions around Antarctica that could see populations of the same species changing differently in different regions. This article reviews current and expected changes in ASO physical habitats in response to climate change. It then reviews how these changes may impact the autecology of marine biota of this polar region: microbes, zooplankton, salps, Antarctic krill, fish, cephalopods, marine mammals, seabirds, and benthos. The general prognosis for ASO marine habitats is for an overall warming and freshening, strengthening of westerly winds, with a potential pole-ward movement of those winds and the frontal systems, and an increase in ocean eddy activity. Many habitat parameters will have regionally specific changes, particularly relating to sea ice characteristics and seasonal dynamics. Lower trophic levels are expected to move south as the ocean conditions in which they are currently found move pole-ward. For Antarctic krill and finfish, the latitudinal breadth of their range will depend on their tolerance of warming oceans and changes to productivity. Ocean acidification is a concern not only for calcifying organisms but also for crustaceans such as Antarctic krill; it is also likely to be the most important change in benthic habitats over the coming century. For marine mammals and birds, the expected changes primarily relate to their flexibility in moving to alternative locations for food and the energetic cost of longer or more complex foraging trips for those that are bound to breeding colonies. Few species are sufficiently well studied to make comprehensive species-specific vulnerability assessments possible. Priorities for future work are discussed. © 2014 John Wiley & Sons Ltd.

  8. The role of abiotic factors in the Cambrian Substrate Revolution: A review from the benthic community replacements of West Gondwana

    Science.gov (United States)

    Álvaro, J. Javier; Zamora, Samuel; Clausen, Sébastien; Vizcaïno, Daniel; Smith, Andrew B.

    2013-03-01

    The Cambrian Substrate Revolution refers to a substantial and "rapid" change to the nature of marine sedimentary substrates in the early Cambrian and is widely interpreted as a biologically-driven event, a direct response to evolutionary innovations in metazoan burrowing and the development of new shelly faunas. However, abiotic factors such as tectonic and climatic evolution also had the potential to restructure Cambrian substrates, and are here shown to be more plausible drivers of change in the benthic faunas of western Gondwana. The western Mediterranean region underwent a southward drift during Cambrian times, which drove a switch from subtropical carbonates to temperate siliciclastic substrates with short-term episodes of temperate carbonate productivity. As a result, microbial and shelly carbonates disappeared diachronously in a stepwise manner across the lower-middle Cambrian boundary interval. Archaeocyathan-microbial reefs were replaced by chancelloriid-eocrinoid-(spiculate) sponge meadows, in which the stepwise immigration of new echinoderm taxa was primarily controlled by extensional tectonic events, first recorded in rifting settings and later in passive-margin platforms. Availability of new kinds of substrate was thus the primary factor that controlled where and when evolutionary innovations in benthic strategies arose. Examples of this include the early Cambrian colonization of phosphatic hardgrounds and thrombolite crusts by chancelloriids, archaeocyathan and spiculate sponges, and the exploitation by benthos to the increasingly widespread availability of shelly grounds and carbonate firmgrounds by early-diagenetic cementation. A microbial mat/epifaunal antagonistic relationship is demonstrated for echinoderm pelmatozoans based on the non-overlapping palaeogeographic distributions of microbial reefs and mats versus mud-sticker pelmatozoans. Cambrian benthic communities thus evolved in parallel with substrates in response to abiotic factors rather

  9. Assessment of Sediment Risk in the North End of Tai Lake, China: Integrating Chemical Analysis and Chronic Toxicity Testing with Chironomus dilutus.

    Science.gov (United States)

    Qi, Hongxue; Ma, Ping; Li, Huizhen; You, Jing

    2015-11-01

    Whole life-cycle bioassays with Chironomus dilutus were performed to evaluate sediment toxicity in Tai Lake, a typical freshwater lake in China. Meanwhile, contaminants of concern were analyzed in sediment. The sediments in Tai Lake showed no acute mortality in 10-day testing to C. dilutus. After chronic exposure to the sediments, however, adverse effects-including decreased survival and sublethal impairments of growth, emergence, and fecundity-were observed at most sites in Tai Lake. A variety of contaminants were detected in sediment with the total concentrations in the range of 504-889 ng/g dry weight (dw) for polycyclic aromatic hydrocarbons, 0.56-1.81 ng/g dw for polychlorinated biphenyls, 38.6-87.8 ng/g dw for polybrominated diphenyl ethers, 8.34-14.2 ng/g dw for organochlorine pesticides, 1.27-2.95 ng/g dw for organophosphate pesticides, 0.11-0.21 ng/g dw for pyrethroid pesticides, and 332-609 µg/g dw for metals. Finally, a canonical correlation analysis was applied to link chronic sediment toxicity to the toxic units of individual contaminants. Results suggested that two pesticides (hexachlorocyclohexane and chlorpyrifos) and two metals (chromium and nickel) in sediments from Tai Lake were the potential contributors to the noted toxicity in C. dilutus in the life-cycle toxicity testing. In conclusion, acute bioassays with the benthos were not sensitive enough to assess sediment toxicity in freshwater lakes in China, and it is desirable to integrate chronic toxicity testing with chemical analysis to better understand sediment risk.

  10. Assessing the impact of diclofenac, ibuprofen and sildenafil citrate (Viagra®) on the fertilisation biology of broadcast spawning marine invertebrates.

    Science.gov (United States)

    Mohd Zanuri, Norlaila Binti; Bentley, Matthew G; Caldwell, Gary S

    2017-06-01

    Exposure to synthetic chemicals is a key environmental challenge faced by aquatic organisms. The time and dose effects of the pharmaceuticals diclofenac, ibuprofen, and sildenafil citrate on sperm motility and successful fertilisation are studied using the echinoderms, Asterias rubens and Psammechinus miliaris, and the polychaete worm Arenicola marina, all important components of the marine benthos. Motility was reduced for all species when exposed to diclofenac concentrations ≥0.1 μg/L. Exposure to ≥1.0 μg/L of ibuprofen affected only P. miliaris gametes and fertilisation success of A. marina. A. rubens and P. miliaris sperm increased in both percentage motility and swimming velocity when exposed to sildenafil citrate at concentrations ≥18 and ≥ 50 ng/L, respectively. Pre-incubation of sperm with sildenafil citrate significantly increased fertilisation success in A. rubens and P. miliaris but not in A. marina. Pre-incubated A. rubens oocytes fertilised successfully in ibuprofen. According to EU Directive 93/67/EEC, diclofenac is classified as a very toxic substance to gametes of A. rubens, P. miliaris, and A. marina (EC 50  = 100-1000 μg/L) while ibuprofen is classified as very toxic to gametes of P. miliaris but non-toxic to gametes of A. marina (EC 50  > 10,000 μg/L). The present study indicates that diclofenac exposure may have negative impacts on invertebrate reproductive success, whereas ibuprofen potentially may compromise P. miliaris reproduction. This study provides a valuable insight into the mechanisms that allow marine invertebrates to survive and reproduce in contaminated and changing habitats. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Importance of benthic prey for fishes in coral reef-associated sediments

    Science.gov (United States)

    DeFelice, R.C.; Parrish, J.D.

    2003-01-01

    The importance of open, sandy substrate adjacent to coral reefs as habitat and a food source for fishes has been little studied in most shallow tropical waters in the Pacific, including Hawai'i. In this study, in Hanalei Bay, Hiwai'i, we identified and quantified the major invertebrate fauna (larger than 0.5 mm) in the well-characterized sands adjoining the shallow fringing reefs. Concurrently, we identified the fish species that seemed to make substantial use of these sand habitats, estimated their density there, sampled their gut contents to examine trophic links with the sand habitat, and made other observations and collections to determine the times, locations, and types of activity there. A variety of (mostly small) polychaeres were dominant in the sediments at most sampling stations, along with many small crustaceans (e.g., amphipods, isopods, ostracods, and small shrimps) and fair numbers of mollusks (especially bivalves) and small echinoids. Fish guts examined contained ???77% of the total number of benthic taxa collected, including nearly all those just listed. However, fish consumption was selective, and the larger shrimps, crabs, and small cryptic fishes were dominant in the diets of most of the numerous predator taxa. Diets of benthic-feeding fishes showed relatively low specific overlap. The fish fauna in this area included substrate-indifferent pelagics, species with various degrees of reef relatedness, reef-restricted species, and (at the other extreme) permanent cryptic sand dwellers. Data on occurrence and movements of fishes indicated that a band of sandy substrate several tens of meters wide next to the reef was an active area for fishes, and activity was considerably different at different times of day and for fish of different ages. These results imply an important trophic role for the benthos in these near-reef habitats in support of reef-associated fishes.

  12. Taxonomic and functional surrogates of sessile benthic diversity in Mediterranean marine caves.

    Science.gov (United States)

    Gerovasileiou, Vasilis; Dimitriadis, Charalampos; Arvanitidis, Christos; Voultsiadou, Eleni

    2017-01-01

    Hard substrates host globally a rich biodiversity, orders of magnitude higher in species number than that in surrounding soft substrates. Among them, marine caves support unique biodiversity and fragile communities but suffer lack of quantitative data on their structure and function, hindering their conservation status assessment. A first approach to the non-destructive ecological monitoring of marine caves by testing surrogates of structural and functional composition of sessile benthos was attempted in two species-rich Mediterranean marine caves. Photographic sampling was performed in different positions on the cave walls, across the horizontal axis, from the entrance inwards. Eighty-four taxa were identified and assigned to 6 biological traits and 32 modalities related to morphology, behavior and ecological affinities, with sponges being the dominant taxon in species richness and coverage. In quest of possible biological surrogates, we examined the spatial variability of the total community structure and function and separately the sponge community structure and function. The observed patterns of the above metrics were significantly correlated with the distance from the entrance, the small-scale variability and their interaction. A positive correlation was found between all examined pairs of those metrics, supporting that: (i) the developed functional approach could be used for the study of marine cave sessile communities, and (ii) sponges could be used as a surrogate taxon for the structural and functional study of these communities. The suggested method could be tested in other types of hard substrate habitats and in multiple locations of the Mediterranean waters, facilitating monitoring schemes and conservation actions.

  13. Climate change and trophic response of the Antarctic bottom fauna.

    Directory of Open Access Journals (Sweden)

    Richard B Aronson

    Full Text Available BACKGROUND: As Earth warms, temperate and subpolar marine species will increasingly shift their geographic ranges poleward. The endemic shelf fauna of Antarctica is especially vulnerable to climate-mediated biological invasions because cold temperatures currently exclude the durophagous (shell-breaking predators that structure shallow-benthic communities elsewhere. METHODOLOGY/PRINCIPAL FINDINGS: We used the Eocene fossil record from Seymour Island, Antarctic Peninsula, to project specifically how global warming will reorganize the nearshore benthos of Antarctica. A long-term cooling trend, which began with a sharp temperature drop approximately 41 Ma (million years ago, eliminated durophagous predators-teleosts (modern bony fish, decapod crustaceans (crabs and lobsters and almost all neoselachian elasmobranchs (modern sharks and rays-from Antarctic nearshore waters after the Eocene. Even prior to those extinctions, durophagous predators became less active as coastal sea temperatures declined from 41 Ma to the end of the Eocene, approximately 33.5 Ma. In response, dense populations of suspension-feeding ophiuroids and crinoids abruptly appeared. Dense aggregations of brachiopods transcended the cooling event with no apparent change in predation pressure, nor were there changes in the frequency of shell-drilling predation on venerid bivalves. CONCLUSIONS/SIGNIFICANCE: Rapid warming in the Southern Ocean is now removing the physiological barriers to shell-breaking predators, and crabs are returning to the Antarctic Peninsula. Over the coming decades to centuries, we predict a rapid reversal of the Eocene trends. Increasing predation will reduce or eliminate extant dense populations of suspension-feeding echinoderms from nearshore habitats along the Peninsula while brachiopods will continue to form large populations, and the intensity of shell-drilling predation on infaunal bivalves will not change appreciably. In time the ecological effects of

  14. Coastal Sedimentation Associated with the Tohoku Tsunami of 11 March 2011 in South Kuril Islands, NW Pacific Ocean

    Science.gov (United States)

    Razjigaeva, N. G.; Ganzey, L. A.; Grebennikova, T. A.; Ivanova, E. D.; Kharlamov, A. A.; Kaistrenko, V. M.; Shishkin, A. A.

    2013-06-01

    Sediment deposited by the Tohoku tsunami of March 11, 2011 in the Southern Kurils (Kunashir, Shikotan, Zeleniy, Yuri, Tanfiliev islands) was radically different from sedimentation during local strong storms and from tsunamis with larger runup at the same location. Sediments from the 2011 Tohoku tsunami were surveyed in the field, immediately and 6 months after the event, and analyzed in the laboratory for sediment granulometry, benthos Foraminifa assemblages, and diatom algae. Run-up elevation and inundation distance were calculated from the wrackline (accumulations of driftwood, woody debris, grass, and seaweed) marking the distal edge of tsunami inundation. Run-up of the tsunami was 5 m at maximum, and 3-4 m on average. Maximum distance of inundation was recorded in river mouths (up to 630 m), but was generally in the range of 50-80 m. Although similar to the local strong storms in runup height, the tsunami generally did not erode the coast, nor leave a deposit. However, deposits uncharacteristic of tsunami, described as brown aleuropelitic (silty and clayey) mud rich in organic matter, were found in closed bays facing the South Kuril Strait. These closed bays were covered with sea ice at the time of tsunami. As the tsunami waves broke the ice, the ice floes enhanced the bottom erosion on shoals and destruction of low-lying coastal peatland even at modest ranges of runup. In the muddy tsunami deposits, silt comprised up to 64 % and clay up to 41.5 %. The Foraminifera assemblages displayed features characteristic of benthic microfauna in the near-shore zone. Deep-sea diatoms recovered from tsunami deposits in two closely situated bays, namely Krabovaya and Otradnaya bays, had different requirements for environmental temperature, suggesting these different diatoms were brought to the bays by the tsunami wave entraining various water masses when skirting the island from the north and from the south.

  15. Jellyfish life histories: role of polyps in forming and maintaining scyphomedusa populations.

    Science.gov (United States)

    Lucas, Cathy H; Graham, William M; Widmer, Chad

    2012-01-01

    Large population fluctuations of jellyfish occur over a variety of temporal scales, from weekly to seasonal, inter-annual and even decadal, with some regions of the world reported to be experiencing persistent seasonal bloom events. Recent jellyfish research has focussed on understanding the causes and consequences of these population changes, with the vast majority of studies considering the effect of changing environmental variables only on the pelagic medusa. But many of the bloom-forming species are members of the Scyphozoa with complex metagenic life cycles consisting of a sexually reproducing pelagic medusa and asexually reproducing benthic polyp. Recruitment success during the juvenile (planula, polyp and ephyrae) stages of the life cycle can have a major effect on the abundance of the adult (medusa) population, but until very recently, little was known about the ecology of the polyp or scyphistoma phase of the scyphozoan life cycle. The aim of this review is to synthesise the current state of knowledge of polyp ecology by examining (1) the recruitment and metamorphosis of planulae larvae into polyps, (2) survival and longevity of polyps, (3) expansion of polyp populations via asexual propagation and (4) strobilation and recruitment of ephyrae (juvenile medusae). Where possible, comparisons are made with the life histories of other bentho-pelagic marine invertebrates so that further inferences can be made. Differences between tropical and temperate species are highlighted and related to climate change, and populations of the same species (in particular Aurelia aurita) inhabiting different habitats within its geographic range are compared. The roles that polyps play in ensuring the long-term survival of jellyfish populations as well as in the formation of bloom populations are considered, and recommendations for future research are presented. Copyright © 2012 Elsevier Ltd. All rights reserved.

  16. Exploring the ecosystem engineering ability of Red Sea shallow benthic habitats using stocks and fluxes in carbon biogeochemistry

    KAUST Repository

    Baldry, Kimberlee

    2017-12-01

    The coastal ocean is a marginal region of the global ocean, but is home to metabolically intense ecosystems which increase the structural complexity of the benthos. These ecosystems have the ability to alter the carbon chemistry of surrounding waters through their metabolism, mainly through processes which directly release or consume carbon dioxide. In this way, coastal habitats can engineer their environment by acting as sources or sinks of carbon dioxide and altering their environmental chemistry from the regional norm. In most coastal water masses, it is difficult to resolve the ecosystem effect on coastal carbon biogeochemistry due to the mixing of multiple offshore end members, complex geography or the influence of variable freshwater inputs. The Red Sea provides a simple environment for the study of ecosystem processes at a coastal scale as it contains only one offshore end-member and negligible freshwater inputs due to the arid climate of adjacent land. This work explores the ability of three Red Sea benthic coastal habitats (coral reefs, seagrass meadows and mangrove forests) to create characteristic ecosystem end-members, which deviate from the biogeochemistry of offshore source waters. This is done by both calculating non-conservative deviations in carbonate stocks collected over each ecosystem, and by quantifying net carbonate fluxes (in seagrass meadows and mangrove forests only) using 24 hour incubations. Results illustrate that carbonate stocks over ecosystems conform to broad ecosystem trends, which are different to the offshore end-member, and are influenced by inherited properties from surrounding ecosystems. Carbonate fluxes also show ecosystem dependent trends and further illustrate the importance of sediment processes in influencing CaCO3 fluxes in blue carbon benthic habitats, which warrants further attention. These findings show the respective advantages of studying both carbonate stocks and fluxes of coastal benthic ecosystems in order to

  17. Consequences of increasing hypoxic disturbance on benthic communities and ecosystem functioning.

    Science.gov (United States)

    Villnäs, Anna; Norkko, Joanna; Lukkari, Kaarina; Hewitt, Judi; Norkko, Alf

    2012-01-01

    Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota) effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface) by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days) in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH(4)(+) and dissolved Si. Although effluxes of PO(4)(3-) were not altered significantly, changes were observed in sediment PO(4)(3-) sorption capability. The duration of hypoxia (i.e. number of days of stress) explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the benthic habitat

  18. Strategies for baseline/environmental impact studies in Nigeria

    International Nuclear Information System (INIS)

    Odu, C.T.

    1991-01-01

    This paper reports that in order to assess the environmental impact of site activities and ecosystem change brought about by stress, basic baseline data are necessary to characterize the normal environment so that environmental quality control programs can be developed with a firm ecological base. The program and methodology adopted in our field surveys to assess the character, magnitude and extent of pollutant effects on soil, vegetation and water, as a basis for economic assessment of pollutant effects on agriculture, forestry and the aquatic system and for preparing environmental impact statements, are presented. These techniques were modified and adopted in the environmental impact study of the Isampou Manifold Oil Spill, a study which circumstances made necessary seven years after the oil spill. Reliance on the extent of pollution soon after the incidence was based on the determination of total hydrocarbons at creek bottoms as well as on the determinations of nickel/vanadium ratios. Hydrocarbon contents of creek banks and creek bottoms were within biogenic levels at the time of field sampling. Ni/V ratios were high in heavy impact areas and decreased in areas of medium and very light impact areas. Use of the Ni/V ratio as evidence of past oil pollution agreed closely with a sketch of the extent of crude oil pollution drawn by the Shell Petroleum Development Company seven years earlier. There were nor abnormal vegetation features. The presence of 10-15 years old Musanga cecropioides at the edge of the manifold slot and creeks indicated that vegetation above water level was not affected by the oil spillage. The physico-chemical properties of the waters, plankton composition and density of the species found, as well as the presence of endroproct bryozoan in the benthos showed that the aquatic system had by the time of sample collection, completely recovered from the oil spillage

  19. High-Up: A Remote Reservoir of Microbial Extremophiles in Central Andean Wetlands.

    Science.gov (United States)

    Albarracín, Virginia H; Kurth, Daniel; Ordoñez, Omar F; Belfiore, Carolina; Luccini, Eduardo; Salum, Graciela M; Piacentini, Ruben D; Farías, María E

    2015-01-01

    The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3700 m. Being isolated and hostile, these so-called "High-Altitude Andean Lakes" (HAAL) are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles) such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern-though quite imperfect-analogs of environments proxy for an earlier time in Earth's history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure). Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e., DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

  20. High-up: a remote reservoir of microbial extremophiles at Central Andean Wetlands

    Directory of Open Access Journals (Sweden)

    Virginia Helena Albarracín

    2015-12-01

    Full Text Available The Central Andes region displays unexplored ecosystems of shallow lakes and salt flats at mean altitudes of 3,700 m. Being isolated and hostile, these so-called High-Altitude Andean Lakes (HAAL are pristine and have been exposed to little human influence. HAAL proved to be a rich source of microbes showing interesting adaptations to life in extreme settings (poly-extremophiles such as alkalinity, high concentrations of arsenic and dissolved salts, intense dryness, large daily ambient thermal amplitude, and extreme solar radiation levels. This work reviews HAAL microbiodiversity, taking into account different microbial niches, such as plankton, benthos, microbial mats and microbialites. The modern stromatolites and other microbialites discovered recently at HAAL are highlighted, as they provide unique modern -though quite imperfect- analogues of environments proxy for an earlier time in Earth’s history (volcanic setting and profuse hydrothermal activity, low atmospheric O2 pressure, thin ozone layer and high UV exposure. Likewise, we stress the importance of HAAL microbes as model poly-extremophiles in the study of the molecular mechanisms underlying their resistance ability against UV and toxic or deleterious chemicals using genome mining and functional genomics. In future research directions, it will be necessary to exploit the full potential of HAAL poly-extremophiles in terms of their biotechnological applications. Current projects heading this way have yielded detailed molecular information and functional proof on novel extremoenzymes: i.e. DNA repair enzymes and arsenic efflux pumps for which medical and bioremediation applications, respectively, are envisaged. But still, much effort is required to unravel novel functions for this and other molecules that dwell in a unique biological treasure despite its being hidden high up, in the remote Andes.

  1. Insights into the benthic communities response to the inflow of Black Sea mesotrophic waters in the North Aegean Sea

    Science.gov (United States)

    Lampadariou, Nikolaos; Sevastou, Katerina; Podaras, Dimitrios; Tselepides, Anastasios

    2017-10-01

    The effects of the Dardanelles inflow of buoyant, modified Black Sea waters (BSW) of low salinity and temperature, on the meio- and macrobenthic communities of the north Aegean ecosystem was investigated during two cruises in October 2013 and March 2014. Sediment samples were collected from two stations subjected to the BSW effect, one shallow and one deep north of the Dardanelles Straits, and from two stations of similar bathymetry, which were considered to be outside the influence of BSW and were located to the south of the Dardanelles Straits. Results suggest that there is an effect of the BSW on benthos, as both meiofaunal and macrofaunal standing stocks were lower at the most distant, and therefore least affected from the inflow, station, and higher at the station of similar bathymetry which was affected the most by the BSW inflow. Univariate and multivariate non-parametric analyses (nMDS, PERMANOVA) provided further support, indicating differences between the two areas (North vs. South) in the case of the deep stations, while differences between depth categories were evident in the area outside the BSW influence zone. Distance-based linear modeling (DISTLM) indicated that meiofauna correlated with proxies of food availability and sediment characteristics. Macrofauna, on the other hand, showed a rather high significant correlation with depth only. Nematode species composition was statistically significant different between depth categories only, yet the nMDS ordination clearly separated the deep southern station from the rest, with non-selective deposit feeders dominating the stations under the influence of the BSW, and epistratum feeders being important at the stations outside the influence of the BSW. It is concluded that both the meiofaunal and macrofaunal communities at the northern stations benefit from a constant input of high amounts of organic matter to the seafloor, while those at the southern area may be occasionally affected by the thermohaline BSW

  2. Long-term patterns of benthic irradiance and kelp production in the central Beaufort sea reveal implications of warming for Arctic inner shelves

    Science.gov (United States)

    Bonsell, Christina; Dunton, Kenneth H.

    2018-03-01

    This study synthesizes a multidecadal dataset of annual growth of the Arctic endemic kelp Laminaria solidungula and corresponding measurements of in situ benthic irradiance from Stefansson Sound in the central Beaufort Sea. We incorporate long-term data on sea ice concentration (National Sea Ice Data Center) and wind (National Weather Service) to assess how ice extent and summer wind dynamics affect the benthic light environment and annual kelp production. We find evidence of significant changes in sea ice extent in Stefansson Sound, with an extension of the ice-free season by approximately 17 days since 1979. Although kelp elongation at 5-7 m depths varies significantly among sites and years (3.8-49.8 cm yr-1), there is no evidence for increased production with either earlier ice break-up or a longer summer ice-free period. This is explained by very low light transmittance to the benthos during the summer season (mean daily percent surface irradiance ± SD: 1.7 ± 3.6 to 4.5 ± 6.6, depending on depth, with light attenuation values ranging from 0.5 to 0.8 m-1), resulting in minimal potential for kelp production on most days. Additionally, on month-long timescales (35 days) in the ice-free summer, benthic light levels are negatively related to wind speed. The frequent, wind-driven resuspension of sediments following ice break-up significantly reduce light to the seabed, effectively nullifying the benefits of an increased ice-free season on annual kelp growth. Instead, benthic light and primary production may depend substantially on the 1-3 week period surrounding ice break-up when intermediate sea ice concentrations reduce wind-driven sediment resuspension. These results suggest that both benthic and water column primary production along the inner shelf of Arctic marginal seas may decrease, not increase, with reductions in sea ice extent.

  3. Diversity and ecological structure of vibrios in benthic and pelagic habitats along a latitudinal gradient in the Southwest Atlantic Ocean.

    Science.gov (United States)

    Chimetto Tonon, Luciane A; Silva, Bruno Sergio de O; Moreira, Ana Paula B; Valle, Cecilia; Alves, Nelson; Cavalcanti, Giselle; Garcia, Gizele; Lopes, Rubens M; Francini-Filho, Ronaldo B; de Moura, Rodrigo L; Thompson, Cristiane C; Thompson, Fabiano L

    2015-01-01

    We analyzed the diversity and population structure of the 775 Vibrio isolates from different locations of the southwestern Atlantic Ocean (SAO), including St. Peter and St. Paul Archipelago (SPSPA), Abrolhos Bank (AB) and the St. Sebastian region (SS), between 2005 and 2010. In this study, 195 novel isolates, obtained from seawater and major benthic organisms (rhodoliths and corals), were compared with a collection of 580 isolates previously characterized (available at www.taxvibrio.lncc.br). The isolates were distributed in 8 major habitat spectra according to AdaptML analysis on the basis of pyrH phylogenetic reconstruction and ecological information, such as isolation source (i.e., corals: Madracis decactis, Mussismilia braziliensis, M. hispida, Phyllogorgia dilatata, Scolymia wellsi; zoanthids: Palythoa caribaeorum, P. variabilis and Zoanthus solanderi; fireworm: Hermodice carunculata; rhodolith; water and sediment) and sampling site regions (SPSPA, AB and SS). Ecologically distinct groups were discerned through AdaptML, which finds phylogenetic groups that are significantly different in their spectra of habitat preferences. Some habitat spectra suggested ecological specialization, with habitat spectra 2, 3, and 4 corresponding to specialization on SPSPA, AB, and SS, respectively. This match between habitat and location may reflect a minor exchange of Vibrio populations between geographically isolated benthic systems. Moreover, we found several widespread Vibrio species predominantly from water column, and different populations of a single Vibrio species from H. carunculata in ecologically distinct groups (H-1 and H-8 respectively). On the other hand, AdaptML detected phylogenetic groups that are found in both the benthos and in open water. The ecological grouping observed suggests dispersal and connectivity between the benthic and pelagic systems in AB. This study is a first attempt to characterize the biogeographic distribution of vibrios in both seawater and

  4. Aura-biomes are present in the water layer above coral reef benthic macro-organisms.

    Science.gov (United States)

    Walsh, Kevin; Haggerty, J Matthew; Doane, Michael P; Hansen, John J; Morris, Megan M; Moreira, Ana Paula B; de Oliveira, Louisi; Leomil, Luciana; Garcia, Gizele D; Thompson, Fabiano; Dinsdale, Elizabeth A

    2017-01-01

    As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1) the coral Mussismilia braziliensis , (2) fleshy macroalgae ( Stypopodium , Dictota and Canistrocarpus ), (3) turf algae, and (4) the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific "aura-biome". The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria , Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms.

  5. Aura-biomes are present in the water layer above coral reef benthic macro-organisms

    Directory of Open Access Journals (Sweden)

    Kevin Walsh

    2017-08-01

    Full Text Available As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1 the coral Mussismilia braziliensis, (2 fleshy macroalgae (Stypopodium, Dictota and Canistrocarpus, (3 turf algae, and (4 the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific “aura-biome”. The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria, Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms.

  6. Diversity and ecological structure of vibrios in benthic and pelagic habitats along a latitudinal gradient in the Southwest Atlantic Ocean

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    Luciane A. Chimetto Tonon

    2015-02-01

    Full Text Available We analyzed the diversity and population structure of the 775 Vibrio isolates from different locations of the southwestern Atlantic Ocean (SAO, including St. Peter and St. Paul Archipelago (SPSPA, Abrolhos Bank (AB and the St. Sebastian region (SS, between 2005 and 2010. In this study, 195 novel isolates, obtained from seawater and major benthic organisms (rhodoliths and corals, were compared with a collection of 580 isolates previously characterized (available at www.taxvibrio.lncc.br. The isolates were distributed in 8 major habitat spectra according to AdaptML analysis on the basis of pyrH phylogenetic reconstruction and ecological information, such as isolation source (i.e., corals: Madracis decactis, Mussismilia braziliensis, M. hispida, Phyllogorgia dilatata, Scolymia wellsi; zoanthids: Palythoa caribaeorum, P. variabilis and Zoanthus solanderi; fireworm: Hermodice carunculata; rhodolith; water and sediment and sampling site regions (SPSPA, AB and SS. Ecologically distinct groups were discerned through AdaptML, which finds phylogenetic groups that are significantly different in their spectra of habitat preferences. Some habitat spectra suggested ecological specialization, with habitat spectra 2, 3, and 4 corresponding to specialization on SPSPA, AB, and SS, respectively. This match between habitat and location may reflect a minor exchange of Vibrio populations between geographically isolated benthic systems. Moreover, we found several widespread Vibrio species predominantly from water column, and different populations of a single Vibrio species from H. carunculata in ecologically distinct groups (H-1 and H-8 respectively. On the other hand, AdaptML detected phylogenetic groups that are found in both the benthos and in open water. The ecological grouping observed suggests dispersal and connectivity between the benthic and pelagic systems in AB. This study is a first attempt to characterize the biogeographic distribution of vibrios in both

  7. Empirical relationships among resilience indicators on Micronesian reefs

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    Mumby, P. J.; Bejarano, S.; Golbuu, Y.; Steneck, R. S.; Arnold, S. N.; van Woesik, R.; Friedlander, A. M.

    2013-03-01

    A process-orientated understanding of ecosystems usually starts with an exploratory analysis of empirical relationships among potential drivers and state variables. While relationships among herbivory, algal cover, and coral recruitment, have been explored in the Caribbean, the nature of such relationships in the Pacific appears to be variable or unclear. Here, we examine potential drivers structuring the benthos and herbivorous fish assemblages of outer-shelf reefs in Micronesia (Palau, Guam and Pohnpei). Surveys were stratified by wave exposure and protection from fishing. High biomass of most herbivores was favoured by high wave exposure. High abundance of large-bodied scarids was associated with low turf abundance, high coral cover, and marine reserves. The remaining herbivores were more abundant in reefs with low coral cover, possibly because space and hence food limitation occur in high-coral-cover reefs. Rugosity had no detectable effect on herbivorous fish abundance once differences in exposure and coral cover were accounted for. At identical depths, high wave exposure was associated with greater volumes (cover × canopy height) of macroalgae and algal turfs, which most likely resulted from high primary productivity driven by flow. In exposed areas, macroalgal cover declined as the acanthurid biomass increased. The volume of algal turfs was negatively associated with coral cover and herbivore biomass. In turn, high coral cover and herbivore biomass are likely to intensify grazing. The density of juvenile corals was variable where macroalgal cover was low but was confined to lower densities where macroalgal cover was high. High coral cover and density of juvenile corals were favoured in sheltered habitats. While a weak positive relationship was found between scarid biomass and juvenile coral density, we hypothesise that high scarid densities may hinder juvenile density through increased corallivory. New hypotheses emerged that will help clarify the role of

  8. Bathymetric gradients within a Paleozoic Island Arc, southeastern Alaska (Alexander Terrane)

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    Soja, C.M. (Smith College, Northampton, MA (USA))

    1990-05-01

    Early to Late Silurian (Wenlock-Ludlow) limestones belonging to the Heceta Formation reflect bathymetric gradients within the ancient island arc exposed in the Alexander terrane of southeastern Alaska. These rocks record the earliest occurrence of widespread carbonate deposition in the region and represent the earliest foundation for shallow-water platform development within the arc. The excellent preservation of platform, platform margin, and slope deposits contrasts with the poor preservation of many marine sediments that originated within other island arcs. Hence, these limestones provide important insights into the styles, processes, and bathymetry of carbonate deposition in island arcs. Carbonate depositional sites within the arc extended laterally from nearshore intertidal and relatively shallow subtidal zones of a marine platform, to the seaward margins of a rimmed shelf, and into deeper subtidal areas of a slope environment. Fossiliferous deposits that originated on the platform comprise a diversity of shelly benthos, including corals and stromatoporoids in growth position. Dasycladacean algae, oncoids, and Amphipora also indicate shallow-water conditions. Organic buildups and reefs were constructed by cyanobacteria, massive stromatoporoids, corals, and algae at the platform margin. Deposition beyond the seaward edge of the shelf is evident from the carbonate turbidites that consist of skeletal debris of shallow-water derivation and an absence of coarse siliciclastic detritus. Sedimentation and resedimentation along a bathymetric gradient within the arc is especially well illustrated by the carbonate breccias that are enclosed within these deep subtidal sediments. They comprise detached stromatolites and clasts of shallow-water origin that were derived from the platform and its margin during periodic slumping of the shelf edge.

  9. Response of sedimentary processes to cyanobacteria loading

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    Mindaugas Zilius

    2015-12-01

    Full Text Available Sedimentation of pelagic cyanobacteria in dystrophic freshwater and oligohaline lagoons results in large inputs of labile organic matter (OM to the benthos. We used an experimental approach to study the short-term impact of such phenomena on the benthic microbial community metabolism and on the nitrogen (N fluxes across the sediment-water interface. We hypothesized an increase of respiratory activity, including N loss via denitrification and its recycling to the water column. Our results show that the incorporation within sediments of the settled bloom increases benthic bacterial activities. This is coupled to large DON and NH4+ effluxes, and to a comparatively smaller increase of N2 production, while no significant effects were detected for the benthic fluxes of NOx-. We constructed flow schemes for N compounds, which show that while denitrification was significantly stimulated by amending cyanobacterial biomass to the sediments, it represented less than 1% of total OM mineralization. Interestingly, we observed that total released nitrogen (DIN+DON+N2 efflux was dominated by DON, which contributed 75–80 % of the net N efflux, suggesting incomplete mineralization of OM. With the measured total N mobilization rate of about 15 mmol N m-2 d-1 it would take more than 4 months to regenerate the total organic N input to sediments (2031 mmol N m-2, which represents the post-bloom deposited particulate organic N. These results suggest limited losses to the atmosphere and slow diffusive recycling of N buried into sediments, mostly as DON. Such regenerated N may eventually be flushed to the open sea or sustain pelagic blooms within the estuarine environment, including cyanobacteria, with a negative feedback for further import of atmospheric nitrogen via N-fixation.

  10. Tidal time-scale variation in nutrient flux across the sediment water interface of an estuarine tidal flat

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    Sakamaki, Takashi; Nishimura, Osamu; Sudo, Ruichi

    2006-05-01

    We determined the range of the tidal variations in nutrient flux across the sediment-water interface and elucidated mechanisms of the flux variation in two estuarine intertidal flats (one sand, one mud) in northeastern Japan. Nutrient flux was measured using in situ light and dark chambers, which were incubated for 2 h, 2-6 times per day. Results showed that nutrient concentration in overlying water varied by tide and was also affected by sewage-treated water inflow. The nutrient fluxes responded quickly to the tidal variation in overlying water chemistry and the range of the variation in flux was as large as the seasonal-scale variation reported in previous studies. In the sand flat, salinity increase likely enhanced benthos respiration and led to increases in both O 2 consumption and PO 43- regeneration under low illumination, while benthic microalgae were likely to actively generate O 2, uptake PO 43- and suppress PO 43- release under high illumination (>900 μmol photons m -2 s -1). Also in the mud flat, PO 43- flux was related with O 2 flux, although the range of temporal variation in PO 43- flux was small. In both the flats, NH 4+ flux was always governed by NH 4+ concentration in the overlying water; either an increase in NH 4+ uptake or a decrease in NH 4+ release was observed as the NH 4+ concentration rose due to inflow of river water or input of sewage-treated water. Although NO 3- tended to be released in both tidal flats when low NO 3- concentration seawater dominated, their relationship was likely to be weakened under conditions of low oxygen consumption and suppressed denitrification. It is likely that tidal variation in nutrient flux is governed more by the nutrient concentration than other factors, such as benthic biological processes, particularly in the case where nutrient concentration in the overlying water is relatively high and with wide amplitude.

  11. Linking benthic biodiversity and environmental conditions at the sea floor combining statistical and mechanistic modeling. Case study on the Black Sea's northwestern shelf.

    Science.gov (United States)

    Drion, Roxanne; Capet, Arthur; Gregoire, Marilaure

    2014-05-01

    The preservation of the health and biodiversity of benthic ecosystems is a crucial priority in order to achieve the Good Environmental Status (GES) of marine waters. The multiple pressures acting on the ocean, and in particular, on the coastal zone may prevent the maintenance of biodiversity either directly (e.g. trawling, dredging) or indirectly by modifying environmental conditions at the sea floor (e.g. eutrophication, pollution, acidification, warming). The management of the GES of the benthos in a changing environment and the definition of management strategies (e.g. nutrient reduction) that would preserve GES require tools able to predict the modifications of environmental conditions and to link these modifications to the status of the benthic system. Coupled biogeochemical-circulation models provide a large amount of information on physical (e.g. currents, salinity, temperature, shear stress) and biochemical conditions (e.g. oxygen, inorganic nutrients, sinking detritus) but cannot provide an information on species richness. We propose to link these aspects by applying canonical ordination techniques (e.g. Redundancy Analysis, CoInertia Analysis) on a large data set on macrobenthos collected on the Black Sea's north-western shelf with in-situ sediment data (e.g. granulometry, carbon and nitrogen content, C/N ratio, CaCO3 content) and bottom conditions (e.g. shear stress, level of oxygen stress, flux of organic matter to the sediments) provided by a three dimensional model. Beyond taxonomic description, the analysis is performed on the functional composition of the macrobenthos: A trait-based approach is used to assess the functional composition of the macrobenthos by associating the considered species to a list of biological, ecological and behavioral traits. This approach allows to appraise how local conditions determine the functional and taxonomical diversity and provides a mean to evaluate the impact of habitat alteration on the ecological role of

  12. Seamount influences on mid-water shrimps (Decapoda) and gnathophausiids (Lophogastridea) of the South-West Indian Ridge

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    Letessier, Tom B.; De Grave, Sammy; Boersch-Supan, Philipp H.; Kemp, Kirsty M.; Brierley, Andrew S.; Rogers, Alex D.

    2017-02-01

    Maintenance of often-observed elevated levels of pelagic diversity and biomass on seamounts, of relevance to conservation and fishery management, involves complex interactions between physical and biological variables that remain poorly understood. To untangle these biophysical processes we explore factors influencing the distribution of epi- and meso-pelagic (0-1000 m) micronektonic crustaceans (>15 mm; order Lophogastridea, family Gnathophausiidea; and order Decapoda) on and off seamounts along the South West Indian Ridge (SWIR, 27° to 42°S) and on a seamount off the Madagascar Ridge (31.6°S, 42.8°E). Thirty-one species of micronektic crustaceans were caught using mid-water trawls within the study area but there was no apparent latitude-related patterns in species richness or abundance. Species richness predicted by rarefraction curves and numerical abundance was highest in the vicinity (seamounts (species richness: 15 to 21; abundance: 10±2 to 20±1 ind.10-3 m-1) compared with over the abyssal plains and ridge slopes (species richness: 9.2-9.9; abundance: 24±2 to 79±8 ind.10-3 m-1). Multivariate analysis of assemblage composition revealed significant groupings of individual trawl samples with respect to whether the sample was on or off a seamount and hydrographic region, but not with time of sampling relative to diel cycle (day/night or dawn) or depth of sampling (0-500, 500-800, >800 m). The dominant species assemblage comprised the shrimps Systellaspis debilis (37%) and Sergia prehensilis (34%), and was restricted to seamounts on the subtropical SWIR. Our observations suggest that the 'oasis effect' of seamounts conventionally associated with higher trophic levels is also applicable to pelagic micronektic crustaceans at lower trophic levels. We suggest that the enhanced biomass and species richness attributed is due to 'habitat enrichment', whereby seamounts provide favourable habitats for both pelagic and bentho-pelagic mid-water crustaceans.

  13. Benthic Light Availability Improves Predictions of Riverine Primary Production

    Science.gov (United States)

    Kirk, L.; Cohen, M. J.

    2017-12-01

    Light is a fundamental control on photosynthesis, and often the only control strongly correlated with gross primary production (GPP) in streams and rivers; yet it has received far less attention than nutrients. Because benthic light is difficult to measure in situ, surrogates such as open sky irradiance are often used. Several studies have now refined methods to quantify canopy and water column attenuation of open sky light in order to estimate the amount of light that actually reaches the benthos. Given the additional effort that measuring benthic light requires, we should ask if benthic light always improves our predictions of GPP compared to just open sky irradiance. We use long-term, high-resolution dissolved oxygen, turbidity, dissolved organic matter (fDOM), and irradiance data from streams and rivers in north-central Florida, US across gradients of size and color to build statistical models of benthic light that predict GPP. Preliminary results on a large, clear river show only modest model improvements over open sky irradiance, even in heavily canopied reaches with pulses of tannic water. However, in another spring-fed river with greater connectivity to adjacent wetlands - and hence larger, more frequent pulses of tannic water - the model improved dramatically with the inclusion of fDOM (model R2 improved from 0.28 to 0.68). River shade modeling efforts also suggest that knowing benthic light will greatly enhance our ability to predict GPP in narrower, forested streams flowing in particular directions. Our objective is to outline conditions where an assessment of benthic light conditions would be necessary for riverine metabolism studies or management strategies.

  14. Accuracy in the estimation of quantitative minimal area from the diversity/area curve.

    Science.gov (United States)

    Vives, Sergi; Salicrú, Miquel

    2005-05-01

    The problem of representativity is fundamental in ecological studies. A qualitative minimal area that gives a good representation of species pool [C.M. Bouderesque, Methodes d'etude qualitative et quantitative du benthos (en particulier du phytobenthos), Tethys 3(1) (1971) 79] can be discerned from a quantitative minimal area which reflects the structural complexity of community [F.X. Niell, Sobre la biologia de Ascophyllum nosodum (L.) Le Jolis en Galicia, Invest. Pesq. 43 (1979) 501]. This suggests that the populational diversity can be considered as the value of the horizontal asymptote corresponding to the curve sample diversity/biomass [F.X. Niell, Les applications de l'index de Shannon a l'etude de la vegetation interdidale, Soc. Phycol. Fr. Bull. 19 (1974) 238]. In this study we develop a expression to determine minimal areas and use it to obtain certain information about the community structure based on diversity/area curve graphs. This expression is based on the functional relationship between the expected value of the diversity and the sample size used to estimate it. In order to establish the quality of the estimation process, we obtained the confidence intervals as a particularization of the functional (h-phi)-entropies proposed in [M. Salicru, M.L. Menendez, D. Morales, L. Pardo, Asymptotic distribution of (h,phi)-entropies, Commun. Stat. (Theory Methods) 22 (7) (1993) 2015]. As an example used to demonstrate the possibilities of this method, and only for illustrative purposes, data about a study on the rocky intertidal seawed populations in the Ria of Vigo (N.W. Spain) are analyzed [F.X. Niell, Estudios sobre la estructura, dinamica y produccion del Fitobentos intermareal (Facies rocosa) de la Ria de Vigo. Ph.D. Mem. University of Barcelona, Barcelona, 1979].

  15. Expanding OBIS beyond species occurrence data, with an extension for environmental data

    Science.gov (United States)

    Appeltans, W.; Provoost, P.; De Pooter, D.; Deneudt, K.; Goldstein, P.; Moncoiffe, G.; Rauch, S.; Nikolopoulou, S.; Van de Putte, A.; Vandepitte, L.; Wambiji, N.; Bailly, N.; Giorgetti, A.; Lewis, M.; Lipizer, M.; Mackay, K.; Roubicek, A.; Torres, C.; De Bruin, T.; Hernandez, F.

    2016-02-01

    The data collected for biological studies often include more than just biological parameters. Also observations on the habitat and additional physical and chemical measurements are collected to study the organisms in their environment, as may be details regarding the nature of the sampling or observation methods, equipment, and effort. These combined data are needed for the analysis of ecosystem functioning, ecological niche modelling, climate change, etc. However, scientists currently lack internationally agreed standards for managing and sharing these mixed datasets with their peers. If, at best, the data are not lost, the biological observations get often split from the physicochemical data and sent to different data repositories. In March 2015, the International Oceanographic Data and Information Exchange (IODE) Committee of UNESCO's Intergovernmental Oceanographic Commission has established a 2-year pilot project, involving 11 institutions from 10 countries in North-America, South-America, Europe, Africa and Australia. This project aims to develop procedures and guidelines for managing and sharing these mixed datasets, making sure that supporting measurements are curated and distributed alongside the species occurrence data. Moreover, it will investigate how these mixed datasets can flow to national, regional and global data repositories. Eventually, it will demonstrate the benefits of the approach for marine sciences, biological analysis and ecosystem modelling and will support the reproducibility of research. Here we will present a few case studies dealing with e.g. benthos and phytoplankton abundance and biomass data including sediment characteristics, water turbidity, temperature, salinity and dissolved oxygen, as well as biometric data and tracks of marine mammals holding CTD devices.

  16. Response of Benthic Macrofauna to Eutrophication in a Mesocosm Experiment: Ecosystem Resilience Prevents Hypoxic Conditions

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    Panagiotis D. Dimitriou

    2017-12-01

    Full Text Available A benthic-pelagic mesocosm experiment was performed to study how the benthic macrofaunal community responds to a eutrophication gradient. The novel experimental setup allowed the induction of an eutrophication gradient in the water column and the detailed documentation of the response of the benthos in terms of biodiversity and ecosystem processes. Nine mesocosms were deployed in the facilities of the Hellenic Center for Marine Research in Crete in the eastern Mediterranean. The mesocosms were 4 m deep, contained 1.5 m3 coastal water, and included 85 liters of undisturbed sediment at the bottom. No water or sediment exchange was allowed. The experimental design included a Control and two eutrophication levels (Low and High for the 58-day duration of the experiment. Macrofaunal samples were collected at the end of the experiment from each mesocosm and compared to the ones collected at the beginning of the experiment from the sediment collection area. Results show that the High eutrophication treatment differed significantly from the Control and Low treatments in terms of macrofaunal species composition, diversity, ecological status and ecosystem processes. The increased availability of organic matter in the sediment caused differences in macrofaunal community structure by favoring deposit-feeding species with high bioturbation ability, which significantly increased their abundance. The increased bioturbation potential of the new community combined with the high organic matter consumption contributed to the oxygenation of the sediment within the mesocosm, preventing the creation of hypoxic conditions in the sediment and maintaining ecosystem health despite the highly eutrophic conditions and significant changes in sediment geochemical variables. In the oligotrophic eastern Mediterranean, healthy benthic ecosystems may use existing ecosystem processes to “buffer” the negative effects caused by eutrophication.

  17. Biology of the invasive ascidian Ascidiella aspersa in its native habitat: Reproductive patterns and parasite load

    Science.gov (United States)

    Lynch, Sharon A.; Darmody, Grainne; O'Dwyer, Katie; Gallagher, Mary Catherine; Nolan, Sinead; McAllen, Rob; Culloty, Sarah C.

    2016-11-01

    The European sea squirt Ascidiella aspersa is a solitary tunicate native to the northeastern Atlantic, commonly found in shallow and sheltered marine ecosystems where it is capable of forming large clumps and outcompeting other invertebrate fauna at settlement. To date, there have been relatively few studies looking at the reproductive biology and health status of this invasive species. Between 2006 and 2010 sampling of a native population took place to investigate gametogenesis and reproductive cycle and to determine the impact of settlement depth on reproduction. In addition, parasite diversity and impact was assessed. A staging system to assess reproductive development was determined. The study highlighted that from year to year the tunicate could change its reproductive strategy from single sex to hermaphrodite, with spawning possible throughout the year. Depth did not impact on sex determination, however, gonad maturation and spawning occurred earlier in individuals in deeper waters compared to shallow depth and it also occurred later in A. aspersa at sites further away from the open sea. Four significant parasite groups including eugregarines, ciliates, trematodes and turbellarians were detected and prevalence of parasite infections increased in A. aspersa at sites with a reduced water flow rate. This study demonstrates the high biotic potential of this ascidian bioinvader to have a negative impact on native fauna in an introduced ecosystem, due to its highly efficient reproductive and resource allocation strategies. Artificial structures such as mooring lines can harbour large aggregations of A. aspersa, however, these manmade habitats may facilitate the colonisation and establishment of this invasive species in the benthos. Additionally, the parasite communities that A. aspersa harbour may also exacerbate its negative impact, both ecologically and economically, in an introduced area by possibly leading to the emergence of new disease in native species i

  18. Urgent and Compelling Need for Coastal and Inland Aquatic Ecosystem Research Using Space-Based Sensors

    Science.gov (United States)

    Otis, D. B.; Muller-Karger, F. E.; Hestir, E.; Turpie, K. R.; Roberts, D. A.; Frouin, R.; Goodman, J.; Schaeffer, B. A.; Franz, B. A.; Humm, D. C.

    2016-12-01

    Coastal and inland waters and associated aquatic habitats, including wetlands, mangroves, submerged grasses, and coral reefs, are some of the most productive and diverse ecosystems on the planet. They provide services critical to human health, safety, and prosperity. Yet, they are highly vulnerable to changes in climate and other anthropogenic pressures. With a global population of over seven billion people and climbing, and a warming atmosphere driven by carbon dioxide now in excess of 400 ppb, these services are at risk of rapidly diminishing globally. We know little about how these ecosystems function. We need to characterize short-term changes in the functional biodiversity and biogeochemical cycles of these coastal and wetland ecosystems, from canopy to benthos, and trace these changes to their underlying environmental influences. This requires an observation-based approach that covers coastal and inland aquatic ecosystems in a repeated, synoptic manner. Space-borne sensing systems can provide this capability, supported by coordinated in situ calibration and product validation activities. The design requires high temporal resolution (weekly or better), medium spatial resolution (30 m pixels at nadir to complement Landsat-class sensors), and highly sensitive, ocean-color radiometric quality, high resolution spectroscopy with Visible and Short-Wave IR bands (order of 10 nm or better) to assess both atmospheric correction parameters and land vegetation composition. The strategy needs to include sunglint avoidance schemes, and methods to maximize signal to noise ratios and temporal coverage of aquatic areas. We describe such a system, and urge the U.S. to implement such an observing strategy in the short-term and sustain it for the benefit of humankind.

  19. Multi-frequency observations of seawater carbonate chemistry on the central coast of the western Antarctic Peninsula

    Directory of Open Access Journals (Sweden)

    Julie B. Schram

    2015-07-01

    Full Text Available Assessments of benthic coastal seawater carbonate chemistry in Antarctica are sparse. The studies have generally been short in duration, during the austral spring/summer, under sea ice, or offshore in ice-free water. Herein we present multi-frequency measurements for seawater collected from the shallow coastal benthos on a weekly schedule over one year (May 2012–May 2013, daily schedule over three months (March–May 2013 and semidiurnal schedule over five weeks (March–April 2013. A notable pH increase (max pH = 8.62 occurred in the late austral spring/summer (November–December 2012, coinciding with sea-ice break-out and subsequent increase in primary productivity. We detected semidiurnal variation in seawater pH with a maximum variation of 0.13 pH units during the day and 0.11 pH units during the night. Daily variation in pH is likely related to biological activity, consistent with previous research. We calculated the variation in dissolved inorganic carbon (DIC over each seawater measurement frequency, focusing on the primary DIC drivers in the Palmer Station region. From this, we estimated net biological activity and found it accounts for the greatest variations in DIC. Our seasonal data suggest that this coastal region tends to act as a carbon dioxide source during austral winter months and as a strong sink during the summer. These data characterize present-day seawater carbonate chemistry and the extent to which these measures vary over multiple time scales. This information will inform future experiments designed to evaluate the vulnerability of coastal benthic Antarctic marine organisms to ocean acidification.

  20. Interactive effects of temperature and habitat complexity on freshwater communities.

    Science.gov (United States)

    Scrine, Jennifer; Jochum, Malte; Ólafsson, Jón S; O'Gorman, Eoin J

    2017-11-01

    Warming can lead to increased growth of plants or algae at the base of the food web, which may increase the overall complexity of habitat available for other organisms. Temperature and habitat complexity have both been shown to alter the structure and functioning of communities, but they may also have interactive effects, for example, if the shade provided by additional habitat negates the positive effect of temperature on understory plant or algal growth. This study explored the interactive effects of these two major environmental factors in a manipulative field experiment, by assessing changes in ecosystem functioning (primary production and decomposition) and community structure in the presence and absence of artificial plants along a natural stream temperature gradient of 5-18°C. There was no effect of temperature or habitat complexity on benthic primary production, but epiphytic production increased with temperature in the more complex habitat. Cellulose decomposition rate increased with temperature, but was unaffected by habitat complexity. Macroinvertebrate communities were less similar to each other as temperature increased, while habitat complexity only altered community composition in the coldest streams. There was also an overall increase in macroinvertebrate abundance, body mass, and biomass in the warmest streams, driven by increasing dominance of snails and blackfly larvae. Presence of habitat complexity, however, dampened the strength of this temperature effect on the abundance of macroinvertebrates in the benthos. The interactive effects that were observed suggest that habitat complexity can modify the effects of temperature on important ecosystem functions and community structure, which may alter energy flow through the food web. Given that warming is likely to increase habitat complexity, particularly at higher latitudes, more studies should investigate these two major environmental factors in combination to improve our ability to predict the

  1. Deterrent activities in the crude lipophilic fractions of Antarctic benthic organisms: chemical defences against keystone predators

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    Laura Núñez-Pons

    2014-04-01

    Full Text Available Generalist predation constitutes a driving force for the evolution of chemical defences. In the Antarctic benthos, asteroids and omnivore amphipods are keystone opportunistic predators. Sessile organisms are therefore expected to develop defensive mechanisms mainly against such consumers. However, the different habits characterizing each predator may promote variable responses in prey. Feeding-deterrence experiments were performed with the circumpolar asteroid macropredator Odontaster validus to evaluate the presence of defences within the apolar lipophilic fraction of Antarctic invertebrates and macroalgae. A total of 51% of the extracts were repellent, yielding a proportion of 17 defended species out of the 31 assessed. These results are compared with a previous study in which the same fractions were offered to the abundant circum-Antarctic amphipod Cheirimedon femoratus. Overall, less deterrence was reported towards asteroids (51% than against amphipods (80.8%, principally in sponge and algal extracts. Generalist amphipods, which establish casual host–prey sedentary associations with biosubstrata (preferentially sponges and macroalgae, may exert more localized predation pressure than sea stars on certain sessile prey, which would partly explain these results. The nutritional quality of prey may interact with feeding deterrents, whose production is presumed to be metabolically expensive. Although optimal defence theory posits that chemical defences are managed and distributed as to guarantee protection at the lowest cost, we found that only a few organisms localized feeding deterrents towards most exposed and/or valuable body regions. Lipophilic defensive metabolites are broadly produced in Antarctic communities to deter opportunistic predators, although several species combine different defensive traits.

  2. Indirect effects of overfishing on Caribbean reefs: sponges overgrow reef-building corals.

    Science.gov (United States)

    Loh, Tse-Lynn; McMurray, Steven E; Henkel, Timothy P; Vicente, Jan; Pawlik, Joseph R

    2015-01-01

    Consumer-mediated indirect effects at the community level are difficult to demonstrate empirically. Here, we show an explicit indirect effect of overfishing on competition between sponges and reef-building corals from surveys of 69 sites across the Caribbean. Leveraging the large-scale, long-term removal of sponge predators, we selected overfished sites where intensive methods, primarily fish-trapping, have been employed for decades or more, and compared them to sites in remote or marine protected areas (MPAs) with variable levels of enforcement. Sponge-eating fishes (angelfishes and parrotfishes) were counted at each site, and the benthos surveyed, with coral colonies scored for interaction with sponges. Overfished sites had >3 fold more overgrowth of corals by sponges, and mean coral contact with sponges was 25.6%, compared with 12.0% at less-fished sites. Greater contact with corals by sponges at overfished sites was mostly by sponge species palatable to sponge predators. Palatable species have faster rates of growth or reproduction than defended sponge species, which instead make metabolically expensive chemical defenses. These results validate the top-down conceptual model of sponge community ecology for Caribbean reefs, as well as provide an unambiguous justification for MPAs to protect threatened reef-building corals. An unanticipated outcome of the benthic survey component of this study was that overfished sites had lower mean macroalgal cover (23.1% vs. 38.1% for less-fished sites), a result that is contrary to prevailing assumptions about seaweed control by herbivorous fishes. Because we did not quantify herbivores for this study, we interpret this result with caution, but suggest that additional large-scale studies comparing intensively overfished and MPA sites are warranted to examine the relative impacts of herbivorous fishes and urchins on Caribbean reefs.

  3. Building a database for long-term monitoring of benthic macrofauna in the Pertuis-Charentais (2004-2014).

    Science.gov (United States)

    Philippe, Anne S; Plumejeaud-Perreau, Christine; Jourde, Jérôme; Pineau, Philippe; Lachaussée, Nicolas; Joyeux, Emmanuel; Corre, Frédéric; Delaporte, Philippe; Bocher, Pierrick

    2017-01-01

    Long-term benthic monitoring is rewarding in terms of science, but labour-intensive, whether in the field, the laboratory, or behind the computer. Building and managing databases require multiple skills, including consistency over time as well as organisation via a systematic approach. Here, we introduce and share our spatially explicit benthic database, comprising 11 years of benthic data. It is the result of intensive benthic sampling that has been conducted on a regular grid (259 stations) covering the intertidal mudflats of the Pertuis-Charentais (Marennes-Oléron Bay and Aiguillon Bay). Samples were taken by foot or by boats during winter depending on tidal height, from December 2003 to February 2014. The present dataset includes abundances and biomass densities of all mollusc species of the study regions and principal polychaetes as well as their length, accessibility to shorebirds, energy content and shell mass when appropriate and available. This database has supported many studies dealing with the spatial distribution of benthic invertebrates and temporal variations in food resources for shorebird species as well as latitudinal comparisons with other databases. In this paper, we introduce our benthos monitoring, share our data, and present a "guide of good practices" for building, cleaning and using it efficiently, providing examples of results with associated R code. The dataset has been formatted into a geo-referenced relational database, using PostgreSQL open-source DBMS. We provide density information, measurements, energy content and accessibility of thirteen bivalve, nine gastropod and two polychaete taxa (a total of 66,620 individuals)​ for 11 consecutive winters. Figures and maps are provided to describe how the dataset was built, cleaned, and how it can be used. This dataset can again support studies concerning spatial and temporal variations in species abundance, interspecific interactions as well as evaluations of the availability of food

  4. Biodiversity and community structure of the mega-epibenthos in the Magellan area (South America

    Directory of Open Access Journals (Sweden)

    Julian Gutt

    1999-12-01

    Full Text Available Epibenthic communites have been investigated at 55 stations in the Magellan region by underwater photogra-phy at water depths between 15 and 430m. Five species assemblages were identified of which the two shallow and the two deep ones in the channel system differed considerably in abundance, number of taxa, diversity and species composition. The dominant systematic group of the shallow assemblages were ascidians. In one of these assemblages decapod crustaceans, in the other mainly sessile suspension feeders e.g. sponges, anthozoans and bryozoans were the characteristic taxa. In the deeper assemblages echinoderms were most abundant. The fifth assemblage, consisting of several offshore stations south of the eastern entrance of the Beagle, was more similar to the shallow stations in the channel system in terms of dominant life forms. Various hypotheses were confirmed or rejected: The benthos at the deeper stations in the channel system was not more homogeneous than at the shallow stations. At both the channel and the offshore stations filter feeders were most dominant whereas at the bottom of the channels deposit feeders were more abundant. Differences between the wide Straits of Magellan and the narrow and steep Beagle Channel were not very distinct. The benthic assemblages inside the channel system did not differ considerably from the assemblage outside the channel system with the exception of the stations close to the continental slope of the Atlantic. Differences due to Pacific or Atlantic influences were not recognisable. The biological patterns could best be explained by the environmental parameters water depth, occurrence of soft sediment and biogenic debris.

  5. An evaluation of intertidal feeding habitats from a shorebird perspective: Towards relevant comparisons between temperate and tropical mudflats

    Science.gov (United States)

    Piersma, Theunis; de Goeij, Petra; Tulp, Ingrid

    Macrozoobenthic communities of intertidal soft sediments are reviewed worldwide from the perspective of a mollusc-eating shorebird species. Based on 19 sites, total biomass figures varied between 5 and 80 g AFDM per m 2 (average 24 g AFDM per m 2); no latitudinal trends are apparent. The contribution made by bivalves and gastropods varies between 1% and 99%, north-temperate intertidal flats having relatively more molluscs than tropical flats. Intertidal flats in the tropics contain a greater variety of taxa, with brachiopods in Indonesia and echinoderms in northwest Australia contributing significantly to biomass only there. Limits to the occurrence of avian predators of intertidal benthos are set by the harvestable fraction of the biomass on offer and the costs of living at a particular site. No systematic differences in the harvestable fraction of the total mollusc-biomass for a worldwide occurring shorebird species specializing on molluscs (knots Calidris canutus) were apparent between temperate and tropical intertidal areas, in spite of large differences in maintenance metabolism incurred by these birds. The harvestable fractions of bivalves in the two West African areas (Banc d'Arguin, Mauritania and Guinea-Bissau) tended to be high (23-84% of total biomass in six species), they were relatively low (2-52% in five species) in the temperate Wadden Sea and the tropical northwest Australian site. Harvestable biomass determines the intake rate of shorebirds, as illustrated by functional-response curves of knots feeding on two bivalves species. We argue that the collection of information on size-depth relationships along with faunal and biomass surveys at a range of sites is bound to greatly increase our understanding of both the biology of tidal-flat invertebrates and the resource base underpinning the spectacular seasonal migrations of shorebirds.

  6. Ecosystem regime shifts disrupt trophic structure.

    Science.gov (United States)

    Hempson, Tessa N; Graham, Nicholas A J; MacNeil, M Aaron; Hoey, Andrew S; Wilson, Shaun K

    2018-01-01

    Regime shifts between alternative stable ecosystem states are becoming commonplace due to the combined effects of local stressors and global climate change. Alternative states are characterized as substantially different in form and function from pre-disturbance states, disrupting the delivery of ecosystem services and functions. On coral reefs, regime shifts are typically characterized by a change in the benthic composition from coral to macroalgal dominance. Such fundamental shifts in the benthos are anticipated to impact associated fish communities that are reliant on the reef for food and shelter, yet there is limited understanding of how regime shifts propagate through the fish community over time, relative to initial or recovery conditions. This study addresses this knowledge gap using long-term data of coral reef regime shifts and recovery on Seychelles reefs following the 1998 mass bleaching event. It shows how trophic structure of the reef fish community becomes increasingly dissimilar between alternative reef ecosystem states (regime-shifted vs. recovering) with time since disturbance. Regime-shifted reefs developed a concave trophic structure, with increased biomass in base trophic levels as herbivorous species benefitted from increased algal resources. Mid trophic level species, including specialists such as corallivores, declined with loss of coral habitat, while biomass was retained in upper trophic levels by large-bodied, generalist invertivores. Recovering reefs also experienced an initial decline in mid trophic level biomass, but moved toward a bottom-heavy pyramid shape, with a wide range of feeding groups (e.g., planktivores, corallivores, omnivores) represented at mid trophic levels. Given the importance of coral reef fishes in maintaining the ecological function of coral reef ecosystems and their associated fisheries, understanding the effects of regime shifts on these communities is essential to inform decisions that enhance ecological

  7. Climate change and trophic response of the Antarctic bottom fauna.

    Science.gov (United States)

    Aronson, Richard B; Moody, Ryan M; Ivany, Linda C; Blake, Daniel B; Werner, John E; Glass, Alexander

    2009-01-01

    As Earth warms, temperate and subpolar marine species will increasingly shift their geographic ranges poleward. The endemic shelf fauna of Antarctica is especially vulnerable to climate-mediated biological invasions because cold temperatures currently exclude the durophagous (shell-breaking) predators that structure shallow-benthic communities elsewhere. We used the Eocene fossil record from Seymour Island, Antarctic Peninsula, to project specifically how global warming will reorganize the nearshore benthos of Antarctica. A long-term cooling trend, which began with a sharp temperature drop approximately 41 Ma (million years ago), eliminated durophagous predators-teleosts (modern bony fish), decapod crustaceans (crabs and lobsters) and almost all neoselachian elasmobranchs (modern sharks and rays)-from Antarctic nearshore waters after the Eocene. Even prior to those extinctions, durophagous predators became less active as coastal sea temperatures declined from 41 Ma to the end of the Eocene, approximately 33.5 Ma. In response, dense populations of suspension-feeding ophiuroids and crinoids abruptly appeared. Dense aggregations of brachiopods transcended the cooling event with no apparent change in predation pressure, nor were there changes in the frequency of shell-drilling predation on venerid bivalves. Rapid warming in the Southern Ocean is now removing the physiological barriers to shell-breaking predators, and crabs are returning to the Antarctic Peninsula. Over the coming decades to centuries, we predict a rapid reversal of the Eocene trends. Increasing predation will reduce or eliminate extant dense populations of suspension-feeding echinoderms from nearshore habitats along the Peninsula while brachiopods will continue to form large populations, and the intensity of shell-drilling predation on infaunal bivalves will not change appreciably. In time the ecological effects of global warming could spread to other portions of the Antarctic coast. The differential

  8. [Feeding habits of sphoeroides testudineus (Perciformes: Tetraodontidae) in the lagoon system of Ria Lagartos, Yucatán, Mexico].

    Science.gov (United States)

    Chi-Espínola, Ariel Adriano; Vega-Cendejas, Maria Eugenia

    2013-06-01

    Sphoeroides testudineus is a dominant species in the coastal systems of Yucatán. Because of its wide distribution, occurrence and abundance performs an important functional role in coastal ecosystems. We assessed the trophic preferences and trophic-level variation in space and time for this species in Ria Lagartos lagoon, an hyperhaline ecosystem located Northwest of Yucatan Peninsula. The specimens were collected bimonthly during two annual periods (2004-2005 and 2007-2008) in 23 sites distributed along the system into four zones (marine, channel, Coloradas West and Coloradas East). Spatial and seasonal trophic variations were evaluated using canonical correspondence analysis (ACC). In a total of 382 individuals, 68 food resources included in 20 trophic groups were obtained. Higher relative importance index values (IIR) were obtained for bivalves, gastropods and macrophytes. Seasonal trophic variation showed that bivalves and gastropods were consumed along the year, while macrophytes were a preferential food during rains and windy seasons. Spatial variation indicates lower gastropods consumption at the inner zone of the system, and the opposite ocurred with bivalves. The consumption ofmacrophytes may be due to their greater abundance during rains and in the channel zone. The ACC showed that spatial trophic variation was due because of the abundance of the preferential preys (bivalves, gastropods), while seasonal differences by the secondary (amphipods, eggs, nematodes, brachyuran, detritus, nematodes). The results contribute to the biological knowledge of the species and highlight the importance and trophic function of S testudineus for the energy transfer from the benthos to higher trophic levels of the food chain.

  9. Benthic foraminifera and environmental changes in Long Island Sound

    Science.gov (United States)

    Thomas, E.; Gapotchenko, T.; Varekamp, J.C.; Mecray, E.I.; Buchholtz ten Brink, Marilyn R.

    2000-01-01

    Benthic foraminiferal faunas in Long Island Sound (LIS) in the 1940s and 1960s were of low diversity, and dominated by species of the genus Elphidium, mainly Elphidium excavatum clavatum, with common Buccella frigida and Eggerella advena. The distribution of these species was dominantly correlated with depth, but it was not clear which depth-related environmental variable was most important. Differences between faunas collected in 1996 and 1997, and in the 1940s and 1960s include a strong decrease in relative abundance of Eggerella advena over all LIS, an increase in relative abundance of Ammonia beccarii in western LIS, and a decrease in species diversity. The decreased diversity suggests that environmental stress caused the faunal changes. Oxygen isotope data for E. excavatum clavatum indicate that a change in salinity is not a probable cause. Carbon isotope data suggest that the supply of organic matter to the benthos increased since the early 1960s, with a stronger increase in western LIS where algal blooms have occurred since the early 1970s, possibly as a result of nutrient input by waste water treatment plants. These blooms or the resulting episodes of anoxia/hypoxia may have played a role in the increased relative abundance of A. beccarii. There is no clear explanation for the decreased abundance of E. advena, but changes in the phytoplankton composition (thus food supply) are a possible cause. Benthic foraminiferal faunal and stable isotope data have excellent potential as indicators of physicochemical environmental changes and their effects on the biota in LIS.

  10. Composition, shell strength, and metabolizable energy of Mulinia lateralis and Ischadium recurvum as food for wintering surf scoters (Melanitta perspicillata)

    Science.gov (United States)

    Berlin, Alicia; Perry, Matthew C.; Kohn, R.A.; Paynter, K.T.; Ottinger, Mary Ann

    2015-01-01

    Decline in surf scoter (Melanitta perspicillata) waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica) has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum), one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis). The composition (macronutrients, minerals, and amino acids), shell strength (N), and metabolizable energy (kJ) of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N) was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum), I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

  11. Critical evaluation of the nonradiological environmental technical specifications. Volume 2. Surry Power Plants, Units 1 and 2

    International Nuclear Information System (INIS)

    Adams, S.M.; Cunningham, P.A.; Gray, D.D.; Kumar, K.D.

    1976-01-01

    A comprehensive study of the data collected as part of the environmental Technical Specifications program for Units 1 and 2 of the Surry Nuclear Power Plant was carried out for the Office of Regulatory Research of the U.S. Nuclear Regulatory Commission. The program included an analysis of the hydrothermal and ecological monitoring data collected from 1973 through 1975. The hydrothermal analysis includes a discussion of models used in plume predictions prior to plant operation and an evaluation of the present hydrothermal monitoring program. The two primary methods used for temperature monitoring employ a fixed thermographs network and boat measurements. Review of data indicates that both the application and formulation of the hydrothermal monitoring program are inadequate to fully characterize the operation of the plant and the behavior of the thermal plume. Furthermore, there are no existing data that can be used to adequately verify or disprove the validity of the various Surry plume predictions. The ecological analysis includes validation of impacts predicted in the Final Environmental Statement using the operational monitoring data. Phytoplankton cell concentrations, chlorophyll a, and carbon-14 measurements were used to monitor changes in the primary producers. Densities of consumers (i.e., zooplankton, benthos, and fish) were sed to monitor changes in the primary producers. Models based on operating data were constructed to determine whether changes were occurring at each trophic level. Analysis of the monitoring data suggests that the thermal discharges at Surry are having a negative effect on the phytoplankton and zooplankton but are enhancing the benthic and nekton populations in the discharge area

  12. Herbivorous snails can increase water clarity by stimulating growth of benthic algae.

    Science.gov (United States)

    Zhang, Xiufeng; Taylor, William D; Rudstam, Lars G

    2017-11-01

    Eutrophication in shallow lakes is characterized by a switch from benthic to pelagic dominance of primary productivity that leads to turbid water, while benthification is characterized by a shift in primary production from the pelagic zone to the benthos associated with clear water. A 12-week mesocosm experiment tested the hypothesis that the herbivorous snail Bellamya aeruginosa stimulates the growth of pelagic algae through grazing on benthic algae and through accelerating nutrient release from sediment. A tube-microcosm experiment using 32 P-PO 4 as a tracer tested the effects of the snails on the release of sediment phosphorus (P). The mesocosm experiment recorded greater total nitrogen (TN) concentrations and a higher ratio of TN:TP in the overlying water, and a higher light intensity and biomass of benthic algae as measured by chlorophyll a (Chl a) in the snail treatment than in the control. Concentrations of total phosphorus (TP), total suspended solids (TSSs), and inorganic suspended solids (ISSs) in the overlying water were lower in the snail treatment than in the control, though no significant difference in Chl a of pelagic algae between the snail treatment and control was observed. In the microcosm experiment, 32 P activity in the overlying water was higher in the snail treatment than in the control, indicating that snails accelerated P release from the sediment. Our interpretation of these results is that snails enhanced growth of benthic algae and thereby improved water clarity despite grazing on the benthic algae and enhancing P release from the sediment. The rehabilitation of native snail populations may therefore enhance the recovery of eutrophic shallow lakes to a clear water state by stimulating growth of benthic algae.

  13. Coral Reef Color: Remote and In-Situ Imaging Spectroscopy of Reef Structure and Function

    Science.gov (United States)

    Hochberg, E. J.

    2016-02-01

    Coral reefs are threatened at local to global scales by a litany of anthropogenic impacts, including overfishing, coastal development, marine and watershed pollution, rising ocean temperatures, and ocean acidification. However, available data for the primary indicator of coral reef condition — proportional cover of living coral — are surprisingly sparse and show patterns that contradict the prevailing understanding of how environment impacts reef condition. Remote sensing is the only available tool for acquiring synoptic, uniform data on reef condition at regional to global scales. Discrimination between coral and other reef benthos relies on narrow wavebands afforded by imaging spectroscopy. The same spectral information allows non-invasive quantification of photosynthetic pigment composition, which shows unexpected phenological trends. There is also potential to link biodiversity with optical diversity, though there has been no effort in that direction. Imaging spectroscopy underlies the light-use efficiency model for reef primary production by quantifying light capture, which in turn indicates biochemical capacity for CO2 assimilation. Reef calcification is strongly correlated with primary production, suggesting the possibility for an optics-based model of that aspect of reef function, as well. By scaling these spectral models for use with remote sensing, we can vastly improve our understanding of reef structure, function, and overall condition across regional to global scales. By analyzing those remote sensing products against ancillary environmental data, we can construct secondary models to predict reef futures in the era of global change. This final point is the objective of CORAL (COral Reef Airborne Laboratory), a three-year project funded under NASA's Earth Venture Suborbital-2 program to investigate the relationship between coral reef condition at the ecosystem scale and various nominal biogeophysical forcing parameters.

  14. Experimental evidence of site specific preferential processing of either ice algae or phytoplankton by benthic macroinfauna in Lancaster Sound and North Water Polynyas, Canada

    Science.gov (United States)

    Mäkelä, Anni; Witte, Ursula; Archambault, Philippe

    2016-04-01

    Rapid warming is dramatically reducing the extent and thickness of summer sea ice of the Arctic Ocean, changing both the quantity and type of marine primary production as the longer open water period favours phytoplankton growth and reduces ice algal production. The benthic ecosystem is dependent on this sinking organic matter for source of energy, and ice algae is thought to be a superior quality food source due to higher essential fatty acid content. The resilience of the benthos to changing quality and quantity of food was investigated through sediment incubation experiments in the summer 2013 in two highly productive Arctic polynyas in the North Water and Lancaster Sound, Canada. The pathways of organic matter processing and contribution of different organisms to these processes was assessed through 13C and 15N isotope assimilation into macroinfaunal tissues. In North Water Polynya, the total and biomass specific uptake of ice algal derived C and N was higher than the uptake of phytoplankton, whereas an opposite trend was observed in Lancaster Sound. Polychaetes, especially individuals of families Sabellidae and Spionidae, unselectively ingested both algal types and were significant in the overall organic matter processing at both sites. Feeding preference was observed in crustaceans, which preferentially fed on ice algae at Lancaster Sound, but preferred phytoplankton in North Water Polynya. Bivalves also had a significant role in the organic matter processing overall, but only showed preferential feeding on phytoplankton at Lancaster Sound polynya. Overall the filter feeders and surface deposit feeders occupying lowest trophic levels were responsible for majority of the processing of both algal types. The results provide direct evidence of preferential resource utilisation by benthic macrofauna and highlight spatial differences in the processes. This helps to predict future patterns of nutrient cycling in Arctic sediments, with implications to benthic

  15. Behavioral Responses of Concholepas concholepas (Bruguière, 1789) Larvae to Natural and Artificial Settlement Cues and Microbial Films.

    Science.gov (United States)

    Rodriguez, S R; Riquelme, C; Campos, E O; Chavez, P; Brandan, E; Inestrosa, N C

    1995-12-01

    different microbial films suggest that microorganisms may have a role in bringing larvae close to settlement inducers on the marine benthos.

  16. Comparison of Two Independent Mapping Exercises in the Primeiras and Segundas Archipelago, Mozambique

    Directory of Open Access Journals (Sweden)

    Luisa Teixeira

    2016-01-01

    Full Text Available Production of coral reef habitat maps from high spatial resolution multispectral imagery is common practice and benefits from standardized accuracy assessment methods and many informative studies on the merits of different processing algorithms. However, few studies consider the full production workflow, including factors such as operator influence, visual interpretation and a-priori knowledge. An end-user might justifiably ask: Given the same imagery and field data, how consistent would two independent production efforts be? This paper is a post-study analysis of a project in which two teams of researchers independently produced maps of six coral reef systems of the archipelago of the Primeiras and Segundas Environmental Protected Area (PSEPA, Mozambique. Both teams used the same imagery and field data, but applied different approaches—pixel based vs. object based image analysis—and used independently developed classification schemes. The results offer a unique perspective on the map production process. Both efforts resulted in similar merged classes accuracies, averaging at 63% and 64%, but the maps were distinct in terms of scale of spatial patterns, classification disparities, and in other aspects where the mapping process is reliant on visual interpretation. Despite the difficulty in aligning the classification schemes clear patterns of correspondence and discrepancy were identified. The maps were consistent with respect to geomorphological level mapping (17 out of 30 paired comparisons at more than 75% agreement, and also agreed in the extent of coral containing areas within a difference of 16% across the archipelago. However, more detailed benthic habitat level classes were inconsistent. Mapping of deep benthic cover was the most subjective result and dependent on operator visual interpretation, yet this was one of the results of highest interest for the PSEPA management since it revealed a continuity of benthos between the islands

  17. Life history of the Small Sandeel, Ammodytes tobianus, inferred from otolith microchemistry. A methodological approach

    Science.gov (United States)

    Laugier, F.; Feunteun, E.; Pecheyran, C.; Carpentier, A.

    2015-11-01

    Knowledge of life history and connectivity between essential ecological habitats are relevant for conservation and management of species and some natural tracers could be used to study the lifecycles of small or short-lived marine fishes. Although sandeels are central in marine food webs and are key species, there is incomplete knowledge about population mixing and migration patterns. For the first time the use of the otolith microchemistry on sandeel species is evaluated in the case of the Small Sandeel. Variations in microchemical fingerprints of 13 trace elements are performed with a Femtosecond LA-ICPM from the core to the margin of sagittal otolith and are compared within and between otoliths extracted from 34 fishes sampled in three different sites along the coast of the south-western English Channel in France. Firstly, preliminary investigations on the validity of the method revealed that Mg/Ca was the only ratio significantly dependant on fish ontogeny and sampling season. Secondly, the Mn/Ca, Zn/Ca, and Cu/Ca ratios enabled us to significantly discriminate among sampling sites. Thirdly, microchemical fingerprints of each life stage varied significantly among sampling sites but not within them, suggesting high site fidelity over relatively short distances. Finally, the fingerprints of all life stages were significantly different from those of the larval and metamorphosis stages. The otolith microchemistry could detect change of signature relative to the shift from a pelagic behaviour to a resident bentho-pelagic behaviour during the middle of the juvenile stage in Small Sandeels. Hence, analysis of trace element fingerprints in otoliths appears to be a valuable method to further studies on ontogenic habitat change, population mixing and variation of life history and be helpful for the management at local or regional scales of short-lived species such as those belonging to other Ammodytidae.

  18. Effects of salt pond restoration on benthic flux: Sediment as a source of nutrients to the water column

    Science.gov (United States)

    Topping, Brent R.; Kuwabara, James S.; Carter, James L.; Garrettt, Krista K.; Mruz, Eric; Piotter, Sarah; Takekawa, John Y.

    2016-01-01

    Understanding nutrient flux between the benthos and the overlying water (benthic flux) is critical to restoration of water quality and biological resources because it can represent a major source of nutrients to the water column. Extensive water management commenced in the San Francisco Bay, Beginning around 1850, San Francisco Bay wetlands were converted to salt ponds and mined extensively for more than a century. Long-term (decadal) salt pond restoration efforts began in 2003. A patented device for sampling porewater at varying depths, to calculate the gradient, was employed between 2010 and 2012. Within the former ponds, the benthic flux of soluble reactive phosphorus and that of dissolved ammonia were consistently positive (i.e., moving out of the sediment into the water column). The lack of measurable nitrate or nitrite concentration gradients across the sediment-water interface suggested negligible fluxes for dissolved nitrate and nitrite. The dominance of ammonia in the porewater indicated anoxic sediment conditions, even at only 1 cm depth, which is consistent with the observed, elevated sediment oxygen demand. Nearby openestuary sediments showed much lower benthic flux values for nutrients than the salt ponds under resortation. Allochthonous solute transport provides a nutrient advective flux for comparison to benthic flux. For ammonia, averaged for all sites and dates, benthic flux was about 80,000 kg/year, well above the advective flux range of −50 to 1500 kg/year, with much of the variability depending on the tidal cycle. By contrast, the average benthic flux of soluble reactive phosphorus was about 12,000 kg/year, of significant magnitude, but less than the advective flux range of 21,500 to 30,000 kg/year. These benthic flux estimates, based on solute diffusion across the sediment-water interface, reveal a significant nutrient source to the water column of the pond which stimulates algal blooms (often autotrophic). This benthic source may be

  19. Polycyclic aromatic and aliphatic hydrocarbons in Chukchi Sea biota and sediments and their toxicological response in the Arctic cod, Boreogadus saida

    Science.gov (United States)

    Harvey, H. Rodger; Taylor, Karen A.; Pie, Hannah V.; Mitchelmore, Carys L.

    2014-04-01

    As part of the Chukchi Sea Offshore Monitoring in Drilling Area-Chemical and Benthos (COMIDA CAB) project, we determined the distribution and concentrations of aliphatic n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in surface sediments (0-1 cm) among 52 sites across the Chukchi Sea and in muscle tissues of the benthic Northern whelk, Neptunea heros, collected opportunistically. In addition, downcore profiles of contaminants were determined at three targeted sites to establish historic patterns. Baseline responses of PAH exposure and its potential toxicological effects were examined in the common Arctic cod, Boreogadus saida, through measures of cytochrome P4501A/ ethoxyresorufin O-deethylase (CYP1A/EROD), glutathione-S-transferase (GST), and Cu/Zn superoxide dismutase (SOD) activity in liver tissue. The total concentration of PAHs in surface sediments throughout the study area, including parent and alkyl-homologs, were very low (<1600 ng g-1 dry wt) except for a single station, where values were 2-20-fold greater than at other baseline sites (2956 ng g-1 dry wt). Alkyl-substituted PAHs were the dominant form in all surface (54-93%) and subsurface sediments (50-81% of the total), with a general decrease in total PAH concentrations observed downcore. In biota, larger Neptunea showed lower total concentrations of PAHs in foot muscles (4.5-10.7 ng g-1 wet wt) compared to smaller animals; yet aliphatic n-alkane (C19-C33) concentrations (0.655-5.20 μg g-1 wet wt) increased in larger organisms with distributions dominated by long-chain (C23-C33) hydrocarbons. In B. saida, CYP1A1, GST, and SOD enzyme levels were comparable to baseline levels previously reported in other pristine systems. Of the three assays, only SOD had a significant correlation between gene expression and enzyme activity.

  20. The challenges of long-term ecological research in springs in the northern and southern Alps: indicator groups, habitat diversity, and medium-term change

    Directory of Open Access Journals (Sweden)

    Sofia WIEDENBRUG

    2011-09-01

    Full Text Available After extensive exploratory investigations into crenic habitats at the beginning of the 1990s, a number of springs were selected and long-term ecological research programmes independently initiated in the Berchtesgaden National Park (north-eastern Alps, Bavaria and the Adamello-Brenta Nature Park (south-eastern Alps, Trentino. Following more than a decade of standardized work, this paper presents a selection of results from both sides of the Alps, with a focus on zoobenthos in Bavaria and on pro- and eukaryotic algae in Trentino. In order to test the assumption that permanent springs are particularly suitable habitats for long-term ecological research, the following topics are addressed: (1 taxonomic diversity and relationships between diversity and spring typology; (2 transverse gradients in crenic habitats, hygrophilous terrestrial invertebrates and xerotolerant algae; (3 possibilities of documenting changes in species composition over decadal time scales ("medium-term" based on emergence traps, benthos, and benthic algae. The data obtained show that: (1 crenic habitats support particularly high biological diversity (but a thorough documentation of insect diversity is impossible without emergence studies; (2 helocrenes are the most species-rich habitats, for both invertebrates and diatoms; (3 dynamic (unstable and occasionally-impacted springs show identifiable signs of medium-term change, whilst particularly complex and stable crenic habitats seem to be controlled by internal processes. Our results suggest that: (1 the meiofauna is likely to react directly to environmental change, while emergers and the hygrophilous terrestrial fauna are indirectly affected, and (2 diatoms react both to direct effects of environmental change, e.g. discharge and hydrochemistry, and to indirect effects on the surroundings of the spring. Based on our results, long-term research strategies are discussed. For long-term studies, we propose a focus on meiofauna and

  1. What happened to gray whales during the Pleistocene? The ecological impact of sea-level change on benthic feeding areas in the North Pacific Ocean.

    Science.gov (United States)

    Pyenson, Nicholas D; Lindberg, David R

    2011-01-01

    Gray whales (Eschrichtius robustus) undertake long migrations, from Baja California to Alaska, to feed on seasonally productive benthos of the Bering and Chukchi seas. The invertebrates that form their primary prey are restricted to shallow water environments, but global sea-level changes during the Pleistocene eliminated or reduced this critical habitat multiple times. Because the fossil record of gray whales is coincident with the onset of Northern Hemisphere glaciation, gray whales survived these massive changes to their feeding habitat, but it is unclear how. We reconstructed gray whale carrying capacity fluctuations during the past 120,000 years by quantifying gray whale feeding habitat availability using bathymetric data for the North Pacific Ocean, constrained by their maximum diving depth. We calculated carrying capacity based on modern estimates of metabolic demand, prey availability, and feeding duration; we also constrained our estimates to reflect current population size and account for glaciated and non-glaciated areas in the North Pacific. Our results show that key feeding areas eliminated by sea-level lowstands were not replaced by commensurate areas. Our reconstructions show that such reductions affected carrying capacity, and harmonic means of these fluctuations do not differ dramatically from genetic estimates of carrying capacity. Assuming current carrying capacity estimates, Pleistocene glacial maxima may have created multiple, weak genetic bottlenecks, although the current temporal resolution of genetic datasets does not test for such signals. Our results do not, however, falsify molecular estimates of pre-whaling population size because those abundances would have been sufficient to survive the loss of major benthic feeding areas (i.e., the majority of the Bering Shelf) during glacial maxima. We propose that gray whales survived the disappearance of their primary feeding ground by employing generalist filter-feeding modes, similar to the

  2. Episodic eruptions of volcanic ash trigger a reversible cascade of nuisance species outbreaks in pristine coral habitats.

    Directory of Open Access Journals (Sweden)

    Tom Schils

    Full Text Available Volcanically active islands abound in the tropical Pacific and harbor complex coral communities. Whereas lava streams and deep ash deposits are well-known to devastate coral communities through burial and smothering, little is known about the effect of moderate amounts of small particulate ash deposits on reef communities. Volcanic ash contains a diversity of chemical compounds that can induce nutrient enrichments triggering changes in benthic composition. Two independently collected data sets on the marine benthos of the pristine and remote reefs around Pagan Island, Northern Mariana Islands, reveal a sudden critical transition to cyanobacteria-dominated communities in 2009-2010, which coincides with a period of continuous volcanic ash eruptions. Concurrently, localized outbreaks of the coral-killing cyanobacteriosponge Terpios hoshinota displayed a remarkable symbiosis with filamentous cyanobacteria, which supported the rapid overgrowth of massive coral colonies and allowed the sponge to colonize substrate types from which it has not been documented before. The chemical composition of tephra from Pagan indicates that the outbreak of nuisance species on its reefs might represent an early succession stage of iron enrichment (a.k.a. "black reefs" similar to that caused by anthropogenic debris like ship wrecks or natural events like particulate deposition from wildfire smoke plumes or desert dust storms. Once Pagan's volcanic activity ceased in 2011, the cyanobacterial bloom disappeared. Another group of well-known nuisance algae in the tropical Pacific, the pelagophytes, did not reach bloom densities during this period of ash eruptions but new species records for the Northern Mariana Islands were documented. These field observations indicate that the study of population dynamics of pristine coral communities can advance our understanding of the resilience of tropical reef systems to natural and anthropogenic disturbances.

  3. Consequences of increasing hypoxic disturbance on benthic communities and ecosystem functioning.

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    Anna Villnäs

    Full Text Available Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential, gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH(4(+ and dissolved Si. Although effluxes of PO(4(3- were not altered significantly, changes were observed in sediment PO(4(3- sorption capability. The duration of hypoxia (i.e. number of days of stress explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the

  4. Taxonomy and life history of the Acropora-eating flatworm Amakusaplana acroporae nov. sp. (Polycladida: Prosthiostomidae)

    Science.gov (United States)

    Rawlinson, K. A.; Gillis, J. A.; Billings, R. E.; Borneman, E. H.

    2011-09-01

    Efforts to culture and conserve acroporid corals in aquaria have led to the discovery of a corallivorous polyclad flatworm (known as AEFW - Acropora-eating flatworm), which, if not removed, can eat entire colonies. Live observations of the AEFW, whole mounts, serial histological sections and comparison of 28S rDNA sequences with other polyclads reveal that this is a new species belonging to the family Prosthiostomidae Lang, 1884 and previously monospecific genus Amakusaplana (Kato 1938). Amakusaplana acroporae is distinguished from Amakusaplana ohshimai by a different arrangement and number of eyes, a large seminal vesicle and dorsoventrally compressed shell gland pouch. Typical of the genus, A. acroporae, lacks a ventral sucker and has a small notch at the midline of the anterior margin. Nematocysts and a Symbiodinium sp. of dinoflagellate from the coral are abundantly distributed in the gut and parenchyma. Individual adults lay multiple egg batches on the coral skeleton, each egg batch has 20-26 egg capsules, and each capsule contains between 3-7 embryos. Embryonic development takes approximately 21 days, during which time characteristics of a pelagic life stage (lobes and ciliary tufts) develop but are lost before hatching. The hatchling is capable of swimming but settles to the benthos quickly, and no zooxanthellae were observed in the animal at this stage. We suggest that intracapsular metamorphosis limits the dispersal potential of hatchlings and promotes recruitment of offspring into the natal habitat. The evolutionary and ecological significance of retaining lobes and ciliary tufts in the embryo are discussed. Camouflage, high fecundity and possible dispersal dimorphisms probably explain how Amakusaplana acroporae can cause Acropora sp. mortality in aquaria where natural predators may be absent.

  5. When are fish sources vs. sinks of nutrients in lake ecosystems?

    Science.gov (United States)

    Vanni, Michael J; Boros, Gergely; McIntyre, Peter B

    2013-10-01

    Animals can be important in nutrient cycling through a variety of direct and indirect pathways. A high biomass of animals often represents a large pool of nutrients, leading some ecologists to argue that animal assemblages can represent nutrient sinks within ecosystems. The role of animals as sources vs. sinks of nutrients has been debated particularly extensively for freshwater fishes. We argue that a large pool size does not equate to a nutrient sink; rather, animals can be nutrient sinks when their biomass increases, when emigration rates are high, and/or when nutrients in animal carcasses are not remineralized. To further explore these ideas, we use a simple model to evaluate the conditions under which fish are phosphorus (P) sources or sinks at the ecosystem (lake) level, and at the habitat level (benthic and water column habitats). Our simulations suggest that, under most conditions, fish are sinks for benthic P but are net P sources to the water column. However, P source and sink strengths depend on fish feeding habits (proportion of P consumed from the benthos and water column), migration patterns, and especially the fate of carcass P. Of particular importance is the rate at which carcasses are mineralized and the relative importance of benthic vs. pelagic primary producers in taking up mineralized P (and excreted P). Higher proportional uptake of P by benthic primary producers increases the likelihood that fish are sinks for water column P. Carcass bones and scales are relatively recalcitrant and can represent a P sink even if fish biomass does not change over time. Thus, there is a need for better documentation of the fraction of carcass P that is remineralized, and the fate of this P, under natural conditions. We urge a more holistic perspective regarding the role of animals in nutrient cycling, with a focus on quantifying the rates at which animals consume, store, release, and transport nutrients under various conditions.

  6. Following a foraging fish-finder: diel habitat use of Blainville's beaked whales revealed by echolocation.

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    Patricia Arranz

    Full Text Available Simultaneous high resolution sampling of predator behavior and habitat characteristics is often difficult to achieve despite its importance in understanding the foraging decisions and habitat use of predators. Here we tap into the biosonar system of Blainville's beaked whales, Mesoplodon densirostris, using sound and orientation recording tags to uncover prey-finding cues available to echolocating predators in the deep-sea. Echolocation sounds indicate where whales search and encounter prey, as well as the altitude of whales above the sea-floor and the density of organisms around them, providing a link between foraging activity and the bio-physical environment. Tagged whales (n = 9 hunted exclusively at depth, investing most of their search time either in the lower part of the deep scattering layer (DSL or near the sea-floor with little diel change. At least 43% (420/974 of recorded prey-capture attempts were performed within the benthic boundary layer despite a wide range of dive depths, and many dives included both meso- and bentho-pelagic foraging. Blainville's beaked whales only initiate searching when already deep in the descent and encounter prey suitable for capture within 2 min of the start of echolocation, suggesting that these whales are accessing prey in reliable vertical strata. Moreover, these prey resources are sufficiently dense to feed the animals in what is effectively four hours of hunting per day enabling a strategy in which long dives to exploit numerous deep-prey with low nutritional value require protracted recovery periods (average 1.5 h between dives. This apparent searching efficiency maybe aided by inhabiting steep undersea slopes with access to both the DSL and the sea-floor over small spatial scales. Aggregations of prey in these biotopes are located using biosonar-derived landmarks and represent stable and abundant resources for Blainville's beaked whales in the otherwise food-limited deep-ocean.

  7. Accumulation and Toxicity of Copper Oxide Engineered Nanoparticles in a Marine Mussel

    Directory of Open Access Journals (Sweden)

    Shannon K. Hanna

    2014-06-01

    Full Text Available Cu is an essential trace element but can be highly toxic to aquatic organisms at elevated concentrations. Greater use of CuO engineered nanoparticles (ENPs may lead to increased concentrations of CuO ENPs in aquatic environments causing potential ecological injury. We examined the toxicity of CuO ENPs to marine mussels and the influence of mussels on the fate and transport of CuO ENPs. We exposed marine mussels to 1, 2, or 3 mg L−1 CuO ENPs for four weeks, and measured clearance rate, rejection, excretion and accumulation of Cu, and mussel shell growth. Mussel clearance rate was 48% less, and growth was 68% less, in mussels exposed to 3 mg L−1 than in control animals. Previous studies show 100% mortality at 1 mg Cu L−1, suggesting that CuO ENPs are much less toxic than ionic Cu, probably due to the slow dissolution rate of the ENPs. Mussels rejected and excreted CuO ENPs in biodeposits containing as much as 110 mg Cu g−1, suggesting the potential for magnification in sediments. Mussels exposed to 3 mg L−1 CuO ENPs accumulated 79.14 ± 12.46 µg Cu g−1 dry weight, which was 60 times more Cu than in control animals. Our results suggest that mussels have the potential to influence the fate and transport of CuO ENPs and potentially cause magnification of CuO ENPs in mussel bed communities, creating a significant source of Cu to marine benthos.

  8. Why is the South Orkney Island shelf (the world's first high seas marine protected area) a carbon immobilization hotspot?

    Science.gov (United States)

    Barnes, David K A; Ireland, Louise; Hogg, Oliver T; Morley, Simon; Enderlein, Peter; Sands, Chester J

    2016-03-01

    The Southern Ocean archipelago, the South Orkney Islands (SOI), became the world's first entirely high seas marine protected area (MPA) in 2010. The SOI continental shelf (~44 000 km(2) ), was less than half covered by grounded ice sheet during glaciations, is biologically rich and a key area of both sea surface warming and sea-ice losses. Little was known of the carbon cycle there, but recent work showed it was a very important site of carbon immobilization (net annual carbon accumulation) by benthos, one of the few demonstrable negative feedbacks to climate change. Carbon immobilization by SOI bryozoans was higher, per species, unit area and ice-free day, than anywhere-else polar. Here, we investigate why carbon immobilization has been so high at SOI, and whether this is due to high density, longevity or high annual production in six study species of bryozoans (benthic suspension feeders). We compared benthic carbon immobilization across major regions around West Antarctica with sea-ice and primary production, from remotely sensed and directly sampled sources. Lowest carbon immobilization was at the northernmost study regions (South Georgia) and southernmost Amundsen Sea. However, data standardized for age and density showed that only SOI was anomalous (high). High immobilization at SOI was due to very high annual production of bryozoans (rather than high densities or longevity), which were 2x, 3x and 5x higher than on the Bellingshausen, South Georgia and Amundsen shelves, respectively. We found that carbon immobilization correlated to the duration (but not peak or integrated biomass) of phytoplankton blooms, both in directly sampled, local scale data and across regions using remote-sensed data. The long bloom at SOI seems to drive considerable carbon immobilization, but sea-ice losses across West Antarctica mean that significant carbon sinks and negative feedbacks to climate change could also develop in the Bellingshausen and Amundsen seas. © 2015 John Wiley

  9. Integrating Ecosystem Engineering and Food Web Ecology: Testing the Effect of Biogenic Reefs on the Food Web of a Soft-Bottom Intertidal Area.

    Science.gov (United States)

    De Smet, Bart; Fournier, Jérôme; De Troch, Marleen; Vincx, Magda; Vanaverbeke, Jan

    2015-01-01

    The potential of ecosystem engineers to modify the structure and dynamics of food webs has recently been hypothesised from a conceptual point of view. Empirical data on the integration of ecosystem engineers and food webs is however largely lacking. This paper investigates the hypothesised link based on a field sampling approach of intertidal biogenic aggregations created by the ecosystem engineer Lanice conchilega (Polychaeta, Terebellidae). The aggregations are known to have a considerable impact on the physical and biogeochemical characteristics of their environment and subsequently on the abundance and biomass of primary food sources and the macrofaunal (i.e. the macro-, hyper- and epibenthos) community. Therefore, we hypothesise that L. conchilega aggregations affect the structure, stability and isotopic niche of the consumer assemblage of a soft-bottom intertidal food web. Primary food sources and the bentho-pelagic consumer assemblage of a L. conchilega aggregation and a control area were sampled on two soft-bottom intertidal areas along the French coast and analysed for their stable isotopes. Despite the structural impacts of the ecosystem engineer on the associated macrofaunal community, the presence of L. conchilega aggregations only has a minor effect on the food web structure of soft-bottom intertidal areas. The isotopic niche width of the consumer communities of the L. conchilega aggregations and control areas are highly similar, implying that consumer taxa do not shift their diet when feeding in a L. conchilega aggregation. Besides, species packing and hence trophic redundancy were not affected, pointing to an unaltered stability of the food web in the presence of L. conchilega.

  10. Effects of flow scarcity on leaf-litter processing under oceanic climate conditions in calcareous streams.

    Science.gov (United States)

    Martínez, Aingeru; Pérez, Javier; Molinero, Jon; Sagarduy, Mikel; Pozo, Jesús

    2015-01-15

    Although temporary streams represent a high proportion of the total number and length of running waters, historically the study of intermittent streams has received less attention than that of perennial ones. The goal of the present study was to assess the effects of flow cessation on litter decomposition in calcareous streams under oceanic climate conditions. For this, leaf litter of alder was incubated in four streams (S1, S2, S3 and S4) with different flow regimes (S3 and S4 with zero-flow periods) from northern Spain. To distinguish the relative importance and contribution of decomposers and detritivores, fine- and coarse-mesh litter bags were used. We determined processing rates, leaf-C, -N and -P concentrations, invertebrate colonization in coarse bags and benthic invertebrates. Decomposition rates in fine bags were similar among streams. In coarse bags, only one of the intermittent streams, S4, showed a lower rate than that in the other ones as a consequence of lower invertebrate colonization. The material incubated in fine bags presented higher leaf-N and -P concentrations than those in the coarse ones, except in S4, pointing out that the decomposition in this stream was driven mainly by microorganisms. Benthic macroinvertebrate and shredder density and biomass were lower in intermittent streams than those in perennial ones. However, the bags in S3 presented a greater amount of total macroinvertebrates and shredders comparing with the benthos. The most suitable explanation is that the fauna find a food substrate in bags less affected by calcite precipitation, which is common in the streambed at this site. Decomposition rate in coarse bags was positively related to associated shredder biomass. Thus, droughts in streams under oceanic climate conditions affect mainly the macroinvertebrate detritivore activity, although macroinvertebrates may show distinct behavior imposed by the physicochemical properties of water, mainly travertine precipitation, which can

  11. Environmental drivers of phototrophic biofilms in an Alpine show cave (SW-Italian Alps)

    International Nuclear Information System (INIS)

    Piano, E.; Bona, F.; Falasco, E.; La Morgia, V.; Badino, G.; Isaia, M.

    2015-01-01

    The proliferation of lampenflora is a major threat for the conservation of show caves, since phototrophic organisms cause physical, chemical and aesthetic damage to speleothems. In this paper we examine the environmental factors influencing the presence and the growth of the three main photosynthetic groups composing phototrophic biofilms in the Bossea show cave (SW-Italian Alps). The presence and the primary production of cyanobacteria, diatoms and green algae were detected with BenthoTorch®, an instrument for in situ measurement of chlorophyll a concentration that has never been used before in caves. By means of different techniques of regression analysis, we highlighted the response of the three photosynthetic groups to different environmental factors. Illuminance proved to be the main factor influencing positively both the probability of the presence and the productivity of the three groups. The presence of seeping water on the substrate and the distance from the cave entrance proved to play an important role in determining patterns of colonization. By means of GIS techniques, we provide thematic maps of the cave, providing a representation of pattern of the density of the three examined photosynthetic groups within different areas of the cave. The same approach may apply to other show caves, aiming at providing suggestions for the cave management (i.e. cleaning of the cave walls and positioning of artificial lights) and reduce impact caused by tourism. - Highlights: • We used a PAM fluorimeter on autotrophic biofilms in a show cave for the first time. • We modelled the environmental factors influencing phototrophic biofilms. • Illuminance, moisture and distance from the entrance proved to be significant. • We produced thematic maps illustrating our results. • We provide suggestions for cave management

  12. Environmental drivers of phototrophic biofilms in an Alpine show cave (SW-Italian Alps)

    Energy Technology Data Exchange (ETDEWEB)

    Piano, E., E-mail: elena.piano@unito.it [Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin (Italy); Bona, F.; Falasco, E. [Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin (Italy); La Morgia, V. [ISPRA, via Ca' Fornacetta, 9, 40064 Ozzano dell' Emilia (Italy); Badino, G. [Department of Physics, University of Turin, Via P. Giuria 1, 10125 Turin (Italy); Isaia, M. [Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Turin (Italy)

    2015-12-01

    The proliferation of lampenflora is a major threat for the conservation of show caves, since phototrophic organisms cause physical, chemical and aesthetic damage to speleothems. In this paper we examine the environmental factors influencing the presence and the growth of the three main photosynthetic groups composing phototrophic biofilms in the Bossea show cave (SW-Italian Alps). The presence and the primary production of cyanobacteria, diatoms and green algae were detected with BenthoTorch®, an instrument for in situ measurement of chlorophyll a concentration that has never been used before in caves. By means of different techniques of regression analysis, we highlighted the response of the three photosynthetic groups to different environmental factors. Illuminance proved to be the main factor influencing positively both the probability of the presence and the productivity of the three groups. The presence of seeping water on the substrate and the distance from the cave entrance proved to play an important role in determining patterns of colonization. By means of GIS techniques, we provide thematic maps of the cave, providing a representation of pattern of the density of the three examined photosynthetic groups within different areas of the cave. The same approach may apply to other show caves, aiming at providing suggestions for the cave management (i.e. cleaning of the cave walls and positioning of artificial lights) and reduce impact caused by tourism. - Highlights: • We used a PAM fluorimeter on autotrophic biofilms in a show cave for the first time. • We modelled the environmental factors influencing phototrophic biofilms. • Illuminance, moisture and distance from the entrance proved to be significant. • We produced thematic maps illustrating our results. • We provide suggestions for cave management.

  13. Trophodynamics of a deep-sea demersal fish assemblage from the bathyal eastern Ionian Sea (Mediterranean Sea)

    Science.gov (United States)

    Madurell, T.; Cartes, J. E.

    2005-11-01

    Daily food consumption of the eight dominant demersal fish species of the bathyal eastern Ionian Sea were determined from field data on four seasonal cruises (April 1999, July August 1999, November 1999 and February 2000). Daily ration (DR) estimates ranged from 0.198 to 4.273% WW/WW. Overall, DR estimates were independent of the model used, and they were comparable to the daily consumption of other deep-sea fauna (e.g. fish and crustaceans). Both sharks studied ( Galeus melastomus and Etmopterus spinax) exhibited the highest values of DRs, together with the macrourid Coelorhynchus coelorhynchus in August. Among osteichthyes, DR estimates were related (in a multi-linear regression model) to the nature of their diet (i.e. their trophic level deduced from δ15N isotopic composition, the mean number of prey and trophic diversity). Thus, species feeding at a lower trophic level, ingesting a large number of prey items and with a very diversified diet had higher DR than species from higher trophic level and feeding fewer prey items. By season, the DR of species feeding mainly on mesopelagic prey ( Hoplostethus mediterraneus and Helicolenus dactylopterus) were higher in summer, while DR for benthos/suprabenthos feeders (i.e. C. coelorhynchus and Nezumia sclerorhynchus) were higher in spring. Higher food consumption coincides with maximum food availability, both among mesopelagic feeders (higher availability of euphausiids, Pasiphaea sivado and Sergestes arcticus in summer) and among Macrouridae (higher suprabenthos densities in spring). In a tentative estimate the energy intake deduced from diet (i.e. mean energy value of food ingested) was constant in all seasons for each species studied. Results for the energy intake also indicate higher energy intake in the diet of mesopelagic feeders than in the diet of benthic feeders. Overall results are discussed in relation to the deep-sea ecosystem structure and functioning.

  14. What happened to gray whales during the Pleistocene? The ecological impact of sea-level change on benthic feeding areas in the North Pacific Ocean.

    Directory of Open Access Journals (Sweden)

    Nicholas D Pyenson

    Full Text Available Gray whales (Eschrichtius robustus undertake long migrations, from Baja California to Alaska, to feed on seasonally productive benthos of the Bering and Chukchi seas. The invertebrates that form their primary prey are restricted to shallow water environments, but global sea-level changes during the Pleistocene eliminated or reduced this critical habitat multiple times. Because the fossil record of gray whales is coincident with the onset of Northern Hemisphere glaciation, gray whales survived these massive changes to their feeding habitat, but it is unclear how.We reconstructed gray whale carrying capacity fluctuations during the past 120,000 years by quantifying gray whale feeding habitat availability using bathymetric data for the North Pacific Ocean, constrained by their maximum diving depth. We calculated carrying capacity based on modern estimates of metabolic demand, prey availability, and feeding duration; we also constrained our estimates to reflect current population size and account for glaciated and non-glaciated areas in the North Pacific. Our results show that key feeding areas eliminated by sea-level lowstands were not replaced by commensurate areas. Our reconstructions show that such reductions affected carrying capacity, and harmonic means of these fluctuations do not differ dramatically from genetic estimates of carrying capacity.Assuming current carrying capacity estimates, Pleistocene glacial maxima may have created multiple, weak genetic bottlenecks, although the current temporal resolution of genetic datasets does not test for such signals. Our results do not, however, falsify molecular estimates of pre-whaling population size because those abundances would have been sufficient to survive the loss of major benthic feeding areas (i.e., the majority of the Bering Shelf during glacial maxima. We propose that gray whales survived the disappearance of their primary feeding ground by employing generalist filter-feeding modes

  15. Composition, Shell Strength, and Metabolizable Energy of Mulinia lateralis and Ischadium recurvum as Food for Wintering Surf Scoters (Melanitta perspicillata.

    Directory of Open Access Journals (Sweden)

    Alicia M Wells-Berlin

    Full Text Available Decline in surf scoter (Melanitta perspicillata waterfowl populations wintering in the Chesapeake Bay has been associated with changes in the availability of benthic bivalves. The Bay has become more eutrophic, causing changes in the benthos available to surf scoters. The subsequent decline in oyster beds (Crassostrea virginica has reduced the hard substrate needed by the hooked mussel (Ischadium recurvum, one of the primary prey items for surf scoters, causing the surf scoter to switch to a more opportune species, the dwarf surfclam (Mulinia lateralis. The composition (macronutrients, minerals, and amino acids, shell strength (N, and metabolizable energy (kJ of these prey items were quantified to determine the relative foraging values for wintering scoters. Pooled samples of each prey item were analyzed to determine composition. Shell strength (N was measured using a shell crack compression test. Total collection digestibility trials were conducted on eight captive surf scoters. For the prey size range commonly consumed by surf scoters (6-12 mm for M. lateralis and 18-24 mm for I. recurvum, I. recurvum contained higher ash, protein, lipid, and energy per individual organism than M. lateralis. I. recurvum required significantly greater force to crack the shell relative to M. lateralis. No difference in metabolized energy was observed for these prey items in wintering surf scoters, despite I. recurvum's higher ash content and harder shell than M. lateralis. Therefore, wintering surf scoters were able to obtain the same amount of energy from each prey item, implying that they can sustain themselves if forced to switch prey.

  16. Carbon and nitrogen uptake of calcareous benthic foraminifera along a depth-related oxygen gradient in the OMZ of the Arabian Sea

    Directory of Open Access Journals (Sweden)

    Annekatrin Julie Enge

    2016-02-01

    Full Text Available Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with 13C and 15N by cal-careous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phy-todetrital carbon within 4 days by all investigated species shows that phytodetritus is a rele-vant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low-oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between spe-cies. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion or hosting of bacteria under almost anoxic condi-tions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availabil-ity and in the presence of other benthic organisms account for observed changes in the pro-cessing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ bounda-ry region of the Indian margin as biological interactions and species distribution of foraminif-era change with depth and oxygen levels.

  17. The infauna of three widely distributed sponge species (Hexactinellida and Demospongiae) from the deep Ekström Shelf in the Weddell Sea, Antarctica

    Science.gov (United States)

    Kersken, Daniel; Göcke, Christian; Brandt, Angelika; Lejzerowicz, Franck; Schwabe, Enrico; Anna Seefeldt, Meike; Veit-Köhler, Gritta; Janussen, Dorte

    2014-10-01

    Due to their high abundance and large body size sponges have a central position in Antarctic zoobenthos, where they form the most extensive sponge grounds of the world. Though research on Antarctic benthos communities is quite established, research on sponge-associated infauna communities is scarce. We analyzed associated infauna of fifteen individuals of the sponge species Mycale (Oxymycale) acerata Kirkpatrick, 1907 (Demospongiae: Mycalina), Rossella antarctica Carter, 1872 and R. racovitzae Topsent, 1901 (both Hexactinellida: Lyssacinosida). Samples were collected from the deep Ekström Shelf at 602 m in the South-Eastern Weddell Sea, Antarctica, during the ANT XXIV-2 (SYSTCO I) expedition of RV Polarstern. The number of species, α- and β-diversity and the significantly different species composition of infauna communities related to sponge species were calculated, the latter via cluster analysis. The sponge-associated infauna consisted of five phyla: Foraminifera, Nematoda, Polychaeta, Mollusca and Arthropoda. In total 11,463 infaunal specimens were extracted and we found at least 76 associated species. Highest values of α-diversity were calculated for a sample of R. antarctica with a Shannon-Index of 1.84 and Simpson-Index of 0.72 respectively. Our results of the cluster-analysis show significant differences between infauna communities and a unique species composition for single sponge species. Polychaetes of the genus Syllis Lamarck, 1818 were numerous in M. acerata and genera like Pionosyllis Malmgren, 1867 and Cirratulus Lamarck, 1801 were numerous in R. antarctica. Individuals of the amphipod species Seba cf. dubia Schellenberg, 1926 were often found in R. antarctica and R. racovitzae while Colomastix fissilingua Schellenberg, 1926 was frequent in samples of M. acerata. Molluscs were present in M. acerata and R. antarctica but absent in R. racovitzae.

  18. Summer co-existence of small-sized cyprinid and percid individuals in natural and impounded stretches of a lowland river: food niche partitioning among fishes.

    Science.gov (United States)

    Lik, J; Dukowska, M; Grzybkowska, M; Leszczyńska, J

    2017-04-01

    Due to changes of discharge regime downstream of a dam reservoir, an alluvial natural stretch of the Warta River changed to a macrophyte-dominated ecosystem. Large patches of submersed, aquatic macrophytes appeared in summer and their effect is analysed in this study. These patches contained enriched macroinvertebrate assemblages (epiphyton and benthos) and they were refuge for both zooplankton and young fishes released from the reservoir. Despite these altered conditions in this stretch, roach Rutilus rutilus, perch Perca fluviatilis and ruffe Gymnocephalus cernua dominated, as they did in the natural backwater. Fishes were sampled every 2 weeks from June to August, together with their food resources to assess the partitioning of the diet among small individuals of the three species in both stretches (the natural and affected ones). The aim of the analysis was to answer how animal food associated with water plants was partitioned between the species. In both stretches, G. cernua were primarily benthivorous, but epiphytic fauna, zooplankton and large-sized benthic chironomid larvae replaced lack of many large, benthic insects in the tailwater. Levins' food breath index decreased from 0·36 in the backwater to 0·29 in the tailwater. An opposite trend was observed for P. fluviatilis occurring among macrophytes. Perca fluviatilis were competitors of R. rutilus and took food not only in or on the river bed, but also in the water column. They ate zooplankton and epiphytic fauna and Levins' index increased from 0·32 to 0·44 in the tailwater. Rutilus rutilus fed on adult insects, algae and plant fragments in the natural stretch. In the tailwater, these food types were chiefly complemented by zooplankton. Despite this, the niche breadth of R. rutilus was similar at the two sites. Abundance of food associated with the macrophytes appeared to facilitate cohabitation in the abundant fish populations, but P. fluviatilis appeared to benefit the most in the altered river

  19. Patterns and trends of macrobenthic abundance, biomass and production in the deep Arctic Ocean

    Directory of Open Access Journals (Sweden)

    Renate Degen

    2015-08-01

    Full Text Available Little is known about the distribution and dynamics of macrobenthic communities of the deep Arctic Ocean. The few previous studies report low standing stocks and confirm a gradient with declining biomass from the slopes down to the basins, as commonly reported for deep-sea benthos. In this study, we investigated regional differences of faunal abundance and biomass, and made for the first time ever estimates of deep Arctic community production by using a multi-parameter artificial neural network model. The underlying data set combines data from recent field studies with published and unpublished data from the past 20 years, to analyse the influence of water depth, geographical latitude and sea-ice concentration on Arctic benthic communities. We were able to confirm the previously described negative relationship of macrofauna standing stock with water depth in the Arctic deep sea, while also detecting substantial regional differences. Furthermore, abundance, biomass and production decreased significantly with increasing sea-ice extent (towards higher latitudes down to values <200 ind m−2, <65 mg C m−2 and <73 mg C m−2 y−1, respectively. In contrast, stations under the seasonal ice zone regime showed much higher standing stock and production (up to 2500 mg C m−2 y−1, even at depths down to 3700 m. We conclude that particle flux is the key factor structuring benthic communities in the deep Arctic Ocean as it explains both the low values in the ice-covered Arctic basins and the higher values in the seasonal ice zone.

  20. Decreasing Methylmercury Export from a Managed Wetland: A Landscape Manipulation Experiment

    Science.gov (United States)

    Marvin-DiPasquale, M. C.; Windham-Myers, L.; Fleck, J.; McQuillen, H.

    2015-12-01

    Wetlands are important areas for methylmercury (MeHg) production and export to adjacent water bodies, and yet are also critical for wildlife and healthy ecosystem function. Thus, preserving or restoring wetland habitat, while limiting MeHg export, provides a unique challenge to wetland managers. This study examined how wetland design and the use of strategically located deep cells could reduce MeHg export. The study area consisted of eight ~10 hectare leveed fields, annually flooded (4-20 cm) during mid-September thru late April to promote waterfowl habitat. In four 'treatment' fields, 20% of the area (~2 hectare) at the outflow end was excavated to a depth of ~1 m, while no elevation adjustments were made in the four remaining 'control' fields. We examined 3 potential mechanisms of MeHg removal in the deep cell areas of the treatment fields (particulate flux to the benthos, benthic demethylation, and photo-demethylation), and compared MeHg export between control and treatment fields. Particulate depositional flux was high across all deep cells (3.5-8.9 g particles/m2/d dry wt.; 25-75% quartile, n=211), as assessed with deposition pads deployed prior to and retrieved after flooding. This compared well to three separate short-term (24 hr) deposition experiments (1.6-4.7 g particles/m2/d dry wt.; 25-75% quartile, n=48) used to assess particulate MeHg depositional flux (7.6-25.5 ng MeHg/m2/d dry wt.; 25-75% quartile, n=48). With additional results pending, this presentation will describe the relative contribution of the above three MeHg removal processes, the MeHg export from treatment vs control fields, and the overall effectiveness of this wetland management option using deep water cells for reducing MeHg export from managed wetlands to adjacent water bodies.

  1. Patterns in reef fish assemblages: Insights from the Chagos Archipelago.

    Science.gov (United States)

    Samoilys, Melita; Roche, Ronan; Koldewey, Heather; Turner, John

    2018-01-01

    Understanding the drivers of variability in the composition of fish assemblages across the Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilst numerous relationships and feedback mechanisms between the functional roles of coral reef fishes and reef benthic composition have been investigated, certain key groups, such as the herbivores, are widely suggested to maintain reefs in a coral-dominated state. Examining links between fishes and reef benthos is complicated by the interactions between natural processes, disturbance events and anthropogenic impacts, particularly fishing pressure. This study examined fish assemblages and associated benthic variables across five atolls within the Chagos Archipelago, where fishing pressure is largely absent, to better understand these relationships. We found high variability in fish assemblages among atolls and sites across the archipelago, especially for key groups such as a suite of grazer-detritivore surgeonfish, and the parrotfishes which varied in density over 40-fold between sites. Differences in fish assemblages were significantly associated with variable levels of both live and recently dead coral cover and rugosity. We suggest these results reflect differing coral recovery trajectories following coral bleaching events and a strong influence of 'bottom-up' control mechanisms on fish assemblages. Species level analyses revealed that Scarus niger, Acanthurus nigrofuscus and Chlorurus strongylocephalos were key species driving differences in fish assemblage structure. Clarifying the trophic roles of herbivorous and detritivorous reef fishes will require species-level studies, which also examine feeding behaviour, to fully understand their contribution in maintaining reef resilience to climate change and fishing impacts.

  2. Bacterial diversity in the bottom boundary layer of the inner continental shelf of Oregon, USA

    KAUST Repository

    Bertagnolli, AD

    2011-06-21

    There have been few studies of the bacterial community within the bottom boundary layer (BBL) the turbulent region of the water column above the benthos in shallow seas. Typically, the BBL has large amounts of particulate organic matter suspended by turbulence, and it is often the first region of the water column to become hypoxic when oxygen declines. Communities at the surface (5 m) and in the BBL (1 to 10 m above the sea floor) were compared by terminal restriction fragment length polymorphism (T-RFLP) analysis and sequencing of the 16S rRNA gene. Multivariate statistical methods (hierarchical clustering, non-metric multidimensional scaling, and analysis of similarity (ANOSIM)) indicated that the microbial community of the BBL is distinct from the surface community. ANOSIM supported the distinction between surface and BBLs (R values 0.427 and 0.463, based on analysis with restriction enzymes BsuR1 and Hin6I, respectively, p < 0.1%). Six terminal restriction fragments showed an increase in abundance with depth. Cloning, screening and sequencing identified these as a novel environmental clade (Eastern North Pacific Chromatiales (ENPC) clade), the ARTIC96BD-19 clade of Gammaproteobacteria, the 6N14 and Agg8 clades of the phylum Planctomycetes, the OM60/NOR5 clade of Gammaproteobacteria, and uncultivated members of the Roseobacter clade in the MB11C09 and ULA23 subgroups. To the best of our knowledge, this analysis is the first to focus on the unique composition of microbial communities of the BBL in shallow, inner-shelf regions off the coast of Oregon, USA, and the first to report that an uncharacterized clade of Chromatiales is indigenous in this habitat.

  3. Developing national on-line services to annotate and analyse underwater imagery in a research cloud

    Science.gov (United States)

    Proctor, R.; Langlois, T.; Friedman, A.; Davey, B.

    2017-12-01

    Fish image annotation data is currently collected by various research, management and academic institutions globally (+100,000's hours of deployments) with varying degrees of standardisation and limited formal collaboration or data synthesis. We present a case study of how national on-line services, developed within a domain-oriented research cloud, have been used to annotate habitat images and synthesise fish annotation data sets collected using Autonomous Underwater Vehicles (AUVs) and baited remote underwater stereo-video (stereo-BRUV). Two developing software tools have been brought together in the marine science cloud to provide marine biologists with a powerful service for image annotation. SQUIDLE+ is an online platform designed for exploration, management and annotation of georeferenced images & video data. It provides a flexible annotation framework allowing users to work with their preferred annotation schemes. We have used SQUIDLE+ to sample the habitat composition and complexity of images of the benthos collected using stereo-BRUV. GlobalArchive is designed to be a centralised repository of aquatic ecological survey data with design principles including ease of use, secure user access, flexible data import, and the collection of any sampling and image analysis information. To easily share and synthesise data we have implemented data sharing protocols, including Open Data and synthesis Collaborations, and a spatial map to explore global datasets and filter to create a synthesis. These tools in the science cloud, together with a virtual desktop analysis suite offering python and R environments offer an unprecedented capability to deliver marine biodiversity information of value to marine managers and scientists alike.

  4. Light regime and components of turbidity in a Mediterranean coastal lagoon

    Science.gov (United States)

    Obrador, Biel; Pretus, Joan Lluís

    2008-03-01

    The underwater light regime of a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) was studied during four years in order to characterise the spatial and temporal variations in the light attenuation coefficient ( K) and to assess the relative contribution of the different water components to total light attenuation. During the studied period K averaged 1.42 m -1 and ranged from 0.63 m -1 to 3.80 m -1. High temporal variability was observed in light attenuation coefficients, but the lagoon was spatially uniform. Percentage bottom irradiance in relation to specific requirements for the dominant macrophyte species ( Ruppia cirrhosa) was used as an indicator of benthic light limitation. Macrophyte light limitation was expected to occur in the deepest areas of the lagoon during winter, the most turbid period of the annual cycle. During the macrophyte growing season, higher bottom irradiances were observed but a significant percentage of the lagoon benthos (17% in spring and 7% in summer) was expected to be light limited. In the deepest areas of the lagoon (>2 m) changes in bottom irradiance were related more to variations in the light attenuation coefficient than to variations in water level. However, water level appeared to play an important role in determining benthic light limitation at intermediate depths (1.5 m) for the range of K from 1.8 m -1 to 3.3 m -1. The partitioning of the light attenuation coefficient showed that phytoplankton was the main driver of the temporal dynamics of K, but only accounted for 44% of total light attenuation on average. The mean contributions of the other water components to K were: DOC (47%), tripton (6%), and water (3%). At low values of K, attenuation by DOC was responsible for up to 75% of total attenuation. An equation to predict K from the concentration of water components explained 93% of the variance.

  5. Habitat modelling limitations - Puck Bay, Baltic Sea - a case study

    Directory of Open Access Journals (Sweden)

    Jan Marcin Węsławski

    2013-02-01

    Full Text Available The Natura 2000 sites and the Coastal Landscape Park in a shallow marine bay in the southern Baltic have been studied in detail for the distribution of benthic macroorganisms, species assemblages and seabed habitats. The relatively small Inner Puck Bay (104.8 km2 is one of the most thoroughly investigated marine areas in the Baltic: research has been carried out there continuously for over 50 years. Six physical parameters regarded as critically important for the marine benthos (depth, minimal temperature, maximum salinity, light, wave intensity and sediment type were summarized on a GIS map showing unified patches of seabed and the near-bottom water conditions. The occurrence of uniform seabed forms is weakly correlated with the distributions of individual species or multi-species assemblages. This is partly explained by the characteristics of the local macrofauna, which is dominated by highly tolerant, eurytopic species with opportunistic strategies. The history and timing of the assemblage formation also explains this weak correlation. The distribution of assemblages formed by long-living, structural species (Zostera marina and other higher plants shows the history of recovery following earlier disturbances. In the study area, these communities are still in the stage of recovery and recolonization, and their present distribution does not as yet match the distribution of the physical environmental conditions favourable to them. Our results show up the limitations of distribution modelling in coastal waters, where the history of anthropogenic disturbances can distort the picture of the present-day environmental control of biota distributions.

  6. Life histories of microalgal species causing harmful blooms: Haploids, diploids and the relevance of benthic stages.

    Science.gov (United States)

    Figueroa, Rosa Isabel; Estrada, Marta; Garcés, Esther

    2018-03-01

    In coastal and offshore waters, Harmful Algal Blooms (HABs) currently threaten the well-being of coastal countries. These events, which can be localized or involve wide-ranging areas, pose risks to human health, marine ecosystems, and economic resources, such as tourism, fisheries, and aquaculture. Dynamics of HABs vary from one site to another, depending on the hydrographic and ecological conditions. The challenge in investigating HABs is that they are caused by organisms from multiple algal classes, each with its own unique features, including different life histories. The complete algal life cycle has been determined in life cycles of bloom-forming species is essential in developing preventative measures. The knowledge obtained thus far has confirmed the complexity of the algal life cycle, which is composed of discrete life stages whose morphology, ecological niche (plankton/benthos), function, and lifespan vary. The factors that trigger transitions between the different stages in nature are mostly unknown, but it is clear that an understanding of this process provides the key to effectively forecasting bloom recurrence, maintenance, and decline. Planktonic stages constitute an ephemeral phase of the life cycle of most species whereas resistant, benthic stages enable a species to withstand adverse conditions for prolonged periods, thus providing dormant reservoirs for eventual blooms and facilitating organismal dispersal. Here we review current knowledge of the life cycle strategies of major groups of HAB producers in marine and brackish waters. Rather than providing a comprehensive discussion, the objective was to highlight several of the research milestones that have changed our understanding of the plasticity and frequency of the different life cycle stages as well as the transitions between them. We also discuss the relevance of benthic and planktonic forms and their implications for HAB dynamics. Copyright © 2018. Published by Elsevier B.V.

  7. Coral reef assessment and monitoring made easy using Coral Point Count with Excel extensions (CPCe software in Calangahan, Lugait, Misamis Oriental, Philippines

    Directory of Open Access Journals (Sweden)

    S. R. M. Tabugo

    2016-03-01

    Full Text Available Coral reef communities are considered as the most diverse marine ecosystems that provide food, shelter and protection to marine organisms. It provides many important benefits to humans but often a subject to impairment through human activities. Cascading human influences and climate change appeared as a reason behind its decline. Thus, coral reef monitoring methods are substantial. This study utilized Coral Point Count with Excel extensions (CPCe software, as a means to increase efficiency of coral reef monitoring efforts because it automates, facilitates and speeds the process of random point count analysis and can perform image calibration, planar area and length calculations of benthic features. The method was used to estimate community statistics of benthos based on captured still images for every 1m marked across four 50m transect line (total 200 m at 4.6-5.6m depth. Transect images were assigned with 30 spatial random points for identification. Multiple image frames were combined for each transect length supplying datasheet containing header information, statistical parameters species / substrate type (relative abundance, mean and standard deviation and Shannon-Weaver and Simpson's Index calculation for species diversity. Generated transect datasets were statistically analyzed to give quantitative population estimates over the area of interest. Data from individual frames were combined per transect to allow both inter- and intra- site/transect comparisons. This study reports the current status of coral reefs across Calangahan, Lugait, Misamis Oriental, Philippines and proved the efficiency of CPCe as a tool in reef assessment and monitoring. Results showed that most common genera Porites and Acropora were dominant, with Porites lobata as the most abundant coral species in the area. Moreover, results also showed that there were various diseases present affecting corals leading to increased mortality.

  8. Paleolimnological records of nitrogen deposition in shallow, high-elevation lakes of Grand Teton National Park, Wyoming, USA

    Science.gov (United States)

    Spaulding, Sarah A.; Otu, Megan K.; Wolfe, Alexander P.; Baron, Jill S.

    2015-01-01

    Reactive nitrogen (Nr) from anthropogenic sources has been altering ecosystem function in lakes of the Rocky Mountains, other regions of western North America, and the Arctic over recent decades. The response of biota in shallow lakes to atmospheric deposition of Nr, however, has not been considered. Benthic algae are dominant in shallow, high-elevation lakes and are less sensitive to nutrient inputs than planktonic algae. Because the benthos is typically more nutrient rich than the water column, shallow lakes are not expected to show evidence of anthropogenic Nr. In this study, we assessed sedimentary evidence for regional Nr deposition, sediment chronology, and the nature of algal community response in five shallow, high-elevation lakes in Grand Teton National Park (GRTE). Over 140 diatom taxa were identified from the sediments, with a relatively high species richness of taxa characteristic of oligotrophic conditions. The diatom assemblages were dominated by benthic taxa, especially motile taxa. The GRTE lakes demonstrate assemblage-wide shifts in diatoms, including 1) synchronous and significant assemblage changes centered on ~1960 AD; 2) pre-1960 assemblages differed significantly from post-1960 assemblages; 3) pre-1960 diatom assemblages fluctuated randomly, whereas post- 1960 assemblages showed directional change; 4) changes in δ15N signatures were correlated with diatom community composition. These results demonstrate recent changes in shallow high18 elevation lakes that are most correlated with anthropogenic Nr. It is also possible, however, that the combined effect of Nr deposition and warming is accelerating species shifts in benthic diatoms. While uncertainties remain about the potential synergy of Nr deposition and warming, this study adds shallow lakes to the growing list of impacted high-elevation localities in western North America.

  9. The Aegean Sea incident: A quantitative evaluation of the fate of the oil

    International Nuclear Information System (INIS)

    Bergueiro Lopez, J.R.; Morales Correas, N.; Dominguez Laseca, F.

    1993-01-01

    In December 1992, the tanker Aegean Sea was shipwrecked at the entrance to a harbor in northwest Spain. The accident was partly due to bad weather conditions and possibly also to the poor condition of the ship, which subsequently broke in two and caught fire. The tanker was carrying 79,000 tons of low-viscosity light oil, of which 40-60% burned. The oil slick coming from the wrecked ship spread westward and northward into nearby bays, impacting 100-200 km of coast with varying degrees of severity. Strong winds and stormy sea conditions at the time of the incident favored evaporation and natural dispersion of much of the spilled oil. Spill response and countermeasures included restriction of fishing zones, manual and mechanical cleaning of beaches and nearby rocks, use of pumps and skimmers to recover oil from water and shore, and stirring oil-penetrated sand to ca 50 cm depth to facilitate oxygenation and ensure degradation of oil traces. About 6,000 m 3 of emulsified oil were collected from the water and another 1,000 m 3 from the shore; 5,000-6,000 tons of unspilled oil was recovered from the tanker. A simulation model estimated that if no burning had occurred, 2/3 of the oil would have dispersed in the sea or evaporated into the air in ca 3 d. Ecological impacts on plankton, benthos, and pelagic and bird communities appears to have been minor or at least relatively localized. Long-term ecological impacts are being studied. However, zones of fish/shellfish breeding were affected, with short-term damages estimated at over $45 million. 9 refs., 5 figs., 1 tab

  10. Drifting algae and zoobenthos — Effects on settling and community structure

    Science.gov (United States)

    Bonsdorff, Erik

    Shallow (5 to 10 m) sandy bottoms in the Baltic Sea are important areas for zoobenthic production. The infaunal communities are generally governed by the hydrographical conditions are transport of the sediment through wind effects. With increasing eutrophication in the Baltic Sea, drifting mats of annual algae ( Cladophora, Stictyosiphon, Polysiphonia, Rhodemela, Sphacelaria, Pilayella, Furcellaria, Ceramium, etc) have become increasingly common, adding to the structuring and regulating factors for the infauna. In 1990 and 91, a field-study (SCUBA diving; zoobenthos and algae sampling) was carried out in the Åland archipelogo, in thennorthern and their structuring effect on the zoobenthos. Algal biomass increased from 150 ± 19 g DW·m -2 in 1990 to 832±60 g DW·m -2 in 1991, having no effect on oxygen saturation in 1990, but showing signs of reduced oxygen saturation in 1991. Organic content of the sediment remained stable (0.60 to 0.74%) during the entire study period. The zoobenthic community showed significant responses to the drifting algae at population level and in terms of community structure (by 1991: significantly reduced species number; low similarity values (40 to 65%) between bare sand and under the algae). The main species affected were the dominating bivalve Macoma balthica, the polychaetes Pygospio elegans and Manayunkia aestuarina, and the amphipod Corophium volutator. The settlement of M. balthica spat was significantly reduced by the algae (>70% in 1990/91), and no individuals of the dominating polychaetes were recorded under the mat. C. volutator, however, benefited from the algae, and greatly increased in numbers. The results clearly demonstrate the types of physical effects drift-algae will have no sandy-bottom benthos, and show that significant changes in the communities over large areas can be expected with increasing eutrophication.

  11. Trophodynamics of Organic Pollutants in Pelagic and Benthic Food Webs of Lake Dianchi: Importance of Ingested Sediment As Uptake Route.

    Science.gov (United States)

    Fan, Senrong; Wang, Beili; Liu, Hang; Gao, Shixiong; Li, Tong; Wang, Shuran; Liu, Yong; Liu, Xueqin; Wan, Yi

    2017-12-19

    Habitat is of great importance in determining the trophic transfer of pollutants in freshwater ecosystems; however, the major factors influencing chemical trophodynamics in pelagic and benthic food webs remain unclear. This study investigated the levels of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE), polycyclic aromatic hydrocarbons (PAHs), and substituted PAHs (s-PAHs) in 2 plankton species, 6 invertebrate species, and 10 fish species collected from Lake Dianchi in southern China. Relatively high concentrations of PAHs and s-PAHs were detected with total concentrations of 11.4-1400 ng/g wet weight (ww) and 5.3-115 ng/g ww, respectively. Stable isotope analysis and stomach content analysis were applied to quantitatively determine the trophic level of individual organisms and discriminate between pelagic and benthic pathways, and the trophodynamics of the detected compounds in the two food webs were assessed. P,p'-DDE was found to exhibit relatively higher trophic magnification rate in the pelagic food web than in the benthic food web. In contrast, PAHs and s-PAHs exhibited greater dilution rates along the trophic levels in the pelagic food web. The lower species differences of pollutants accumulated in benthic organisms compared to pelagic organisms is attributable to extra uptake via ingested sediment in benthos. The average uptake proportions of PAHs and s-PAHs via ingested sediment in benthic biotas were estimated to be 31-77%, and that of p,p'-DDE was 46%. The uptake routes are of importance for assessing the trophic magnification potentials of organic pollutants, especially in eutrophic freshwater ecosystems.

  12. Quantifying water flow within aquatic ecosystems using load cell sensors: a profile of currents experienced by coral reef organisms around Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Johansen, Jacob L

    2014-01-01

    Current velocity in aquatic environments has major implications for the diversity, abundance and ecology of aquatic organisms, but quantifying these currents has proven difficult. This study utilises a simple and inexpensive instrument (reef system around Lizard Island (Great Barrier Reef, Australia) at a spatial and temporal scale relevant to the ecology of individual benthos and fish. The instrument uses load-cell sensors to provide a correlation between sensor output and ambient current velocity of 99%. Each instrument is able to continuously record current velocities to >500 cms⁻¹ and wave frequency to >100 Hz over several weeks. Sensor data are registered and processed at 16 MHz and 10 bit resolution, with a measuring precision of 0.06±0.04%, and accuracy of 0.51±0.65% (mean ±S.D.). Each instrument is also pressure rated to 120 m and shear stresses ≤20 kNm⁻² allowing deployment in harsh environments. The instrument was deployed across 27 coral reef sites covering the crest (3 m), mid-slope (6 m) and deep-slope (9 m depth) of habitats directly exposed, oblique or sheltered from prevailing winds. Measurements demonstrate that currents over the reef slope and crest varies immensely depending on depth and exposure: currents differ up to 9-fold within habitats only separated by 3 m depth and 15-fold between exposed, oblique and sheltered habitats. Comparisons to ambient weather conditions reveal that currents around Lizard Island are largely wind driven. Zero to 22.5 knot winds correspond directly to currents of 0 to >82 cms⁻¹, while tidal currents rarely exceed 5.5 cms⁻¹. Rather, current velocity increases exponentially as a function of wave height (0 to 1.6 m) and frequency (0.54 to 0.20 Hz), emphasizing the enormous effect of wind and waves on organisms in these shallow coral reef habitats.

  13. Long-term observations of epibenthic fish zonation in the deep northern Gulf of Mexico.

    Directory of Open Access Journals (Sweden)

    Chih-Lin Wei

    Full Text Available A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth from three deep-sea studies, R/V Alaminos cruises (1964-1973, Northern Gulf of Mexico Continental Slope (NGoMCS study (1983-1985 and Deep Gulf of Mexico Benthos (DGoMB program (2000 to 2002, were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared consistently reoccurred over time on the shelf-break (ca. 200 m, upper-slope (ca. 300 to 500 m and upper-to-mid slope (ca. 500 to 1500 m depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05. Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m(-2, suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.

  14. Estimating In Situ Zooplankton Non-Predation Mortality in an Oligo-Mesotrophic Lake from Sediment Trap Data: Caveats and Reality Check.

    Directory of Open Access Journals (Sweden)

    Olga P Dubovskaya

    Full Text Available Mortality is a main driver in zooplankton population biology but it is poorly constrained in models that describe zooplankton population dynamics, food web interactions and nutrient dynamics. Mortality due to non-predation factors is often ignored even though anecdotal evidence of non-predation mass mortality of zooplankton has been reported repeatedly. One way to estimate non-predation mortality rate is to measure the removal rate of carcasses, for which sinking is the primary removal mechanism especially in quiescent shallow water bodies.We used sediment traps to quantify in situ carcass sinking velocity and non-predation mortality rate on eight consecutive days in 2013 for the cladoceran Bosmina longirostris in the oligo-mesotrophic Lake Stechlin; the outcomes were compared against estimates derived from in vitro carcass sinking velocity measurements and an empirical model correcting in vitro sinking velocity for turbulence resuspension and microbial decomposition of carcasses. Our results show that the latter two approaches produced unrealistically high mortality rates of 0.58-1.04 d(-1, whereas the sediment trap approach, when used properly, yielded a mortality rate estimate of 0.015 d(-1, which is more consistent with concurrent population abundance data and comparable to physiological death rate from the literature.Zooplankton carcasses may be exposed to water column microbes for days before entering the benthos; therefore, non-predation mortality affects not only zooplankton population dynamics but also microbial and benthic food webs. This would be particularly important for carbon and nitrogen cycles in systems where recurring mid-summer decline of zooplankton population due to non-predation mortality is observed.

  15. Critical evaluation of the nonradiological environmental technical specifications. Volume 2. Surry Power Plants, Units 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S.M.; Cunningham, P.A.; Gray, D.D.; Kumar, K.D.

    1976-08-10

    A comprehensive study of the data collected as part of the environmental Technical Specifications program for Units 1 and 2 of the Surry Nuclear Power Plant was carried out for the Office of Regulatory Research of the U.S. Nuclear Regulatory Commission. The program included an analysis of the hydrothermal and ecological monitoring data collected from 1973 through 1975. The hydrothermal analysis includes a discussion of models used in plume predictions prior to plant operation and an evaluation of the present hydrothermal monitoring program. The two primary methods used for temperature monitoring employ a fixed thermographs network and boat measurements. Review of data indicates that both the application and formulation of the hydrothermal monitoring program are inadequate to fully characterize the operation of the plant and the behavior of the thermal plume. Furthermore, there are no existing data that can be used to adequately verify or disprove the validity of the various Surry plume predictions. The ecological analysis includes validation of impacts predicted in the Final Environmental Statement using the operational monitoring data. Phytoplankton cell concentrations, chlorophyll a, and carbon-14 measurements were used to monitor changes in the primary producers. Densities of consumers (i.e., zooplankton, benthos, and fish) were sed to monitor changes in the primary producers. Models based on operating data were constructed to determine whether changes were occurring at each trophic level. Analysis of the monitoring data suggests that the thermal discharges at Surry are having a negative effect on the phytoplankton and zooplankton but are enhancing the benthic and nekton populations in the discharge area.

  16. Identification of fish nursery areas in a free tributary of an impoundment region, upper Uruguay River, Brazil

    Directory of Open Access Journals (Sweden)

    Patrícia Alves da Silva

    2012-01-01

    Full Text Available This study aims to determine the importance of different environments of the Ligeiro River (upper Uruguay River, Brazil in fish reproduction. For this purpose, three environments (sampling sites were selected: rapids, a pool, and the mouth of the Ligeiro River. Ichthyoplankton, zooplankton, and benthos were sampled six times per month from September, 2006 to March, 2007. Zooplankton and ichthyoplankton samples were collected early in the evening with plankton nets (64 µm and 500 µm, respectively. Benthos samples were also collected early in the evening with a Van Veen dredge. Local abiotic variables (temperature, dissolved oxygen, pH, electrical conductivity, water speed, alkalinity, water hardness, and water transparency were measured simultaneously with the biotic data sampling and were complemented by regional variables (water flow and precipitation. A total of 43,475 eggs and 2,269 larvae were captured. Of these larvae, 80.1% were in the pre-flexion and larval yolk stages. Digestive tract content showed that the greatest degree of repletion among the larvae in more advanced phases occurred in the pool environment. Water speed was the main characteristic used to differentiate the river's rapids and mouth from the pool. The abundance of zooplankton and benthos was not related to the distribution of densities among the different components of the ichthyoplankton. A greater abundance of eggs and larvae with yolk was found in the rapids and river mouth. Ordination analyses showed a connection between the advanced stage larvae and the pool environment. In conclusion, the rapids and river mouth of the Ligeiro River's are important locations for fish reproduction, particularly in regard to spawning and drifting of the ichthyoplankton's initial stages, whereas the pool represents a nursery place for larval growth.O presente estudo visa determinar a importância de diferentes ambientes do rio Ligeiro (alto rio Uruguai/Brasil na reprodução dos

  17. Biological oceanography of the red oceanic system

    Science.gov (United States)

    Theil, Hjalmar; Weikert, Horst

    1. In 1977, 1979 and 1980-81, investigations were carried out which aimed at evaluating the potential risks from mining metalliferous muds precipating in the Atlantis II Deep of the central Red Sea. This environmental research was initiated by the Saudi Sudanese Red Sea Joint Commission in order to avoid any danger for the Red Sea ecosystem. The broad environmental research programme coherent studies in physical, chemical, biological, and geological oceanography as well as toxicological investigations in the oceanic and in reef zones. We summarise the results from our biological fiels studies in the open sea. 2. The biological investigations were concentrated on the area of the Atlantis II Deep. Benthos was sampled between 700-2000m. For comparison a few samples were also taken further north in the central Red Sea, and to east and west along the flanking deep terraces (500-1000m). Plankton studies covered the total water column above the Deep, and were extended along the axial through to north and south. 3. Benthos sampling was carried out using a heavy closing trawl, a large box grab (box size 50 × 50 cm), Van Veen grabs and traps; photographic surveys were made a phototrap and a photosled. Community respiration was measured with a ship-board method using grab subsamples. Nutrient concentrations, seston and phytoplankton standing stocks as well as in situ primary production were determined from hydrocast samples. Data on zooplankton and micronekton composition and standing stock were obtained from samples collected using different multiple opening-and-closing nets equipped with 100 μm, 300 μm, and 1000 μm mesh sizes. Daily and ontogenetical vertical migration patterns were studied by comparisons of data from midday and midnight tows. 4. Throughout the whole area the sediment is a pteropod ooze containing low contentrations of organic matter; measured organic carbon and nitrogen contents were 0.5 and 0.05% respectively, and chloroplastic pigment equivalents

  18. Seabed images from Southern Ocean shelf regions off the northern Antarctic Peninsula and in the southeastern Weddell Sea

    Science.gov (United States)

    Piepenburg, Dieter; Buschmann, Alexander; Driemel, Amelie; Grobe, Hannes; Gutt, Julian; Schumacher, Stefanie; Segelken-Voigt, Alexandra; Sieger, Rainer

    2017-07-01

    Recent advances in underwater imaging technology allow for the gathering of invaluable scientific information on seafloor ecosystems, such as direct in situ views of seabed habitats and quantitative data on the composition, diversity, abundance, and distribution of epibenthic fauna. The imaging approach has been extensively used within the research project DynAMo (Dynamics of Antarctic Marine Shelf Ecosystems) at the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research Bremerhaven (AWI), which aimed to comparatively assess the pace and quality of the dynamics of Southern Ocean benthos. Within this framework, epibenthic spatial distribution patterns have been comparatively investigated in two regions in the Atlantic sector of the Southern Ocean: the shelf areas off the northern tip of the Antarctic Peninsula, representing a region with above-average warming of surface waters and sea-ice reduction, and the shelves of the eastern Weddell Sea as an example of a stable high-Antarctic marine environment that is not (yet) affected by climate change. The AWI Ocean Floor Observation System (OFOS) was used to collect seabed imagery during two cruises of the German research vessel Polarstern, ANT-XXIX/3 (PS81) to the Antarctic Peninsula from January to March 2013 and ANT-XXXI/2 (PS96) to the Weddell Sea from December 2015 to February 2016. Here, we report on the image and data collections gathered during these cruises. During PS81, OFOS was successfully deployed at a total of 31 stations at water depths between 29 and 784 m. At most stations, series of 500 to 530 pictures ( > 15 000 in total, each depicting a seabed area of approximately 3.45 m2 or 2.3 × 1.5 m) were taken along transects approximately 3.7 km in length. During PS96, OFOS was used at a total of 13 stations at water depths between 200 and 754 m, yielding series of 110 to 293 photos (2670 in total) along transects 0.9 to 2.6 km in length. All seabed images taken during the two cruises

  19. Ontogenetic changes in the bacterial symbiont community of the tropical demosponge Amphimedon queenslandica: metamorphosis is a new beginning

    Directory of Open Access Journals (Sweden)

    Rebecca A Fieth

    2016-11-01

    Full Text Available Vertical transmission of bacterial symbionts, which is known in many species of sponge (Porifera, is expected to promote strong fidelity between the partners. Combining 16S rRNA gene amplicon sequencing and electron microscopy, we have assayed the relative abundance of vertically-inherited bacterial symbionts in several stages of the life cycle of Amphimedon queenslandica, a tropical coral reef sponge. We reveal that adult A. queenslandica house a low diversity microbiome dominated by just three proteobacterial OTUs, with a single gammaprotebacterium clearly dominant through much of the life cycle. This ontogenetic perspective has revealed that, although vertical transmission occurs very early in development, the inherited symbionts do not maintain proportional dominance of the bacterial community at every developmental stage. A reproductive bottleneck in the A. queenslandica life cycle is larval settlement, when a free-swimming pelagic larva settles out of the water column onto the benthos and completes metamorphoses into the sessile body plan within just 3 to 4 days. During this dramatic life cycle transition, an influx of environmentally-derived bacteria leads to a major reorganization of the microbiome, potentially challenging the fidelity and persistence of the vertically-inherited symbiotic relationships. However, dominance of the primary, vertically-inherited symbionts is restored in adult sponges. The mechanisms underlying ontogenetic changes in the bacterial community are unknown, including how the dominance of the primary symbionts is restored in the adult sponge – does the host or symbiont regulate this process? Using high-resolution transcriptional profiling in multiple stages of the A. queenslandica life cycle combined with this natural perturbation of the microbiome immediately following larval settlement, we are beginning to identify candidate host genes associated with animal-bacterial crosstalk. Among the sponge host genes

  20. Nematode communities in sediments of the Kermadec Trench, Southwest Pacific Ocean

    Science.gov (United States)

    Leduc, Daniel; Rowden, Ashley A.

    2018-04-01

    Hadal trenches are characterized by environmental conditions not found in any other deep-sea environment, such as steep topography and periodic disturbance by turbidity flows, which are likely responsible for the distinct nature of benthic communities of hadal trenches relative to those of the abyssal plain. Nematodes are the most abundant metazoans in the deep-sea benthos, but it is not yet clear if different trenches host distinct nematode communities, and no data are yet available on the communities of most trenches, including the Kermadec Trench in the Southwest Pacific. Quantitative core samples from the seafloor of the Kermadec Trench were recently obtained from four sites at 6000-9000 m depth which allowed for analyses of meiofauna, and nematodes in particular, for the first time. Nematode community and trophic structure was also compared with other trenches using published data. There was a bathymetric gradient in meiofauna abundance, biomass, and community structure within the Kermadec Trench, but patterns for species richness were ambiguous depending on which metric was used. There was a change in community structure from shallow to deep sites, as well as a consistent change in community structure from the upper sediment layers to the deeper sediment layers across the four sites. These patterns are most likely explained by variation in food availability within the trench, and related to trench topography. Together, deposit and microbial feeders represented 48-92% of total nematode abundance in the samples, which suggests that fine organic detritus and bacteria are major food sources. The relatively high abundance of epigrowth feeders at the 6000 and 9000 m sites (38% and 31%, respectively) indicates that relatively freshly settled microalgal cells represent another important food source at these sites. We found a significant difference in species community structure between the Kermadec and Tonga trenches, which was due to both the presence/absence of

  1. Activities of radionuclides in the Pacific coastal area of Fukushima since the TEPCO Fukushima Daiichi Nuclear Power Station accident - Activities of radionuclides in the coast area off Fukushima after TEPCO's Fukushima Daiichi Nuclear Power Station accident

    Energy Technology Data Exchange (ETDEWEB)

    Aono, Tatsuo; Fukuda, Miho; Yoshida, Satoshi [National Institute of Radiological Sciences, 263-8555, Chiba (Japan); Sohtome, Tadahiro; Mizuno, Takuji [Fukushima Prefecture Fisheries Experimental Station, 970-0316, Fukushima (Japan); Igarashi, Satoshi [Fukushima Prefecture Fisheries Experimental Station, 970-0316, Fukushima (Japan); Fukushima Prefecture Sea-Farming Association, 970-8044, Fukushima (Japan); Ito, Yukari; Kanda, Jota; Ishimaru, Takashi [Tokyo University of Marine Science and Technology, 108-0075, Tokyo (Japan)

    2014-07-01

    The accident of TEPCO's Fukushima Daiichi Nuclear Power Station (FDNPS) has caused the release of the huge quantities of radionuclide by the 2011 Great East Japan Earthquake and Tsunami, and then the serious problems gave rise to pollution in marine environment widely in the coast area off Fukushima. Monitoring of radioactivity in seawater and biota are important for understanding the dispersion of radionuclides and the effects of radioecology in the marine environment around the coast of Fukushima and the Pacific. The activities of Cs-134 and Cs-137 in seawater decreased exponentially and then were almost same levels before the accident around off Fukushima after about three years from the accident. However, the high activities of radio caesium (Cs) have been monitored in marine biota off Fukushima. The aims of the present study were to examine the temporal changes in radioactivity and to clarify the variation factor and the effect of radioecology in marine biota. Cs-134 and Cs-137, and Ag-110m, were released by this accident, determined in biota sample such as the plankton, fish and benthos, although it is well-known that molluscs and crustaceans concentrate silver in visceral parts. However, Sr-90 was not detected and the activities of plutonium were almost same level before this accident in the marine biota around off Fukushima. Concentration ratios of Cs (CR-Cs) in marine organism were from 2.6 E+1 in the muscle part of squid to 1.0 E+4 in the viscera of clam. The large differences in CR-Cs by the parts of marine organism were not observed. It is suggested that rapid change in the activities of radio Cs and silver in seawater, resuspension of particles from sediments and food chain effects led to high radionuclide activities in marine biota after this accident. CR-Cs in plankton was also calculated with the activities in seawater, which were collected around sampling area during this monitoring period. These resulting values ranged from 5.8 E+1 to 7.8 E+2

  2. Interactive effects of dissolved zinc and orthophosphate on phytoplankton from Coeur d'Alene Lake, Idaho

    Science.gov (United States)

    Kuwabara, James S.; Topping, Brent R.; Woods, Paul F.; Carter, James L.; Hager, Stephen W.

    2006-01-01

    Within the longitudinal chemical-concentration gradient in Coeur d'Alene Lake, generated by inputs from the St. Joe and Coeur d'Alene Rivers, two dominant algal species, Chlorella minutissima and Asterionella formosa, were isolated and cultured in chemically defined media to examine growth response to a range of dissolved orthophosphate concentrations and zinc-ion activities representative of the region within- and up-gradient of the Coeur d'Alene River inlet to the lake. Although zinc is an essential micronutrient, the toxicity of algal species to elevated concentrations of uncomplexed zinc has been demonstrated, and affects the metabolism of phosphorus (Kuwabara, 1985a; Kuwabara and others, 1986), the limiting nutrient in the lake. This interaction between solutes could be of management interest. As an extension of field work conducted in August, 1999 (Kuwabara and others, 2003b), the water column and benthos of Coeur d'Alene Lake were sampled in August 2001, June 2004 and June 2005 (Fig. 1; Table 1) to provide the biological characterization in terms of phytoplankton community composition, benthic macroinvertebrate community composition and benthic chlorophyll concentrations, as well as chemical characterizations at six sites (three depths per site) within the lake. This work, in support of the Idaho Department of Environmental Quality and regional tribal organizations, provides the first phytoplankton response models in a format that may be incorporated into a process-interdependent water-quality model like CAEDYM (Fig. 2; Brookes and others, 2004; Centre for Water Research, 2006) as a management tool for the lake. This study provides information in support of developing process-interdependent solute-transport models for the watershed (that is, models integrating physical, geochemical and biological processes), and hence in support of subsequent evaluation of remediation or load-allocation strategies. The following two questions are posed: Are dissolved zinc

  3. Bioassessment tools in novel habitats: an evaluation of indices and sampling methods in low-gradient streams in California.

    Science.gov (United States)

    Mazor, Raphael D; Schiff, Kenneth; Ritter, Kerry; Rehn, Andy; Ode, Peter

    2010-08-01

    Biomonitoring programs are often required to assess streams for which assessment tools have not been developed. For example, low-gradient streams (slopeindices in the state were developed in high-gradient systems. This study evaluated the performance of three sampling methods [targeted riffle composite (TRC), reach-wide benthos (RWB), and the margin-center-margin modification of RWB (MCM)] and two indices [the Southern California Index of Biotic Integrity (SCIBI) and the ratio of observed to expected taxa (O/E)] in low-gradient streams in California for application in this habitat type. Performance was evaluated in terms of efficacy (i.e., ability to collect enough individuals for index calculation), comparability (i.e., similarity of assemblages and index scores), sensitivity (i.e., responsiveness to disturbance), and precision (i.e., ability to detect small differences in index scores). The sampling methods varied in the degree to which they targeted macroinvertebrate-rich microhabitats, such as riffles and vegetated margins, which may be naturally scarce in low-gradient streams. The RWB method failed to collect sufficient numbers of individuals (i.e., >or=450) to calculate the SCIBI in 28 of 45 samples and often collected fewer than 100 individuals, suggesting it is inappropriate for low-gradient streams in California; failures for the other methods were less common (TRC, 16 samples; MCM, 11 samples). Within-site precision, measured as the minimum detectable difference (MDD) was poor but similar across methods for the SCIBI (ranging from 19 to 22). However, RWB had the lowest MDD for O/E scores (0.20 versus 0.24 and 0.28 for MCM and TRC, respectively). Mantel correlations showed that assemblages were more similar within sites among methods than within methods among sites, suggesting that the sampling methods were collecting similar assemblages of organisms. Statistically significant disagreements among methods were not detected, although O/E scores were higher

  4. Radionuclide transfer in marine coastal ecosystems, a modelling study using metabolic processes and site data.

    Science.gov (United States)

    Konovalenko, L; Bradshaw, C; Kumblad, L; Kautsky, U

    2014-07-01

    This study implements new site-specific data and improved process-based transport model for 26 elements (Ac, Ag, Am, Ca, Cl, Cm, Cs, Ho, I, Nb, Ni, Np, Pa, Pb, Pd, Po, Pu, Ra, Se, Sm, Sn, Sr, Tc, Th, U, Zr), and validates model predictions with site measurements and literature data. The model was applied in the safety assessment of a planned nuclear waste repository in Forsmark, Öregrundsgrepen (Baltic Sea). Radionuclide transport models are central in radiological risk assessments to predict radionuclide concentrations in biota and doses to humans. Usually concentration ratios (CRs), the ratio of the measured radionuclide concentration in an organism to the concentration in water, drive such models. However, CRs vary with space and time and CR estimates for many organisms are lacking. In the model used in this study, radionuclides were assumed to follow the circulation of organic matter in the ecosystem and regulated by radionuclide-specific mechanisms and metabolic rates of the organisms. Most input parameters were represented by log-normally distributed probability density functions (PDFs) to account for parameter uncertainty. Generally, modelled CRs for grazers, benthos, zooplankton and fish for the 26 elements were in good agreement with site-specific measurements. The uncertainty was reduced when the model was parameterized with site data, and modelled CRs were most similar to measured values for particle reactive elements and for primary consumers. This study clearly demonstrated that it is necessary to validate models with more than just a few elements (e.g. Cs, Sr) in order to make them robust. The use of PDFs as input parameters, rather than averages or best estimates, enabled the estimation of the probable range of modelled CR values for the organism groups, an improvement over models that only estimate means. Using a mechanistic model that is constrained by ecological processes enables (i) the evaluation of the relative importance of food and water

  5. Seasonal changes and biochemical composition of the labile organic matter flux in the Cretan Sea

    Science.gov (United States)

    Danovaro, Roberto; Della Croce, Norberto; Dell'Anno, Antonio; Mauro Fabiano; Marrale, Daniela; Martorano, Daniela

    2000-08-01

    Downward fluxes of labile organic matter (lipids, proteins and carbohydrates) at 200 (trap A) and 1515 m depth (trap B), measured during a 12 months sediment trap experiment, are presented, together with estimates of the bacterial and cyanobacterial biomasses associated to the particles. The biochemical composition of the settling particles was determined in order to provide qualitative and quantitative information on the flux of readily available organic carbon supplying the deep-sea benthic communities of the Cretan Sea. Total mass flux and labile carbon fluxes were characterised by a clear seasonality. Higher labile organic fluxes were reported in trap B, indicating the presence of resuspended particles coming from lateral inputs. Particulate carbohydrates were the major component of the flux of labile compounds (on annual average about 66% of the total labile organic flux) followed by lipids (20%) and proteins (13%). The biopolymeric carbon flux was very low (on annual average 0.9 and 1.2 gC m -2 y -1, at trap A and B). Labile carbon accounted for most of the OC flux (on annual average 84% and 74% in trap A and B respectively). In trap A, highest carbohydrate and protein fluxes in April and September, corresponded to high faecal pellet fluxes. The qualitative composition of the organic fluxes indicated a strong protein depletion in trap B and a decrease of the bioavailability of the settling particles as a result of a higher degree of dilution with inorganic material. Quantity and quality of the food supply to the benthos displayed different temporal patterns. Bacterial biomass in the sediment traps (on average 122 and 229 μgC m -2 d -1 in trap A and B, respectively) was significantly correlated to the flux of labile organic carbon, and particularly to the protein and carbohydrate fluxes. Cyanobacterial flux (on average, 1.1 and 0.4 μgC m -2 d -1, in trap A and B, respectively) was significantly correlated with total mass and protein fluxes only in trap A

  6. Toxic effect of the combined antibiotics ciprofloxacin, lincomycin, and tylosin on two species of marine diatoms.

    Science.gov (United States)

    Hagenbuch, Isaac M; Pinckney, James L

    2012-10-15

    The role that antibiotics and other "emerging contaminants" play in shaping environmental microbial communities is of growing interest. The use of the prokaryotic metabolic inhibitors tylosin (T), lincomycin (L), and ciprofloxacin (C) in livestock and humans is both global and extensive. Each of these antibiotic compounds exhibits an affinity for sediment particles, increasing the likelihood of their deposition in the benthos of aquatic systems and each are often present in environmental samples. The purpose of this study was to determine if T, L, and C and their mixtures exhibit significant toxicity to two species of marine diatoms, an algal class comprised of ubiquitous eukaryotic primary producers. Subpopulations from laboratory cultures of Cylindrotheca closterium and Navicula ramosissima were reared in 24-well microtiter plates in the presence of single or combined antibiotics in dilution series. Population growth rates were assessed via epifluorescent microscopic cell counts, from which the half-max inhibitory concentrations (IC(50)) were calculated and used as part of a toxic unit (TU) method for assessing mixture interactions. The single-compound IC(50)'s were, for C. closterium: T = 0.27 mg L(-1), L = 14.16 mg L(-1), C = 55.43 mg L(-1), and for N. ramosissima: T = 0.99 mg L(-1), L = 11.08 mg L(-1), C = 72.12 mg L(-1). These values were generally higher than similar metrics for freshwater species. Mixture IC(50)'s were generally synergistic against C. closterium and additive for N. ramosissima. Both single and combined treatments reduced or eliminated diatom motility. Monochemical responses were similar between species and were not useful for predicting mixture interactions. Mixtures had compound-specific and species-specific effects, favoring N. ramosissima. These results suggest that anthropogenic antibiotics may play a significant role in the ecology of environmental benthic microbial communities. They also suggest single-compound/species studies do not

  7. Testing the applicability of a benthic foraminiferal-based transfer function for the reconstruction of paleowater depth changes in Rhodes (Greece) during the early Pleistocene.

    Science.gov (United States)

    Milker, Yvonne; Weinkauf, Manuel F G; Titschack, Jürgen; Freiwald, Andre; Krüger, Stefan; Jorissen, Frans J; Schmiedl, Gerhard

    2017-01-01

    We present paleo-water depth reconstructions for the Pefka E section deposited on the island of Rhodes (Greece) during the early Pleistocene. For these reconstructions, a transfer function (TF) using modern benthic foraminifera surface samples from the Adriatic and Western Mediterranean Seas has been developed. The TF model gives an overall predictive accuracy of ~50 m over a water depth range of ~1200 m. Two separate TF models for shallower and deeper water depth ranges indicate a good predictive accuracy of 9 m for shallower water depths (0-200 m) but far less accuracy of 130 m for deeper water depths (200-1200 m) due to uneven sampling along the water depth gradient. To test the robustness of the TF, we randomly selected modern samples to develop random TFs, showing that the model is robust for water depths between 20 and 850 m while greater water depths are underestimated. We applied the TF to the Pefka E fossil data set. The goodness-of-fit statistics showed that most fossil samples have a poor to extremely poor fit to water depth. We interpret this as a consequence of a lack of modern analogues for the fossil samples and removed all samples with extremely poor fit. To test the robustness and significance of the reconstructions, we compared them to reconstructions from an alternative TF model based on the modern analogue technique and applied the randomization TF test. We found our estimates to be robust and significant at the 95% confidence level, but we also observed that our estimates are strongly overprinted by orbital, precession-driven changes in paleo-productivity and corrected our estimates by filtering out the precession-related component. We compared our corrected record to reconstructions based on a modified plankton/benthos (P/B) ratio, excluding infaunal species, and to stable oxygen isotope data from the same section, as well as to paleo-water depth estimates for the Lindos Bay Formation of other sediment sections of Rhodes. These comparisons

  8. History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

    Science.gov (United States)

    Dauvin, Jean-Claude

    2015-06-01

    Benthic studies in the English Channel (EC), a shallow megatidal and epicontinental sea, began in the 1960s and 1970s with the work of teams led by Norman Holme (UK) and Louis Cabioch (F). During this period, benthic sampling was mainly qualitative, i.e. using a device such as the 'Rallier du Baty' dredge in the case of the French team and a modified anchor dredge in the case of the British team. Studies were focused on acquiring knowledge of the main distributions of benthic communities and species. Surveys on the scale of the whole EC led to the recognition of general features and two main patterns were identified: 1) the role of hydrodynamics on the spatial distribution of sediment, benthic species and communities; 2) the presence of a west-east climatic gradient of faunal impoverishment. Benthic studies in the 1980s-1990s were focused on the beginning of the implementation of long-term survey at a limited number of sites to identify seasonal and multi-annual changes. In the first decade of the 2000s, the implementation of the European Water Framework Directive and the Marine Strategy Framework Directive to define the Ecological Quality Status of marine environments increased the need to acquire better information of the structure and functioning of benthic communities, since benthic species and habitats were recognised as good indicators of human pressure on marine ecosystems. Faced with the increase of human maritime activities, the appearance of invasive species and the need to preserve sensitive marine habitats, benthic studies have been focused on developing a 'toolkit' to help in the decision-making and planning for both sound governance and sustainable management of marine resources and human activities in the English Channel. Multidisciplinary approaches were used to differentiate habitats in a more precise detail. Both indirect (side-scan sonar, ROV) and direct (grab sampling with benthos identification and grain-size analyses) approaches were used and

  9. Different feeding strategies in Antarctic scavenging amphipods and their implications for colonisation success in times of retreating glaciers.

    Science.gov (United States)

    Seefeldt, Meike Anna; Campana, Gabriela Laura; Deregibus, Dolores; Quartino, María Liliana; Abele, Doris; Tollrian, Ralph; Held, Christoph

    2017-01-01

    Scavenger guilds are composed of a variety of species, co-existing in the same habitat and sharing the same niche in the food web. Niche partitioning among them can manifest in different feeding strategies, e.g. during carcass feeding. In the bentho-pelagic realm of the Southern Ocean, scavenging amphipods (Lysianassoidea) are ubiquitous and occupy a central role in decomposition processes. Here we address the question whether scavenging lysianassoid amphipods employ different feeding strategies during carcass feeding, and whether synergistic feeding activities may influence carcass decomposition. To this end, we compared the relatively large species Waldeckia obesa with the small species Cheirimedon femoratus, Hippomedon kergueleni, and Orchomenella rotundifrons during fish carcass feeding ( Notothenia spp.). The experimental approach combined ex situ feeding experiments, behavioural observations, and scanning electron microscopic analyses of mandibles. Furthermore, we aimed to detect ecological drivers for distribution patterns of scavenging amphipods in the Antarctic coastal ecosystems of Potter Cove. In Potter Cove, the climate-driven rapid retreat of the Fourcade Glacier is causing various environmental changes including the provision of new marine habitats to colonise. While in the newly ice-free areas fish are rare, macroalgae have already colonised hard substrates. Assuming that a temporal dietary switch may increase the colonisation success of the most abundant lysianassoids C. femoratus and H. kergueleni , we aimed to determine their consumption rates (g food x g amphipods -1 x day -1 ) and preferences of macroalgae and fish. We detected two functional groups with different feeding strategies among scavenging amphipods during carcass feeding: carcass 'opener' and 'squeezer'. Synergistic effects between these groups were not statistically verified under the conditions tested. C. femoratus switched its diet when fish was not available by consuming

  10. Modelling spatial distribution of Patagonian toothfish through life-stages and sex and its implications for the fishery on the Kerguelen Plateau

    Science.gov (United States)

    Péron, Clara; Welsford, Dirk C.; Ziegler, Philippe; Lamb, Timothy D.; Gasco, Nicolas; Chazeau, Charlotte; Sinègre, Romain; Duhamel, Guy

    2016-02-01

    Size and sex specific habitat preferences are common in animal populations and can have important implications for sound spatial management of harvested species. Patagonian toothfish (Dissostichus eleginoides) is a commercially exploited fish species characterised by its longevity (>50 yo) and its extremely broad distribution in depths ranging from 10 m to 2500 m on most of the Plateaux, banks and seamounts of the Southern Ocean. As many bentho-pelagic fish species, Patagonian toothfish exhibits sexual dimorphism and ontogenetic habitat shift towards deeper waters as they grow. In this study, we modelled the spatial structure of Patagonian toothfish population (median total length and sex composition) in a data-rich area, the Kerguelen Plateau (Southern Indian Ocean), to better understand the ecological drivers of their distributional patterns and inform current and future fishery management strategies. We applied spatially-explicit statistical models to quantify and predict the effects of the complex topography of the Kerguelen Plateau in structuring the spatial distribution of Patagonian toothfish total length and sex ratio, while controlling for gear selectivity and season. Model predictions showed that juvenile toothfish live in shallow regions (shelf and banks) and move downward progressively up to 600 m while they grow. Between 600 m and 1200 m, the downward movement stops and fish settle at their preferred depths. While in this depth range, fish are ∼75 cm long and most vulnerable to fisheries. As they approach maturity large fish move downward to deep-sea habitats (from 1200 m to >2300 m) and head towards the spawning grounds on the western side of the plateau and around Skiff Bank. Importantly, the sex ratio was not evenly distributed across the Plateau; prediction maps revealed a higher proportion of females in the South whereas a strong male-bias sex ratio (70%) occurred in the North-West. Large-scale prediction maps derived from our models assisted in

  11. LE COLMATAGE MINÉRAL DU LIT DES COURS D’EAU : REVUE BIBLIOGRAPHIQUE DES MÉCANISMES ET DES CONSÉQUENCES SUR LES HABITATS ET LES PEUPLEMENTS DE MACROINVERTÉBRÉS.

    Directory of Open Access Journals (Sweden)

    GAYRAUD S.

    2002-04-01

    Full Text Available Le développement des activités humaines a conduit dans de nombreuses régions à une augmentation du transfert de sédiments fins vers les cours d’eau, multipliant les phénomènes de colmatage. Le colmatage fait référence au dépôt de sédiments organiques ou minéraux et à leur infiltration dans le benthos et l’hyporhéos. Dans cet article de synthèse, le colmatage par les sédiments minéraux est présenté du point de vue de ses mécanismes et de sa variabilité spatio-temporelle dans un schéma d’organisation global du cours d’eau. Le colmatage entraîne une modification des habitats benthique et interstitiel, ainsi que des échanges d’eau et de matières entre la surface et l’hyporhéos. Il affecte la structure du peuplement d’invertébrés en modifiant la structure et la stabilité du substrat, la disponibilité des ressources trophiques et de l’oxygène, ainsi que de la pression de prédation. Les conséquences à court terme sont une augmentation de la dérive et une réduction de l’abondance totale des organismes. Sur le long terme le colmatage affecte la survie, le développement et la croissance des invertébrés ainsi que la biomasse et la productivité du peuplement. Les espèces sensibles adaptées aux substrats grossiers disparaissent au profit des espèces adaptées aux sédiments fins. Les conséquences sur la faune hyporhéique sont peu connues mais l’importance de l’hyporhéos dans le fonctionnement du cours d’eau suggère que son altération pourrait avoir des conséquences importantes en terme de capacité de résilience du peuplement face aux perturbations.

  12. Stable isotope trophic patterns in echinoderm megafauna in close proximity to and remote from Gulf of Mexico lower slope hydrocarbon seeps

    Science.gov (United States)

    Carney, Robert Spencer

    2010-11-01

    benthos may not be as food-poor as assumed from biomass measurements and flux estimates.

  13. Mercury Dynamics in Aquatic Food Webs of the Finger Lakes, New York

    Science.gov (United States)

    Cleckner, L.; Razavi, N. R.; Halfman, J. D.; Cushman, S. F.; Foust, J.; Gilman, B.

    2016-12-01

    Mercury (Hg) contamination of fish is a global concern due to the deleterious health effects in humans and wildlife associated with ingesting fish with elevated concentrations. A key to understanding elevated fish Hg concentrations is to examine methyl Hg dynamics at the base of food webs, including algae and zooplankton. Predicting determinants of methyl Hg concentrations in lower trophic level biota remains an active area of research. This study was conducted to assess Hg concentrations in biota of the Finger Lakes (New York, USA), a region where fisheries are an important economic driver, but where no comprehensive assessment of food web Hg dynamics has been completed to date. Sources of Hg in the region include atmospheric pollution from an active coal-fired power plant. The objectives of this study were to: 1) determine if fish Hg concentrations were of concern, 2) assess differences in Hg accumulation among lakes and determine predictors of fish Hg concentrations, and 3) evaluate the predictive power of monthly zooplankton methyl Hg concentrations on fish Hg concentrations. From May - October 2015, suspended particulate matter, zooplankton, and benthos were sampled monthly in five of the Finger Lakes (Honeoye, Canandaigua, Seneca, Cayuga, and Owasco Lakes). Fish were sampled once over the same study period and species were targeted from all trophic levels. Results for top predatory fish including Lake Trout (Salvelinus namaycush), Largemouth Bass (Micropterus salmoides), and Walleye (Sander vitreus) showed significant differences among lakes, and elevated concentrations are above US Environmental Protection Agency's screening value (300 ng/g wet weight). No clear pattern in Hg levels among lakes was evident in lower trophic level fishes such as Yellow Perch (Perca flavescens) and Golden Shiner (Notemigonus crysoleucas), but concentrations were low. Benthivorous Brown Bullhead (Ameiurus nebulosus) exhibited significant differences in Hg among lakes with

  14. Secondary production at the Polar Front, Barents Sea, August 2007

    Science.gov (United States)

    Basedow, Sünnje L.; Zhou, Meng; Tande, Kurt S.

    2014-02-01

    ) of small zooplankton may contribute a substantial amount of carbon to the benthos and to pelagic predators such as young capelin. AtW was the most productive water mass, with surface chl a maxima and an estimated population growth of 134 mg C m- 3 d- 1 for small zooplankton, 3.6 mg C m- 3 d- 1 for medium-sized copepods and 0.9 mg C m- 3 d- 1 for CIV-CVI Calanus. For those Calanus spp. in the surface layer, the estimated specific mortality rates were up to - 0.35 d- 1, partly due to high predation pressure by hydrozoans and chaetognaths.

  15. Will a rising sea sink some estuarine wetland ecosystems?

    Science.gov (United States)

    Grenfell, S E; Callaway, R M; Grenfell, M C; Bertelli, C M; Mendzil, A F; Tew, I

    2016-06-01

    Sea-level rise associated with climate change presents a major challenge to plant diversity and ecosystem service provision in coastal wetlands. In this study, we investigate the effect of sea-level rise on benthos, vegetation, and ecosystem diversity in a tidal wetland in west Wales, the UK. Present relationships between plant communities and environmental variables were investigated through 50 plots at which vegetation (species and coverage), hydrological (surface or groundwater depth, conductivity) and soil (matrix chroma, presence or absence of mottles, organic content, particle size) data were collected. Benthic communities were sampled at intervals along a continuum from saline to freshwater. To ascertain future changes to the wetlands' hydrology, a GIS-based empirical model was developed. Using a LiDAR derived land surface, the relative effect of peat accumulation and rising sea levels were modelled over 200 years to determine how frequently portions of the wetland will be inundated by mean sea level, mean high water spring and mean high water neap conditions. The model takes into account changing extents of peat accumulation as hydrological conditions alter. Model results show that changes to the wetland hydrology will initially be slow. However, changes in frequency and extent of inundation reach a tipping point 125 to 175 years from 2010 due to the extremely low slope of the wetland. From then onwards, large portions of the wetland become flooded at every flood tide and saltwater intrusion becomes more common. This will result in a reduction in marsh biodiversity with plant communities switching toward less diverse and occasionally monospecific communities that are more salt tolerant. While the loss of tidal freshwater wetland is in line with global predictions, simulations suggest that in the Teifi marshes the loss will be slow at first, but then rapid. While there will be a decrease in biodiversity, the model indicated that at least for one ecosystem

  16. ADDOSS: Autonomously Deployed Deep-ocean Seismic System - Communications Gateway for Ocean Observatories

    Science.gov (United States)

    Laske, Gabi; Berger, Jon; Orcutt, John; Babcock, Jeff

    2014-05-01

    We describe an autonomously deployable, communications gateway designed to provide long-term and near real-time data from ocean observatories. The key features of this new system are its abilities to telemeter sensor data from the seafloor to shore without cables or moorings, and to be deployed without a ship, thereby greatly reducing life-cycle costs. The free-floating surface communications gateway utilizes a Liquid Robotics wave glider comprising a surfboard-sized float towed by a tethered, submerged glider, which converts wave motion into thrust. For navigation, the wave glider is equipped with a small computer, a GPS receiver, a rudder, solar panels and batteries, and an Iridium satellite modem. Acoustic communications connect the subsea instruments and the surface gateway while communications between the gateway and land are provided by the Iridium satellite constellation. Wave gliders have demonstrated trans-oceanic range and long-term station keeping capabilities. The acoustics communications package is mounted in a shallow tow body which utilizes a WHOI micro modem and a Benthos low frequency, directional transducer. A matching modem and transducer is mounted on the ocean bottom package. Tests of the surface gateway in 4350 m of water demonstrated an acoustic efficiency of approximately 396 bits/J. For example, it has the ability to send 4 channels of compressed, 1 sample per second data from the ocean bottom to the gateway with an average power draw of approximately 0.15 W and a latency of less than 3 minutes. This gateway is used to send near real-time data from a broadband ocean bottom seismic observatory, first during short week-to-months long test deployments but will ultimately be designed for a two-year operational life. Such data from presently unobserved oceanic areas are critical for both national and international agencies in monitoring and characterizing earthquakes, tsunamis, and nuclear explosions. We present initial results from a two short

  17. A Robotic Communications Gateway for Ocean Observations

    Science.gov (United States)

    Orcutt, J. A.; Berger, J.; Laske, G.; Babcock, J.

    2015-12-01

    We describe a new technology that can provide real-time telemetry of sensor data from the ocean bottom. The breakthrough technology that makes this system possible is an autonomous surface vehicle called the Wave Glider developed by Liquid Robotics, Inc. of Sunnyvale, CA., which harvests wave and solar energy for motive and electrical power. The free-floating surface communications gateway uses a Liquid Robotics wave glider comprising a surfboard-sized float towed by a tethered, submerged glider, which converts wave motion into thrust. For navigation, the wave glider is equipped with a small computer, a GPS receiver, a rudder, solar panels and batteries, and an Iridium satellite modem. Acoustic communications connect the subsea instruments and the surface gateway while communications between the gateway and land are provided by the Iridium satellite constellation. Wave gliders have demonstrated trans-oceanic range and long-term station keeping capabilities. The topside acoustics communications package is mounted in a shallow tow body, which uses a WHOI micro modem and a Benthos low frequency, directional transducer. A matching bottom side modem and transducer are mounted on the ocean bottom package. Tests of the surface gateway in 4000 m of water demonstrated an acoustic efficiency of approximately 256 bits/J. For example, it has the ability to send four channels of compressed, one sample per second data from the ocean bottom to the gateway with an average power draw of approximately 0.36 W and a latency of about three minutes. This gateway is used to send near-real-time data from a broadband ocean bottom seismic observatory; we are presently designing and constructing a seafloor package with a two-year operational life. We have found that for frequencies f where f~3Hz, the vertical component, seafloor system noise characteristics are generally superior to similar observatories on land. Increasing the density of these stations over the majority of the surface of

  18. Assessing the impact of the Tunoe Knob wind park on sea ducks: the influence of food resources

    International Nuclear Information System (INIS)

    Laursen, K.; Guillemette, M.; Kyed larsen, J.; Clausager, I.

    1999-02-01

    This study deals with the influence of benthos abundance when assessing the potential impact of a small wind park on wintering sea ducks. Using the Before-After-Control-Impact design, it was suggested in a recent study that the wind park provoked a decline in the abundance and a change in the distribution of common eiders Somateria mollissima and common scoters Melanitta nigra. However, the observed decline in sea duck abundance occurred concomitantly with a decline of benthic food supplies. We measured concomitant food and common eider abundance for a fourth year at Tunoe Knob to test the hypothesis that, if food abundance increases again, we should also observe an increase in duck abundance. The methods used in this study are similar to those applied in the aforementioned study. The results showed that the average number of common eiders increased considerably in 1997-98 (3,361 individuals) compared to 1996-97 (458), even surpassing the level observed during the baseline years in 1994-95 (1,821). A significant increase in the abundance of common scoters occurred in 1997-98 compared to 1995-96 and 1996-97, but not in relation to the baseline year. The abundance of food for sea ducks also increased in 1997-98 where the frequency of occurrence of most potential prey reached the level observed during the baseline year. The density of blue mussels, a preferred prey species, was 1,113 individuals m -2 in 1997-98 compared to 11,111 individuals m -2 during the baseline year and only 100 individuals m -2 in 1996-97. Computations of the amount of food supply eaten by wintering common eiders suggest that, during the baseline year, prey were superabundant. This may explain why we observed a great abundance of common eiders in 1997-98 despite the fact that mussel abundance did not reach the level observed during the baseline year. Finally, the distribution of common eiders in 1997-98 on the study site as a whole was very similar to the distribution observed during the

  19. Effects of exploitation, environmental changes, and new species on the fish habitats and resources of Lake Erie

    Science.gov (United States)

    Hartman, Wilbur L.

    1973-01-01

    No other lake as large as Lake Erie (surface area, 25,690 km2) has been subjected to such extensive changes in the drainage basin, the lake environment, and the fish populations over the last 150 years. Deforestation and prairie burning led to erosion of the watershed and siltation of valuable spawning grounds. Marsh spawning areas were drained. Lake-to-river spawning migrations of sturgeon, walleye, and other fishes were blocked by mill dams. Accelerated cultural nutrient loading increased total dissolved solids by nearly 50% (1920-70). Phosphate loading reached 469 metric tons per year by the 1950's and continued to increase. The biomass of phytoplankton increased 20-fold between 1919 and 1963. Oxygen demand for decomposition of these algae so degraded oxygen regimes in the western and central basins by the 1950's that the once abundant mayfly nymphs were destroyed and the central basin hypolimnion became anoxic. The sequence of disappearance or severe depletion of fish species was as follows: lake trout, sturgeon, lake herring, lake whitefish, sauger, blue pike, and walleye. Yellow perch are now declining. All resources were intensively exploited at one time or another. Lake trout suffered only this stress, but changes in the watershed significantly stressed sturgeon and lake whitefish. Degradation of the lake spawning grounds, benthos, and oxygen regimes culminated in severe stress by the 1950's on the remnants of the lake herring and lake whitefish, and on the sauger, blue pike, and walleye. Additional mortality may have been imposed on walleye and blue pike fry by predacious smelt that successfully colonized Lake Erie after first appearing in 1932. The cultural stresses, in the probable order of greatest to least net effects on the fish community of Lake Erie, appear to have been: (1) an intense, opportunistic, ineffectively controlled commercial fishery; (2) changes in the watershed, such as erosion and siltation of stream beds and inshore lake areas, and

  20. Characterization of the current status of ichthyofauna in the Techa river

    Energy Technology Data Exchange (ETDEWEB)

    Pryakhin, E.; Tryapitsina, G.; Akleyev, A. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation); Rudolfsen, G. [Norwegian Radiation Protection Authority - NRPA, and University of Tromsoe (Norway); Teien, H.C. [Norwegian University of Life Sciences - UMB, Center of Excellence in Environmental Radioactivity - CERAD (Norway)

    2014-07-01

    Within the period from 1949 to 1956 industrial non-technological low-level radioactive wastes of Mayak PA were released into the Techa River and associated wetland (Chelyabinsk Oblast, Russia). Over the whole period 76 millions m{sup 3} of effluents were discharged with total activity of about 1.1*10{sup 17} Bq. Ichthyofauna is one of the groups of hydrobionts which are most sensitive to the impact of a wide range of adverse environmental factors, including radioactive contamination of the water ecosystems. In the years 2011 - 2013 the research into the status of the ichthyofauna of the Techa River due to long term exposure to radionuclides was conducted. Sampling and fish catching were performed twice a year (in may during spawning and in august during feeding) at three sampling stations with different levels of radioactive contamination: in the upper reaches (RT1), in the middle reaches (RT2), and in the low reaches (RT3) of the river. At each station, samples of water, bottom sediments, zooplankton, zoo-benthos, algae, and fish (roach, perch, and pike) were collected. {sup 137}Cs, {sup 90}Sr and {sup 3}H were determined in all samples. The following parameters were measured in each fish specimen: weight and size of the body, age, sex, fin color, sperm motility during spawning, and morphometric parameters. Hematologic, cytogenetic, cytologic investigations of the studied fish specimen were also conducted. In spring, samples of sperm were taken from male fish at stations RT1 and in a River Mias (RM) as a control for the determination of sperm mobility. The content of {sup 137}Cs, {sup 90}Sr and {sup 3}H in water of the Techa River at different sampling stations (2012) is given in the Table 1. ERICA Assessment Tool was used for the calculation of absorbed dose rate in a body of fish with in approximation of the equilibrium distribution of radionuclides in an organism and in the surrounding medium (Table 2). The following biological effects, which could be

  1. Bioavailability of sinking organic matter in the Blanes canyon and the adjacent open slope (NW Mediterranean Sea)

    Science.gov (United States)

    Lopez-Fernandez, P.; Bianchelli, S.; Pusceddu, A.; Calafat, A.; Sanchez-Vidal, A.; Danovaro, R.

    2013-05-01

    Submarine canyons are sites of intense energy and material exchange between the shelf and the deep adjacent basins. To test the hypothesis that active submarine canyons represent preferential conduits of available food for the deep-sea benthos, two mooring lines were deployed at 1200 m depth from November 2008 to November 2009 inside the Blanes canyon and on the adjacent open slope (Catalan Margin, NW Mediterranean Sea). We investigated the fluxes, biochemical composition and food quality of sinking organic carbon (OC). OC fluxes in the canyon and the open slope varied among sampling periods, though not consistently in the two sites. In particular, while in the open slope the highest OC fluxes were observed in August 2009, in the canyon the highest OC fluxes occurred in April-May 2009. For almost the entire study period, the OC fluxes in the canyon were significantly higher than those in the open slope, whereas OC contents of sinking particles collected in the open slope were consistently higher than those in the canyon. This result confirms that submarine canyons are effective conveyors of OC to the deep sea. Particles transferred to the deep sea floor through the canyons are predominantly of inorganic origin, significantly higher than that reaching the open slope at a similar water depth. Using multivariate statistical tests, two major clusters of sampling periods were identified: one in the canyon that grouped trap samples collected in December 2008, concurrently with the occurrence of a major storm at the sea surface, and associated with increased fluxes of nutritionally available particles from the upper shelf. Another cluster grouped samples from both the canyon and the open slope collected in March 2009, concurrently with the occurrence of the seasonal phytoplankton bloom at the sea surface, and associated with increased fluxes of total phytopigments. Our results confirm the key ecological role of submarine canyons for the functioning of deep-sea ecosystems

  2. Radionuclide transfer in marine coastal ecosystems, a modelling study using metabolic processes and site data

    International Nuclear Information System (INIS)

    Konovalenko, L.; Bradshaw, C.; Kumblad, L.; Kautsky, U.

    2014-01-01

    This study implements new site-specific data and improved process-based transport model for 26 elements (Ac, Ag, Am, Ca, Cl, Cm, Cs, Ho, I, Nb, Ni, Np, Pa, Pb, Pd, Po, Pu, Ra, Se, Sm, Sn, Sr, Tc, Th, U, Zr), and validates model predictions with site measurements and literature data. The model was applied in the safety assessment of a planned nuclear waste repository in Forsmark, Öregrundsgrepen (Baltic Sea). Radionuclide transport models are central in radiological risk assessments to predict radionuclide concentrations in biota and doses to humans. Usually concentration ratios (CRs), the ratio of the measured radionuclide concentration in an organism to the concentration in water, drive such models. However, CRs vary with space and time and CR estimates for many organisms are lacking. In the model used in this study, radionuclides were assumed to follow the circulation of organic matter in the ecosystem and regulated by radionuclide-specific mechanisms and metabolic rates of the organisms. Most input parameters were represented by log-normally distributed probability density functions (PDFs) to account for parameter uncertainty. Generally, modelled CRs for grazers, benthos, zooplankton and fish for the 26 elements were in good agreement with site-specific measurements. The uncertainty was reduced when the model was parameterized with site data, and modelled CRs were most similar to measured values for particle reactive elements and for primary consumers. This study clearly demonstrated that it is necessary to validate models with more than just a few elements (e.g. Cs, Sr) in order to make them robust. The use of PDFs as input parameters, rather than averages or best estimates, enabled the estimation of the probable range of modelled CR values for the organism groups, an improvement over models that only estimate means. Using a mechanistic model that is constrained by ecological processes enables (i) the evaluation of the relative importance of food and water

  3. On Branchiostoma californiense (Cephalochordata from the Gulf of Nicoya estuary, Costa Rica

    Directory of Open Access Journals (Sweden)

    José A Vargas

    2010-12-01

    Full Text Available The cephalochordates are represented by the lancelets, of which species of the genus Branchiostoma are the best known. In recent years, these organisms have been the center of activity of studies focusing on the phylogenetic relationships of the chordates. In 1980, a survey of the benthos at 48 stations in the Gulf of Nicoya estuary, Pacific coast of Costa Rica, yielded 265 specimens of the lancelet Branchiostoma californiense. A total of 48 specimens was also collected at an intertidal flat in the mid upper estuary. Of the 48 subtidal stations, only eight had B. californiense, and these sites all had a sand fraction above 72%. The remaining stations ranged in their sand content from as low as 1% to as high as 92%, with an average of 25.9%, with 29 stations having a sand content lower than 72%. Lower salinities and muddy sediments may limit the distribution of the lancelet further upstream. This information is useful when changes over decades in the ecology of the estuary need to be evaluated against the background of local, regional, and global dynamics. Rev. Biol. Trop. 58 (4: 1143-1148. Epub 2010 December 01.Los cefalocordados están representados por los anfioxos, de los que especies del género Branchiostoma son los más conocidos. En los últimos años, estos organismos han sido muy estudiados, principalmente sus relaciones filogenéticas. Durante 1980, realizamos un muestreo del bentos en 48 estaciones del Golfo de Nicoya, costa Pacífica de Costa Rica y reportamos 265 ejemplares del anfioxo, Branchiostoma californiense. También recolectamos un total de 48 individuos en una planicie fangosa de la zona entre mareas de la región superior media del estuario. De las 48 estaciones solamente en ocho encontramos especímenes de B. californiense y estos sitios tenían un porcentaje de arena superior al 72%. Las otras estaciones tenían un porcentaje de arena en un ámbito tan bajo como 1% y tan alto como 92%, con un promedio de 25.9%, 29

  4. Catchment source contributions to the sediment-bound organic matter degrading salmonid spawning gravels in a lowland river, southern England

    Energy Technology Data Exchange (ETDEWEB)

    Collins, A.L., E-mail: adrian.collins@adas.co.uk [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Williams, L.J.; Zhang, Y.S. [ADAS, Pendeford House, Wobaston Road, Wolverhampton WV9 5AP (United Kingdom); Marius, M. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dungait, J.A.J. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Smallman, D.J. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Dixon, E.R. [Department of Sustainable Systems and Grassland Science, Rothamsted Research—North Wyke, Okehampton, Devon EX20 2SB (United Kingdom); Stringfellow, A. [Civil Engineering and Environment, University of Southampton, Highfield, Southampton S017 1BJ (United Kingdom); Sear, D.A. [Geography and Environment, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Jones, J.I. [School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS (United Kingdom); Naden, P.S. [CEH Wallingford, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB (United Kingdom)

    2013-07-01

    and can be applied alongside apportionment for the minerogenic component of fine-grained sediment ingressing the benthos. The findings suggest that human septic waste contributes to the interstitial fines ingressing salmonid spawning habitat in the study area. - Highlights: • Stable carbon and nitrogen isotopes and NIR reflectance spectra used as fingerprints • Results suggest human septic waste contributes to organic matter in spawning gravels. • Source contributions are: instream decaying vegetation > road verges > septic tanks > farm manures.

  5. Testing the saprobity hypothesis in a Mediterranean lagoon: effects of confinement and organic enrichment on benthic communities.

    Science.gov (United States)

    Foti, A; Fenzi, G A; Di Pippo, F; Gravina, M F; Magni, P

    2014-08-01

    The macrobenthic community was compared at four sites characterized by varying degrees of freshwater input, organic enrichment and confinement in the Cabras lagoon (Sardinia, Italy). Three sites, riverine (C1), confined (C2) and seaward (C3), were studied on two dates of summer 2010 and on two dates of winter 2011. A fourth site (C12), representative of the central sector of the Cabras lagoon, was included in this study using the extensive historical datasets at our disposal from previously published work. We aimed to test the hypothesis that (1) the benthos is distributed according to the recently proposed concept of habitat saprobity for coastal lagoons that unifies the Pearson-Rosenberg (sensu organic enrichment) and Guélorget-Perthuisot (sensu confinement) models, and (2) indicator species of different saprobic levels can be identified among dominant species occurring along the saprobity gradient. Salinity was also considered as an additional agent of selection in brackish environments. Irrespective of significant seasonal changes within each site, our results highlighted major environmental and biotic differences between sites. At the northward riverine site (C1), most affected by freshwater input and with limited organic matter (OM) enrichment, Corophium orientale was the single dominant species. The most confined site (C2) was characterized by the highest levels of sedimentary OM and benthic Chlorophyll-a and by mesohaline conditions; the site was inhabited mainly by the halolimnobic Hediste diversicolor and Hydrobia spp. Site C12, characterized by a high OM load and high residence time, was dominated by the opportunistic detritivorous Alitta succinea and Polydora ciliata. At the southernmost seaward site (C3) the considerable seawater renewal, resulting in high salinity (only in summer) and limited OM load, favored a much more diverse macrobenthic assemblage, essentially composed of both marine species, such as Corophium insidiosum, Gammarus aequicauda

  6. Long-term dynamics of the state of the fouling community in the Odessa Bay (Black Sea

    Directory of Open Access Journals (Sweden)

    A. Y. Varigin

    2017-04-01

    Full Text Available This article examines the long-term dynamics of the qualitative and quantitative characteristics of the coastal fouling community of OdessaBay(Black Sea for the last 40 years. It compares the data on this community obtained by different researchers in 1976, 1994 and 2016 . The number of species included in the fouling community decreased from 103 (1976 to 43 (1994 and then rose to 62 by 2016. As a possible reason for this reduction in the species composition of the community the influence of large-scale anthropogenic eutrophication, which was already strongly evident in the north-western part of the Black Seain the 1970s, is proposed. This phenomenon was accompanied by periodic outbreaks of mass abundance of planktonic algae, secondary water pollution, the development of hypoxia and a frequent suffocation effect on the benthos, which caused the disappearance from the community of 41 species of invertebrates. The reduction in the number of species affected representatives of the following taxons: Polychaeta, Amphipoda, Gastropoda and Bivalvia. Currently, the core of the community includes the same species of invertebrates as in the past. It is based on Bivalvia mussels Mytilus galloprovincialis. Among the attached forms , Mytilaster lineatus (Bivalvia and Amphibalanus improvisus (Cirripedia play a leading role, and among mobile – representatives of Polychaeta, Isopoda, Amphipoda and Gastropoda. It is shown that 10 of the 25 species, recorded the first time for this community in the 1970s, have become abundant in modern conditions. The primacy in the relative density in the composition of the community at the present time has passed from the amphipod crustaceans to bivalve molluscs. The highest relative biomass, both in the past and in the present-day conditions was observed in representatives of Bivalvia. The structure of the resistance of the fouling community to the effects of unstable environmental factors specific to the coastal zone is

  7. A transport and fate model of C-14 in a bay of the Baltic Sea at SFR. Today and in future

    Energy Technology Data Exchange (ETDEWEB)

    Kumblad, L. [Stockholm Univ. (Sweden). Dept. of Systems Ecology

    2001-06-01

    The environmental transport and fate of a hypothetical release of radioactive carbon-14 from SFR-1 (the final repository for radioactive operational waste) was investigated using an ecosystem modelling approach. The approach involved identification, quantification and dynamic modelling of the main flows and storages of carbon both in the physical environment and in the food web. Carbon-14 was in the model introduced into the food web via photosynthesising organisms. Contamination of the aquatic ecosystem above SFR-1 was then assessed assuming a release of 5.13 x 10{sup 7} Bq/year for 1,000 years. Modelling results were used to estimate steady-state C-14 concentrations in biota, exposure (Gy) of biota and dose (Sv) to humans consuming contaminated organisms both if the discharge occurred today (2000 AD)and if it occurred in the future (4000 AD). Since the modelled area is characterised by a fast water exchange, most of the discharged C-14 was flushed out of the system more or less immediately (99.8% and 98.4% at 2000 AD and 4000 AD, respectively). However, a small fraction of the discharge was assimilated by primary producers (0.18% and 2.11%), which enabled subsequent transfer of C-14 to organisms at higher trophic levels (e.g. fish, seals and humans). The exported C-14 from the area was diluted to very low concentrations in the large recipient outside. Estimated exposures were very low, and differed significantly among the studied biota (17.2 x 10{sup -12} to 2.3 x 10{sup -6} Gy). In general the highest exposures were observed in benthic plants and benthic grazers followed by fish and benthos. Humans consuming large quantities of locally produced food (e.g.fish, mussels and algae) will receive an exposure in case of C-14 contamination. Estimated doses to humans were approximately 10-100 nSv per year, which is significantly lower than restrictions by the authorities. The developed model was also used to evaluate implications of various assumptions concerning the

  8. Indirect effects of lemming cycles on sandpiper dynamics: 50 years of counts from southern Sweden.

    Science.gov (United States)

    Blomqvist, Sven; Holmgren, Noél; Åkesson, Susanne; Hedenström, Anders; Pettersson, Jan

    2002-10-01

    primarily influenced by biotic factors in the breeding area, rather than by abiotic factors, such as climate oscillations. Annual variations in migratory arctic bird populations may have far reaching effects in habitats along their migration routes and in their wintering areas. We suggest a link between lemming cyclicity in the Northern Hemisphere and predation pressure on Southern Hemisphere benthos, in which the signal is carried between continents by long distance migrating waders.

  9. An evaluation of the zooplankton community at the Sheboygan River Area of Concern and non-Area of Concern compariso