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Sample records for benthos

  1. Bottom dwelling animals: Benthos

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.

    . At the bottom/sediment dwelling animal communities are collectively termed as 'BENTHOS'. This extremely valuable component of the marine environment consumes the sediment organic matter from the overlying water column and effectively converts into benthic...

  2. Marine benthos - A future perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Govindan, K.

    Benthic organisms are reported from different kinds of substrate like hard bottom, soft bottom, coarse bottom and also from organic matter and other macrodebris. Benthos are in general, sessile and slow moving in nature. 75% of benthic animals live...

  3. 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...

  4. Benthos of Spanish lakes and reservoirs

    OpenAIRE

    Prat i Fornells, Narcís; Real i Ortí, Montserrat; Rieradevall i Sant, Maria

    1992-01-01

    A summary of the results from the study of benthos of lakes and reservoirs in Spain is provided, with a list of the species found to date. Spanish natural lakes are smaller than European lakes; the largest is Lake Sanabria, of glacial origin, which is 3 Km long and half a kilorneter wide. Many are very small and situated in the mountains; more than 200 hundred have been recorded in Spain, but only in Lake Sanabria and Lake Banyoles have the benthos been studied. Lake Sanabria is a cold oligot...

  5. WHIDBEY ISLAND INTERTIDAL AND SHALLOW SUBTIDAL BENTHOS

    Science.gov (United States)

    The objectives of this study were to quantitatively characterize the benthos of the intertidal and shallow subtidal areas of three habitats on the west coast of Whidbey Island. The study area was between +6.0' above mean low water to -10.0 m below mean low water. Stratified rando...

  6. Benthos of Lake Orta in the year 1996

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    Monica SABOLLA

    2001-08-01

    Full Text Available Lake Orta has been interested since 1926 by severe industrial pollution, due to the effluents of a rayon (artificial silk factory that discharged huge amounts of copper and ammonia. As a consequence, the benthic fauna faced noticeable changes, becoming extremely poor in species. However, after extensive liming (in 1989-90, the biotic communities of the lake showed many signs of recovery, and in 1996 it was decided to study the benthos composition and abundance in detail, to assess whether the lake restoration resulted in a complete recovery of this biotic compartment. Actually, both the small number of taxa, and the low abundance of the benthos, indicate that the sedimentary environment is still very stressed. In fact, albeit this study shows that benthos fauna is actively recolonising Lake Orta bottom, spreading from river mouths, in 1996 the benthic community cannot be considered fully organised.

  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. The biodiversity of the deep Southern Ocean benthos

    OpenAIRE

    Brandt, A.; Broyer, C. de; De Mesel, I.G.; Ellingsen, K.E.; Gooday, A.J; Hilbig, B.; Linse, K.; Thomson, M.R.A; Tyler, P. A.

    2006-01-01

    Our knowledge of the biodiversity of the Southern Ocean (SO) deep benthos is scarce. In this review, we describe the general biodiversity patterns of meio-, macro- and megafaunal taxa, based on historical and recent expeditions, and against the background of the geological events and phylogenetic relationships that have influenced the biodiversity and evolution of the investigated taxa. The relationship of the fauna to environmental parameters, such as water depth, sediment type, food availab...

  9. 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.

  10. 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.

    During the first stage of the project work on the Indian Deep-Sea Environment Experiment (INDEX), the abundance and distribution of deep-sea benthos were surveyed in the Central Indian Basin for the collection of baseline data. The deep...

  11. 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...

  12. Climate change and marine benthos: a review of existing research and future directions in the North Atlantic

    OpenAIRE

    Birchenough, S.N.R.; Reiss, H.; Degraer, S.; Mieszkowska, N.; Borja, A.; Buhl-Mortensen, L.; Braeckman, U.; Craeymeersch, J; Mesel, I. de; Kerckhof, F; Kröncke, I.; Parra, S.; Rabaut, M.; Schröder, A. (Anke); van Colen, C.

    2015-01-01

    There is growing evidence that climate change could affect marine benthic systems. This review provides information of climate change-related impacts on the marine benthos in the North Atlantic. We cover a number of related research aspects, mainly in connection to two key issues. First, is the relationship between different physical aspects of climate change and the marine benthos. This section covers: (a) the responses to changes in seawater temperature (biogeographic shifts and phenology);...

  13. Genetic population structure in the Antarctic benthos: insights from the widespread amphipod, Orchomenella franklini.

    Directory of Open Access Journals (Sweden)

    Helena Phoenix Baird

    Full Text Available Currently there is very limited understanding of genetic population structure in the Antarctic benthos. We conducted one of the first studies of microsatellite variation in an Antarctic benthic invertebrate, using the ubiquitous amphipod Orchomenella franklini (Walker, 1903. Seven microsatellite loci were used to assess genetic structure on three spatial scales: sites (100 s of metres, locations (1-10 kilometres and regions (1000 s of kilometres sampled in East Antarctica at Casey and Davis stations. Considerable genetic diversity was revealed, which varied between the two regions and also between polluted and unpolluted sites. Genetic differentiation among all populations was highly significant (F(ST = 0.086, R(ST = 0.139, p<0.001 consistent with the brooding mode of development in O. franklini. Hierarchical AMOVA revealed that the majority of the genetic subdivision occurred across the largest geographical scale, with N(em≈1 suggesting insufficient gene flow to prevent independent evolution of the two regions, i.e., Casey and Davis are effectively isolated. Isolation by distance was detected at smaller scales and indicates that gene flow in O. franklini occurs primarily through stepping-stone dispersal. Three of the microsatellite loci showed signs of selection, providing evidence that localised adaptation may occur within the Antarctic benthos. These results provide insights into processes of speciation in Antarctic brooders, and will help inform the design of spatial management initiatives recently endorsed for the Antarctic benthos.

  14. Mapping Coral Reef Benthos, Substrates, and Bathymetry, Using Compact Airborne Spectrographic Imager (CASI Data

    Directory of Open Access Journals (Sweden)

    Ian A. Leiper

    2014-07-01

    Full Text Available This study used a reef-up approach to map coral reef benthos, substrates and bathymetry, with high spatial resolution hyperspectral image data. It investigated a physics-based inversion method for mapping coral reef benthos and substrates using readily available software: Hydrolight and ENVI. Compact Airborne Spectrographic Imager (CASI data were acquired over Heron Reef in July 2002. The spectral reflectance of coral reef benthos and substrate types were measured in-situ, and using the HydroLight 4.2 radiative transfer model a spectral reflectance library of subsurface reflectance was simulated using water column depths from 0.5–10.0 m at 0.5 m intervals. Using the Spectral Angle Mapper algorithm, sediment, benthic micro-algae, algal turf, crustose coralline algae, macro-algae, and live coral were mapped with an overall accuracy of 65% to a depth of around 8.0 m; in waters deeper than 8.0 m the match between the classified image and field validation data was poor. Qualitative validation of the maps showed accurate mapping of areas dominated by sediment, benthic micro-algae, algal turf, live coral, and macro-algae. A bathymetric map was produced for water column depths 0.5–10.0 m, at 0.5 m intervals, and showed high correspondence with in-situ sonar data (R2 value of 0.93.

  15. The recovery of benthos following the impact of low oxygen content in the German Bight

    Science.gov (United States)

    Niermann, U.; Bauerfeind, E.; Hickel, W.; Westernhagen, H. V.

    The oxygen deficiency in the German Bight and in Danish waters 1981-1983 with ensuing benthos mortality was the reason for studying the development and re-establishment of the macrofauna in the following years. These years, from 1984-1987, exhibited more favourable oxygen conditions. The macrofauna of this region with its predominantly sandy substrate belongs to the Tellina fabula community. It is dominated by regular seasonal and ephemeral species such as Spio filicornis, Phoronis spec., Spiophanes bombyx and Lanice conchilega. In 1983, a year with exceptionally low oxygen content in bottom waters (Echinocardium cordatum and crustaceans have been observed since 1984 in larger numbers.

  16. Caddisflies as biomonitors identifying thresholds of toxic metal bioavailability that affect the stream benthos

    International Nuclear Information System (INIS)

    It has been proposed that bioaccumulated concentrations of toxic metals in tolerant biomonitors be used as indicators of metal bioavailability that could be calibrated against the ecological response to metals of sensitive biotic assemblages. Our hypothesis was that metal concentrations in caddisfly larvae Hydropsyche siltalai and Plectrocnemia conspersa, as tolerant biomonitors, indicate metal bioavailability in contaminated streams, and can be calibrated against metal-specific ecological responses of mayflies. Bioaccumulated concentrations of Cu, As, Zn and Pb in H. siltalai from SW English streams were related to the mayfly assemblage. Mayflies were always sparse where bioavailabilities were high and were abundant and diverse where bioavailabilities of all metals were low, a pattern particularly evident when the combined abundance of heptageniid and ephemerellid mayflies was the response variable. The results offer promise that bioaccumulated concentrations of metals in tolerant biomonitors can be used to diagnose ecological impacts on stream benthos from metal stressors. - Highlights: ► Metal concentrations in caddisfly larvae can be calibrated against mayfly ecological responses. ► Cu, As, Zn and Pb concentrations in Hydropsyche siltalai were related to stream mayfly assemblages. ► Mayflies were sparse in high metal bioavailabilities, and abundant in low bioavailabilities. ► Joint heptageniid and ephemerellid mayfly abundance was the most sensitive response variable. ► Copper, arsenic and, in one catchment, lead were the primary stressors limiting mayfly abundance. - Accumulated metal concentrations in tolerant biomonitors can be used to detect and diagnose ecological impacts on freshwater stream benthos from metal stressors.

  17. SEDIMENT TOXICITY AND COMMUNITY COMPOSITION OF BENTHOS AND COLONIZED PERIPHYTON IN THE EVERGLADES - FLORIDA BAY TRANSITIONAL ZONE.

    Science.gov (United States)

    Lewis, Michael A., Larry R. Goodman, John M. Macauley and James C. Moore. 2004. Sediment Toxicity and Community Composition of Benthos and Colonized Periphyton in the Everglades-Florida Bay Transitional Zone. Ecotoxicology. 13(3):231-244. (ERL,GB 1164). This survey provid...

  18. Application of a spectrofluorimetric tool (bbe BenthoTorch) for monitoring potentially toxic benthic cyanobacteria in rivers.

    Science.gov (United States)

    Echenique-Subiabre, Isidora; Dalle, Caroline; Duval, Charlotte; Heath, Mark W; Couté, Alain; Wood, Susanna A; Humbert, Jean-François; Quiblier, Catherine

    2016-09-15

    Over the last decade reports of animal poisoning following accidental consumption of neurotoxin-producing benthic cyanobacteria (mainly Phormidium spp.) have increased. There is a need for rapid and cost-effective tools to survey benthic cyanobacteria. In this study we assessed the performance of the BenthoTorch, a fluorometric probe that provides in situ estimations of cyanobacteria, diatoms and green algae biomass in biofilms. Biofilms (n = 288) were analysed from two rivers in France and eight in New Zealand. Correlations between chlorophyll-a measured using the BenthoTorch and spectrophotometry were higher for thin (2 mm) biofilms (r(2) = 0.58 and 0.27 respectively; p cyanobacteria represented less than 50% of the total biomass (based on biovolumes), microscopic and BenthoTorch compositional estimations were significantly correlated (r(2) = 0.53, p cyanobacteria exceeded 50% of the total biomass. Under this scenario diatoms were overestimated. Our results suggest that the observed biases occur because the BenthoTorch only measures the upper biofilm layer and it underestimates the biomass of phycoerythrin-containing cyanobacteria. To improve the performance of this sensor and render it a useful tool for a rapid evaluation of benthic cyanobacterial biomass in rivers, we propose that: (i) the algorithms based on the LEDs responses currently available on this tool need revision, (ii) new excitation wavelengths should be included that allow the fingerprints of phycoerythrin-containing cyanobacteria to be discriminated, and (iii) a sensor that penetrates the biofilms is needed to obtain more accurate estimates of cyanobacterial biomass. PMID:27286469

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

    Science.gov (United States)

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

    2015-09-01

    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, as in the multivariate m-AMBI. The latter MMI has been adopted by several European countries in the context of WFD implementation. In contrast to m-AMBI, the BEQI2 calculation procedure has been strongly simplified and consists of two steps, i.e. the separate indicator values are normalized using their long-term reference values resulting in three Ecological Quality Ratios (EQRs), which are subsequently averaged to give one BEQI2 value. Using this method only small numbers of samples need to be analysed by Dutch benthos laboratories annually, without the necessity to co-analyse a larger historical dataset. BEQI2 EQR values appeared to correlate quantitatively very well with m-AMBI EQR values. In addition, a data pooling procedure has been added to the BEQI2 tool which enables the pooling of small core samples (0.01-0.025 m2) into larger standardized data pools of 0.1 m2 in order to meet the data requirements of the AMBI indicator and to obtain comparable reference values. Furthermore, the BEQI2 tool automatically and efficiently converts species synonym names into standardized species names. The BEQI2 tool has been applied to all Dutch benthos data monitored by Rijkswaterstaat in the period of 1991-2010 in the transitional and coastal waters and salt lakes and these results are reported here for the first time. Reference values for species richness and Shannon index (99 percentile values) and AMBI reference values (1 percentile values) were estimated for all water body-ecotopes and are discussed. BEQI2 results for all these water bodies are discussed in view of natural and human pressures. The pressure sensitivity of the BEQI2 for sewage and dredging/dumping, via the

  20. DeepPIV: Measuring in situ Biological-Fluid Interactions from the Surface to Benthos

    Science.gov (United States)

    Katija, K.; Sherman, A.; Graves, D.; Kecy, C. D.; Klimov, D.; Robison, B. H.

    2015-12-01

    The midwater region of the ocean (below the euphotic zone and above the benthos) is one of the largest ecosystems on our planet, yet it remains one of the least explored. Little known marine organisms that inhabit midwater have developed strategies for swimming and feeding that ultimately contributes to their evolutionary success, and may inspire engineering solutions for societally relevant challenges. Fluid mechanics governs the interactions that midwater organisms have with their physical environment, but limited access to midwater depths and lack of non-invasive methods to measure in situ small-scale fluid motions prevent these interactions from being better understood. Significant advances in underwater vehicle technologies have only recently improved access to midwater. Unfortunately, in situ small-scale fluid mechanics measurement methods are still lacking in the oceanographic community. Here we present DeepPIV, an instrumentation package that can be affixed to remotely operated underwater vehicles that quantifies small-scale fluid motions from the surface of the ocean down to 4000 m depths. Utilizing ambient, suspended particulate in the coastal regions of Monterey Bay, fluid-structure interactions are evaluated on a range of marine organisms in midwater. Initial science targets include larvaceans, biological equivalents of flapping flexible foils, that create mucus houses to filter food. Little is known about the structure of these mucus houses and the function they play in selectively filtering particles, and these dynamics can serve as particle-mucus models for human health. Using DeepPIV, we reveal the complex structures and flows generated within larvacean mucus houses, and elucidate how these structures function.

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

    International Nuclear Information System (INIS)

    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)

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

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    L. A. Levin

    2009-04-01

    Full Text Available Coastal hypoxia (<1.42 ml L−1; 62.5 μM; 2 mg L−1, approx. 30% oxygen saturation occurs seasonally in many estuaries, fjords, and along open coasts subject to upwelling or excessive riverine nutrient input, and permanently in some isolated seas and marine basins. Underlying causes of hypoxia include enhanced nutrient input from natural causes (upwelling or anthropogenic origin (eutrophication and reduction of mixing by limited circulation or enhanced stratification; combined these lead to higher surface water production, microbial respiration and eventual oxygen depletion. Advective inputs of low-oxygen waters may initiate or expand hypoxic conditions. Responses of estuarine, enclosed sea, and open shelf 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, thereby providing 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

  3. 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.; Craeymeersch, J.A.M.

    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 las

  4. Long-term changes of physicochemical parameters and benthos in Lake Qarun (Egypt: Can we make a correct forecast of ecosystem future?

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    Shadrin N. V.

    2016-01-01

    Full Text Available Biotic changes and a salinity increase (from 13 to 40 g.L-1 occurred in Lake Qarun (Egypt since 1901. Was salinity increasing a cause of observed biotic changes? To answer this question we used benthos as a model group. Benthos and water sampling was conducted in different seasons (2008–2013. Comparing our and literature data, we discuss the long-term trends and possible causes of benthos changes. Salinity reached 3 g.L-1 in middle of 19th century; and biotic changes caused by this were started. From middle 19th century to 1928 a biotic transformation was driven by the salinity increase; after 1928 a regular alien species introduction caused that a marine community formed. In 1970–2000 eutrophication played a main role in species composition changes. In 2014 ctenophore Mnemiopsis leidyi introduced in the lake; eutrophication, chemical pollution, and a population dynamics of this ctenophore may be main drivers of the ecosystem change now. Benthos biomass gradually decreased during interval 1975–2013 without any correlation with salinity change. A variety of other factors than salinity may be significant in determining the structure and dynamics of communities, and we conclude that we have a small chance to make a correct forecast of possible future ecosystem changes in Lake Qarun.

  5. BIOAVAILABILITY OF 2,3,7,8-TCDD, 2,3,7,8-TCDF AND PCBS TO MARINE BENTHOS FROM PASSAIC RIVER SEDIMENTS

    Science.gov (United States)

    The bioaccumulation and depuration of 2,3,7,8-tetrachloro-dibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran and polychlorinated biphenyls by marine benthos exposed to environmentally contaminated sediment were measured in a laboratory study. andworms (Nereis virens), clams (Macom...

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

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    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.

  7. Can parasites be indicators of free-living diversity? Relationships between species richness and the abundance of larval trematodes and of local benthos and fishes

    Science.gov (United States)

    Hechinger, R.F.; Lafferty, K.D.; Huspeni, T.C.; Brooks, A.J.; Kuris, A.M.

    2007-01-01

    Measuring biodiversity is difficult. This has led to efforts to seek taxa whose species richness correlates with the species richness of other taxa. Such indicator taxa could then reduce the time and cost of assessing the biodiversity of the more extensive community. The search for species richness correlations has yielded mixed results, however. This may be primarily because of the lack of functional relationships between the taxa studied. Trematode parasites are highly promising bioindicators. Diverse assemblages of larval trematode parasites are easily sampled in intermediate host snails. Through their life cycles these parasites are functionally coupled with the surrounding free-living diversity of vertebrate and invertebrate animals. It has been shown that larval trematodes in snails correlate positively with bird diversity and abundance. Here, we explore whether trematodes also correlate with standard measures of fishes, and large and small benthos, for 32 sites in three wetlands. We found associations between trematodes and benthic communities that were not consistent across wetlands. The associations were, however, consistently positive for large benthic species richness and density. Some of the contrasting associations between trematode and benthos may be explained by negative associations between large and small benthos. We found no associations with fish communities (probably because of the inadequacy of standard "snapshot" sampling methods for highly mobile fishes). The results support further exploration of trematodes as bioindicators of diversity and abundance of animal communities. ?? 2006 Springer-Verlag.

  8. 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

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    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.

  9. Effects of season and altitude on copper and zinc concentrations in benthos (Chironomids and Gammarids and sediment

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    Arash Javanshir

    2013-04-01

    Full Text Available Concentration of heavy metals in aquatic ecosystems is considered as an important environmantal issue. In this study, the Namrood River located in Firoozkooh (Tehran province, Iran was assessed for the existence of heavy metals. The Namrood river is situated by the main road being by pollutants from tourism and recreational centers, gas stations, sewage of villages, agricultural wastewater and fish culture effluent. The water is extremely contaminated in some parts and possibly contains heavy metals. In the present study, two stations up- and downstream were determined to sample the sediments and Chironomidae and Gammarus pluex in both cold and warm seasons of the year (middle of March and middle of August. The copper and zinc were measured in sediment and benthos. The results showed that copper and zinc concentrations ranged 0.170-0.966 and 0.187-3.846 ppm, respectively. Sediments of the upstream station had the highest copper concentration among the samples in both cold and warm seasons of the year.

  10. Effects of wild fish and motile epibenthic invertebrates on the benthos below an open water fish farm

    Science.gov (United States)

    Sanz-Lázaro, Carlos; Belando, María Dolores; Navarrete-Mier, Francisco; Marín, Arnaldo

    2011-01-01

    A manipulative caging experiment was carried out to evaluate the role of wild fish and motile epibenthic invertebrates on the benthic system influenced by an open water fish farm. Chemical and biological parameters of the sediment were measured as indicators of the ecological benthic status. The combination of wild fish and currents notably lowered aquaculture waste sedimentation below the fish farm. The limited waste sedimentation rate could have limited the scavenger and predation activity of wild fish on the benthos, whose role may be taken over by motile epibenthic invertebrates. The interaction of these motile epibenthic invertebrates with the sediment differed from that observed with fish. The motile epibenthic invertebrates led to more reduced conditions with lower redox values, significantly decreased the number of species of macrofaunal benthic assemblages and significantly modified macrofaunal benthic assemblages. Therefore, epibenthic invertebrates do not seem to have an ameliorative effect on the benthic status produced by fish farming. Since the effects of epibenthic species on the benthic system can greatly vary according to their identity, further experiments should be performed to better understand the drivers that influence the epibenthic species identity that modulate the benthic system affected by fish farming.

  11. Bioavailability of 2,3,7,8-TCDD, 2,3,7,8-TCDF and PCBs to marine benthos from passaic river sediments

    Energy Technology Data Exchange (ETDEWEB)

    Rubinstein, N.I.; Pruell, R.J.; Taplin, B.K.; LiVolsi, J.A.; Norwood, C.B.

    1990-01-01

    The bioaccumulation and depuration of 2,3,7,8-tetrachlorodibenzo-p-dioxin, 2,3,7,8-tetrachlorodibenzofuran and polychlorinated biphenyls by marine benthos exposed to environmentally contaminated sediment were measured in a laboratory study. Sandworms (Nereis virens), clams (Macoma nasuta) and shrimp (Palaemonetes pugio) were exposed to sediment from the Passaic River, New Jersey for up to 180 days. Worms accumulated the highest concentrations of these compounds. Uptake and depuration rates were slowest in the worms and most rapid in the clams.

  12. 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 and

  13. 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

  14. Influence of mode of exposure and the presence of a tubiculous polychaete on the fate of benz[a]anthracene in the benthos

    International Nuclear Information System (INIS)

    The distribution and metabolism of [14C-12]benz[a]-anthracene (BA) was followed in benthic microcosms in the presence and absence of the polychaete Nereis virens for periods of 4-25 days to simultaneously assess the effects of mode of introduction and the presence of large burrowing organisms on the fate of polycyclic aromatic hydrocarbons (PAH) and their metabolites in the benthos. Radiolabeled BA was added to the chambers in three ways: already sorbed to the entire sediment reservoir, directly into the water column, or incorporated into food for the worms. BA added to the water column was more available for uptake and metabolism by worms and microbial mineralization to CO2 than BA previously sorbed to the entire sediment reservoir. In experiments with the sediment reservoir uniformly labeled with BA, worms increased flux of BA from the sediment, and with time, their presence led to increased rates of microbial mineralization of BA to CO2. Dietary BA was most rapidly metabolized by Nereis

  15. Effets de la marée noire de l' ''Amoco Cadiz '' sur le benthos sublittoral du nord de la Bretagne

    Science.gov (United States)

    Cabioch, L.; Dauvin, J. C.; Mora Bermudez, J.; Rodriguez Babio, C.

    1980-03-01

    Effects of the “Amoco Cadiz ” oil spill on the sublittoral benthos, north of Brittany. Effects of hydrocarbons on the sublittoral macrobenthic communities have been observed through (1) studies of population dynamics of selected communities, conducted prior to the spill by the tanker “Amoco Cadiz ” in spring 1978 and (2) comparisons between the situation in summer 1978 with that in earlier years, with continuation of the observations in some selected sites. The effect of the spill has been selective, involving a limited number of species, mainly crustaceans, molluscs and the sand-urchin Echinocardium cordatum. The spill mainly affected communities on fine sediments and, to a lesser degree, those on mixed sediments. Notably, the destruction of the dominant populations of Ampelisca, in areas of fine sands in the Bay of Morlaix, has led to a marked decrease of biomass and production. Moreover, repopulation will be difficult because of the isolation of such communities on the southern side of the English Channel. The effects evolved with time; after a phase of sharp and selective mortality, which did not last more than a few weeks, secondary effects on the recruitment of the remaining species do not seem to have occurred on a large scale. Nevertheless, a proliferation of polychaetes has been noticed.

  16. Influence of mode of exposure and the presence of a tubiculous polychaete on the fate of benz(a)anthracene in the benthos

    Energy Technology Data Exchange (ETDEWEB)

    McElroy, A.E.; Farrington, J.W.; Teal, J.M. (Woods Hole Oceanographic Institution, MA (USA))

    1990-11-01

    The distribution and metabolism of ({sup 14}C-12)benz(a)-anthracene (BA) was followed in benthic microcosms in the presence and absence of the polychaete Nereis virens for periods of 4-25 days to simultaneously assess the effects of mode of introduction and the presence of large burrowing organisms on the fate of polycyclic aromatic hydrocarbons (PAH) and their metabolites in the benthos. Radiolabeled BA was added to the chambers in three ways: already sorbed to the entire sediment reservoir, directly into the water column, or incorporated into food for the worms. BA added to the water column was more available for uptake and metabolism by worms and microbial mineralization to CO{sub 2} than BA previously sorbed to the entire sediment reservoir. In experiments with the sediment reservoir uniformly labeled with BA, worms increased flux of BA from the sediment, and with time, their presence led to increased rates of microbial mineralization of BA to CO{sub 2}. Dietary BA was most rapidly metabolized by Nereis.

  17. Change in runoff characteristics of alpine flowing waters caused by the use of hydroelectric power and its effects on the macro-benthos

    International Nuclear Information System (INIS)

    A typical form of change in runoff characteristics caused by the widespread use of hydroelectric power in Switzerland is the intermittent draining (torrent operation). It is the aim of the present work to help elucidate possible consequences of these changes in drain onto the benthobiocoenosis. The study was carried through on the Secklisbach at Oberrickenbach (in the semicanton of Nidwalden) and one of its side streamlets (800m above sea level). The macroinvertebrate coenosis was studied at four locations with similar conditions of drainage basin, population density and topography but varying in the degree of impairment to the draining. There were monthly benthos samples taken using a Surber sampling-device. Results show that the locations not only varied in drain, but also in temperature, this being a consequence of water storage by the power plant. The readings pointed out different values for the locations in daily average temperature, day amplitudes and half-yearly temperature sums. The annual average temperatures, however, did hardly differ. With the water, there is warmth being held back as well in the storage basin in summer, which in winter flows off with the process water. The hydroelectric operation with water storage leads to an intermittent drain with ecological consequences. In order to preserve a stretch of water as a biotope for the naturally found lotic organisms a constant minimum drain has to be guaranteed all year long. In order to avoid clogging, the interstitium has to be cleaned regularly by flooding drains. However, the possibility of changes in the development of organisms cannot be excluded, even though they have not been established. (author) figs., tabs., refs

  18. 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

    Full Text Available BACKGROUND: 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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: 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

  19. 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.

  20. Primary Analysis of Two Kinds of Heavy Metals and Petroleum Hydrocarbons Content in Benthos in Yacheng Oil Field%崖城气田底栖动物中2种重金属及石油烃残毒量初步分析

    Institute of Scientific and Technical Information of China (English)

    黄颖华; 张浩

    2011-01-01

    Based on the investigation data in 2009-2010 about the residual poison in the organism, the contents of contamination in benthos in Yacheng oil field were analyzed and assessed. The results showed that the change of contamination content in benthos was not obvious from 2009 to 2010 and the benthos were not severely polluted by heavy metal and petroleum hydrocarbons. The quality of the various species of benthos in this area was good and the impact of oil field on nearby waters was little.%根据2009年和2010年的调查资料,对崖城气田附近海域底栖动物污染物含量现状进行分析与评价.结果表明,2009年到2010年该气田附近生物体内污染物含量变化不明显,底柄动物未严重受到重金属和石油烃污染,该区域底柄动物各类群的生物质量状况良好,气田的开发活动对附近海区影响相对较小.

  1. Community Ecology of Benthos in Intertidal Zone near Lianyungang Tianwan Nuclear Power Plant%连云港田湾核电站附近潮间带底栖动物的群落生态

    Institute of Scientific and Technical Information of China (English)

    唐峰华; 沈新强; 张衡; 王云龙

    2012-01-01

    根据2008年4个季度的生态调查取样,对连云港海州湾田湾核电站附近潮间带A、B断面底柄动物的生物多样性、结构特征及资源密度等进行了研究.经统计分析:养殖区B断面底栖动物的生物量和栖息密度分别为42.32g· m-2和71.83个·m-2,明显高于天然海滨浴场A断面处的11.24 g·m-2和63.67个·m-2;A、B断面配对站位群落相似性指数超过0.50的有6对,而其他有显著性关系的却不是非常明显,表明海洋工程可能使附近海域内各生境之间底栖动物群落的分化程度降低;群落多样性的季节变化中,春、夏、秋、冬季的多样度分别为1.72、1.20、1.68、0.84,其中冬季达到重度污染,这可能与人为扰动有关,海洋工程活动会导致生态群落结构发生改变,甚至生境遭到破坏,生物多样性受到严重影响.整体上田湾核电站附近潮间带底栖动物群落结构不稳定,受田湾核电站相关工程活动影响的程度尚不能得出定论,需要继续调查监测该海域的生物资源状况,形成一个长期有效的监测机制.%Biological diversity, structural characteristics and habitat density of the benthos in the intertidal zone near Lianyungang Tianwan Nuclear Power Plant were studied, according to the seasonal ecological surveys conducted in 2008. In ecological aspects, the benthic biomass and the density of Bsection (fish culture zones; 42. 32 g ? M"2 and 71. 83 ind ? M~2) were higher than those of A Division (natural habitat Beach; 11. 24 g ? M"2 and 63. 67 ind ? M" ). Community similarity data had shown that marine engineering may make benthos communities reduce the degree of differentiation of the area between the various habitats. The diversity index for the 4 seasons is 1. 72, 1. 20, 1. 68 and 0. 84, respectively. The seasonal changes in community diversity displayed in the most polluted winter probably had a relationship with the disturbance of marine engineering activities, which was

  2. 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 ...

  3. 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...

  4. Ficoflora de ambientes lênticos: estudo preliminar da região de Charqueadas, Rio Grande do Sul, Brasil, com vistas à avaliação ambiental Metaphyton, benthos and phytoplantonic communities in lentic systems in the region of Charqueadas Rio Grande do Sul, Brazil

    Directory of Open Access Journals (Sweden)

    Zulanira Meyer Rosa

    1987-07-01

    Full Text Available São apresentados os resultados do estudo do metafíton, bentos e de comunidades fitoplanctônicas ocorrentes em ambientes lênticos de Charqueadas e municípios vizinhos, região esta sujeita à influência de mineração e processamento de carvão mineral. O estudo baseou-se em 46 amostras coletadas em julho e agosto de 1986. Dos 213 táxons específicos e infra-específicos identificados, 95 constituem-se em primeiro registro de ocorrência no Estado. Os grupos melhor representados quanto ao número de espécies ocorrentes foram Chlorophyta (Desmídias e Bacillariophyta (Diatomáceas. Foi constatada presença de espécies indicadas na literatura como organismos de ambientes ácidos, com maior representatividade no bentos e metafíton de biótopos sujeitos à influência direta de rejeito de carvão. Nesses sistemas ácidos, foi registrada no fitoplâncton dominância de organismos nanoplanctônicos da classe Chrysophyceae, estando quantitativamente bem representadas, no bentos, as Euglenophyta, Bacillariophyta e Chlorophyta. A estrutura das comunidades fitoplanctônicas mostrou baixos índices de diversidade, caracterizando um desequilíbrio na composição específica das mesmas.Metaphyton, benthos and phytoplanktonic communities occurring in lentic systems were studied in July and August 1986. The study was based on 46 samples collected in Charqueadas and other neighboring areas in the State of Rio Grande do Sul, a region which suffers the effects of coal mining and processing. Out of the 213 specific and infraspecific taxa identified, 95 are a first record in the State of Rio Grande do Sul. As far as the number of occurring species is concerned, the best represented groups were Chlorophyta (Desmids and Bacillariophyta (Diatoms. Organisms indicative of acid systems were found, mostly in benthos and metaphyton environments subject to the influence of coal wastes. In these acid systems, phytoplankton showed nanoplanktonic organisms of the

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    activity. To test this hypothesis, we sampled seston, zooplankton and sediment trap material for FA analysis during 5 campaigns spanning 4 seasons at a coastal site on the west coast of Sweden. Saturated (SAFAs) and monounsaturated (MUFAs) FAs dominated seston and trap material, while copepods contained 75...

  6. 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.

  7. Benthos distribution modelling and its relevance for marine ecoysystem management

    NARCIS (Netherlands)

    Reiss, H.; Birchenough, S.N.R.; Borja, A.; Buhl-Mortensen, L.; Craeymeersch, J.A.M.

    2015-01-01

    Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as

  8. Benthos distribution modelling and its relevance for marine ecosystem management

    OpenAIRE

    Reiss, H.; Birchenough, S.; A. Borja; Buhl-Mortensen, L.; Craeymeersch, J.; Dannheim, J.; Darr, A.; Galparsoro, I.; Gogina, M; H. Neumann; Populus, J.; Rengstorf, M; Valle, M.; Van Hoey, G.; Zettler, L

    2015-01-01

    Marine benthic ecosystems are difficult to monitor and assess, which is in contrast to modern ecosystem-based management requiring detailed information at all important ecological and anthropogenic impact levels. Ecosystem management needs to ensure a sustainable exploitation of marine resources as well as the protection of sensitive habitats, taking account of potential multiple-use conflicts and impacts over large spatial scales. The urgent need for large-scale spatial data on benthic speci...

  9. Riparian land use and the relationship between the benthos and litter decomposition in tropical montane streams

    NARCIS (Netherlands)

    A.C. Encalada; J. Calles; V. Ferreira; C.M. Canhoto; M.A.S. Graça

    2010-01-01

    1. Although stream-catchment interactions have been analysed in some detail in temperate environments, little is known about the effects of land-use changes in the tropics. Here, we analyse differences in benthic communities (macroinvertebrates and fungi) under two contrasting land uses (mature seco

  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.

    and the size of the clusters show a steady decline from sts 1 to 8. Maximum affinity is for adjacent stations and never exceeded 60%. Negative affinity indices obtained are deemed indicative of the varied environmental conditions. Results indicate limited...

  11. 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 AMB

  12. 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,

  13. Impact of Deepwater Horizon spill on food supply to deep-sea benthos communities

    Science.gov (United States)

    Prouty, N. G.; Campbell, P. L.; Mienis, F.; Duineveld, G.; Demopoulos, A. W. J.; Ross, S. W.; Brooke, S.

    2016-02-01

    Deep-sea ecosystems encompass unique and often fragile communities that are sensitive to a variety of anthropogenic and natural impacts. After the 2010 Deepwater Horizon (DWH) oil spill, sampling efforts documented the acute impact of the spill on some deep-sea coral colonies. To investigate the impact of the DWH spill on quality and quantity of biomass delivered to the deep-sea, a suite of geochemical tracers (e.g., stable and radio-isotopes, lipid biomarkers, and compound-specific isotopes) was measured from monthly sediment trap samples deployed near a high-density deep-coral site in the Viosca Knoll area of the north-central Gulf of Mexico prior to (Oct-2008 to Sept-2009) and after the spill (Oct-10 to Sept-11). Marine (e.g., autochthonous) sources of organic matter (OM) dominated the sediment traps in both years, however after the spill, there was a pronounced reduction in marine-sourced OM, including a reduction in marine-sourced sterols and n-alkanes and a concomitant decrease in sediment trap organic carbon and pigment flux. Results from this study indicate a reduction in primary production and carbon export to the deep-sea in 2010-2011, at least 6-18 months after the spill started. Whereas satellite observations indicate an initial increase in phytoplankton biomass, results from this sediment trap study define a reduction in primary production and carbon export to the deep-sea community. In addition, a dilution from a low-14C carbon source (e.g., petro-carbon) was detected in the sediment trap samples after the spill, in conjunction with a change in the petrogenic composition. The data presented here fills a critical gap in our knowledge of biogeochemical processes and sub-acute impacts to the deep-sea that ensued after the 2010 DWH spill.

  14. Impact of Deepwater Horizon spill on food supply to deep-sea benthos communities

    OpenAIRE

    Prouty, N.G.; Campbell, P L; Mienis, F.; G. Duineveld; A. W. J. Demopoulos; Ross, S. W.; Brooke, S.

    2016-01-01

    Deep-sea ecosystems encompass unique and often fragile communities that are sensitive to a variety of anthropogenic and natural impacts. After the 2010 Deepwater Horizon (DWH) oil spill, sampling efforts documented the acute impact of the spill on some deep-sea coral colonies. To investigate the impact of the DWH spill on quality and quantity of biomass delivered to the deep-sea, a suite of geochemical tracers (e.g., stable and radio-isotopes, lipid biomarkers, and compound-specific isotopes)...

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

    International Nuclear Information System (INIS)

    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.

  16. 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.

    significant component of food of prawns. Substratum characteristics, bottom temperature, salinity, pH, oxygen. Eh and organic carbon content of the mud are the parameters examined for identifying the governing factors controlling the benthic abundance...

  17. Multiple indicators reveal river plume influence on sediments and benthos in a New Zealand coastal embayment

    International Nuclear Information System (INIS)

    Multiple physico-chemical and biological indicators were used to delineate the spatial influence of the Motueka River plume on coastal surface sediments and associated biota in Tasman Bay, New Zealand. Sediments were primarily muds at nearshore sites on all transects and comprised coarser sediments at the most seaward sites in Tasman Bay. Organic carbon/nitrogen ratios, stable carbon and nitrogen isotope signatures, and certain lipid biomarkers and trace metals provided suitable indicators of terrestrial and riverine influence on subtidal sediments. Analysis of these parameters revealed a discernible catchment influence extending at least 6 km offshore in the river outwelling plume, with a pronounced signature evident at two sampling stations within approximately 2 km of the Motueka River mouth. At these two nearshore sites, nickel and chromium from natural upper-catchment sources were present at concentrations greatly exceeding sediment quality thresholds for probable ecological effects. The infaunal assemblage at these sites comprised low densities of a few opportunistic taxa, with the spatial distribution of organisms strongly correlated with trace metal concentrations. Although a causal relationship with trace metals is possible, other unmeasured influences such as gradients of salinity, depth and physical disturbance could conceivably be the primary drivers of the biological pattern. By contrast with the effects on infauna, analyses of stable carbon and nitrogen isotopes and trace metals in epibenthic shellfish did not reveal any evidence of a direct terrestrial or riverine influence. Overall, the results from this work indicate a relatively localised river plume effect on subtidal sediments and the associated infaunal assemblage. However, because previous work has shown that the river plume can extend tens of kilometres offshore during flood flows, further investigation is required to understand changes in seabed parameters within the context of spatio-temporal variation in catchment inputs and river plume discharge. (auth)

  18. 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.

  19. Benthos of a sublittoral sandbank in the Southern Bight of the North Sea: general considerations

    OpenAIRE

    Willems, K.A.; Vanosmael, C.; Claeys, D; Vincx, M.; Heip, C. H. R.

    1982-01-01

    The benthic fauna of the Kwinte Bank, a linear sandbank in the Belgian coastal waters of the North Sea, was sampled on ten stations in September 1978. This sandbank shows a linear gradient from fine sandy sediments in the south to coarser sandy sediments in the north as a result of the tidal current pattern in the region. The influence of this gradient on macro- and meiofauna was studied. Diversity of polychaetes and harpacticoid copepods is correlated with median grain size of the sand fract...

  20. A seafloor crater in the German Bight and its effects on the benthos

    Science.gov (United States)

    Thatje, S.; Gerdes, D.; Rachor, E.

    1999-08-01

    In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform 'Mr. Louie'. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura filiformis association (sensu Salzwedel et al. 1985). The crater, sometimes called 'Figge-Maar', functions as a sediment trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation rates of about 50 cm, on average, per year. Crater stations, compared with stations situated in the vicinity, show enrichments of juveniles. Echinoderms, especially the subsurface-dwelling heart urchin Echinocardium cordatum and ophiuroids are responsive to enrichment. Other species that are typical of the Amphiura filiformis association are shown to be unable to cope with the special conditions in the crater.

  1. A seafloor crater in the German Bight and its effect on the benthos

    OpenAIRE

    Thatje, S.; Gerdes, Dieter; Rachor, Eike

    1999-01-01

    In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform ŽMr. LouieŽ. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura-filiformis-association (sensu Salzwedel et al., 1985). The crater, sometimes called ŽFigge-MaarŽ, functions as a sediment-trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation r...

  2. A seafloor crater in the German Bight and its effects on the benthos

    OpenAIRE

    Thatje, S.; Gerdes, D.; Rachor, E.

    1999-01-01

    In 1963 a deep crater was formed about 65 m below sea level in the western part of the German Bight, due to a gas eruption caused by drilling carried out from the platform ’Mr. Louie'. The study area is situated in a sandy to muddy bottom area inhabited by an Amphiura filiformis association (sensu Salzwedel et al. 1985). The crater, sometimes called ’Figge-Maar', functions as a sediment trap, concentrating particles and organisms from the water column, thus leading to extreme sedimentation ra...

  3. Inventory of vegetation and benthos in newly laid and natural ponds in Forsmark 2012

    International Nuclear Information System (INIS)

    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

  4. Impact of Deepwater Horizon spill on food supply to deep-sea benthos communities

    NARCIS (Netherlands)

    Prouty, N.G.; Campbell, P.L.; Mienis, F.; Duineveld, G.; Demopoulos, A.W.J.; Ross, S.W.; Brooke, S.

    2016-01-01

    Deep-sea ecosystems encompass unique and often fragile communities that are sensitive to a variety of anthropogenic and natural impacts. After the 2010 Deepwater Horizon (DWH) oil spill, sampling efforts documented the acute impact of the spill on some deep-sea coral colonies. To investigate the imp

  5. Community variability and ecological functioning: 40 years of change in the North Sea benthos.

    Science.gov (United States)

    Clare, D S; Robinson, L A; Frid, C L J

    2015-06-01

    Using established associations between species traits (life history, morphological and behavioural characteristics) and key ecological functions, we applied biological traits analysis (BTA) to investigate the consequences of 40 years of change in two North Sea benthic communities. Ecological functioning (trait composition) was found to be statistically indistinguishable across periods that differed significantly in taxonomic composition. A temporary alteration to functioning was, however, inferred at both sampling stations; coinciding with the North Sea regime shift of the 1980s. Trait composition recovered after 1 year at the station located inside the grounds of a trawl fishery, whereas the station located outside the main area of fishing activity underwent a six-year period of significantly altered, and temporally unstable, trait composition. A further alteration to functioning was inferred at the fished station, when the population of a newly established species rapidly increased in numbers. The results suggest that density compensation by characteristically similar (redundant) taxa acts to buffer changes to ecological functioning over time, but that functional stability is subject to aperiodic disruption due to substitutions of dissimilar taxa or uncompensated population fluctuations. The rate at which ecological functioning stabilises and recovers appears to be dependent on environmental context; e.g. disturbance regime. PMID:25876194

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

    Directory of Open Access Journals (Sweden)

    DANA POPA

    2013-12-01

    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.

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

    DEFF Research Database (Denmark)

    Forbes, T. L.

    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....

  8. Benthos of the Kwinte Bank (an exploited sandbank in the Southern Bight)

    OpenAIRE

    Vanosmael, C.; Willems, K.; Vincx, M.; Claeys, D; C. H. R. Heip

    1982-01-01

    This paper summarizes studies on the meio- and macrofauna of a linear subtidal sandbank, the Kwinte Bank, situated in the Belgian Coastal waters, which is exploited for sand and gravel. The distribution of the macrofauna is strongly correlated with the gradient in grain size, but this is much less the case for the meiofauna. Especially nematodes seem to be able to exploit microhabitats more efficiently than the macrofauna.

  9. The deep benthos of Prince William Sound, Alaska, 16 months after the Exxon Valdez oil spill

    International Nuclear Information System (INIS)

    In 1990, 16 months after the T/V Exxon Valdez oil spill (EVOS) in Prince William Sound, Alaska, an assessment of the benthic macrofauna and associated environmental parameters at 40 and 100 m was made. Assessment of the biota and environmental data demonstrated patterns in deep benthic assemblages reflective of oceanographic conditions, as indicated by sediment differences, rather than EVOS toxicity. Comparison of polynuclear aromatic stations within the oil trajectory and reference stations outside of the trajectory showed no significant differences. This investigation uncovered no signals of disturbance 16 months after the EVOS. These results agree with conclusions of studies of intertidal and shallow subtidal regions following the EVOS that demonstrated disturbance effects decreasing with depth. (author)

  10. 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.

  11. 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

    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......Non-indigenous marine species (NIMS) have only recently caught general interest in Denmark, and baseline studies are needed to identify what species are of particular importance in order to prioritize management and research efforts. We used large data sets compiled in monitoring databases...... 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...

  12. 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.

    following the return of hypoxia. Similar results have been obtained for macrofauna in the Bay of In- dependencia (14◦20prime S) (Tarazona et al., 2001; Arntz et al., 2006). Massive wash-ups of the Humboldt squid (Dosidi- cus gigas) (Fig. 6c) that occur off...

  13. 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...

  14. Modelling climate change effects on benthos: Distributional shifts in the North Sea from 2001 to 2099

    Science.gov (United States)

    Weinert, Michael; Mathis, Moritz; Kröncke, Ingrid; Neumann, Hermann; Pohlmann, Thomas; Reiss, Henning

    2016-06-01

    In the marine realm, climate change can affect a variety of physico-chemical properties with wide-ranging biological effects, but the knowledge of how climate change affects benthic distributions is limited and mainly restricted to coastal environments. To project the response of benthic species of a shelf sea (North Sea) to the expected climate change, the distributions of 75 marine benthic species were modelled and the spatial changes in distribution were projected for 2099 based on modelled bottom temperature and salinity changes using the IPCC scenario A1B. Mean bottom temperature was projected to increase between 0.15 and 5.4 °C, while mean bottom salinity was projected to moderately increase by 1.7. The spatial changes in species distribution were modelled with Maxent and the direction and extent of these changes were assessed. The results showed a latitudinal northward shift for 64% of the species (maximum 109 km; brittle star Ophiothrix fragilis) and a southward shift for 36% (maximum 101 km; hermit crab Pagurus prideaux and the associated cloak anemone Adamsia carciniopados; 105 km). The relatively low rates of distributional shifts compared to fish or plankton species were probably influenced by the regional topography. The environmental gradients in the central North Sea along the 50 m depth contour might act as a 'barrier', possibly resulting in a compression of distribution range and hampering further shifts to the north. For 49 species this resulted in a habitat loss up to 100%, while only 11 species could benefit from the warming in terms of habitat gain. Particularly the benthic communities of the southern North Sea, where the strongest temperature increase was projected, would be strongly affected by the distributional changes, since key species showed northward shifts and high rates of habitat loss, with potential ramifications for the functioning of the ecosystem.

  15. Is long-term ecological functioning stable: The case of the marine benthos?

    Science.gov (United States)

    Frid, C. L. J.; Caswell, B. A.

    2015-04-01

    It is widely acknowledged that human activities are contributing to substantial biodiversity loss and that this threatens ecological processes underpinning human exploitation of 'ecosystem services' (defined by the Millennium Ecosystem Assessment as 'the benefits people obtain from ecosystems'). In the present study we consider three 'intermediate ecosystem services' in both contemporary and ancient marine systems and although 'ecosystem services' per se did not exist in the Jurassic our study seeks to consider the future provision of these services and so the term is retained. We consider the temporal patterns in benthic marine ecosystems: (1) spanning four decades at two offshore stations in the North Sea, UK and (2) over millennial scales in Late Jurassic UK palaeocommunities. Biological traits analysis is used to link changes in taxonomic composition to variations in ecological functioning and the potential supply of three 'intermediate' ecosystem services: the ability to provide food to fish and other predators, benthic nutrient regeneration and carbon cycling. We examine whether changes in taxonomic composition drive temporal variation in functioning, whether this variation increases over time and the extent to which species turnover is comparable in contemporary and ancient systems. Taxonomic variability was of a similar magnitude in all three systems and there was evidence for changes in functioning linked to changes in several (key or rivet) taxa. During other periods resilience maintained functioning in the face of taxonomic change. These results suggest that in these benthic systems the Biodiversity-Ecosystem Functioning relationship is idiosyncratic, but a degree of temporal stability in functioning is maintained such that the ecosystem services they underpin would also be stable during decadal and longer-term changes.

  16. 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...

  17. 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...

  18. 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.

  19. Morphometry, benthos, and sedimentation rates of a floodplain lake in Pool 9 of the Upper Mississippi River

    International Nuclear Information System (INIS)

    Big Lake is a shallow (mean depth = 0.89 m in 1973) 256-ha backwater lake on the floodplain of the Mississippi River in NE Iowa. During the summers of 1973 and 1974 Sphaerium and Hexagenia made up 81% of the benthic macroinvertebrate abundance and 92% of the benthic biomass; both taxa had greatly reduced abundance and biomass within stands of emergent Sagittaria along the lake margin. During July 1974 the Sagittaria net productivity was about 19 g/m2/day. Cesium-137 levels were determined in sediment samples showing that between 1896 and 1973 about 76 cm of sediment had accumulated in Big Lake, and the recent sedimentation rate (1964-1974) was about 1.7 cm/year. The calculated annual reduction in lake volume of about 37,400 m3/year suggests that the physical and biological components of this productive aquatic habitat will be greatly modified during the next few decades

  20. 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...

  1. Biodiversity and density of subtidal benthos of an oceanic tropical island (a comparison within the Pacific Ocean)

    Science.gov (United States)

    Sibaja-Cordero, Jeffrey A.; Troncoso, Jesús S.; Cortés, Jorge; Moreira, Juan; Vargas, José A.; Benavides-Varela, Catalina

    2016-09-01

    The marine macrofauna of the shallow sandy bottom of Isla del Coco, Costa Rica (5°32‧N-87°04‧W) was assessed in April 2010. Comparisons of richness, density and diversity between levels of exposure to ocean influence were carried out. During this study 15,407 specimens with a mean density of 1826 ind m- 2 were found between 3-75 m depth. The specimens were distributed in 267 taxa (29% new additions) with a mean of 55 ± 14 expected taxa m- 2. The values of density, richness and diversity were higher at the exposed coast, whereas they decreased at inner bays due to the influence of freshwater input. These estimates were compared with 40 studies in the Tropical Pacific Ocean (TPO). Taxa and density previously reported from the TPO were dependent on the area and depth range studied. Additionally, these parameters varied according to the sampling gear used. For example, higher densities were reported by using corers or boxcorers. The Shannon-Wiener index was most effective in identifying sediment and geographical patterns of variation along the TPO. Differences in these diversity parameters were also found between islands and mainland studies. Moreover, richness and density values from Isla del Coco were higher than the same parameters reported in studies using grabs in the TPO. At Isla del Coco annelids were dominant in terms of relative abundance (49.6%), followed by crustaceans (10.1%), mollusks (2.8%), and others faunal groups (37.5%). The faunistic composition at Isla del Coco differed when compared to the rest of localities of TPO due to the higher contribution of miscellaneous groups. In conclusion, the comparison with previous studies in the TPO indicate that islands like Isla del Coco have high numbers of taxa and diversity than those of the mainland, but lower density. However, this value is influenced by the sampling methodology. The taxa accumulation curve at Isla del Coco did not reach the asymptote, suggesting that an intensive sampling, especially at deep waters, would increase the number of taxa.

  2. 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 (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: plitter 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.

  3. 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 (rivers crossing an extensive banana 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.

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

    International Nuclear Information System (INIS)

    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)

  5. β-Diversity and Species Accumulation in Antarctic Coastal Benthos: Influence of Habitat, Distance and Productivity on Ecological Connectivity

    OpenAIRE

    Thrush, Simon F.; Hewitt, Judi E.; Cummings, Vonda J.; Norkko, Alf; Chiantore, Mariachiara

    2010-01-01

    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 β-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 accumula...

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

    Science.gov (United States)

    Williams, Ivor D; White, Darla J; Sparks, Russell T; Lino, Kevin C; Zamzow, Jill P; Kelly, Emily L A; Ramey, Hailey L

    2016-01-01

    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. PMID:27462981

  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. Cytological-cytogenetic analyses of winter flounder embryos collected from the Benthos at the barge North Cape oil spill

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, J.B. [Milford Laboratory, CT (United States). Northeast Fisheries Science Center

    1999-01-01

    The oil barge North Cape ran aground on Moonstone Beach in Rhode Island on January 19, 1996, spilling 828 000 gallons (US) of a combination of diesel and home heating oils. Samples of winter flounder embryos were collected from salt ponds in the area of the spill using an epibenthic sled. An examination of the field-sampled embryos based on gross morphology, levels of moribund embryos, mitotic index, and chromosomal anomalies found that a significant number exhibited high levels of one or more of these conditions when compared with flounder embryos raised under laboratory-controlled conditions. No chorion damage was noted in embryos collected from the field nor were there any significant findings of lordosis or scoliosis. The cumulative impact on winter flounder embryos of North Cape oil exposure was an estimated 51% reduction in the number of embryos surviving to the larval stage. (author)

  9. Cytological-cytogenetic analyses of winter flounder embryos collected from the Benthos at the barge North Cape oil spill

    International Nuclear Information System (INIS)

    The oil barge North Cape ran aground on Moonstone Beach in Rhode Island on January 19, 1996, spilling 828 000 gallons (US) of a combination of diesel and home heating oils. Samples of winter flounder embryos were collected from salt ponds in the area of the spill using an epibenthic sled. An examination of the field-sampled embryos based on gross morphology, levels of moribund embryos, mitotic index, and chromosomal anomalies found that a significant number exhibited high levels of one or more of these conditions when compared with flounder embryos raised under laboratory-controlled conditions. No chorion damage was noted in embryos collected from the field nor were there any significant findings of lordosis or scoliosis. The cumulative impact on winter flounder embryos of North Cape oil exposure was an estimated 51% reduction in the number of embryos surviving to the larval stage. (author)

  10. Exploiting Habitat and Gear Patterns for Efficient Detection of Rare and Non-native Benthos and Fish in Great Lakes Coastal ecosystems

    Science.gov (United States)

    There is at present no comprehensive early-detection monitoring for exotic species in the Great Lakes, despite their continued arrival and impacts and recognition that early detection is key to effective management. We evaluated strategies for efficient early-detection monitorin...

  11. 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 ostatní: EC(XE) MOLAR ENV4-CT95-007; EC(XE) EMERGE EVK1-CT1999-00032 Keywords : modeling * palaeolimnology * hydrochemistry Subject RIV: DA - Hydrology ; Limnology

  12. Bentho-Pelagic Divergence of Cichlid Feeding Architecture Was Prodigious and Consistent during Multiple Adaptive Radiations within African Rift-Lakes

    OpenAIRE

    W. James Cooper; Kevin Parsons; Alyssa McIntyre; Brittany Kern; Alana McGee-Moore; R. Craig Albertson

    2010-01-01

    Background 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. ...

  13. 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

    OpenAIRE

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

    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 contras...

  14. Global sensitivity analysis of an end-to-end marine ecosystem model of the North Sea: Factors affecting the biomass of fish and benthos

    OpenAIRE

    Morris, David J.; Speir, Douglas C.; Cameron, Angus I; Heath, Michael R.

    2014-01-01

    Comprehensive analysis of parameter and driver sensitivity is key to establishing the credibility of models representing complex systems. This is especially so for models of natural systems where experimental manipulation of the real-world to provide controlled validation data is not possible. End-to-end ecosystem models (nutrients to birds and mammals) of marine ecosystems fall into this category with applications for evaluating the effects of climate change and fishing on nutrient fluxes an...

  15. Benthos response following petroleum exploration in the southern Caspian Sea: Relating effects of nonaqueous drilling fluid, water depth, and dissolved oxygen.

    Science.gov (United States)

    Tait, R D; Maxon, C L; Parr, T D; Newton, F C

    2016-09-15

    The effects of linear alpha olefin (LAO) nonaqueous drilling fluid on benthic macrofauna were assessed over a six year period at a southern Caspian Sea petroleum exploration site. A wide-ranging, pre-drilling survey identified a relatively diverse shelf-depth macrofauna numerically dominated by amphipods, cumaceans, and gastropods that transitioned to a less diverse assemblage dominated by hypoxia-tolerant annelid worms and motile ostracods with increasing depth. After drilling, a similar transition in macrofauna assemblage was observed with increasing concentration of LAO proximate to the shelf-depth well site. Post-drilling results were consistent with a hypothesis of hypoxia from microbial degradation of LAO, supported by the presence of bacterial mats and lack of oxygen penetration in surface sediment. Chemical and biological recoveries at ≥200m distance from the well site were evident 33months after drilling ceased. Our findings show the importance of monitoring recovery over time and understanding macrofauna community structure prior to drilling. PMID:27417570

  16. Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda

    Science.gov (United States)

    Fourqurean, J. W.; Manuel, S. A.; Coates, K. A.; Kenworthy, W. J.; Boyer, J. N.

    2015-10-01

    Striking spatial patterns in stable isotope ratios (isoscapes) and elemental ratios (stoichioscapes) of seagrass leaves and the water column nutrients indicate general P-limitation of both water column and benthic primary productivity on the Bermuda Platform, and they highlight the role of the Bermuda Islands as a source of N and P. We found consistent differences among the four seagrass species (Syringodium filiforme, Thalassia testudinum, Halodule sp. and Halophila decipiens) in the N, P, δ13C and δ15N of leaf tissues. The δ15N of seagrass leaves was especially variable, with values from -10.1 to 8.8 ‰, greatly expanding the reported range of values for all seagrass species globally. Spatial patterns from both the water column and the seagrass leaves indicated that P availability was higher near shore, and δ15N values suggest this was likely a result of human waste disposal. Spatially contiguous areas of extremely depleted seagrass 15N suggest unique N sources and cycling compared to other seagrass-dominated environments. Seagrass N : P values were not as far from the stoichiometric balance between N and P availability as in the water column, and there were no strong relationships between the water column N : P and the seagrass N : P. Such isoscapes and stoichioscapes provide valuable ecogeochemical tools to infer ecosystem processes as well as provide information that can inform food web and animal movement studies.

  17. 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.

  18. 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 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.

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

    OpenAIRE

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

    2006-01-01

    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 d...

  20. Macrobenthos van de Zeeschelde, met bijzondere aandacht voor het voorkomen en de rol van Oligochaeta: eindrapport OMES 1995-1998, partim Benthos

    OpenAIRE

    Seys, J.; Vincx, M.; Meire, P.

    1999-01-01

    The results of a study on spatial and temporal distribution of macro-invertebrates in the soft sediments of the entire Zeeschelde, i.e. the Belgian part of the Schelde estuary are presented in this report. This study, part of the OMES-program (Study on Environmental Impact of the Sigma plan), has been carried out at the University of Gent (Prof. M. Vincx) in close cooperation with the Institute of Nature Conservation (Prof. P. Meire), in the period November 1995 – June 1998. It focussed on t...

  1. Effects of common carp Cyprinus carpio (L.) and feed addition in rohu Labeo rohita (Hamilton) ponds on nutrient partitioning among fish, plankton and benthos

    NARCIS (Netherlands)

    Rahman, M.M.; Verdegem, M.C.J.; Nagelkerke, L.A.J.; Wahab, M.A.; Milstein, A.; Verreth, J.A.J.

    2008-01-01

    The effects of introducing common carp (CC) and of adding artificial feed to fertilized rohu ponds on water quality and nutrient accumulation efficiency were studied. All ponds were stocked with 15 000 rohu ha¿1. Treatments included ponds with rohu alone, rohu plus 5000 common carp ha¿1 and rohu plu

  2. 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.

  3. Ficoflora de ambientes lênticos: estudo preliminar da região de Charqueadas, Rio Grande do Sul, Brasil, com vistas à avaliação ambiental Metaphyton, benthos and phytoplantonic communities in lentic systems in the region of Charqueadas Rio Grande do Sul, Brazil

    OpenAIRE

    Zulanira Meyer Rosa; Ieti Ungaretti; Lisete Maria Kremer; Sandra Maria Alves da Silva; Vera Lucia Maröstica Callegaro; Vera Regina Werner

    1987-01-01

    São apresentados os resultados do estudo do metafíton, bentos e de comunidades fitoplanctônicas ocorrentes em ambientes lênticos de Charqueadas e municípios vizinhos, região esta sujeita à influência de mineração e processamento de carvão mineral. O estudo baseou-se em 46 amostras coletadas em julho e agosto de 1986. Dos 213 táxons específicos e infra-específicos identificados, 95 constituem-se em primeiro registro de ocorrência no Estado. Os grupos melhor representados quanto ao número de es...

  4. 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...

  5. 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...

  6. 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...

  7. 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...

  8. 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...

  9. ACCUMULATION OF POLYCHLORINATED ORGANIC CONTAMINANTS FROM SEDIMENT BY THREE BENTHIC MARINE SPECIES

    Science.gov (United States)

    A laboratory experiment was conducted to measure the accumulation of selected polychlorinated compounds by marine benthos exposed to environmentally contaminated sediment. andworms (Nereis virens), clams (Macoma nasuta), and grass shrimp (Palaemonetes pugio) were exposed to sedim...

  10. Pacific Remote Islands MNM: Initial Survey Instructions for Calcium Carbonate Accretion

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of the survey is to quantify the rate of calcium carbonate accretion to the coral reef benthos and to examine spatial and temporal variability in...

  11. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    OpenAIRE

    Bode, A.; Fernández, C.; Mompeán, C.; S. Parra; Rozada, F.; Valencia-Vila, J.; Viana, I. G.

    2014-01-01

    In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteristically enriched in nutrients provided either by marine processes (as coastal upwelling) or by urban and agricultural waste. Stable isotope composition in trophic guilds of infaunal benthos revealed spatial differences related to their nutrient inputs. The mai...

  12. 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...

  13. 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 ecosys...

  14. Recruitment of meroplanktonic larvae in the Southern Bight of the North Sea

    OpenAIRE

    Belgrano, A.; Vincx, M.; Dewarumez, J.-M.; A. Richard; Craeymeersch, J.A.; Heip, C. H. R.

    1990-01-01

    The density distribution of meroplanktonic larvae is compared with the density distribution of adults in the benthos, at five coastal stations in the Southern Bight of the North Sea (Abra alba community). Plankton communities were sampled during one tidal cycle, along a buoy traject or at a fixed point; southern and northern locations, 250 m from each central sampling point, have been investigated too. Benthos samples were taken only at the central points of this traject. Meroplankton consist...

  15. 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. PMID:26394097

  16. [Fouling: terminology and definitions].

    Science.gov (United States)

    Khalaman, V V

    2009-01-01

    Current classification of principal ecological groups of hydrobionts is an eclectic one as it confuses two fundamentals, one dealing with organismic ecomorphology and another with water body's topology. This leads to difficulties in determination of interrelations between benthos and fouling communities. The littoral fouling communities cannot be considered as an independent ecological group of the same rank as plankton or benthos because it lacks a unique species composition. The fouling is always a derivate of the benthos, so it could be defined as a community formed by benthic organisms during succession on a solid substrate more or less remote from the water body's bottom. All peculiarities of the fouling communities distinguishing them from similar benthic communities are determined by topology and other properties of the substrate, by relatively short period of the latter's exposition and by hydrological conditions under which the fouling is developing. There is continual transitions between benthic and fouling communities both in space (along gradients of abiotic environmental factors) and in time (along successional series). Such a continuum becomes most frequently broken due to both significant remoteness of the substrate, on which a fouling develops, from the bottom and permanent extreme factors disturbing or retarding fouling communities development. Thus, littoral foulings are just benthos being formed under specific conditions. At the same time, oceanic foulings are connected both evolutionary and ecologically with littoral foulings and benthos. PMID:20063771

  17. Examination of the influence of juvenile Atlantic salmon on the feeding mode of juvenile steelhead in Lake Ontario tributaries

    Science.gov (United States)

    Johnson, James H.; Waldt, Emily M.

    2014-01-01

    We examined diets of 1204 allopatric and sympatric juvenile Atlantic salmon (Salmo salar) and steelhead (Oncorhynchus mykiss) in three tributaries of Lake Ontario. The diet composition of both species consisted primarily of ephemeropterans, trichopterans, and chironomids, although juvenile steelhead consumed more terrestrial invertebrates, especially at the sympatric sites. Subyearlings of both species consumed small prey (i.e. chironomids) whereas large prey (i.e. perlids) made up a higher percentage of the diet of yearlings. The diet of juvenile steelhead at the allopatric sites was more closely associated with the composition of the benthos than with the drift, but was about equally associated with the benthos and drift at the sympatric sites. The diet of both subyearling and yearling Atlantic salmon was more closely associated with the benthos than the drift at the sympatric sites. The evidence suggests that juvenile steelhead may subtly alter their feeding behavior in sympatry with Atlantic salmon. This behavioral adaptation may reduce competitive interactions between these species.

  18. Comparing new and conventional methods to estimate benthic algal biomass and composition in freshwaters.

    Science.gov (United States)

    Kahlert, Maria; McKie, Brendan G

    2014-11-01

    We compared conventional microscope-based methods for quantifying biomass and community composition of stream benthic algae with output obtained for these parameters from a new instrument (the BenthoTorch), which measures fluorescence of algal pigments in situ. Benthic algae were studied in 24 subarctic oligotrophic (1.7-26.9, median 7.2 μg total phosphorus L(-1)) streams in Northern Sweden. Readings for biomass of the total algal mat, quantified as chlorophyll a, did not differ significantly between the BenthoTorch (median 0.52 μg chlorophyll a cm(-2)) and the conventional method (median 0.53 μg chlorophyll a cm(-2)). However, quantification of community composition of the benthic algal mat obtained using the BenthoTorch did not match those obtained from conventional methods. The BenthoTorch indicated a dominance of diatoms, whereas microscope observations showed a fairly even distribution between diatoms, blue-green algae (mostly nitrogen-fixing) and green algae (mostly large filamentous), and also detected substantial biovolumes of red algae in some streams. These results most likely reflect differences in the exact parameters quantified by the two methods, as the BenthoTorch does not account for variability in cell size and the presence of non-chlorophyll bearing biomass in estimating the proportion of different algal groups, and does not distinguish red algal chlorophyll from that of other algal groups. Our findings suggest that the BenthoTorch has utility in quantifying biomass expressed as μg chlorophyll a cm(-2), but its output for the relative contribution of different algal groups to benthic algal biomass should be used with caution. PMID:25277172

  19. 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.

  20. 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.

    benthos. Blackwell Scientific Publications, Oxford and Edinburgh, pp. 41e645. Clarke, K. R., & Gorley, R. N. (2001). PRIMER v5: User manual/Tutorial. PRIMER-E Ltd, Plymouth, United Kingdom, 91 p. Crisp, D. J. (1971). Energy flow measurements. In...: Holme N.A. and Mcintyre A.D. (Eds) methods for the study of marine benthos. IBP Handbook 16, Blackwell Scientific Publications Oxford: 197- 279. Day, J. H. (1967). A monograph on the polychaete of Southern Africa Part-I and II, Trustees...

  1. 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.

  2. Application of a Tenax Model to Assess Bioavailability of Polychlorinated Biphenyls in Field Sediments

    Science.gov (United States)

    Recent literature has shown that bioavailability-based techniques, such as Tenax extraction, can estimate sediment exposure to benthos. In a previous study by the authors,Tenax extraction was used to create and validate a literature-based Tenax model to predict oligochaete bioac...

  3. NEW RECORDS AND RANGE EXTENSIONS FOR SEVERAL CHIRONOMID GENERA IN LAKE SUPERIOR

    Science.gov (United States)

    Recent USEPA investigations of Lake Superior benthos in Minnesota, Wisconsin, and Michigan waters have resulted in the discovery of six uncommon genera of Chironomidae. Five new records of genera for Lake Superior and five significant Nearctic range extensions are reported. New r...

  4. Colloquium on diatom-copepod interactions

    DEFF Research Database (Denmark)

    Paffenhofer, G.A.; Ianora, A.; Miralto, A.; Turner, J.T.; Kleppel, G.S.; d'Alcala, M.R.; Casotti, R.; Caldwell, G.S.; Pohnert, G.; Fontana, A.; Muller-Navarra, D.; Jonasdottir, Sigrun; Armbrust, V.; Bamstedt, U.; Ban, S.; Bentley, M.G.; Boersma, M.; Bundy, M.; Buttino, I.; Calbet, A.; Carlotti, F.; Carotenuto, Y.; d'Ippolito, G.; Frost, B.; Guisande, C.; Lampert, W.; Lee, R.F.; Mazza, S.; Mazzocchi, M.G.; Nejstgaard, J.C.; Poulet, S.A.; Romano, G.; Smetacek, V.; Uye, S.; Wakeham, S.; Watson, S.; Wichard, T.

    2005-01-01

    From 3 to 6 November 2002, a colloquium was convened at the Benthos Laboratory of the Stazione Zoologica Anton Dohrn on Ischia, Italy, with the goal of evaluating the present status of the effects of diatoms on their main consumers, planktonic copepods, and to develop future research strategies t...

  5. An elutriation apparatus for macroinvertebrates

    Science.gov (United States)

    Worswick, Joseph M., Jr.; Barbour, Michael T.

    1974-01-01

    An inexpensive hydropneumatic apparatus screens macroinvertebrates from bottom samples containing silt, mud, or clay. The elutriator, an acrylic cylinder with screened windows, cemented on an upright plastic funnel, retains benthic fauna while the sediment is washed away. The apparatus yields clean samples and has reduced the time required to sort benthos samples by more than 80%.

  6. A note on Antarctic benthic mollusks collected with a beam-trawl from Breid Bay by the 25th Japanese Antarctic Research Expedition

    OpenAIRE

    Takashi, Okutani

    1986-01-01

    The molluscan specimens sorted out from benthos samples trawled from depths of 310 and 215m in Breid Bay were studied. A single species of Polyplacophora, 7 gastropods, one scaphopod, 6 bivalves and 2 octopod cephalopods were identified. The general compositions of the present collection represents typical shelf fauna in the Antarctic.

  7. 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).

  8. 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)

    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

  9. The food niche overlap of five fish species in the Úpoř brook (Central Bohemia

    Directory of Open Access Journals (Sweden)

    Vlach P.

    2013-09-01

    Full Text Available The diet and food niche overlap of five fish species in the Úpoř brook was evaluated. The supply of food represented by benthos was studied, and the proportion of total food particles in the intestine of brown trout Salmo trutta L., chub Squalius cephalus (L., dace Leuciscus leuciscus (L., bullhead Cottus gobio (L. and stone loach Barbatula barbatula (L. was measured. Evaluations were performed using a new index (Mtotp. All fish species except stone loach exhibited a balanced consumption of the food supply. The food components were systematically grouped, but no differences in the ingestion of these groups were found. However, a new approach in the evaluation of food competition based on observation of species-specific preferences/avoidance in ingestion of food particles was applied. The particles were divided into four ecological categories according to their availability for fish. Brown trout concentrated on easily accessible sources of benthos or that hiding below stones, and also distinctly preyed on terrestrial insects. Chub displayed a similar feeding habit, though concentrating more on drift and allochthonous sources. The food spectrum of dace was mostly composed of easily accessible benthic organisms, consuming fewer hidden benthos and terrestrial insects. The food of bullhead and stone loach was similar, both preferring benthos. Bullhead consumed hidden species while stone loach consumed more accessible species rather than hidden ones.

  10. 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

  11. Comprehensive studies in the Black Sea and the Sea of Azov in the Summer of 2012

    Science.gov (United States)

    Matishov, G. G.; Nabozhenko, M. V.; Shokhin, I. V.; Zolotareva, A. E.; Bulysheva, N. I.; Semin, V. L.; Polshin, V. V.; Povazhnyi, V. V.; Verbitskyi, R. E.; Verbitskyi, E. V.; Sapozhnikov, F. V.; Spiridonov, V. A.; Zalota, A. K.

    2013-05-01

    The shelf zones of the Black Sea, Taman Bay, and the Sea of Azov are currently subjected to gross load related to the impact of invasive species, large-scale construction activities near the coast, intensive recreation activity, water pollution in large cities and ports, active navigation, unreasonable coastal arrangement, and dam construction. Another factor substantially affecting the composition of bottom sediments and, thus, the benthos environment is the terrigenous material carried by rivers in the course of catastrophic overflows. An example is the Kubansk flood in 2012, which significantly affected the sea coast near Novorossiysk, Gelendzhik, and Divnomorsk. The intensive onshore dumping results in the delivery of abundant allochthonous material, bottom silting causing changes in the dominants in the benthos associations, a decrease in the photic layer and the death of the phytobenthos, and also debris formation at the bottom. Debris can play the role of artificial reefs contributory for the formation of periphytic biocoenoses.

  12. [An example of anthropogeneous succession in the ecosystem of the Verkhnetulomsky Water Reservoir (the Tuloma River Basin, the Kola region)].

    Science.gov (United States)

    Mitenev, V K; Shul'man, B S; Karasev, A B; Ponomarev, S V

    2010-01-01

    The destruction of initial biocenoses in the ecosystem of the Verkhnetulomsky Water Reservoir caused deep succession processes. As a result of the loss of the amphipod group in the benthos, replacement of the trophic links in fishes took place in the biocenosis of the reservoir. Benthos feeders changed over to the feeding on zooplankton and, as a result, became the constituent of the predators'diet. The structure of parasitic systems has changed. The parasites using amphipods as intermediate hosts have been and, on the contrary, the abundance of parasites infesting fishes through feeding of the latter on zooplankton has increased. Among the parasites, Triaenophorus crassus Forel became the cause of the appearance of stable triaenophorosis focus. PMID:21061595

  13. Quantifying pelagic-benthic coupling in the North Sea: Are we asking the right question?

    DEFF Research Database (Denmark)

    Richardson, K.; Cedhagen, T.

    2002-01-01

    study that we consider to be important in order to, ultimately, quantify the pelagic-benthic coupling on the basin-scale. Current knowledge on regional annual differences in new production (i.e., that which leads to the production of new organic material and, ultimately, sedimentation from the water...... considers whether the organic signal reaching the benthos might be most readily interpretable through measurement of meiofaunal biomass and activity, rather than through the more common practice of examining the macrofaunal benthos community. The meiofauna has been shown to be important in the flux of...... energy and nutrients. We argue that foraminiferans may deserve more study in this respect. Their large numbers in combination with structural and physiological adaptations suggest that these organisms may be of greater importance than other meiofaunal organisms of comparative size and abundance....

  14. Comparative diets of subyearling Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) in the Salmon River, New York

    Science.gov (United States)

    Johnson, J.H.

    2007-01-01

    Chinook salmon (Oncorhynchus tshawytscha) and steelhead (O. mykiss) have established naturalized populations throughout the Great Lakes. Young-of-year of these species occur sympatrically for about one month in Lake Ontario tributaries. This study examined the diets of subyearling Chinook salmon and steelhead relative to available food in the Salmon River, New York. Terrestrial invertebrates and trichopterans were the major prey of Chinook salmon, whereas steelhead fed primarily on baetid nymphs and chironomid larvae. Diet overlap was low (0.45) between the species. The diet of Chinook was closely associated to the composition of the drift (0.88). Steelhead diet drew equally from the drift and benthos during the first year of the study, but more closely matched the benthos during the second year. Differences in prey selection, perhaps associated with differences in fish size, in addition to apparent differences in feeding mode (drift versus benthic), likely reduce competitive interactions between these species.

  15. ABUNDANCE AND SEASONAL DYNAMICS OF MAYFLY COMMUNITIES (INSECTA: EPHEMEROPTERA FROM SOMESUL MIC RIVER (ROMANIA

    Directory of Open Access Journals (Sweden)

    Milca Petrovici

    2001-01-01

    Full Text Available The collecting of quantitative benthos samples in 1996-1997, at three sampling sites on the Someşul Mic River, allowed the identification of 12 species of 5 families. The highest diversity was found upstream Cluj-Napoca, and it had decreased downstream town, the mayfly being absent downstream Gherla. Baëtis lutheri along with Baëtis vernus, were the dominant species upstream the town. Baëtis vernus was the only species present downstream Cluj Napoca, in every season. The presence of that species, with very low densities, and being the only identified species in some seasons, reflect a high depreciation of the water quality by the city of Cluj-Napoca. This species although known as very pollution tolerant, absent in the benthos of the river after crossing Gherla industrial town.

  16. 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.

  17. Impacts of anthropogenic activities on the Changjiang (Yangtze) estuarine ecosystem (1998-2012)

    Institute of Scientific and Technical Information of China (English)

    CHEN Dong; DAI Zhijun; XU Ren; LI Daoji; MEI Xuefei

    2015-01-01

    Estuarine ecosystem has greatly changed in the recent decades due to anthropogenic perturbations in the Changjiang Estuary. Change patterns and impact factors were analyzed based on the continuous data in relation to the Changjiang estuarine ecosystem from 1998 to 2012. The results showed significant decreases in plankton species and annual output ofCoilia nasus,Coilia mystus. Furthermore, species and biomass of benthos showed abrupt change in 2003, downward before that and upward after that. It was noted that,Eriocheir sinensis, a high value commercial fish, had an annual production increase of 97%. Reduction of riverine nutrients, especially dissolved silicate (DSI) loads into the estuary could contribute to the decline inBacillariophyta species. Dredging and dumping works of the North Passage led to the decreases in regional plankton species. However, the species reproduction and releasing projects could restore the estuarine ecosystem through increasing the output ofE. sinensis, as well as species and biomass of benthos.

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

    DEFF Research Database (Denmark)

    Beare, Doug; Rijnsdorp, Adriaan D.; Blæsbjerg, Mette; Damm, Ulrich; Egekvist, Josefine; Fock, Heino; Kloppmann, Matthias; Röckmann, Christine; Schroeder, Alexander; Schulze, Torsten; Tulp, Ingrid; Ulrich, Clara; Hal, Ralf van; Kooten, Tobias van; Verweij, Marieke

    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...... main food items of plaice (polychaetes and small bivalves) remained stable or decreased both inside and outside the PB. Currently catches of both plaice and sole from within the PB are lower than in the late 1980s and the exemption fleet often prefers to fish outside the Plaice Box alongside much...... setting testable objectives 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...

  19. Biodiversity hotspots on the Dutch Continental Shelf: a marine strategy framework directive perspective

    OpenAIRE

    Bos, O.G.; Witbaard, R.; Lavaleye, M.S.S.; Moorsel, G.W.N.M.; Teal, L.R.; Hal, van, R.; Hammen, van der, L.; Hofstede, ter, R.; Bemmelen, van, R.S.A.; Witte, R.H.; Geelhoed, S.C.V.; Dijkman, E.M.

    2011-01-01

    This report presenst hotspots of biodiversity for benthos, fish, birds, marine mammals and habitats on the Dutch Continental Shelf. These hotspots are based on a spatial application of biodiversity metrics developed in this study for the GES(Good Environmental Status)-descriptor 1 ‘Biological diversity is maintained’ of the Marine Strategy Framework Directive (MSFD) (EU 2008). The choice of the biodiversity metrics is based on the proposed indicators of biodiversity in the Commission Decision...

  20. Heeft de Zandmotor een aantrekkende werking op Futen in de Hollandse kustzone?

    OpenAIRE

    Bemmelen, van, R.S.A.; Geelhoed, S.C.V.

    2012-01-01

    Voor de kust van Zuid-Holland heeft een megasuppletie plaatsgevonden waarmee de kustveiligheid voor de lange termijn wordt gecombineerd met de realisatie van ruimte voor natuur en recreatie: De Zandmotor. Voor (zee)vogels in de kustzone zijn twee hypotheses uit het Uitvoeringsprogramma van belang:"als gevolg van het positieve effect van de Zandmotor op benthos en jonge vis heeft het een positief effect op zeevogels die foerageren op schelpdieren en vis in de ondiepe kustzone" en "de lagune za...

  1. Effect of tropical rainfall in structuring the macrobenthic community of Mandovi estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gaonkar, U.V.; Sivadasa, S.K.; Ingole, B.S.

    with sites and benthic variables represented by points and environmental parameters by arrows (ter Braak, 1986). The benthic variables and site points jointly represent the dominant patterns in community while benthic group point and the arrow... of environmental variables jointly reflect the distribution of benthos along each of the variables. The analyses were carried out using Primer 6, Multivariate statistical package program (MVstep) 3.1 (Kovach, 1998) and Statistica 10 software packages. Results...

  2. Environmental studies of the proposed North Coast Nuclear Plant Unit No. 1 site. Final report

    International Nuclear Information System (INIS)

    The physical parameters used in hydrology studies were tides, currents, bathymetry, temperature, salinity, and density structure of the water column. Terrestrial ecological studies were carried out in five vegetational zones: beach, sand dune, north facing slopes parallel to the coast, south facing slopes, and lowlands. Studies on phytoplankton and zooplankton included determination of standing crop, diversity, seasonal variations, and species composition. Similar studies were carried out on benthos and intertidal invertebrates. Fish populations were studied with regard to species distribution and abundance

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

    OpenAIRE

    Sánchez Lizaso, J.L.; Bayle Sempere, J.; Sánchez Jerez, P.

    2011-01-01

    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.

  4. 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.

  5. The influence of the anthropic activities on the benthonic macroinvertebrates communities existing in the Jiu and Jiul de Vest rivers, southwest of Romania

    OpenAIRE

    Milca Petrovici; Mălina Dumbravă-Dodoacă

    2010-01-01

    The different sensibility of the benthonic macro-invertebrates has been used in determiningthe manner in which these communities are being influenced by the alteration of the water quality. Thepresent study aims at following this precise aspect. The benthos samples have been collected from tworivers in the south-west of Romania: Jiu (3 stations) and Jiul de Vest (2 stations). There have beenstudied 10 groups of benthonic invertebrates. The benthonic communities’ density, abundance andfrequenc...

  6. 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.

    , 1998). There is no such approach from Indian seas, although there are a number of publications on benthos (Parulekar et al., 1980; Harkantra and Parulekar, 1985, 1994). Some deal with pollution aspects based on diversity index or dominance of polychaete... species (Raman and Ganapati, 1983; Parulekar et al., 1986; Devi et al., 1991). In view of this, an approach is made in this study to test the applicability and effectiveness of some of the univariate and multivariate techniques mentioned above by applying...

  7. Invertebrate communities of Nabugabo Lakes: a vital support resource for the fisheries and ecosystem diversity

    OpenAIRE

    Ndawula, L.M.; Kiggundu, V.; Pabire Ghandi, W.

    2005-01-01

    A field study of the invertebrate communities of the Nabugabo lakes(Nabugabo,Kayanja and Kayugi)showed the occurrence of copepoda, cladocera and rotifera(micro-invertebrates or zooplankton); Ephemeroptera and Diptera(macro-invertebrates or zoo-benthos). The most commonly encountered taxa were thermocyclops neglectus, moinamicrura,several rotiferan species(micro-invertebrates);P.adusta,chironomus, tanipodinae and trichoptera(macro- invertebrates). These organisms are assumed to be readily avai...

  8. Long-term trends in Loch Leven invertebrate communities

    OpenAIRE

    Gunn, I.D.M.; O'Hare, M.T.; Maitland, P.S.; May, L.

    2012-01-01

    Detailed studies of the macroinvertebrate benthos and zooplankton communities in Loch Leven, the largest shallow lowland lake in Scotland, UK, were carried out from 1966 to 1973 as part of the International Biological Programme (IBP). The results revealed a reduction in species diversity that was attributed to increasing eutrophication. This work provides a baseline against which the response of the invertebrate communities to subsequent changes in management can be...

  9. Macrobenthos monitoring in the Gulf of Suez, Egypt

    Institute of Scientific and Technical Information of China (English)

    Mohamed M.El - Komi

    2008-01-01

    The biogeography of macrobenthic communities with large-scale differences in species distribution and abundance was studied along the eastern and western coastal regions of the Gulf of Suez to indicate biodiversity of benthos in relation to the prevailing en-virunmental conditions.In general,benthos have a wide variety of species of mainly polychaet worms,crustaceans,bivalves,and other bottom invertebrates hying in burrows in/or on the sediment surface.Coastal development clearly affects the ecosystem after the construction of coastal projects.The highest values of benthic diversity,evenness,richness and dominance are found at the Gulf of Suez (WG 1,WG 3),Ras Gharib ( WG 7,WG 8) and Ras Shukier (WG 9a) by contrast to others.The abundance of macrobenthic organsims along the coasts of Gulf of Suez can be arranged in the following sequence:other groups (34%) greater than crustaceans (25%) greater than polychaetes (22%) greater than molluscs (17%) greater than echinoderms (2%).The biomass of benthic assemblages at different sampling sites can also be ranked as follows:echinoderms (52%) greater than mol-luscs (27%) greater than crustaceans (16%) greater than polychaetes (2%) greater than other groups (3%).Some benthic groups or species indicated a distinctive correlation to pollution sources in the marine ecosystem which obviously increased in the coastal areas due to the extension of the coastal development.These activities needed regular information to establish database for the biology and distribution of marine benthic communities.The density and diversity of benthos are significantly affected by eu-trophication at Ain Sukhna,whereas the benthos in the open Gulf of Suez do not seem to be adversely affected by pollution.

  10. Benthic Faunal Composition of Penaeus monodon Fabricius Culture Pond in West Coast of Peninsular Malaysia

    OpenAIRE

    Abu Hena M.K.; O. Hshamuddin; K. Misri; Abdullah, F.; Loo, K. K.

    2004-01-01

    The present study deals with the results on benthic faunal abundance and diversity of tiger shrimp P. monodon culture ponds in Perak, West coast of Peninsular Malaysia. To observe the abundance and composition of benthic organisms, sampling was carried out every three weeks interval throughout the culture period. In addition, observations on water temperature, dissolved oxygen, salinity, transparency, pH and organic matter of soil were also made. The major groups of macro-benthos comprised of...

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

    OpenAIRE

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

    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;...

  12. Distribution of blue-green algae (Cyanophyta) in streams of Mt. Stara planina: Serbia

    OpenAIRE

    Simić Snežana B.

    2002-01-01

    Distribution of blue-green algae was studied at 14 sites along five streams in the Stara Planina mountains. Algological samples were taken from the community of benthos and periphyton in the spring (March-May 1991), summer (June-August 1991, August 1996, July 1997), and autumn (September-November 1991, September 1997). Algae of the classes Chamaesiphonophyceae (species of the genus Chamaesiphon) and Hormogoniophyceae (species of the genera Symploca, Phormidium, Oscillatoria, Schizothrix, Nost...

  13. Invertebrate communities of Lake Nabisojjo

    OpenAIRE

    Ndawula, L.M.; Kiggundu, V.; Pabire Ghandi, W.

    2000-01-01

    Invertebrates are organisms without a backbone on the basis of body size. Aquatic invertebrates can be divided into two broad categories: micro-and macro-invertebrates. The former commonly known as zooplankton, ranging in size from < 100um 10 ca.1500um and are mainly planktonic (i.e living suspended in the water column). The latter, also known as benthos, (bottom dwelling) are associated with bottom sediments(ie, living on sediment surface or burrowing in sediments), are much bigger organism ...

  14. How does the resuspension of the biofilm alter the functioning of the benthos–pelagos coupled food web of a bare mudflat in Marennes-Oléron Bay (NE Atlantic)?

    OpenAIRE

    Saint-Béat, Blanche; Dupuy, Christine; Agogué, Hélène; Carpentier, Alexandre; Chalumeau, Julien; Como, Serena; David, Valérie; De Crignis, Margot; Duchêne, Jean-Claude; Fontaine, Camille; Feunteun, Eric; Guizien, Katell; Hartmann, Hans; Lavaud, Johann; Lefebvre, Sébastien

    2014-01-01

    Intertidal mudflats are ecosystems submitted to natural hydrodynamical forcings during each tide. When the off-shore water flows at high tide, a proportion of the biofilm produced at low tide can be resuspended in the water column and interact with the pelagic food web. As a consequence, the resuspension creates a link between the benthos and the pelagos, modifying their properties and the stability of the meta-ecosystem they form together. The aim of this study is to describe the consequence...

  15. Ecología química en el bentos marino de la Antártida: productos naturales y defensa química en esponjas hexactinélidas, corales blandos y ascidias coloniales

    OpenAIRE

    Núñez Pons, Laura

    2012-01-01

    The inhabitants of marine benthos must combat the ecological pressure caused by predation, competition and fouling through a series of mechanisms, one of which is chemical defense. This type of protection is particularly extended among sessile and/or sluggish organisms, such as sponges, soft corals or ascidians. The strategies to prevent predation are related to bad taste rather than to toxicity. Moreover, they must be considered along with nutritional quality, since the more nutritious the p...

  16. Equilibrium passive sampling as a tool to study polycyclic aromatic hydrocarbons in Baltic Sea sediment pore-water systems

    DEFF Research Database (Denmark)

    Lang, Susann-Cathrin; Hursthouse, Andrew; Mayer, Philipp;

    2015-01-01

    ) diffusion gradients at the sediment water interface and within the sediment cores and (v) site specific distribution ratios. Contamination levels were low in the northern Baltic Sea, moderate to elevated in the Baltic Proper and highest in the Gulf of Finland. Chemical activities were well below levels...... expected to cause narcosis to benthos organisms. The SPME method is a very sensitive tool that opens new possibilities for studying the PAHs at trace levels in marine environments....

  17. 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.

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

    OpenAIRE

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

    2013-01-01

    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...

  19. Population structure and biological characteristics of Siriella gracilis (Mysida) from the Exclusive Economic Zone of India

    Digital Repository Service at National Institute of Oceanography (India)

    Biju, A.; Honey, U.K.; Kusum, K.K.; Jagadeesan, L.

    crustacean components of macro-zooplankton, oc- cupying a wide variety of aquatic environments. In general, mysids are omnivores, feeding on detritus, zooplankton and phytoplankton, and thus form a link between microbial producers and secondary consumers.... Seasonality and biological characteristic of the shallow water mysid Mesopodopsis orientalis (Crustacea: Mysida) on a tropical sandy beach, Malaysia. Plankton Benthos Res., 4: 53-61. HOSTENS, K. & J. MEES, 1999. The mysid-feeding guild of demersal fishes...

  20. A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia

    OpenAIRE

    Z. M. Easton; D. R. Fuka; White, E.D.; A. S. Collick; B. Biruk Asharge; M. McCartney; S. B. Awulachew; Ahmed, A A; Steenhuis, T. S.

    2010-01-01

    A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT) model was developed to predict runoff and sediment losses from the Ethiopia...

  1. A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia

    OpenAIRE

    Z. M. Easton; D. R. Fuka; White, E.D.; A. S. Collick; B. Biruk Ashagre; M. McCartney; S. B. Awulachew; Ahmed, A A; Steenhuis, T. S.

    2010-01-01

    A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT) model was developed to predict runoff and sediment losses from the Ethiopian Blue ...

  2. Estimating natural mortality rates and simulating fishing scenarios for Gulf of Mexico red grouper (Epinephelus morio) using the ecosystem model osmose-wfs

    OpenAIRE

    Gruss, A; Schirripa, M. J.; Chagaris, D.; Velez, Laure; Shin, Yunne-Jai; Verley, Philippe; Oliveros-Ramos, R.; Ainsworth, C. H.

    2016-01-01

    The ecosystem model OSMOSE-WFS was employed to evaluate natural mortality rates and fishing scenarios for Gulf of Mexico (GOM) red grouper (Epinephelus mono). OSMOSE-WFS represents major high trophic level (HIT.) groups of species of the West Florida Shelf, is forced by the biomass of plankton and benthos groups, and has a monthly tin-se step. The present application of the model uses a recently developed 'stochastic mortality algorithm' to resolve the mortality processes of HTL groups. OSMOS...

  3. Fish Food in the Deep Sea: Revisiting the Role of Large Food-Falls

    OpenAIRE

    Higgs, Nicholas D.; Andrew R Gates; Jones, Daniel O. B.

    2014-01-01

    The carcasses of large pelagic vertebrates that sink to the seafloor represent a bounty of food to the deep-sea benthos, but natural food-falls have been rarely observed. Here were report on the first observations of three large 'fish-falls' on the deep-sea floor: a whale shark (Rhincodon typus) and three mobulid rays (genus Mobula). These observations come from industrial remotely operated vehicle video surveys of the seafloor on the Angola continental margin. The carcasses supported moderat...

  4. Invertebrate communities in northern Lake Victoria, with reference to their potential for fishery production

    OpenAIRE

    Ndawula, L.M.; Kiggundu, V.; Ochieng, H.

    1999-01-01

    The zooplankton and macrobenthic communities of Lake Victoria were sampled by lift net and Ponar grab, respectively. The zooplankton comprised copepods and cladocerans, rotifers and aquatic insect larvae. Most taxa exhibited wide distribution in the lake, with the exception of rotifers which were rare in deep offshore waters. The main components in the macro-benthos were chaoborid and chironomid larvae and molluscs. Caridina nilotica (Roux) and other groups were rare in the samples. Zooplankt...

  5. Biological valorisation of the southern Baltic Sea (Polish Exclusive Economic Zone)

    OpenAIRE

    Jan Marcin Węsławski; Jan Warzocha; Józef Wiktor; Jacek Urbański; Katarzyna Bradtke; Lucyna Kryla; Agnieszka Tatarek; Lech Kotwicki; Joanna Piwowarczyk

    2009-01-01

    A biological valuation system to assess the value associated with ecosystem stability and richness (and not that from the point of view of users) is proposed to provide scientific decision support for marine protected areas and marine spatial planning. The system is based on the assessment of individual species and habitat/species assemblages. An extensive set of recently collected (2007-08) and archival (1970-2000) data on the occurrence of marine benthos was analysed for the Polish Marine A...

  6. Diversity and structure of nematode communities across mangrove and seagrass vegetations at Gazi Bay, Kenya

    OpenAIRE

    C. Bezerra, T.N.; Mesel, I. de; Bouillon, S.; Vanreusel, A.; T. Moens

    2007-01-01

    Mangrove benthos has long been assumed to rely primarily on mangrove litter fall, but in recent years, several studies have shown that bacteria, macrobenthos and meiobenthos may preferentially utilize more labile sources such as microphytobenthos and inwelled phytoplankton and seagrass detritus from adjacent shallow waters. The relative importance of these different carbon sources for different consumer taxa, however, remains unclear. We have studied the meiofauna at Gazi Bay, Kenya, based up...

  7. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: The Lanice conchilega case study

    OpenAIRE

    De Smet, B; D'Hondt, A.-S.; Verhelst, P.; Fournier, J.; Godet, L.; Desroy, N.; Rabaut, M.; Vincx, M.; Vanaverbeke, J.

    2015-01-01

    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locatio...

  8. The situation of marine sediments in the pathway of radionuclides to man

    International Nuclear Information System (INIS)

    It is widely accepted that the marine sediments are the major reservoir of the radionuclides which are discharged into the coastal sea water. The radionuclides sorpted on the sediments would be recycled in the sea water and be accumulated by marine organisms. And some of the sorpted radionuclides would be transfered to the worm (a kind of benthos) habited in the sediments through their surface or digestive tract and then to the fishes which prey upon the benthos. Therefore, it is important to learn whether the sediments as a ''sink'' may not later become a ''source'' of these contaminants. In this paper, the problem is discussed refering to few reports which are published up to this time. Renfro estimated that about one per cent of 65Zn in the sediment would be transfered to Nereis diversicolor which directly contacts with the sediments: On the recycling of 65Zn from the sediments to the sea water, Seymour and Nelson determined the 65Zn level of 8/100 in the sea water after twelve months following shutdown of reactor. Thus they calculated the ecological half-lives which were affected by the radionuclides retention of the sediments. In our laboratory experiment on the interaction of sediments and Nereis diversicolor using 95Zr, 106Ru, 137Cs and 60Co, the similar results were observed except 137Cs which showed rather high rate of remobilization from the sediments to the sea water. Thus, it could be generally considered that the transfer of radionuclides via sediment would be minor to man. However, it should be born in mind that the increased amount of radionuclides by continuous discharge into sea may raise the level of radionuclides in the sediments and then benthos even with one per cent transfer rate from sediment to benthos. (auth.)

  9. Feeding habit and mode of living of benthic organisms, in relation to the radioecology

    International Nuclear Information System (INIS)

    The type of feeding habit, size spectrum (megalo-, macro-, meio-, and micro-benthos), life form (epi-, and endo-biose) and other modes of living of benthic organisms on and within the bottom sediments are briefly mentioned. Knowledge hitherto obtained concerning radio-ecology is also briefly reviewed in relation to those items mentioned above. Special attention is given to the relationship between the stratification and the mixing of bottom deposits, and the reworking and feeding activities of benthic animals. (auth.)

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

    OpenAIRE

    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 competitive dynamics is a potential mechanism driving coral−algal phase shifts. Here we surveyed the types and outcomes of coral interactions with benthic algae in the Line Islands of the Central Pac...

  11. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    OpenAIRE

    Guilini, K.; Levin, L. A.; Vanreusel, A.

    2012-01-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, expose...

  12. Investigation of geochemical characteristics of some natural water systems by nondestructive radioactivation analysis

    International Nuclear Information System (INIS)

    In this thesis the new theoretical and systematized approaches to the investigation of continental water systems (rivers, lakes, swamps etc) with the aim of its biogeochemical characterization are given and discussed. By nondestructive radioactivation analysis some elements (Cr, Fe, Co, Sb, Sc, Na acro and trace elements level) in components of investigated water system are determined. These elements has been determined in materials dissolved in water, suspended and bed materials, soils and the living matter populating the rivers systems Danube, Sava, V.Morava, Tisa, Karas and some lakes also (plankton, algae, benthos, crustacea, benthos, shalls and fishes) in Yugoslavia. The results are presented and discussed on the basis of parameters ''content of elements'' (new theoretical approaches) for these systems (Csub(w)-water; Csub(s)-suspended and bed materials; Csub(t)-soils; Csub(vivo)-living matter: plankton - Csub(p); aglae - Csub(al); benthos - Csub(b); crustacea - Csub(c); fishes - Csub(f)) expressed in ppm. Distribution on parameters (Fsub(x,y)) for the pairs of components of water systems also are given. The ''contents of elements'' - parameters are biogeochemical standards characterizing investigated water systems and ecological and environmental important parameters, too

  13. TRANSFERABLE PHOSPHORUS IN SEDIMENTS OF THE HUANGHE RIVER ESTUARY'S ADJACENT WATERS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on a new idea for research on cycling of marine biogenic elements, this study showed that only the leachable form phosphorus in natural grain sizes marine sediments constitutes the transferable phosphorous in the sediments. The transferable phosphorus content in the natural grain sizes surface sediments in the Huanghe River estuary adjacent waters ranges from 58.5-69.8 μg/g, accounting for only 9.1%-11.0% of the total phosphorus content, whereas the leachable form (“transferable") phosphorus content in the sediment after it was totally ground into powder was found to be 454.8-529.2 μg/g, accounting for 73.4%-89.1% of the total phosphorus. Analysis of the correlation between the biomass of benthos and the leachable form (“transferable") phosphorus showed that most of the leachable form (“transferable") phosphorus in the totally ground sediment did not participate in the marine biogeochemical cycling. Furthermore, a synchronous survey on benthos showed that the biomass of meio-and macro-benthos exhibited good positive correlation with the leachable form of phosphorus in the natural grain sizes sediment, but poorer correlation with the leachable form (“transferable") phosphorus in the totally ground sediment, indicating that transferable phosphorus in marine sediment is the leachable form of phosphorus in the natural grain sizes sediments, and is not the previously known leachable form (“transferable") phosphorus obtained from the totally ground sediment.

  14. Environmental monitoring of the Robertson Reservoir (1990-2005) : evolution of the mercury levels in the flesh of fish

    International Nuclear Information System (INIS)

    This paper provided details of an environmental monitoring analysis of the stomach contents and mercury levels in the flesh of main fish species in the Robertson Reservoir. The report noted that smelt species were dominant in the reservoir and in the adjoining Ivry Lake, while benthos were dominant the brackish waters of Lake Monger. Sticklebacks were found in the stomachs of the examined fish, while the diet of brook trout was comprised mainly of benthos in lakes and reservoirs. Arctic char mainly ate benthos in the reservoir. Landlocked salmon mainly ate fish in the reservoirs and lakes. Smelt was the primary diet of Arctic char until 2003. After 2003, Arctic char fed mainly on sticklebacks. It was observed that average mercury levels of fish of a standardized length increased by a factor of 2.7 to 4.9 after the impoundment of the reservoir. However, average mercury levels stopped increasing for dwarf Arctic char in 2003. Levels of mercury in brook trout have not increased since 1999. A significant decrease in mercury levels of rainbow smelt were observed. Average mercury levels of fish in the brackish waters of Lake Monger were lower than levels observed in most other freshwater lakes in the region. It was concluded that the number of monthly meals recommended by the fish consumption guide produced in 2001 for the Gros Mecatina region are still appropriate for the reservoir

  15. 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)

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

    International Nuclear Information System (INIS)

    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)

  17. Benthic community structure in the Gorgan Bay (Southeast of the Caspian Sea, Iran: Correlation to water physiochemical factors and heavy metal concentration of sediment

    Directory of Open Access Journals (Sweden)

    Mahmood Saghali

    2013-11-01

    Full Text Available Macrobentos frequency and biomass was investigated in the Gorgan Bay in 2011. Five sampling sites were chosen to collect benthos and sediment from the Bay using a Van Veen grab sampler. Samples were collected seasonally. Macrobenthos were indentified and their biomass was recorded. Sediment heavy metals concentration were measured using Atomic Absorption Spectroscopy. A total of 11 families belonging to three phyla of invertebrates were found. The phyla were Annelids (Nereidae, Naididae, Ampharetidae, Lumbriculidae, Tubificidae and Amphiporidae, Arthropods (Pontogammaridae, Balanidae and Chironomidae and Mollusks (Cardiidae and Scrobicularidae. Lumbriculidae (413 individuals m-2, corresponding to 18.7% and Cardiidae (55.2 g m-2, corresponding to 82.4% had the highest frequency and biomass, respectively. Annelids with an average of 1557 individuals m-2 was the most frequent groups, while, mollusks with the average of 141 g per m2 had the highest biomass. Results showed that macrobenthos frequency in summer was significantly higher than those of the other seasons, however, in the case of biomass, there was a significantly higher biomass in the spring than the other seasons. The maximum metal concentration was related to Zn and Pb, whereas, Cr and Cd had the lowest values. There was no significant difference in Zn and Cr concentrations among the sampling seasons. Pb concentration in winter was significantly lower than the other seasons, whereas, Cd concentrations in the spring and summer were significantly lower than the autumn and winter. There were some correlations between benthos frequency and water physiochemical characteristics and sediment heavy metal levels. This study indicated that benthic fauna of the Gorgan Bay and the Caspian Sea are not similar. Also, results showed that benthic fauna communities are affected by sediment heavy metal concentrations and water physiochemical characteristics, however, different benthos groups show

  18. The benthic ecosystem of the northeastern Chukchi Sea: An overview of its unique biogeochemical and biological characteristics

    Science.gov (United States)

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

    2014-04-01

    In February 2008, Lease Sale 193 generated renewed interest for oil and gas exploration in the northeastern Chukchi Sea and prompted a series of studies designed to increase our scientific knowledge of this biologically rich area. We present in this special issue the results from major field expeditions during open-water periods in the summers of 2009 and 2010. Our work focused on the biological and chemical characteristics of the benthos with the goal of establishing a strong baseline for assessing future changes that may occur in response to (1) impacts from oil and gas activities, and (2) variations in hydrography, circulation or ice retreat associated with climatic change. We found concentrations of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and 17 trace metals in sediments at natural background levels throughout the study area except at two previous (1989) drilling sites; there was no evidence that showed bioaccumulation of these substances above natural concentrations. Inorganic-N was recycled within one day throughout the water column, with evidence of substantial remineralization of organic matter in the sediments. Active efflux of sediment NO3- supports water column primary production that, in turn, sustains a rich benthos dominated by crustaceans and echinoderms that also receive, based on isotopic evidence, a benthic carbon subsidy. Benthic food webs are complex, with high trophic redundancy based on the diversity of both infaunal and epifaunal populations. The highest trophic levels in the benthos were dominated by predatory gastropods. Comparisons of gray whale and walrus distributions from aerial sightings showed a large difference between the two study years relative to the more stable benthic prey base for these animals over that period. A nearly ice-free shelf by early summer 2009 compared to 2010 revealed that walrus distributions were more closely linked to sea ice rather than to benthic prey items, indicating that rapid

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

    Science.gov (United States)

    Stief, P.

    2013-12-01

    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) 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 of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna 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 enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and

  20. Life history of a free-living marine nematode Daptonema normandicum reared in laboratory

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, R.; Ingole, B.S.

    of Environmental Biology circleshadowdwnMarch 2011circleshadowdwn Introduction Free-living nematodes are the most numerous animal group in the marine benthos. Their density includes several million m-2 of the sea floor in many shallow subtidal environments... by transferring gravid female into individual cavity block (3.7 cm diameter and 2.3 cm height) with enriched 0.8% sterile bacto-nutrient agar with following constituents (peptic digest of animal tissue 5 g, sodium chloride 5 g, beef extract 1.5 g, yeast extract 1...

  1. 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.

  2. 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.

  3. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    OpenAIRE

    Bode, A.; Fernández, C.; Mompeán, C.; Parra, S.; Rozada, F.; Valencia-Vila, J. (Joaquín); Viana, I. G.

    2014-01-01

    proyectos ANILE (CTM2009- 08396 and CTM2010-08804-E) del Plan Nacional de I+D+i y RADIALES del Instituto Español de Oceanografía (IEO). C.M. e I.G.V. disfrutaron de contratos FPI del IEO y del Ministerio de Economía y Competividad respectivamente. In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteri...

  4. Colloquium on diatom-copepod interactions

    DEFF Research Database (Denmark)

    Paffenhofer, G.A.; Ianora, A.; Miralto, A.; Turner, J.T.; Kleppel, G.S.; d'Alcala, M.R.; Casotti, R.; Caldwell, G.S.; Pohnert, G.; Fontana, A.; Muller-Navarra, D.; Jonasdottir, Sigrun; Armbrust, V.; Bamstedt, U.; Ban, S.; Bentley, M.G.; Boersma, M.; Bundy, M.; Buttino, I.; Calbet, A.; Carlotti, F.; Carotenuto, Y.; d'Ippolito, G.; Frost, B.; Guisande, C.; Lampert, W.; Lee, R.F.; Mazza, S.; Mazzocchi, M.G.; Nejstgaard, J.C.; Poulet, S.A.; Romano, G.; Smetacek, V.; Uye, S.; Wakeham, S.; Watson, S.; Wichard, T.

    2005-01-01

    From 3 to 6 November 2002, a colloquium was convened at the Benthos Laboratory of the Stazione Zoologica Anton Dohrn on Ischia, Italy, with the goal of evaluating the present status of the effects of diatoms on their main consumers, planktonic copepods, and to develop future research strategies to...... diatom defense, as well as of their nutritional quality. These working groups focused on suggesting future research needs for the different topics. As a result, several recommendations were outlined, including experimental studies. It became evident that interdisciplinary efforts are needed, involving...

  5. Mediterranean deep-sea ecosystems: Biodiversity, functioning and vulnerability = Ecosistemes profunds de la Mediterrània: Biodiversitat, funcionament i vulnerabilitat

    OpenAIRE

    Tecchio, Samuele

    2013-01-01

    Tesi realitzada a l'Institut de Ciències del Mar (ICM - CSIC) The Mediterranean Sea can be considered an excellent natural laboratory for benthic ecologists, due to its peculiar environmental conditions, its broad-scale gradients, and its deep-sea fauna. Primary production levels in the Mediterranean follow a longitudinal gradient, decreasing from west to east. The present thesis focused on the fine-mud benthos habitat of the Mediterranean Sea, on its bathyal and abyssal zones, and the com...

  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. The influence of the anthropic activities on the benthonic macroinvertebrates communities existing in the Jiu and Jiul de Vest rivers, southwest of Romania

    Directory of Open Access Journals (Sweden)

    Milca Petrovici

    2010-07-01

    Full Text Available The different sensibility of the benthonic macro-invertebrates has been used in determiningthe manner in which these communities are being influenced by the alteration of the water quality. Thepresent study aims at following this precise aspect. The benthos samples have been collected from tworivers in the south-west of Romania: Jiu (3 stations and Jiul de Vest (2 stations. There have beenstudied 10 groups of benthonic invertebrates. The benthonic communities’ density, abundance andfrequency values have varied according to the physic-chemical conditions of the collecting station.

  8. Contribución al estudio de las cubetas supralitorales (Tossa, Costa Brava)

    OpenAIRE

    Jordi CATALAN; Ballesteros, Enric

    1984-01-01

    CONTRIBUTION TO THE STUDY OF ROCK POOLS AT TOSSA, COSTA BRAVA (SPAlN). Physic~l, chemic~l and biological conditions were studied during une rainy day (21-4-1981) in ten rock pools from Tossa (Costa Brava). The srrong changes of the water conductivity (80,000 to 2,500pS. cmi ) in a short time show the osmotic regulation capacity that the organisms living there must have. Composition and concentration of neuston, plankton and benthos are also given from other visits to the po...

  9. The life cycle of the free-living marine nematode Innocuonema tentabunda De Man 1890

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, R.; Ingole, B.S.; Nanajkar, M.R.

    chromadorids, Prochromadorella sp. and Spiliphera sp. Compared to the 10-20 eggs laid by a female of I. tentabunda, specimens of Chromadora macrolaimoides Steiner are known to lay fewer eggs (10 to 12 eggs; Tiet- jen and Lee, 1973), while 14 to 19 eggs were...: Chromadoridae), cul- tured in the laboratory. Benthos Research, 53: 89-93. Thun W. von., 1968. Autökologische Untersuchungen an freilebenden Nematoden des Brackwassers, Ph.D. Thesis, University of Kiel, Germany, 72 pp. Tietjen J.H. and Lee J.J., 1973. Life...

  10. Design of underwater video attached to buoy for observing shallow water substrate

    Science.gov (United States)

    Dingtian, Y.; Wenxi, C.; Delu, P.

    2007-01-01

    Knowledge of shallow water substrate is very important for protection and management of coastal ecosystem. Traditional methods for observing shallow water substrate was by sending diver to photography and recorded with eye, which was laborious and money taking. In order to obtain the easier way to study the shallow water substrate, an underwater video system was designed. Underwater video sensor, optical sensor, sonar sensor, tiltometer, GPS system, and ascending and descending system were all attached to the buoy system, and data was gathered and processed by the computer on the ship. The obtained data could be used for analyzing substrate type, activity of benthos and ground truth data for satellite remote sensing.

  11. 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

  12. Polychaetes from a southwestern shallow shelf Atlantic area (Argentina, 38 S) affected by sewage discharge

    OpenAIRE

    RODOLFO ELÍAS; CLAUDIA S BREMEC; EDUARDO A. VALLARINO

    2001-01-01

    A benthos-sampling program was carried out in the coastal area of Mar del Plata city in order to know the composition and distribution of infaunal polychaetes living on a subtidal soft-bottom substrate affected by the sewage discharge. Sandy bottoms showed heterogeneous sediment composition and very low organic matter content. Thirty three polychaete species were identified in a range depth between 6.5 to 12.5 m. A comparison with data from 30 years ago from adjacent areas deeper than 12 m is...

  13. 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)

    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. Biodiversity, biogeography and phylogeography of Ordovician rhynchonelliform brachiopods

    DEFF Research Database (Denmark)

    Harper, David A T; Rasmussen, Christian M Ø; Liljeroth, Maria;

    2013-01-01

    local biodiversity epicentres, notably on the South China Palaeoplate; low-latitude porambonitoid-dominated faunas with early plectambonitoid and clitambonitoid representatives, as well as high-latitude assemblages mostly dominated by orthoids, can be recognized, but many taxa are rooted in Late....... Biodiversity epicentres were located on most of the larger palaeoplates, as well as within the Iapetus Ocean. Provincial patterns were disrupted during the Sandbian and early Katian with the migration of many elements of the benthos into deeper-water regimes, enjoying a more cosmopolitan distribution. Later...

  15. Review of habitat classification schemes appropriate to streams, rivers, and connecting channels in the Great Lakes drainage system

    Science.gov (United States)

    Hudson, Patrick L.; Griffiths, R.W.; Wheaton, T.J.

    1992-01-01

    Studies of lotic classification, zonation, and distribution carried out since the turn of the century were reviewed for their use in developing a habitat classification scheme for flowing water in the Great Lakes drainage basin. Seventy papers, dealing mainly with fish but including benthos, were organized into four somewhat distinct groups. A heirarchical scale of habitat measurements is suggested, and sources of data and inventory methods, including statistical treatment, are reviewed. An outline is also provided for developing a classification system for riverine habitat in the Great Lakes drainage basin.

  16. MARINE LIFE OF URUGUAY: CRITICAL UPDATE AND PRIORITIES FOR FUTURE RESEARCH LA VIDA MARINA DE URUGUAY: REVISION CRITICA Y PRIORIDADES PARA INVESTIGACIONES FUTURAS

    OpenAIRE

    Danilo Calliari; Omar Defeo; Guillermo Cervetto; Mónica Gómez; Luis Giménez; Fabrizio Scarabino; Alejandro Brazeiro; Walter Norbis

    2003-01-01

    The marine areas of Uruguay consist of the Río de la Plata estuary and the adjacent shelf and slope, part of the Subtropical Convergence Ecosystem. In this paper, the main advances in the knowledge of marine life in these areas (the known) are reviewed in order to discuss future lines of research (the unknown). Information has been separately analysed for the plankton, nekton, and benthos in each of 3 areas-the littoral, the shelfs and the "open ocean". Current knowledge of marine life is une...

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

    DEFF Research Database (Denmark)

    Stief, P.

    2013-01-01

    (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 of...... significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii......) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen....

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

    OpenAIRE

    Michela Borges; Leonardo Q Yokoyama; Antonia C. Z. Amaral

    2009-01-01

    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...

  19. Long-term changes in the composition and diversity of deep-slope megabenthos and trophic webs off Catalonia (western Mediterranean): Are trends related to climatic oscillations?

    Science.gov (United States)

    Cartes, J. E.; Maynou, F.; Fanelli, E.; Papiol, V.; Lloris, D.

    2009-07-01

    For depths ranging between 650 and 1700 m we have compared recent (2007-2008) to older (from 1988 to 1992) data, searching for long-term changes in the distribution, abundance and composition of deep megafauna (fish and decapods) off the central Catalonian coasts (western Mediterranean). Overall, in the depth interval between 600 and 1100 m, we found higher abundance of fish in 1988-1992 than in 2007, a decrease simultaneous with an increase of decapod crustaceans. Older and more recent haul replicates (after 20 years) had similar assemblage composition in the depth range 1300-1700 m, whereas we found significant changes at 1000 m. Diversity of fish was greater in 1988-1992 than in 2007, while diversity of decapod crustaceans increased between the two periods. Thus, there was a reorganization in benthopelagic communities, rather than a loss of biodiversity. This was in agreement with long-term changes described for diversity of (neritic) zooplankton in the western Mediterranean. We found a dominance of plankton-suprabenthos feeders (e.g. fish such as Lepidion lepidion, Hymenocephalus italicus and Alepocephalus rostratus; the decapods Plesionika spp. and Sergestes arcticus) in 1988-1992. In 2007 by contrast, dominance of plankton-suprabenthos feeders decreased, and assemblages were increasingly composed of benthos-feeding decapods (e.g. Aristeus antennatus, Pontophilus norvegicus and some hermit crabs) preying for instance on polychaetes. These results coincided with low/negative North Atlantic Oscillation index (NAO) in 2007 and in the period immediately before (2004-2006) 2007 (increase of benthos feeders), and with high average NAO in 1988-1992 (decrease of benthos feeders, which in turn may enhance abundance of plankton feeders). The benthic decapod Calocaris macandreae and suprabenthos (small crustaceans, mostly peracarids, living on and just beneath the sediment surface) are key prey in food webs off Catalonian margins, acting as links between surface

  20. Prediction of benthic community structure from environmental variables in a soft-sediment tidal basin (North Sea)

    Science.gov (United States)

    Puls, W.; van Bernem, K.-H.; Eppel, D.; Kapitza, H.; Pleskachevsky, A.; Riethmüller, R.; Vaessen, B.

    2012-09-01

    The relationship between benthos data and environmental data in 308 samples collected from the intertidal zone of the Hörnum tidal basin (German Wadden Sea) was analyzed. The environmental variables were current velocity, wave action, emersion time (all of which were obtained from a 2-year simulation with a numerical model) and four sediment grain-size parameters. A grouping of sample stations into five benthos clusters showed a large-scale (>1 km) zoning of benthic assemblages on the tidal flats. The zoning varied with the distance from the shore. Three sample applications were examined to test the predictability of the benthic community structure based on environmental variables. In each application, the dataset was spatially partitioned into a training set and a test set. Predictions of benthic community structure in the test sets were attempted using a multinomial logistic regression model. Applying hydrodynamic predictors, the model performed significantly better than it did when sediment predictors were applied. The accuracy of model predictions, given by Cohen's kappa, varied between 0.14 and 0.49. The model results were consistent with independently attained evidence of the important role of physical factors in Wadden Sea tidal flat ecology.

  1. 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.

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

    International Nuclear Information System (INIS)

    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. Differential processing of anthropogenic carbon and nitrogen in benthic food webs of A Coruña (NW Spain) traced by stable isotopes

    Science.gov (United States)

    Bode, Antonio; Fernández, Consolación; Mompeán, Carmen; Parra, Santiago; Rozada, Fernando; Valencia-Vila, Joaquín; Viana, Inés G.

    2014-08-01

    In this study the effect of inputs of organic matter and anthropogenic nitrogen at small spatial scales were investigated in the benthos of the Ria of A Coruña (NW Spain) using stable carbon and nitrogen isotopes. This ria is characteristically enriched in nutrients provided either by marine processes (as coastal upwelling) or by urban and agricultural waste. Stable isotope composition in trophic guilds of infaunal benthos revealed spatial differences related to their nutrient inputs. The main difference was the presence of an additional chemoautotrophic food web at the site with a large accumulation of organic matter. The enrichment in heavy nitrogen isotopes observed in most compartments suggests the influence of sewage-derived nitrogen, despite large inputs of marine nitrogen. Macroalgae (Fucus vesiculosus) resulted significantly enriched at the site influenced by estuarine waters. In contrast, no differences were found in mussels (Mytilus galloprovincialis), thus suggesting a major dependence on marine nutrient sources for this species. However, the estimations of anthropogenic influence were largely dependent on assumptions required to model the different contributions of sources. The measurement of stable isotope signatures in various compartments revealed that, despite anthropogenic nutrients are readily incorporated into local food webs, a major influence of natural marine nutrient sources cannot be discarded.

  4. Late Paleocene-middle Eocene benthic foraminifera on a Pacific seamount (Allison Guyot, ODP Site 865): Greenhouse climate and superimposed hyperthermal events

    Science.gov (United States)

    Arreguín-Rodríguez, Gabriela J.; Alegret, Laia; Thomas, Ellen

    2016-03-01

    We investigated the response of late Paleocene-middle Eocene (~60-37.5 Ma) benthic foraminiferal assemblages to long-term climate change and hyperthermal events including the Paleocene-Eocene Thermal Maximum (PETM) at Ocean Drilling Program (ODP) Site 865 on Allison Guyot, a seamount in the Mid-Pacific Mountains. Seamounts are isolated deep-sea environments where enhanced current systems interrupt bentho-pelagic coupling, and fossil assemblages from such settings have been little evaluated. Assemblages at Site 865 are diverse and dominated by cylindrical calcareous taxa with complex apertures, an extinct group which probably lived infaunally. Dominance of an infaunal morphogroup is unexpected in a highly oligotrophic setting, but these forms may have been shallow infaunal suspension feeders, which were ecologically successful on the current-swept seamount. The magnitude of the PETM extinction at Site 865 was similar to other sites globally, but lower diversity postextinction faunas at this location were affected by ocean acidification as well as changes in current regime, which might have led to increased nutrient supply through trophic focusing. A minor hyperthermal saw less severe effects of changes in current regime, with no evidence for carbonate dissolution. Although the relative abundance of infaunal benthic foraminifera has been used as a proxy for surface productivity through bentho-pelagic coupling, we argue that this proxy can be used only in the absence of changes in carbonate saturation and current-driven biophysical linking.

  5. Comparative diets of subyearling Atlantic salmon and subyearling coho salmon in Lake Ontario tributaries

    Science.gov (United States)

    Johnson, James H.; Ringler, Neil H.

    2016-01-01

    Restoration of Atlantic salmon (Salmo salar) in Lake Ontario could potentially be negatively affected by the presence of non-native salmonids that are naturalized in the basin. Coho salmon (Oncorhynchus kisutch) have been spawning successfully in Lake Ontario tributaries for over 40 years and their juveniles will reside in streams with juvenile Atlantic salmon for one year. This study sought to examine interspecific diet associations between these species, and to compare diets to the composition of the benthos and drift in three Lake Ontario tributaries. Aquatic insects, mainly ephemeropterans and chironomids were the major prey consumed by subyearling Atlantic salmon whereas terrestrial invertebrates made up only 3.7% of the diet. Ephemeropterans and chironomids were the primary aquatic taxa consumed by subyearling coho salmon but, as a group, terrestrial invertebrates (41.8%) were the major prey. In sympatry, Atlantic salmon fed more actively from the benthos whereas the diet of coho salmon was more similar to the drift. The different feeding pattern of each species resulted in low interspecific diet similarity. There is likely little competition between these species for food in Lake Ontario tributaries as juveniles.

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

    Science.gov (United States)

    Johnson, James H.; McKenna Jr, 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.

  7. 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.

  8. Organochlorines, brominated flame retardants and mercury levels in six seabird species from the Gulf of St. Lawrence (Canada): Relationships with feeding ecology, migration and molt

    Energy Technology Data Exchange (ETDEWEB)

    Lavoie, Raphael A., E-mail: lavoie.raphael@gmail.co [Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5 (Canada); Champoux, Louise [Wildlife and Landscape Science, Science and Technology Branch, Environment Canada, 1 141 Route de l' Eglise, C.P. 10 100, Quebec, QC, G1V 4H5 (Canada); Rail, Jean-Francois [Canadian Wildlife Service, Environmental Stewardship Branch, Environment Canada, 1 141 Route de l' Eglise, C.P. 10 100, Quebec, QC, G1V 4H5 (Canada); Lean, David R.S. [Biology Department, University of Ottawa, 30 Marie Curie, Ottawa, ON, K1N 6N5 (Canada)

    2010-06-15

    Concentrations of organochlorines (OCs), brominated flame retardants (BFRs) and mercury (Hg) were measured in eggs of six seabird species breeding in the Gulf of St. Lawrence, Canada. Stable nitrogen (delta{sup 15}N) and carbon (delta{sup 13}C) isotopes were used as ecological tracers to measure trophic level and connectivity with benthos, respectively. Concentrations, patterns as well as ecological tracers varied significantly between species. The sum of polychlorinated biphenyls (SIGMAPCBs) was the most important group measured in all seabird species based on concentration followed generally by the sum of chlorinated pesticides (SIGMACPs), the sum of brominated flame retardants (SIGMABFRs) and finally total Hg (THg). SIGMAPCBs, SIGMACPs and SIGMABFRs increased with trophic level, whereas THg did not. Only SIGMABFRs increased with a higher connectivity with the benthos. Seabird species resident to the Great Lakes-St. Lawrence ecosystem showed higher Hg and BFR levels than migratory species. Molt patterns were used to explain variations of contaminant levels. - Concentrations and patterns of contaminants in seabirds are highly species-specific and related to trophic position, migration and molt.

  9. Climate change and glacier retreat drive shifts in an Antarctic benthic ecosystem.

    Science.gov (United States)

    Sahade, Ricardo; Lagger, Cristian; Torre, Luciana; Momo, Fernando; Monien, Patrick; Schloss, Irene; Barnes, David K A; Servetto, Natalia; Tarantelli, Soledad; Tatián, Marcos; Zamboni, Nadia; Abele, Doris

    2015-11-01

    The Antarctic Peninsula (AP) is one of the three places on Earth that registered the most intense warming in the last 50 years, almost five times the global mean. This warming has strongly affected the cryosphere, causing the largest ice-shelf collapses ever observed and the retreat of 87% of glaciers. Ecosystem responses, although increasingly predicted, have been mainly reported for pelagic systems. However, and despite most Antarctic species being benthic, responses in the Antarctic benthos have been detected in only a few species, and major effects at assemblage level are unknown. This is probably due to the scarcity of baselines against which to assess change. We performed repeat surveys of coastal benthos in 1994, 1998, and 2010, analyzing community structure and environmental variables at King George Island, Antarctica. We report a marked shift in an Antarctic benthic community that can be linked to ongoing climate change. However, rather than temperature as the primary factor, we highlight the resulting increased sediment runoff, triggered by glacier retreat, as the potential causal factor. The sudden shift from a "filter feeders-ascidian domination" to a "mixed assemblage" suggests that thresholds (for example, of tolerable sedimentation) and alternative equilibrium states, depending on the reversibility of the changes, could be possible traits of this ecosystem. Sedimentation processes will be increasing under the current scenario of glacier retreat, and attention needs to be paid to its effects along the AP. PMID:26702429

  10. Selected trace metals (As, Cd and Hg) distribution and contamination in the coastal wetland sediment of the northern Beibu Gulf, South China Sea

    International Nuclear Information System (INIS)

    Highlights: ► Spatial and temporal distributions of As, Cd and Hg were presented. ► Mean sedimentation rates were 0.93–1.37 cm year−1 during 1920s to 2008. ► Metal content increased evidently in 1985–2008 due to anthropogenic impacts. ► Locally the surface sediments have potential ecological risk of As to benthos. -- Abstract: Contamination with As, Cd and Hg, their spatial and temporal distribution are reported from the coastal wetland sediments of the northern Beibu Gulf, South China Sea. The content of As, Cd, Hg and TOC in surface sediments is 8.1 ± 5.8 μg g−1, 0.08 ± 0.14 μg g−1, 0.034 ± 0.028 μg g−1 and 0.45 ± 0.39%, respectively. The mean sedimentation rates are 0.93–1.37 cm year−1 during 1920s to 2008 determined by 210Pb and 137Cs dating in three cores. The vertical profiles of As, Cd and Hg content in the cores retrieved from Qin and Nanliu River estuaries show increasing trends during 1985–2008 due to anthropogenic impact caused by local economic development. Locally the surface sediments have potential ecological risk of As to benthos according to the NOAA sediment quality guidelines

  11. Central Northwest Pacific biota and their radioactivity

    International Nuclear Information System (INIS)

    Ecological and radiological surveys of biota around a proposed dumping site have been carried out by the Japanese Fisheries Agency. Micronekton were collected with a KOC net towed at prescribed depths. Fish nekton were collected with a KMT net towed from 1 to 2 hours either obliquely or horizontally at prescribed depths. This large net enabled the collection of larger organisms not collectable with KOC nets. Benthos were collected via benthos nets. Deep sea rattails and gammarids were collected with trapnets. In 1985, larger gear with mouth diameters of 1.8m were used with older gear having mouth diameters of 0.9m and used previously. New large gear allowed better collecting efficiency. Radioactivity measurements were carried out by gammaspectrometry with GeLi detectors on ashed samples. In almost all samples, Cs-137 was detected. In addition Co-60 was detected in some samples. Data obtained by the Tokai Regional Fisheries Research Laboratory were examined and summarized by the Ecology Working Group under the Executive Committee on Environmental Safety Assessment of Sea Dumping of Low level Radioactive Wastes in the Radioactive Waste Management Center

  12. Organochlorines, brominated flame retardants and mercury levels in six seabird species from the Gulf of St. Lawrence (Canada): Relationships with feeding ecology, migration and molt

    International Nuclear Information System (INIS)

    Concentrations of organochlorines (OCs), brominated flame retardants (BFRs) and mercury (Hg) were measured in eggs of six seabird species breeding in the Gulf of St. Lawrence, Canada. Stable nitrogen (δ15N) and carbon (δ13C) isotopes were used as ecological tracers to measure trophic level and connectivity with benthos, respectively. Concentrations, patterns as well as ecological tracers varied significantly between species. The sum of polychlorinated biphenyls (ΣPCBs) was the most important group measured in all seabird species based on concentration followed generally by the sum of chlorinated pesticides (ΣCPs), the sum of brominated flame retardants (ΣBFRs) and finally total Hg (THg). ΣPCBs, ΣCPs and ΣBFRs increased with trophic level, whereas THg did not. Only ΣBFRs increased with a higher connectivity with the benthos. Seabird species resident to the Great Lakes-St. Lawrence ecosystem showed higher Hg and BFR levels than migratory species. Molt patterns were used to explain variations of contaminant levels. - Concentrations and patterns of contaminants in seabirds are highly species-specific and related to trophic position, migration and molt.

  13. The natural diet of a hexactinellid sponge: Benthic pelagic coupling in a deep-sea microbial food web

    Science.gov (United States)

    Pile, Adele J.; Young, Craig M.

    2006-07-01

    Dense communities of shallow-water suspension feeders are known to sidestep the microbial loop by grazing on ultraplankton at its base. We quantified the diet, rates of water processing, and abundance of the deep-sea hexactinellid sponge Sericolophus hawaiicus, and found that, like their demosponge relatives in shallow water, hexactinellids are a significant sink for ultraplankton. S. hawaiicus forms a dense bed of sponges on the Big Island of Hawaii between 360 and 460 m depth, with a mean density of 4.7 sponges m -2. Grazing of S. hawaiicus on ultraplankton was quantified from in situ samples using flow cytometry, and was found to be unselective. Rates of water processing were determined with dye visualization and ranged from 1.62 to 3.57 cm s -1, resulting in a processing rate of 7.9±2.4 ml sponge -1 s -1. The large amount of water processed by these benthic suspension feeders results in the transfer of approximately 55 mg carbon and 7.3 mg N d -1 m -2 from the water column to the benthos. The magnitude of this flux places S. hawaiicus squarely within the functional group of organisms that link the pelagic microbial food web to the benthos.

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

    International Nuclear Information System (INIS)

    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

  15. Biological impact of eutrophication in the bay of somme and the induction and impact of anoxia

    Science.gov (United States)

    Desprez, M.; Rybarczyk, H.; Wilson, J. G.; Ducrotoy, J. P.; Sueur, F.; Olivesi, R.; Elkaim, B.

    The first effects of eutrophication in the Bay of Somme became apparent in the years 1982-1985, when the cockle population collapsed. Areas of high mortality were mapped. Following exceptionally high summer temperatures, other effects were seen in 1982, 1983 and 1989, notably a mass mortality of the benthos. It appeared that the mortality of the benthos was a direct result of anoxia in the water promoted by phytoplankton blooms which were due to high nitrogen levels (nitrates from river and land runoff; ammonium from estuarine bivalve populations). Effects from the change in the benthic community (the disappearance of Cerastoderma edule and the proliferation of Pygospio elegans) were also apparent higher up in the food chain, viz. changes in the diet of the two main predators of the bivalve, the oystercatcher ( Haematopus ostralegus) and the common gull ( Larus canus). Following respirometry measurements of the water, sediment and the major macrobenthic species ( Cerastoderma edule, Macoma balthica, Nereis diversicolor, Hydrobia ulvae), a model for anoxia was constructed.

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

    International Nuclear Information System (INIS)

    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 cycle. In reservoir R-3 there was no

  17. 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

  18. 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

  19. Macrobenthos of Kakinada Bay in the Godavari delta, East coast of India: comparing decadal changes

    Science.gov (United States)

    Raut, Dipti; Ganesh, T.; Murty, N. V. S. S.; Raman, A. V.

    2005-03-01

    A one-year study (1995-1996) on the macrobenthos over a spread of (37) hydrographically differing GPS-fixed sites in Kakinada Bay (mean salinity 27.16±0.4) and adjacent mangrove channels (14.78±0.55) in the Godavari delta, one of India's largest estuarine systems, revealed a great preponderance of benthic life. There were 11 diverse taxa represented by 95 species collected through several (303) grab and dredge hauls. Based on Bray-Curtis similarity through hierarchical clustering implemented in PRIMER, it was possible to distinguish the benthos into four assemblages each of which represented sites in the Central and North bay ( Paphia textrix - Typhlocarcinus sp. Assemblage), South-East bay ( Protankyra similis - Paphia malabarica Assemblage), Mangrove Outlets ( Cerithidea cingulata Assemblage) and Mangrove channels ( Diopatra neapolitana Assemblage). Benthos densities (mean nos. dredge haul -1) were highest (299 individuals) at sites close to mangrove outlets. Species diversity (Margalef, d; Shannon-Wiener, H') was low in general ( d 1.244 to 2.251 and H' 0.038 to 1.502). Sediments were mostly clayey-silt in nature except in southeast bay where they are silt-sand. Organic matter (mean) was at or near 1.3%. The observations have revealed marked changes in benthic community structure relative to an earlier investigation held in 1958-1963 in this area. Over the years, species such as Turritella duplicata, Tonna dolium and Placuna placenta found in considerable numbers previously have dwindled. Anomia, Bursa and Atrina and echinoderms, Astropecten indica, Echinodiscus auritus and Temnopleurus toreumaticus and the brachiopod, Lingula sp. of common occurrence in early 60s are absent altogether attributable to long-term natural trends during the intervening years and/or events accompanying human impingement (e.g. industrial and urban growth, port expansion measures, aquaculture, mangrove denudation etc.). Despite such large-scale alterations in benthos community

  20. 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)

    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)

  1. The reconstruction of hydrobiological data for lakes of Karelia

    Directory of Open Access Journals (Sweden)

    Kalinkina Nataliya Michailovna

    2012-03-01

    Full Text Available The factors which determined the variability of hydrochemical and hydrobiological pa-rameters of lakes of Karelia (in total 225 lakes are analyzed. It is shown that oligo-mesotrophic lakes dominate among studied water bodies whereas the share of eutrophic lakes is low (about 10%. The biomass of phytoplankton and zooplankton was not exactly reconstructed by using the total phosphorous concentration as the argument in regression analysis due to high variability of these parameters. The hydrochemical and hydrobiological indexes were worked to classify the lakes of Karelia. The methods of prognoses of zooplankton biomass (with accuracy of 55–86% and benthos biomass (with accuracy of 71–78% on the base of the total phosphorous concentration were worked by using the contingency tables.

  2. Case Study of Marine Ecological Compensation Criteria Based on Environmental Risk

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ji-wei; YANG Zhi-feng; TANG Jun-jian; CHEN Chu-han

    2009-01-01

    This paper forecasted and identified the environmental risks and ecological effect caused by chemical spill by simulating the xylene spill in Xiamen waters. The evaluation objects of ecological damage include four parts: marine ecosystem services, sea water quality, marine biological resources (plankton, benthos, nekton, etc.), and beach habitat. The ecological compensation criterion was confirmed as 1.73 million Yuan per year in the short term and 8.09 million Yuan in the long term. And an ecological compensation mode was suggested to be that if the chemical spill does not occur this year, the compensation will return to the enterprise next year; while if chemical spill occurs, the compensation will not be returned. The encouragement mechanism "returning compensation if no spill" might motivate enterprises to improve the environmental risk management and avoid the risks.

  3. A laboratory study on sediment resuspension within arrays of rigid cylinders

    Science.gov (United States)

    Tinoco, Rafael O.; Coco, Giovanni

    2016-06-01

    We present results from laboratory experiments on flow through submerged arrays of rigid cylinders embedded in a sandy bed. Using rigid, cylindrical elements to mimic vegetation and benthos, we account for only the physical effects resulting from their presence, eliminating biological factors, such as biofilms and root systems. In line with previous findings, rigid arrays modify the flow mean and turbulent velocity statistics. However, even if the flow speed is significantly damped within dense arrays, the amount of sediment that gets lifted into suspension increases as the density of the array increases due to array- and cylinder-scale turbulence. We present a first attempt to provide predictive relationships of suspended sediment concentration using an alternative approach for the Shields parameter with an empirical coefficient to account for turbulence generated by submerged arrays of rigid cylinders. A similar analysis, using a ratio of populated to non-populated Shields parameter, is conducted to predict resuspension as a function of array density.

  4. Changing of the HSP70 Content in the Baikal Endemic Sponges Lubomirskiidae Under Conditions of Hyperthermia

    Directory of Open Access Journals (Sweden)

    Itskovich V.B.

    2015-12-01

    Full Text Available Baikal endemic sponges (Lubomirskiidae make up the bulk of the benthos biomass of the lake. For the first time the changes in the content of HSP70 in response to elevated environment temperature were analyzed in three endemic species of Baikal sponges: Baikalospongia bacillifera (Dybowski, 1880, B. intermedia (Dybowski, 1880 and Swartschewskia papyracea (Dybowski, 1880. Interspecific variability of constitutive HSP70 level was revealed for representatives of the three analyzed Lubomirskiidae species. After exposure at 13 °С for 3 and 7 days opposite changes were noted in the amount of HSP70. Under conditions of hyperthermia the protein level decrease at Baikalospongia species, while at the S. papyracea HSP70 content slightly increased. The differences in the mechanisms of stress adaptation probably affect the thermal resistance of the species, as well as are evidence supporting their specific status.

  5. Calcification generates protons for nutrient and bicarbonate uptake

    Science.gov (United States)

    McConnaughey, T. A.; Whelan, J. F.

    1997-03-01

    The biosphere's great carbonate deposits, from caliche soils to deep-sea carbonate oozes, precipitate largely as by-products of autotrophic nutrient acquisition physiologies. Protons constitute the critical link: Calcification generates protons, which plants and photosynthetic symbioses use to assimilate bicarbonate and nutrients. A calcium ATPase-based "trans" mechanism underlies most biological calcification. This permits high calcium carbonate supersaturations and rapid carbonate precipitation. The competitive advantages of calcification become especially apparent in light and nutrient-deficient alkaline environments. Calcareous plants often dominate the lower euphotic zone in both the benthos and the plankton. Geographically and seasonally, massive calcification concentrates in nutrient-deficient environments including alkaline soils, coral reefs, cyanobacterial mats and coccolithophorid blooms. Structural and defensive uses for calcareous skeletons are sometimes overrated.

  6. 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. PMID:25817311

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

    International Nuclear Information System (INIS)

    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

  8. Biogeochemical characterization of some continental water systems in Yugoslavia by instrumental activation analysis

    International Nuclear Information System (INIS)

    Trace elements in some continental water systems in Yugoslavia have been investigated by IAA. The results of the determination of trace elements are presented in this paper on the basis of the theory of concentration parameters for the components of the rivers (dissolved materials in water, suspended and bed materials, plankton, benthos, algae, crustacea and fish) lakes, swamps and in the soils. The investigated water systems were rivers Danube, Sava, Tisa and V. Morava, lakes of Skadar, Ohrid, Dorjan, Bor, the Melenci Swamp and soils from different regions of the Danube basin. Samples up to 0.1g were sealed in quartz ampoules and irradiated at a thermal neutron flux of 1.5x1013 n cm-2s-1 for 2-5 days together with standards. After cooling for 4-7 days the samples were measured with a Ge/Li/ detector for 800 to 2000 s. (T.G.)

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

    International Nuclear Information System (INIS)

    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.)

  10. 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.

  11. Earth's earliest biosphere: Its origin and evolution

    International Nuclear Information System (INIS)

    Some of the subjects discussed are related to the early biogeologic history, the nature of the earth prior to the oldest known rock record, the early earth and the Archean rock record, the prebiotic organic syntheses and the origin of life, Precambrian organic geochemistry, the biochemical evolution of anaerobic energy conversion, the isotopic inferences of ancient biochemistries, Archean stromatolites providing evidence of the earth's earliest benthos, Archean microfossils, the geologic evolution of the Archean-Early Proterozoic earth, and the environmental evolution of the Archean-Early Proterozoic earth. Other topics examined are concerned with geochemical evidence bearing on the origin of aerobiosis, biological and biochemical effects of the development of an aerobic environment, Early Proterozoic microfossils, the evolution of earth's earliest ecosystems, and geographic and geologic data for processed rock samples. Attention is given to a processing procedure for abiotic samples and calculation of model atmospheric compositions, and procedures of organic geochemical analysis

  12. 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)

    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 134Cs, 137Cs, and 110mAg in marine biota, including not only fish and shellfish but also benthos. It is well known that 108mAg, one of the radioactive isotopes of Ag, was observed in some kinds of squid and octopus before this accident. As the results, 110mAg 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)

  13. 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.

  14. Radio-capacity of different types of natural ecosystems (without man) and their ecological standardization principles

    International Nuclear Information System (INIS)

    In this article the theory of radio-capacity of natural ecosystems (excluding mankind) is applied to the definition of ecological standards for permissible releases in the environment. A specific limit of radionuclide contamination of wild life which can be considered as the basis of an ecological standardization (64-640 kb kg-1) is proposed. BAsic equations for evaluation of maximum permissible releases into a lake ecosystem are presented. Ecological standards for benthos are 10 to 100 times less than the ecological standards for inhabitants of the water column. It is shown that the existing levels of radionuclide contamination of terrestrial slope ecosystems in the 30-km zone around Chernobyl Nuclear Power Plant (NPP) exceed the proposed ecological standards. (authors)

  15. Trace fossils assemblage and depositional environment of Turonian calcareous sandstones in the southern Benue Trough, Nigeria

    Science.gov (United States)

    Akpan, Etie B.; Nyong, Eyo E.

    A calcareous sandstone sequence that forms part of the Eze-Aku Formation (Reyment) features an assemblage of ichnofossils in a section exposed on a quarry face. The traces encountered include horizontal burrows, some of which are preserved as casts, lined with organic matter and belonging to the ichnogenera Gyrolithes, Pholeus and Arthrophycus. Three other types of trace fossils are described as horizontal crawling trails, flat impressions and cylindrical shafts without formal names. Gyrolithes are by far the dominant traces in this sequence. The degree of bioturbation is high in every horizon. Body fossils are very rare except for scattered occurrence of fragments of calcitic pelecypod shells. Ichnological and lithological considerations suggest that the sediments were deposited in an aerated shallow shelf environment which supported an assemblage of decapods, worms and other shallow water marine benthos. Deposition was generally below wave base under a continuous but relatively slow rate of sedimentation.

  16. North Sea Forum report: March 1987

    International Nuclear Information System (INIS)

    The North Sea forum includes voluntary and statutory organisations interested in many aspects of the marine environment and its management. Thirty 'topic briefs' have been compiled to make recommendations on a variety of subjects. These have been consolidated in the Statement of the North Sea Forum which is included. The thirty topic briefs include the oceanography of the North Sea, reports on imputs of inorganic and organic contaminants from rivers, direct discharges, the atmosphere, dumping ships and platforms. One of this group, on the radioactivity in the North Sea, is indexed separately. (9 papers) The ecological effects of man's activities on plankton, benthos, fishes, shellfish, mammals, seabirds, waders, wildfowl, seaducks and plants are covered. (11 papers). The effects of other human uses on the marine environment are covered in 9 papers -military activities, recreation etc. (UK)

  17. Osseous skeletal material and fish scales in marine sediments under the oxygen minimum zone off northern and central Chile

    Science.gov (United States)

    Milessi, Andrés C.; Sellanes, Javier; Gallardo, Víctor A.; Lange, Carina B.

    2005-08-01

    The significance of whale falls for the study of the biogeography, evolution and biodiversity of deep-sea biota has been recently recognized by international programs since large carcasses are known to give rise to biogenic chemosynthetic ecosystems. However, the plain accumulation of smaller bone material in the shallower settings of the continental shelf and upper slope under the hypoxic conditions of the Oxygen Minimum Zone (OMZ), has received much less attention. Here we describe new findings of skeletal material and fish scales in marine sediments under the OMZ off northern and central Chile which, combined with previous reports for the study area, lead us to suggest the existence of a band in the benthos of accumulation of bones and scales extending at least twenty degrees in latitude (18-38° S). Future studies should focus on the characterization of biotic communities living upon these resources in order to elucidate their peculiarities and importance in the Eastern South Pacific.

  18. Changes in the fish community and water quality during seven years of stocking piscivorous fish in a shallow lake

    DEFF Research Database (Denmark)

    Skov, Christian; Perrow, M.R.; Berg, Søren; Skovgaard, H.

    2002-01-01

    zooplanktivorous and benthivorous fish, with resultant effects on lower trophic levels and ultimately water quality. 2. The fish community and water quality parameters (Secchi depth, concentrations of total phosphorus, chlorophyll a and suspended solids) were monitored between 1996 and 2000 and relationships were...... evaluated between predatory fish and potential prey and between zooplanktivorous or benthivorous fish and water quality parameters. In addition, potential consumption of piscivorous fishes was calculated. 3. The density of fish feeding on larger zooplankton or benthos (roach >15 cm, crucian carp >15 cm......) declined distinctly during the study period. This effect was attributed to predation by large (>50 cm) pike. Based on scale readings, we cautiously suggest that the stocking of 0+ pike boosted the adult pike population to produce an unexpected impact in later years. Conversely, no direct impact of stocked...

  19. Biological valorisation of the southern Baltic Sea (Polish Exclusive Economic Zone

    Directory of Open Access Journals (Sweden)

    Jan Marcin Węsławski

    2009-09-01

    Full Text Available A biological valuation system to assess the value associated with ecosystem stability and richness (and not that from the point of view of users is proposed to provide scientific decision support for marine protected areas and marine spatial planning. The system is based on the assessment of individual species and habitat/species assemblages. An extensive set of recently collected (2007-08 and archival (1970-2000 data on the occurrence of marine benthos was analysed for the Polish Marine Areas. Based on matching data sets of sediments, the euphotic zone, temperature and salinity, as well as fetch and sea current values, a GIS model was used to visualise the results; a map indicates the two areas which are considered to be biologically the most valuable (Puck Bay and the stony shallows of the central coast.

  20. 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.

  1. 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.

  2. 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...... include relatively few groups normally regarded as oxygen-sensitive. Nevertheless, high altitude assemblages react more strongly to lowering of oxygen saturation, and are thus more sensitive to organic pollution. 5. Oxygen deficiency has been overlooked completely in studies of the altitudinal...

  3. 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.

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

    DEFF Research Database (Denmark)

    Richardson, Kathrine; Visser, Andre; Pedersen, Flemming

    2000-01-01

    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...... 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...... 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...

  5. Comparison of stomach contents and condition of two catfish species living at ambient temperatures and in a heated discharge

    International Nuclear Information System (INIS)

    The lower condition factors for two catfish species in water heated by effluents from APCo's Glen Lyn, Virginia plant as compared to control areas probably is not due to lack of food as evidenced by macroinvertebrate sampling and the fact that only 4.3 percent of the catfish stomachs were empty. Results suggested that young-of-the-year channel catfish were nonselectively eating food organisms present at both control and heated stations. The difference between stomach contents of flatheat catfish from the heated site and fauna available at that site indicated that fish were either moving out of the heated area to feed or were selectively feeding on organisms (particularly mayflies) which were in the substrate or drifted into the heated area. Stomach contents of the two species and distribution and abundance of the macroinvertebrate benthos community are detailed

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

    International Nuclear Information System (INIS)

    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)

  7. 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.

  8. 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.

  9. Seasonal proliferation rates and the capacity to express genes involved in cell cycling and maintenance in response to seasonal and experimental food shortage in Laternula elliptica from King George Island.

    Science.gov (United States)

    Husmann, G; Philipp, E E R; Abele, D

    2016-07-01

    Melting of coastal glaciers at the West Antarctic Peninsula (WAP) causes shorter winter sea ice duration, intensified ice scouring, sediment erosion and surface freshening in summer, which alters coastal productivity and feeding conditions for the benthos. The soft shell clam Laternula elliptica is a fast growing and abundant filter feeder in coastal Antarctica and a key element for bentho-pelagic carbon recycling. Our aim was to assess the cellular growth and maintenance capacity of small and large clams during natural winter food shortage (seasonal sampling) and in response to experimental starvation exposure. We measured tissue specific proliferation rates, the expression of cell cycling genes, and the iron binding protein Le-ferritin in freshly collected specimens in spring (Nov 2008) and at the end of summer (March 2009). For the experimental approach, we focused on 14 cell cycling and metabolic genes using the same animal size groups. Mantle tissue of young bivalves was the only tissue showing accelerated proliferation in summer (1.7% of cells dividing per day in March) compared to 0.4% dividing cells in animals collected in November. In mantle, siphon and adductor muscle proliferation rates were higher in younger compared to older individuals. At transcript level, Le-cyclin D was upregulated in digestive gland of older animals collected in spring (Nov) compared to March indicating initiation of cell proliferation. Likewise, during experimental starvation Le-cyclin D expression increased in large clam digestive gland, whereas Le-cyclin D and the autophagic factor beclin1 decreased in digestive gland of smaller starved clams. The paper corroborates earlier findings of size and age dependent differences in the metabolic response and gene expression patterns in L. elliptica under energetic deprivation. Age structure of shallow water populations can potentially change due to differences in cellular response between young and old animals as environmental stress

  10. 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

  11. 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)

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

    International Nuclear Information System (INIS)

    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. Effect of deposit feeders on migration of 137Cs in lake sediments

    International Nuclear Information System (INIS)

    Illite clay particles with adsorbed 137Cs were added as a submillimeter layer to the surface of silt-clay sediments contained in rectangular Plexiglas cells stored in a temperature-regulated aquarium, in order to trace the effect of the oligochaete, Tubifex tubifex, and the amphipod, Pontoporeia hoyi, on mass redistribution near the sediment-water interface. A well-collimated NaI gamma detector scanned each sediment column (approximately 10 cm deep) at daily or weekly intervals of six months, depicting the time evolution of radioactivity with and without added benthos. In a cell with tubificids (approximately 5 X 104 m-2), which feed below 3 cm and defecate on surface sediments, the labeled layer was buried at a rate of 0.052 +- 0.007 cm/day (200C). When labeled particles entered the feeding zone, 137Cs reappeared in surface sediments creating a bimodal activity profile. In time, the activity tended toward a uniform distribution over the upper 6 cm, decreasing exponentially below to undetectable levels by 9 cm. In a cell with amphipods (approximately 1.6 X 104 m-2) uniform activity developed rapidly (approximately 17 days) down to a well-defined depth (1.5 cm). The mixing of sediments by Pontoporeia is described by a simple quantitative model of eddy diffusive mixing of sediment solids. The value of the diffusion coefficient, 4.4 cm2/yr (70C) was computed from a least squares fit of theoretical to observed profile broadening over time. In a cell without benthos, small but measurable migration of 137Cs indicated an effective molecular diffusion coefficient of 0.02 cm2/yr. (Auth.)

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

    Science.gov (United States)

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

    2011-07-01

    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.

  15. Food for the deep sea: utilization, dispersal, and flux of nekton falls at the Santa catalina basin floor

    Science.gov (United States)

    Smith, Craig R.

    1985-04-01

    The role of large food falls in the ecology of deep-sea benthos has been the topic of much speculation and little direct study. The submersible Alvin and free vehicles were used to assess experimentally the fate and flux of nekton falls at a depth of 1310 m in the Santa Catalina Basin. Parcels of dead fish (1 to 40 kg) placed on the basin floor rapidly attracted large aggregations of fish and invertebrate scavengers, which consumed the bulk of the carrion within hours to days. The most strongly attracted megafaunal scavenger was the ophiuroid Ophiophthalmus normani, the dominant megabenthic species in the background epifaunal assemblage. O. normani attained densities of 700 m -2 in aggregations containing thousands of individuals, and remained at elevated abundance around baitfalls for weeks. Six other megafaunal species also appeared to feed directly on carrion, including two of the next ten most abundant megabenthic organisms. Several of these species exhibited roosting behavior near baitfalls; this is probably an adaptation for exploiting rich but unpredictable food resources. Scavengers consumed bait parcels so rapidly and then dispersed so broadly that energy from nekton falls apparently reaches infaunal benthos only in very attenuated form, yielding at most minor community enhancement. Necrophagy was not the sole cause of megafaunal attraction to bait parcels; there is evidence that three predacious species were drawn to high concentrations of their ophiuroid prey. Benthic standing-crop and turnover-rate estimates for nekton falls suggest that perhaps 11% of benthic community respiratory requirements are met by nekton carcasses reaching the basin floor; the flux of energy to the deep sea through such fall events thus merits further study. These energy bonanzas occur frequently enough that O. normani, and other common necrophages, are likely to encounter at least one nekton fall per year. Such windfalls thus could influence the life histories of several

  16. Thermal ecological study on the water quality and biological impact assessment in the vicinity of Madras Atomic Power Station, Kalpakkam, India

    International Nuclear Information System (INIS)

    Madras Atomic Power Station (MAPS), Kalpakkam uses seawater as tertiary coolant at the rate of 35m3/sec employing a once through type of circuit. The discharged water travels as a canal and mixes with seawater at the mixing zone. The present study investigated the impact of the discharged thermal effluent on the physical chemical and biological quality of the receiving seawater body. Measurements of ΔT between Intake and Outfall ranged from 6.1 to 9.8 deg C and between Intake and Mixing zone from 3.2 to 6.0 deg C. These values are well within the legal limits. The thermal plume is shore attached and extended up to 300 m from the shore and registered a ΔT of 3-4 deg C. No measurable Change in the physical and chemical parameters of seawater (DO, Salinity NO3, NO2, NH3, PO4 and SiO3) in relation to thermal discharges was observed. However, these parameters fluctuated with seasonal changes. The shore attached thermal plume adversely affected the density and distribution of macro benthic animals. The benthos are absent in the mixing zone and their density decreased about 500 m on either side of the mixing zone. The natural shift in the mixing zone provides opportunities for the recolonization of macro benthos. The thermal tolerance study revealed that the experimental fish species Mugil cephalus and Alepeus djidapa did not show any mortality or loss of equilibrium at Δ5 degC (33 degC) and Δ T 7 degC (35 degC) and the maximum ΔT recorded at the impact area is 6 degC. The gradual increase in temperature as found in the plume favors the fishes to escape the acute thermal exposures. (author)

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

    International Nuclear Information System (INIS)

    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. 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

  19. 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

  20. 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

  1. 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

  2. Community characteristics of macrobenthos in the Huanghe (Yellow River) Estuary during water and sediment discharge regulation

    Institute of Scientific and Technical Information of China (English)

    REN Zhonghua; LI Fan; WEI Jiali; LI Shaowen; LV Zhenbo; GAO Yanjie; CONG Xuri

    2016-01-01

    The community characteristics of macrobenthos in the Huanghe (Yellow River) Estuary is influenced by a combination of natural and anthropogenic factors. Here, we investigated short-term changes (1-month) in macrobenthic community structure in response to water and sediment discharge regulation (WSDR) in 2011. Specifically, we sampled the macrobenthos at 18 sampling stations situated at four distances (5, 10, 20, and 40 km) from the mouth of the Huanghe Estuary before (mid-June), during (early-July), and after (mid-July) WSDR. The results showed that a total of 73, 72, and 85 species were collected before, during, and after WSDR, respectively. Then, 13, 1, and 16 dominant species were detected at this three periods. Four phyla were primarily detected at all three periods (Annelida, Mollusca, Arthropoda, and Echinodermata). However, while Mollusca and Annelida were the most important phyla in our study, Echinodermata and Annelida were the most important phyla in 1982, demonstrating major changes to community structure over a 3-decadal period. All stations were of high quality BOPA index before WSDR, whereas two and three stations were of reduced quality BOPA index during and after WSDR, respectively. The results of ABC curves showed that had incurred disturbed conditions after human activities WSDR. Most important of all, multivariate analyses and RDA analysis indicated that the structure of the macrobenthic community was closely linked to environment factors, including that organic content factor caused the distribution of macrobenthic community mostly during WSDR, while water depth after WSDR affected the macro benthos community structure seriously, and during WSDR, the environment factor influencing it was not single, including organic content, sulfide content, Hg and As. These differences may have been due to changes in water transparency negatively impacting the growth and development of macrobenthos, due to specific life-history requirements. Our results

  3. 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

  4. Rates of Ocean Acidification: Decoupling of Planktic and Benthic Extinctions?

    Science.gov (United States)

    Thomas, E.; Alegret, L.

    2012-12-01

    Deep-sea benthic organisms derive food from export of organic matter produced in the photic zone, so that pelagic and benthic productivity are coupled, suggesting that severe extinction of plankton and benthos in the geological past should have been coupled. An asteroid impact at the Cretaceous/Paleogene (K/Pg) boundary (~65 Ma), however, caused mass extinction of calcifying plankton (foraminifera and nannoplankton), whereas benthic calcifyers (foraminifera) did not suffer significant extinction. Also, pelagic calcifyers did not suffer severe extinction during the carbon-cycle perturbation and global warming at the Paleocene-Eocene (P/E) boundary 10 myr later, when deep-sea benthic foraminifera did. The K/Pg extinction has been interpreted as darkness-caused collapse of productivity, but this is not supported by the lack of benthic extinction. To evaluate extinction mechanisms, we compared benthic foraminiferal and stable isotope records at ODP sites in the Pacific, SE Atlantic and Southern Oceans. Across the K/Pg boundary, the decrease in export productivity was moderate, regionally variable, and insufficient to explain the mass extinction at higher levels of the food chain. Across the P/E boundary, productivity increased in epicontinental seas and on continental margins, whereas pelagic productivity may have declined (increased trophic resource continuum). We thus found no evidence that the different benthic and pelagic extinction patterns at K/Pg and P/E were linked to changes in (export) productivity. Instead, the difference between planktic and benthic extinction patterns may have been caused by the occurrence of ocean acidification at different rates. Very rapid (faster than present anthropogenic) surface ocean acidification at the K/Pg boundary may have been due to influx of impact-generated nitric acid, followed by rapid oceanic buffering. This may have been a factor in the massive extinction of pelagic calcifyers, ammonites and top-level predators such as

  5. 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

  6. Role of Sediments and Nutrients in the Condition of a Coral Reef Under Tourist Pressure: Akumal México.

    Science.gov (United States)

    Naranjo-Garcia, M. J.; Vadés Lozano, D. S.; Real-De-Leon, E.; Lopez-Aguiar, K.; Garza-Perez, J. R.

    2014-12-01

    Akumal, Mexico, was the first tourist resort in the Mexican Caribbean mainland, its highly developed coastal zone lies directly above the phreatic, and it is directly connected to the sub-littoral waters. Akumal is also known as a well-developed fringing coral reef, now in a critical condition. The main objective of this study was to explore the relationship between two of the main indicators of human pressure (nutrients and sedimentation, linked to coastal development and water run-offs) and the condition of the reef benthos, during a year. The sampling design used four transects perpendicular to shore, associated to different tourist and water run-off exposure, for a total of 12 stations distributed in three different reef zones (transition zone, shallow and deep spurs and grooves). Monthly samples were collected: water samples close to the reef lagoon drain channels and at bottom depth at each station, and sediment traps were recovered and replaced also at each station. Reef Benthos videotransects were recorded bi-monthly at each station to assess its condition. Macroalgae and filamentous algae dominate benthic cover (up to 50%), hard-coral cover ranges from 5-9%. Five coral-diseases were recorded, affecting 10.16% of the coral colonies: Caribbean Ciliate Infection, White Band, Purple Spots, White Spots and Yellow Band. The sedimentation rate -sr- ranged from 0.13 to 83.7 mg/cm2/day during the year; 86% of the samples had a sr ≤ 10 mg/cm2/day (reefs not stressed); 13% of the samples had a sr ranging from 10 to 50 mg/cm2/day (stressed reefs); and 1% of the samples were over the critical threshold (>50 mg/cm2/day). Dissolved Inorganic Nitrogen concentrations during the year were above those recorded previously in Caribbean reefs. The most abundant fraction was ammonium, surpassing both Mexican norms: For protection of aquatic life in coastal zones (0.01 mg/L), and the critical threshold for aquatic life (0.4 mg/L). These concentration limits are considered as

  7. Environmental assessment report to BEPCo Canada Company on exploratory drilling on EL2407

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-19

    BEPCo. Canada Company (BEPCo) is planning to drill exploratory deepwater wells offshore from Nova Scotia. This environmental assessment report was prepared to satisfy regulatory requirements associated with offshore drilling. It focuses on valued environmental components chosen during a scoping process. This report evaluated the potential project-related effects on marine benthos, marine fish, marine mammals, marine turtles, marine birds, special areas, and other ocean users. Discharges and emissions from the project include drilling mud and rock cuttings, small amounts of produced water, ship discharges and atmospheric emissions. This report includes oceanographic plume modelling for allowable discharges of mud and cuttings at sea. The report predicts that the potential adverse effects of the valued environmental components will be short term and highly localized around the drilling rigs. It was suggested that any adverse effects could be mitigated through the use of technically feasible mitigation and standard offshore oil and gas industry procedures for environmental health and safety. It was concluded that BEPCo's proposed drilling program for EL-2407 can be conducted without any significant adverse effects on Nova Scotia's offshore environment. 121 refs., 27 tabs., 24 figs.

  8. 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.

  9. 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.

  10. New insights on Antarctic gorgonians' age, growth and their potential as paleorecords

    Science.gov (United States)

    Martinez-Dios, Ariadna; Dominguez-Carrió, Carlos; Zapata-Guardiola, Rebeca; Gili, Josep-Maria

    2016-06-01

    Antarctic benthic communities have long been regarded as relicts of the past, since they have developed in a very stable environment and are formed by slow-growing and extraordinary long-lived organisms. However, little is known about the life history traits of gorgonian species, which are considered key components of the Antarctic benthos. In this study, age, Radial Growth Rates (RGR) and skeletal composition of Thouarella variabilis, Fannyella abies and Fannyella rossii colonies (Octocorallia, Primnoidae) that inhabit Antarctic shelf waters were examined. The radioisotopes 14C and 210Pb used for dating revealed that these colonies are long-lived, with ages spanning from 50 to 1100 years, thus confirming the archaic character of the Antarctic ecosystem. Some RGR obtained are among the lowest rates ever reported for primnoid species and gorgonians as a whole, with Thouarella species showing rates of 5.08 μm yr-1. Growth ring deposition seemed to occur every 2-3 years on average, although this result cannot be confirmed. Irregularities in the growth rings could be observed under the Scanning Electron Microscope (SEM) as fluctuations in the skeletal composition, which may be indicative of changes in the environmental conditions, most possibly primary production.

  11. STATE OF THE RIGHT BANK OF THE CHELBAS RIVER IN CHELBASSKAYA VILLAGE IN THE KRASNODAR REGION

    Directory of Open Access Journals (Sweden)

    Mamas N. N.

    2015-01-01

    Full Text Available The river Chelbas – is the steppe river passing through all Chelbasskaya village of the Kanevsky area. Selting of small rivers leads to rise in level of ground waters and bogging of flood plains which become unsuitable for any use. Harmful influence can conduce coming in a reservoir of a large number of suspensions. Suspensions increase water turbidity, reduce depth of penetration of sunshine, i.e. reduce a layer in which there is a photosynthesis that conducts to decrease of primary production of a waterway and deficiency of oxygen. The increase in ground rainfall can lead to change of fauna of a benthos, a silting of spawning areas, death from suffocation of have already spawned caviar of fishes. Research of the right river bank of Chelbas in the territory of stanitsa Chelbasskaya included studying of qualitative structure of wood, shrubby and grassy vegetation of a coastal strip, visual assessment of its state and definition of the general projective covering. In the lower current of these rivers the mineralization raises to 3-5 g/l. It speaks, apparently, by that the water containing alluvial deposits in the top parts of valleys have higher filtrational properties better are washed out, than on surrounding watersheds and slopes, and also down valleys. Works on bank protection will improve a condition of a right-bank strip of river Chelbas

  12. Compound-specific isotopes of fatty acids as indicators of trophic interactions in the East China Sea ecosystem

    Science.gov (United States)

    Wu, Ying; Wang, Na; Zhang, Jing; Wan, Ruijing; Dai, Fangqun; Jin, Xianshi

    2016-01-01

    The composition and compound-specific isotopes of fatty acids were studied within food webs in the East China Sea. Lipid-normalized stable carbon isotopes of total organic carbon had a good correlation with trophic level. Variations in fatty acid compositions among diff erent species were observed but were unclear. Diff erent dietary structures could be traced from molecular isotopes of selected fatty acids in the Shiba shrimp (Matapenaeus joyneri), the coastal mud shrimp (Solenocera crassicornis) and the northern Maoxia shrimp (Acetes chinensis). Both M. joyneri and S. crassicornis are mainly benthos feeders, while A. chinensis is a pelagic species, although they have a similar fatty acid composition. There was a good correlation for isotopes of arachidonic acid (C20:4n6; ARA) and docosahexaenoic acid (C22:6n3; DHA) among pelagic species from higher trophic levels. The isotopic compositions of DHA in benthic species were more negative than those of pelagic species at the same trophic level. The fact that the diet of benthic species contains more degraded items, the carbon isotopes of which are derived from a large biochemical fraction, may be the reason for this variation. A comparative study of benthic and pelagic species demonstrated the diff erent carbon sources in potential food items and the presence of a more complex system at the water-sediment interface.

  13. Case study on rehabilitation of a polluted urban water body in Yangtze River Basin.

    Science.gov (United States)

    Wu, Juan; Cheng, Shuiping; Li, Zhu; Guo, Weijie; Zhong, Fei; Yin, Daqiang

    2013-10-01

    In the past three decades, the fast development of economy and urbanization has caused increasingly severe pollutions of urban water bodies in China. Consequently, eutrophication and deterioration of aquatic ecosystem, which is especially significant for aquatic vegetation, inevitably became a pervasive problem across the Yangtze River Basin. To rehabilitate the degraded urban water bodies, vegetation replanting is an important issue to improve water quality and to rehabilitate ecosystem. As a case study, a representative polluted urban river, Nanfeihe River, in Hefei City, Anhui Province, was chosen to be a rehabilitation target. In October 2009 and May 2010, 13 species of indigenous and prevalent macrophytes, including seven species emergent, one species floating leaved, and five species submersed macrophytes, were planted along the bank slopes and in the river. Through 1.5 years' replanting practice, the water quality and biodiversity of the river had been improved. The concentrations of total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH4 (+)-N) declined by 46.0, 39.5, and 60.4 %, respectively. The species of macrophytes increased from 14 to 60, and the biodiversity of phytoplankton rose significantly in the river (p<0.05). The biomasses of zooplankton and benthos were also improved after the vegetation replanting. The study confirmed that vegetation replanting could alleviate the increasing water pollution and rehabilitate the degraded aquatic ecosystem. The case study would be an example for polluted urban waters restoration in the middle-downstream area of Yangtze River Base. PMID:23247519

  14. Sediments and herbivory as sensitive indicators of coral reef degradation

    Directory of Open Access Journals (Sweden)

    Christopher H. R. Goatley

    2016-03-01

    Full Text Available Around the world, the decreasing health of coral reef ecosystems has highlighted the need to better understand the processes of reef degradation. The development of more sensitive tools, which complement traditional methods of monitoring coral reefs, may reveal earlier signs of degradation and provide an opportunity for pre-emptive responses. We identify new, sensitive metrics of ecosystem processes and benthic composition that allow us to quantify subtle, yet destabilizing, changes in the ecosystem state of an inshore coral reef on the Great Barrier Reef. Following severe climatic disturbances over the period 2011-2012, the herbivorous reef fish community of the reef did not change in terms of biomass or functional groups present. However, fish-based ecosystem processes showed marked changes, with grazing by herbivorous fishes declining by over 90%. On the benthos, algal turf lengths in the epilithic algal matrix increased more than 50% while benthic sediment loads increased 37-fold. The profound changes in processes, despite no visible change in ecosystem state, i.e., no shift to macroalgal dominance, suggest that although the reef has not undergone a visible regime-shift, the ecosystem is highly unstable, and may sit on an ecological knife-edge. Sensitive, process-based metrics of ecosystem state, such as grazing or browsing rates thus appear to be effective in detecting subtle signs of degradation and may be critical in identifying ecosystems at risk for the future.

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

    International Nuclear Information System (INIS)

    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

  16. Steady-state mass balance model for mercury in the St. Lawrence River near Cornwall, Ontario, Canada

    International Nuclear Information System (INIS)

    We have developed a local mass balance model for the St. Lawrence River near Cornwall, Ontario that describes the fate and transport of mercury in three forms, elemental, divalent, and methylated, in a five compartment environment (air, water, sediments, periphyton, and benthos). Our objective was to construct a steady-state mass balance model to determine the dominant sources and sinks of mercury in this environment. We compiled mercury concentrations, fluxes, and transformation rates from previous studies completed in this section of the river to develop the model. The inflow of mercury was the major source to this system, accounting for 0.42 mol month−1, or 95.5% of all mercury inputs, whereas outflow was 0.28 mol month−1, or 63.6% of all losses, and sediment deposition was 0.12 mol month−1, or 27.3% of all losses. Uncertainty estimates were greatest for advective fluxes in surface water, porewater, periphyton, and benthic invertebrates. -- Highlights: ► Inflow accounted for 95.5% of all mercury inputs to the St. Lawrence River near Cornwall. ► Major losses of mercury were by outflow (63%) and sedimentation (27%). ► Sediments account for over 94% of all mercury in the system. -- A steady-state mass balance model is presented for mercury species in the St. Lawrence River near Cornwall, Ontario

  17. Distribution of Cd and Pb in a wetland ecosystem

    Institute of Scientific and Technical Information of China (English)

    何文珊; 陆健健

    2001-01-01

    Cadmium and lead contents in sediments, dominant species of plants (Phargmites aus-tralis and Scripus mariquter), benthos (Helice tridens tientsinensis, llyoplax deschampsi, and Bul-lacta exarata), and waders (Calidris ruficollis) on the Eastern End of Chongming Island were measured. The results showed that, for cadmium, there are clear stratification in the sediment of reclaimed area and bio-amplification in food chain. However, for lead, a phenomenon was different. The amplification factors (AFs) for cadmium of primary producers, primary consumers, and secondary consumers were 2.59-12.38, 0.09-8.44, and 51.1, respectively. For lead, AFs of primary producers, primary consumers and the top trophic layer were 0.29-2.62, 0.06-5.62, and 7.31, respectively. Each species of macrobenthos showed different strategies to cadmium and lead. Large-sized crabs accumulated more lead, while small-sized crabs and snails accumulated more cadmium. Waders had significantly highest AFs for cadmium and lead in the study. Tha

  18. 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.

  19. 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; von Westernhagen, H.

    2002-01-01

    Quantitative data collected with different bottom trawls at the Great Meteor Scamount (subtropical NE Atlantic, 30degreesN; 28.5degreesW) in 1967, 1970 and 1998 are compared. Bootstrap estimates of total catch per unit effort increased from 6.96 and 10.8 ind. m(-1) h(-1) in 1967 and 1970, respect......Quantitative data collected with different bottom trawls at the Great Meteor Scamount (subtropical NE Atlantic, 30degreesN; 28.5degreesW) in 1967, 1970 and 1998 are compared. Bootstrap estimates of total catch per unit effort increased from 6.96 and 10.8 ind. m(-1) h(-1) in 1967 and 1970.......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...

  20. Cytogenetic study of natural chironomini (diptera, chiromedae) populations from open water bodies of former Semipalatinsk test site

    International Nuclear Information System (INIS)

    In the paper genetic variability of natural population of chironomidae inhabiting in waters on the territory of Semipalatinsk test site (STS) is studied. Ten Chironomini species of Chironomidae subfamily and one species of Tanypodinae subfamily were identified using cyto-taxonomic methods of analysis. Cytophotomap of polythene chromosomes of salivary glands were established for four species: Glyptotendipes salinus, Captochironomus setivalva, Camptochriomonus tentas and Chironomus plumosus. For the first time a new previously unknown species of Chironomus gender, and namely C, genelenus 1. sp. n. was described and a cytophotomap of its polythene chromosomes was established. A detailed quantative and qualitative analysis of chromosome polymorphism was carried out and the spectrum and frequency of the disk sequences and genotypic combination were identified. New evidence on change in the polythene chromosomes structure were revealed in certain Chironomini species dwelling in the radioactively contaminated water bodies of STS: rare, unique disk sequences of chromosomes were found, a series of specific homo zygote and heterozygote inversions were observed, which evidently resulted from long-term adaptive selection under conditions of the chronic ionizing radiation. Increase of in frequency of structural mutations of chromosomes was found in mitotic cells of imago disk of Chironomini larvae is revealed. This increase indicates that at the STS many population of benthos organisms are directly affected by the ionizing radiation

  1. Importance of Chemolithoautotrophic Production to Mobile Benthic Predators in the Gulf of Mexico

    Science.gov (United States)

    Morgan, E.; Macavoy, S.; Carney, R.

    2005-05-01

    The continental slope of the Gulf of Mexico is characterized by substantial hydrocarbon seepage which provides reduced energy sources, both CH4 and H2S, for chemolithoautotrophs existing as endosymbionts within mussels and tubeworms found in dense colonies that provide habitat for an array of endemic and colonial fauna. The extent of trophic export of chemosynthetic biomass to the seep communities and the surrounding benthic communities in the Gulf, however, remains an open question. To elucidate the nutritional associations between seep residents and the surrounding benthos the carbon, nitrogen and sulfur stable isotope values of the hagfish Eptatretus sp., the giant isopod Bathynomus giganteus and the predatory snail Phymorhyncus sp. were interpreted through a three source, dual isotope mixing model. The model was able to assess the contributions of different isotopic signals to a mixture and thus could distinguish between photosynthetic/phytodetritus based sources, methanotrophic sources and thiotrophic sources. Incorporation of chemosynthetic based food sources was minimal on the whole and species specific; however some of the organisms considered in this study did incorporate nutrition from chemolithoautotrophic sources.

  2. DeepPIV: Particle image velocimetry measurements using deep-sea, remotely operated vehicles

    Science.gov (United States)

    Katija, Kakani; Sherman, Alana; Graves, Dale; Klimov, Denis; Kecy, Chad; Robison, Bruce

    2015-11-01

    The midwater region of the ocean (below the euphotic zone and above the benthos) is one of the largest ecosystems on our planet, yet remains one of the least explored. Little-known marine organisms that inhabit midwater have developed life strategies that contribute to their evolutionary success, and may inspire engineering solutions for societally relevant challenges. Although significant advances in underwater vehicle technologies have improved access to midwater, small-scale, in situ fluid mechanics measurement methods that seek to quantify the interactions that midwater organisms have with their physical environment are lacking. Here we present DeepPIV, an instrumentation package affixed to remotely operated vehicles that quantifies fluid motions from the surface of the ocean down to 4000 m depths. Utilizing ambient suspended particulate, fluid-structure interactions are evaluated on a range of marine organisms in midwater. Initial science targets include larvaceans, biological equivalents of flapping flexible foils, that create mucus houses to filter food. Little is known about the structure of these mucus houses and the function they play in selectively filtering particles, and these dynamics can serve as particle-mucus models for human health. Using DeepPIV, we reveal the complex structures and flows generated within larvacean mucus houses, and elucidate how these structures function. Funding is gratefully acknowledged from the Packard Foundation.

  3. Horizontal transmission of Symbiodinium cells between adult and juvenile corals is aided by benthic sediment

    Science.gov (United States)

    Nitschke, Matthew R.; Davy, Simon K.; Ward, Selina

    2016-03-01

    Of all reef-building coral species, 80-85 % initially draw their intracellular symbionts (dinoflagellates of the genus Symbiodinium) from the environment. Although Symbiodinium cells are crucial for the growth of corals and the formation of coral reefs, little is known about how corals first encounter free-living Symbiodinium cells. We report how the supply of free-living Symbiodinium cells to the benthos by adult corals can increase the rate of horizontal symbiont acquisition for conspecific recruits. Three species of newly settled aposymbiotic (i.e., symbiont-free) corals were maintained in an open aquarium system containing: sterilized sediment and adult coral fragments combined; adult coral fragments alone; sterilized sediment alone; or seawater at Heron Island, Great Barrier Reef, Australia. In all instances, the combination of an adult coral and sediment resulted in the highest symbiont acquisition rates by juvenile corals (up to five-fold greater than seawater alone). Juvenile corals exposed to individual treatments of adult coral or sediment produced an intermediate acquisition response (symbiont acquisition from unfiltered seawater was comparatively low (<20 % of recruits). Additionally, benthic free-living Symbiodinium cells reached their highest densities in the adult coral + sediment treatment (up to 1.2 × 104 cells mL-1). Our results suggest that corals seed microhabitats with free-living Symbiodinium cells suitable for many coral species during the process of coral recruitment.

  4. 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.

  5. 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)

    Contamination of 137Cs in sediment is a far more serious problem than in water because sediment is a main transport factor of 137Cs to the aquatic environmental. Most of 137Cs 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 137Cs from water to sediment that the study method by treat 137Cs 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 137Cs adsorption. CEC and clay content correlated positively with the accumulation of 137Cs in the marine sediment samples. On the other hand, organic matter in sediment correlated negatively with the accumulation of 137Cs in samples. The study of environmental effects (pH and potassium) found that the 137Cs 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 137Cs adsorption in the samples.

  6. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    International Nuclear Information System (INIS)

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and CODMn 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

  7. Concentration of 134Cs + 137Cs bonded to the organic fraction of sediments offshore Fukushima, Japan

    International Nuclear Information System (INIS)

    We conducted a sequential chemical extraction experiment for radiocesium (134Cs + 137Cs) using 21 surface sediment samples and two sets of size-fractionated surface sediment samples collected offshore Fukushima. Our results support earlier reports in this area that organic substances in marine sediments have an apparently higher preference for radiocesium than mineral substances. Observations suggest that mineral and organic substances in the marine sediments offshore Fukushima have the same order of preference for radiocesium, primarily because of the existence of ionic competitors in seawater. The apparent preference of radiocesium for organic material is greater because of the partial coverage of sediment mineral surfaces by organic substances. By using these relationships, we created a 2-D map of radiocesium concentration in sediment organic fraction in offshore-Fukushima region. Combining our results with existing monitoring data of marine benthos in offshore-Fukushima sediments, we estimated a transfer coefficient of radiocesium from sediment organic materials to benthic polychaetes as less than 0.03-0.008. (author)

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

    Directory of Open Access Journals (Sweden)

    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.

  9. 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.

  10. 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.

  11. Hydrogeology and hydrodynamics of coral reef pore waters

    Energy Technology Data Exchange (ETDEWEB)

    Buddemeier, R.W.; Oberdorfer, J.A.

    1988-06-29

    A wide variety of forces can produce head gradients that drive the flow and advective mixing of internal coral reef pore waters. Oscillatory gradients that produce mixing result from wave and tide action. Sustained gradients result from wave and tide-induced setup and ponding, from currents impinging on the reef structure, from groundwater heads, and from density differenced (temperature or salinity gradients). These gradients and the permeabilities and porosities of reef sediments are such that most macropore environments are dominated by advection rather than diffusion. The various driving forces must be analyzed to determine the individual and combined magnitudes of their effects on a specific reef pore-water system. Pore-water movement controls sediment diagenesis, the exchange of nutrients between sediments and benthos, and coastal/island groundwater resources. Because of the complexity of forcing functions, their interactions with specific local reef environments, experimental studies require careful incorporation of these considerations into their design and interpretation. 8 refs., 3 figs., 1 tab.

  12. 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. PMID:22650431

  13. 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.

  14. Environmental and economic assessment of discharges from Gulf of Mexico Region Oil and Gas Operations. Quarterly technical progress report, 1 October--31 December 1993

    Energy Technology Data Exchange (ETDEWEB)

    Gettleson, D.A.

    1994-01-28

    Task 2 (Preparation of the Sampling and Analysis Plan) activities involved the incorporation of the offshore site selection process into the Sampling and Analysis Plan. Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included making decisions on tissue analyses and performing analyses of water and sediment samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the completion of the spring benthos samples collection on pre-termination samples at Four Isle Dome and the first post-termination samples at Delacroix Island. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gum of Mexico Region) activities included continued work on development of a base case production forecast, modeling future production, and determining economic impact of treatment technologies. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work involved the completion of the fall survey season and the initiation of the survey data assembly. Task 7 (Technology Transfer Plan) activities included presentations at the Society of Environmental Toxicology and Chemistry annual meeting and Minerals Management Service Information Transfer Meeting. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management.

  15. Environmental assessment of cooling reservoirs

    International Nuclear Information System (INIS)

    The environmental impacts, both adverse and beneficial, of cooling reservoirs are compared to cooling towers as an alternative closed cycle cooling system. Generally, the impacts associated with the construction of a cooling reservoir system are greater than for a comparable cooling tower system. Operational impacts are generally greater for cooling towers due to their visual impact, plus icing, fogging, and noise problems. The principle advantages of cooling reservoirs are their lower operating and maintenance costs, greater reliability, greater cooling efficiency, reduced water consumption in areas where cooling water storage is required, and their multiple use potential. A review of pertinent literature on cooling reservoir ecosystems, has revealed that entrainment, thermal, and chemical effects generally result in reduced populations of phytoplankton, zooplankton, and benthos in the vicinity of the power plant discharge. Adverse far field effects are generally less significant and are sometimes stimulatory. The overall effects of a power plant on the fish populations of cooling reservoirs appear to be minor. Based on the thermal characteristics of a model 6400 acre cooling reservoir with four 1150 MWe reactors, the ecological characteristics of the reservoir were predicted. The multiple use possibilities of cooling reservoirs provide their most significant beneficial aspect when compared to cooling towers. In addition, the cage culture of food fishes in cooling reservoirs provides an economical and practical method of commercially utilizing the waste heat discharged by power plants. For many areas of the country, cooling reservoirs appear to provide an environmentally and socially desirable alternative to cooling towers

  16. Oxygen and evolutionary patterns in the sea: onshore/offshore trends and recent recruitment of deep-sea faunas

    Science.gov (United States)

    Jacobs, D. K.; Lindberg, D. R.

    1998-01-01

    Over the last 15 years a striking pattern of diversification has been documented in the fossil record of benthic marine invertebrates. Higher taxa (orders) tend to originate onshore, diversify offshore, and retreat into deep-water environments. Previous studies attribute this macroevolutionary pattern to a variety of causes, foremost among them the role of nearshore disturbance in providing opportunities for the evolution of novel forms accorded ordinal rank. Our analysis of the post-Paleozoic record of ordinal first appearances indicates that the onshore preference of ordinal origination occurred only in the Mesozoic prior to the Turonian stage of the Cretaceous, a period characterized by relatively frequent anoxic/dysoxic bottom conditions in deeper marine environments. Later, in the Cretaceous and Cenozoic, ordinal origination of benthic organisms did not occur exclusively, or even preferentially, in onshore environments. This change in environmental pattern of ordinal origination roughly correlates with Late Cretaceous: (i) decline in anoxia/dysoxia in offshore benthic environments; (ii) extinction of faunas associated with dysoxic conditions; (iii) increase in bioturbation with the expansion of deep burrowing forms into offshore environments; and (iv) offshore expansion of bryozoan diversity. We also advance a separate argument that the Cenomanian/Turonian and latest Paleocene global events eliminated much of the deep-water benthos. This requires a more recent origin of modern vent and deep-sea faunas, from shallower water refugia, than the Paleozoic or early Mesozoic origin of these faunas suggested by other workers.

  17. Stability and resilience of seagrass meadows to seasonal and interannual dynamics and environmental stress

    Science.gov (United States)

    Carr, Joel A.; D'Odorico, Paolo; McGlathery, Karen J.; Wiberg, Patricia L.

    2012-03-01

    Shallow coastal bays provide habitat for diverse fish and invertebrate populations and are an important source of sediment for surrounding marshes. The sediment dynamics of these bays are strongly affected by seagrass meadows, which limit sediment resuspension, thereby providing a more favorable light environment for their own survival and growth. Due to this positive feedback between seagrass and light conditions, it has been suggested that bare sediment and seagrass meadows are potential alternate stable states of the benthos in shallow coastal bays. To investigate the stability and resilience of seagrass meadows subjected to variation in environmental conditions (e.g., light, temperature), a coupled model of vegetation-sediment-water flow interactions and vegetation growth was developed. The model was used to examine the effect of dynamically varying seasonal and interannual seagrass density on sediment resuspension, water column turbidity, and the subsequent light environment on hourly time steps and then run over decadal time scales. A daily growth model was designed to capture both belowground biomass and the growth and senescence of aboveground biomass structural components (e.g., leaves and stems). This allowed us to investigate how the annual and seasonal variability in shoot and leaf density within a meadow affects the strength of positive feedbacks between seagrass and their light environment. The model demonstrates both the emergence of bistable behavior from 1.6 to 1.8 m mean sea level due to the strength of the positive feedback, as well as the limited resilience of seagrass meadows within this bistable range.

  18. Response of rocky invertebrate diversity, structure and function to the vertical layering of vegetation

    Science.gov (United States)

    Bustamante, María; Tajadura, Javier; Gorostiaga, José María; Saiz-Salinas, José Ignacio

    2014-06-01

    Macroalgae comprise a prominent part of the rocky benthos where many invertebrates develop, and are believed to be undergoing severe declines worldwide. In order to investigate how the vegetation structure (crustose, basal and canopy layers) contributes to the diversity, structure and function of benthic invertebrates, a total of 31 subtidal transects were sampled along the northeast Atlantic coast of Spain. Significant positive relationships were found between the canopy layer and faunal abundance, taxonomic diversity and functional group diversity. Canopy forming algae were also related to epiphytic invertebrates, medium size forms, colonial strategy and suspensivores. By contrast, basal algae showed negative relationships with all variables tested except for detritivores. Multivariate multiple regression analyses (DISTLM) point to crustose as well as canopy layers as the best link between seaweeds and invertebrate assemblage structure. A close relationship was found between taxonomic and functional diversities. In general, low levels of taxonomic redundancy were detected for functional groups correlated with vegetation structure. A conceptual model based on the results is proposed, describing distinct stages of invertebrate assemblages in relation to the vertical structure of vegetation.

  19. Macrobenthic community structure over the continental margin of Crete (South Aegean Sea, NE Mediterranean)

    Science.gov (United States)

    Tselepides, Anastasios; Papadopoulou, Konstantia-N.; Podaras, Dimitris; Plaiti, Wanda; Koutsoubas, Drosos

    2000-08-01

    Macrobenthic faunal composition, abundance, biomass and diversity together with a suite of sedimentary environmental parameters were investigated on a seasonal basis in order to determine factors regulating faunal distribution over the oligotrophic continental margin of the island of Crete (South Aegean Sea, North Eastern Mediterranean). Macrofaunal species composition was similar to that of the western Mediterranean and the neighboring Atlantic having several common dominant species. Mean benthic biomass, abundance and diversity decreased with depth, with a major transition zone occurring at 540 m, beyond which values declined sharply. At comparable depths biomass and abundance values were considerably lower to those found in the Atlantic, high-lighting the extreme oligotrophy of the area. The continental margin of Crete was characterised by a high diversity upper continental shelf environment (dominated by surface deposit feeding polychaetes) and a very low diversity slope and deep-basin environment (dominated by carnivorous and filter feeding polychaetes). Classification and ordination analyses revealed the existence of four principle clusters divided by a faunal boundary between 200 and 540 m, as well as beyond 940 m depth. Significant correlations between macrofauna and sediment parameters led to the conclusion that besides depth, food availability (as manifested by the concentration of chloroplastic pigments) is the principle regulating factor in the system. Such being the case, the prevailing hydrographic features that structure the pelagic food web and are directly responsible for the propagation of organic matter to the benthos also affect its community structure.

  20. Carbon and nitrogen stable isotopes reveal the use of pelagic resources by the invasive Ponto-Caspian mysid Limnomysis benedeni.

    Science.gov (United States)

    Fink, Patrick; Harrod, Chris

    2013-01-01

    The Ponto-Caspian mysid shrimp Limnomysis benedeni has rapidly invaded freshwater systems throughout Europe and is now found in extremely high abundances in invaded systems. However, very little is known about the trophic ecology of this mysid in invaded ecosystems, in particular the relative degree of herbivory, carnivory and detritivory of this potentially omnivorous species and where it derives its energy, i.e. via carbon fixed by algae inhabiting benthic or pelagic habitats or through allochthonous inputs. Here, we investigate the trophic ecology of L. benedeni in a recently established population in North-Western Germany using stable carbon and nitrogen isotopes. Our results suggest that in contrast to its previous classifications as a benthic or bentho-pelagic herbivore, L. benedeni is an omnivorous species, which can derive the bulk of its carbon from pelagic resources. Its trophic niche in different invaded ecosystems will be determined by multiple, system-dependent factors which have to be considered in order to predict the mysids' invasion potential. PMID:24117428

  1. Carbon flow and trophic structure of an Antarctic coastal benthic community as determined by δ 13C and δ 15N

    Science.gov (United States)

    Gillies, C. L.; Stark, J. S.; Johnstone, G. J.; Smith, S. D. A.

    2012-01-01

    Stable isotopes of carbon and nitrogen were used to determine the different carbon pathways and trophic assemblages amongst coastal benthic fauna of the Windmill Islands, East Antarctica. Macroalgae, pelagic POM, sediment POM and sea ice POM had well-separated δ 13C signatures, which ranged from -36.75‰ for the red alga Phyllophora antarctica, to -10.35‰ for sea ice POM. Consumers were also well separated by δ 13C, ranging from -21.42‰ for the holothurian Staurocucumis sp. up to -7.47‰ for the urchin Sterechinus neumayeri. Analysis of δ 13C and δ 15N revealed distinct groups for suspension feeders, grazer/herbivores and deposit feeders, whilst predators and predator/scavengers showed less grouping. Consumers spanned a δ 15N range of 8.71‰, equivalent to four trophic levels, although δ 15N ratios amongst consumers were continuous, rather than grouped into discrete trophic levels. The study has built a trophic model for the Windmill Islands and summarises three main carbon pathways utilised by the benthos: (1) pelagic POM; (2) macroalgae/epiphytic/benthic diatoms and (3) sediment POM/benthic diatoms. The movement of carbon within the coastal benthic community of the Windmill Islands is considered complex, and stable isotopes of carbon and nitrogen were valuable tools in determining specific feeding guilds and in tracing carbon flow, particularly amongst lower-order consumers.

  2. Levels and distribution of organochlorine pesticides, polychlorinated biphenyls and polybrominated diphenyl ethers in sediments and biota from the Danube Delta, Romania

    International Nuclear Information System (INIS)

    Concentrations of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and analogues, hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB), were measured in sediments and biota (invertebrates, 11 fish species and cormorant tissues) collected in 2001 from the Danube Delta, the biggest European wetland. DDTs were the predominant pollutants in all samples. A high variability in the concentrations of pollutants within the same species was observed and this was related to sampling location, age, length and sex. DDTs were also the main organohalogenated contaminants in cormorant muscle and liver, followed by PCBs, HCHs, HCB and PBDEs. The present levels of DDTs in cormorant tissues are lower than levels measured in cormorant eggs sampled from the Danube Delta in 1982 and 1997, respectively. The variance of δ 15N for herbivores was much greater than for carnivores, while carp and bream showed higher δ 15N signatures than expected, probably due to a higher dietary proportion of benthos, typically more δ 15N enriched relative to pelagic biota. - Levels of persistent organohalogenated pollutants in sediments and biota from the Danube Delta are low

  3. Site-Specific Variability in the Chemical Diversity of the Antarctic Red Alga Plocamium cartilagineum

    Directory of Open Access Journals (Sweden)

    Ryan M. Young

    2013-06-01

    Full Text Available Plocamium cartilagineum is a common red alga on the benthos of Antarctica and can be a dominant understory species along the western Antarctic Peninsula. Algae from this region have been studied chemically, and like “P. cartilagineum” from other worldwide locations where it is common, it is rich in halogenated monoterpenes, some of which have been implicated as feeding deterrents toward sympatric algal predators. Secondary metabolites are highly variable in this alga, both qualitatively and quantitatively, leading us to probe individual plants to track the possible link of variability to genetic or other factors. Using cox1 and rbcL gene sequencing, we find that the Antarctic alga divides into two closely related phylogroups, but not species, each of which is further divided into one of five chemogroups. The chemogroups themselves, defined on the basis of Bray-Curtis similarity profiling of GC/QqQ chromatographic analyses, are largely site specific within a 10 km2 area. Thus, on the limited geographical range of this analysis, P. cartilagineum displays only modest genetic radiation, but its secondary metabolome was found to have experienced more extensive radiation. Such metabogenomic divergence demonstrated on the larger geographical scale of the Antarctic Peninsula, or perhaps even continent-wide, may contribute to the discovery of cryptic speciation.

  4. Distribution of blue-green algae (Cyanophyta in streams of Mt. Stara planina: Serbia

    Directory of Open Access Journals (Sweden)

    Simić Snežana B.

    2002-01-01

    Full Text Available Distribution of blue-green algae was studied at 14 sites along five streams in the Stara Planina mountains. Algological samples were taken from the community of benthos and periphyton in the spring (March-May 1991, summer (June-August 1991, August 1996, July 1997, and autumn (September-November 1991, September 1997. Algae of the classes Chamaesiphonophyceae (species of the genus Chamaesiphon and Hormogoniophyceae (species of the genera Symploca, Phormidium, Oscillatoria, Schizothrix, Nostoc, Rivularia Homoeothrix, Tolypothrix, and Plectonema were recorded. The species Chamaesiphon cylindricus, Symploca radians, Phormidium coutinhoi, Nostoc coeruleum, Homoeothrix janthina, Plectonema thomasinianum, and Tolypothrix distorta were registered herein first time in Serbia. Occurrence of blue-green algae in highland brooks and rivers of the Stara Planina mountains was monitored in relation to a large number of abiotic factors e.g. altitude above level, stream dimensions (width and depth, substrate bottom type (%, current flow rate, water temperature and pH oxygen concentration, concentrations of nitrates and phosphates, and BOD5, using Principal Coordinates analysis (PCX.

  5. 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.

  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. PMID:26740615

  7. Biotic recovery from the Late Devonian F-F mass extinction event in China

    Institute of Scientific and Technical Information of China (English)

    廖卫华

    2002-01-01

    The Frasnian-Famennian (F-F) mass extinction is one of the five great extinctions of marine life during the Phanerozoic. The F-F event killed most of the Devonian reefs, the characteristic Devonian corals, stromatoporoids, bryozoans, nearly all tentaculites, a few superfamilies of brachiopods, such as Atrypacea and Pentameracea and some important elements of goniatites, such as Manticoceras.``The end-Frasnian was a phase of mass extinction. A large number of shelly benthos were killed by the F-F event. Early and middle Famennian was the survival interval. The marine faunas were very rare at that time. The late Famennian was the recovery interval. There appeared to have many new taxa in the Strunian stage. It lacked a radiation interval in Late Devonian Famennian because another event (the D-C mass extinction) happened at the Devonian-Carboniferous boundary.``Several causes for the F-F mass extinction have been proposed by some geologists, which have been grouped into two broad types, terrestrial and extraterrestrial. The former is related to sea level changes, climate changes and anoxic water event. The latter is linked with some forms of meteorite impact.``A large-scale eustatic change of sea level and black shales representing an anoxic environment has been invoked to explain one of the causes for the F-F mass extinction.``

  8. The Operation Consequence of Nuclear Energy to Environment

    International Nuclear Information System (INIS)

    Objective of the paper is to give information the operation consequence of nuclear energy to environment, so that expected as organizer of PLTN can anticipate or depress as minimum as possible radiology impact to the radiation workers and society in general, and also socialization that operation of nuclear energy do not give the negative impact, if conducted its control to environment seriously. Parts of which it is important to know from this paper are : one. Estimate of equivalent dose of collective effective in a normal condition is the operation cycle for nuclear energy at worker and local or regional resident 10, 100 or 10.000 next years. 2. Equivalent dose of global collective effective is for various the radiation sources. 3. Estimate of dose per cap ut annual of nuclear electric power until year 2500. 4. Aspect of non-radiology is to cooler system, usage of farm, dismissal of chemistry, advantage of hot water waste, its effect to fish, benthos, plankton, vegetation, animal and preparation of nuclear emergency

  9. Temporal changes in the bacterioplankton of a Northeast Ohio (USA) River.

    Science.gov (United States)

    Liu, J; Leff, L G

    2002-12-01

    To examine temporal changes in a bacterial community, water samples were collected monthly for one year from five sites along a major use-reuse river, the Cuyahoga River, in northeastern Ohio (USA). Fluorescent in situ hybridization (FISH) was used to enumerate population sizes of two species of common bacteria, Pseudomonas putida and Acinetobacter calcoaceticus; FISH was also performed with a Domain Bacteria specific probe. In addition, the total bacteria (based on DAPI staining), colony forming units (on modified Nutrient agar) and coliforms were enumerated and supporting physical/chemical data were collected. Each variable examined exhibited a different seasonal pattern. Temporal changes in total number of bacteria and population size of P. putida were correlated with turbidity and precipitation suggesting that allochthonous sources and scouring of the benthos may be major contributors to these portions of the community. In contrast, the number of cells hybridizing the Domain Bacteria and A. calcoaceticus probes were correlated with temperature. Thus, different aspects of the bacterial community are potentially controlled by different factors and the role of allochthonous and autochthonous sources may vary among species. PMID:14552350

  10. Brine-induced advection of dissolved aromatic hydrocarbons to arctic bottom waters

    International Nuclear Information System (INIS)

    Extruded brine, generated during sea ice formation in nearshore arctic waters, will sink to the bottom and can form a stable bottom boundary layer. This layer can persist for periods of up to 4-6 months. Limited quantities of dissolved aromatic hydrocarbons resulting from a spill of crude oil or refined petroleum distillate products during periods of ice growth can be transported as conservative components to the benthos with sinking brine. Once incorporated into the stable bottom boundary layer, these aromatic components are no longer subject to loss by evaporative processes, and they only can be diluted by ultimately mixing with uncontaminated water masses, a process that proceeds slowly throughout the ice-covered period. This mechanism for the transport of dissolved hydrocarbons has been demonstrated through a laboratory test-tank simulation and a chemical/physical oceanographic field program conducted in the Chukchi Sea near Pt. Frankline, AK (March 1985). The results are pertinent to shallow nearshore oil and gas exploration, development, production, and transportation activities in high latitude marine systems

  11. Depth shapes α- and β-diversities of microbial eukaryotes in surficial sediments of coastal ecosystems.

    Science.gov (United States)

    Gong, Jun; Shi, Fei; Ma, Bin; Dong, Jun; Pachiadaki, Maria; Zhang, Xiaoli; Edgcomb, Virginia P

    2015-10-01

    Little is known about the relative influence of historic processes and environmental gradients on shaping the diversity of single-celled eukaryotes in marine benthos. By combining pyrosequencing of 18S ribosomal RNA genes with data on multiple environmental factors, we investigated the diversity of microeukaryotes in surficial sediments of three basins of the Yellow Sea Large Marine Ecosystem. A considerable proportion (about 20%) of reads was affiliated with known parasitoid protists. Dinophyta and Ciliophora appeared dominant in terms of relative proportion of reads and operational taxonomic unit (OTU) richness. Overall, OTU richness of benthic microeukaryotes decreased with increasing water depth and decreasing pH. While community composition was significantly different among basins, partial Mantel tests indicated a depth-decay pattern of community similarity, whereby water depth, rather than geographic distance or environment, shaped β-diversity of benthic microeukaryotes (including both the abundant and the rare biosphere) on a regional scale. Similar hydrographic and mineralogical factors contributed to the biogeography of both the abundant and the rare OTUs. The trace metal vanadium had a significant effect on the biogeography of the rare biosphere. Our study sheds new light on the composition, diversity patterns and underlying mechanisms of single-celled eukaryote distribution in surficial sediments of coastal oceans. PMID:25581721

  12. 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. PMID:21272183

  13. Heavy metals in surface sediments of the Jialu River, China: Their relations to environmental factors

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Jie [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); Zhao, Changpo [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Luo, Yupeng [Department of Mathematics and Statistics, Auburn University, Auburn, AL 36849 (United States); Liu, Chunsheng, E-mail: liuchunshengidid@126.com [College of Fisheries, Huazhong Agricultural University, Wuhan 430070 (China); Kyzas, George Z. [Laboratory of General and Inorganic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124 (Greece); Luo, Yin [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhao, Dongye [Environmental Engineering Program, Department of Civil Engineering, Auburn University, Auburn, AL 36849 (United States); An, Shuqing [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China); Zhu, Hailiang, E-mail: zhuhl@nju.edu.cn [State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing 210093 (China)

    2014-04-01

    Highlights: • Zhengzhou City had major effect on the pollution of the Jialu River. • TN, OP, TP and COD{sub 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.

  14. 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.

  15. 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.

  16. The level and bioaccumulation of Cd, Cu, Cr and Zn in benthopelagic species from the Bering Sea

    Institute of Scientific and Technical Information of China (English)

    SHI Ronggui; LIN Jing; YE Yi; MA Yifan; CAI Minggang

    2015-01-01

    The Bering Sea is an area of high biological productivity, with large populations of sea-birds, demersal and pelagic fishes, so it seemed desirable to assess the bioaccumulation of trace metals in the marine organisms from this area. However, few data on trace metal concentrations are available for the benthopelagic organisms from the Bering Sea till now. Ten specimens of benthos (including 120 biological samples) were collected in the western Bering Sea in August 2008 during the 3rd Chinese National Arctic Research Expeditions, and the concentration of Cd, Cu, Cr and Zn determined using atomic absorption spectrometry. Zn, Cr and Cd concentrations in muscle tissues of the crab species were much higher than those from fish and cephalopod species, and the highest concentration of Cu was observed in the muscle tissues ofCylichna nucleoli. The results showed a similar hierarchy for Zn, Cr, Cd and Cu concentrations among different tissues as follows: hepatopancreas>muscle tissue>gonad. Bioconcentration factors indicated that benthic organisms had high accumulation abilities for Zn and Cu.

  17. Marine biology

    International Nuclear Information System (INIS)

    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

  18. Total, chemical, and biological oxygen consumption of the sediments in the Ziya River watershed, China.

    Science.gov (United States)

    Rong, Nan; Shan, Baoqing

    2016-07-01

    Sediment oxygen demand (SOD) is a critical dissolved oxygen (DO) sink in many rivers. Understanding the relative contributions of the biological and chemical components of SOD would improve our knowledge of the potential environmental harm SOD could cause and allow appropriate management systems to be developed. A various inhibitors addition technique was conducted to measure the total, chemical, and biological SOD of sediment samples from 13 sites in the Ziya River watershed, a severely polluted and anoxic river system in the north of China. The results showed that the major component of SOD was chemical SOD due to iron predominate. The ferrous SOD accounted for 21.6-78.9 % of the total SOD and 33.26-96.79 % of the chemical SOD. Biological SOD represented 41.13 % of the overall SOD averagely. Sulfide SOD accounted for 1.78-45.71 % of the total SOD and it was the secondary predominate of the chemical SOD. Manganous SOD accounted for 1.2-16.6 % of the total SOD and it was insignificant at many sites. Only four kinds of benthos were collected in the Ziya River watershed, resulting from the low DO concentration in the sediment surface due to SOD. This study would be helpful for understanding and preventing the potential sediment oxygen depletion during river restoration. PMID:27026547

  19. Enhancing the detection and classification of coral reef and associated benthic habitats: A hyperspectral remote sensing approach

    Science.gov (United States)

    Mishra, Deepak R.; Narumalani, Sunil; Rundquist, Donald; Lawson, Merlin; Perk, R.

    2007-08-01

    Coral reefs and associated benthic habitats are heterogeneous in nature. A remote sensor designed to discriminate these environments requires a high number of narrow, properly placed bands which are not currently available in existing satellite sensors. Optical hyperspectral sensors mounted on aerial platforms seem to be appropriate for overcoming the lack of both high spectral and spatial resolution of satellite sensors. This research presents results of an innovative coral reef application by such a sensor. Using hyperspectral Airborne Imaging Spectroradiometer for Applications (AISA) Eagle data, the approach presented solves the confounding influence of water column attenuation on substrate reflectance on a per-pixel basis. The hyperspectral imagery was used in band ratio algorithms to derive water depth and water column optical properties (e.g., absorption and backscattering coefficients). The water column correction technique produced a bottom albedo image which revealed that the dark regions comprised of sea grasses and benthic algae had albedo values ≈15%, whereas sand- and coral-dominated areas had albedos >30% and ≈15-35%, respectively. The retrieved bottom albedo image was then used to classify the benthos, generating a detailed map of benthic habitats, followed by accuracy assessment.

  20. Integrated Sr isotope variations and global environmental changes through the Late Permian to early Late Triassic

    Science.gov (United States)

    Song, Haijun; Wignall, Paul B.; Tong, Jinnan; Song, Huyue; Chen, Jing; Chu, Daoliang; Tian, Li; Luo, Mao; Zong, Keqing; Chen, Yanlong; Lai, Xulong; Zhang, Kexin; Wang, Hongmei

    2015-08-01

    New 87Sr/86Sr data based on 127 well-preserved and well-dated conodont samples from South China were measured using a new technique (LA-MC-ICPMS) based on single conodont albid crown analysis. These reveal a spectacular climb in seawater 87Sr/86Sr ratios during the Early Triassic that was the most rapid of the Phanerozoic. The rapid increase began in Bed 25 of the Meishan section (GSSP of the Permian-Triassic boundary, PTB), and coincided closely with the latest Permian extinction. Modeling results indicate that the accelerated rise of 87Sr/86Sr ratios can be ascribed to a rapid increase (>2.8×) of riverine flux of Sr caused by intensified weathering. This phenomenon could in turn be related to an intensification of warming-driven runoff and vegetation die-off. Continued rise of 87Sr/86Sr ratios in the Early Triassic indicates that continental weathering rates were enhanced >1.9 times compared to those of the Late Permian. Continental weathering rates began to decline in the middle-late Spathian, which may have played a role in the decrease of oceanic anoxia and recovery of marine benthos. The 87Sr/86Sr values decline gradually into the Middle Triassic to an equilibrium values around 1.2 times those of the Late Permian level, suggesting that vegetation coverage did not attain pre-extinction levels thereby allowing higher runoff.

  1. ASSESSMENT OF STOCK AND SPATIAL DISTRIBUTION OF SOLE (SOLEA SOLEA, L. IN ALBANIAN COAST USING RAPIDO TRAWL

    Directory of Open Access Journals (Sweden)

    Enton Spaho

    2012-06-01

    Full Text Available Common sole (Solea solea Linnaeus, 1758 is still not a specific target of fishery in Albania, but it represents an important target of the mixed-species catches of bottom trawlers and set netters operating in the coastal areas in the upper part of Albanian Adriatic Sea. Sole landings are low, amounting very few tonnes, but the demand will likely increase in the next future, because of the high quality of the fish fillet and the increase of consumers demand for wild sea fish. In order to identify the spawning areas and assess the spatial distribution and biomass of this species a rapido trawl survey was performed in year 2007. The smallest specimens were mostly concentrated in the shallowest stratum and the largest ones between 30 and 100 m depth. Solea Stock Biomass (SSB was 354 t, corresponding to 64% of the overall population recorded at sea at that time. In the context of fisheries, the Albanian fishing fleet involve a number of different fishing gears, while rapido trawl is introduced recently. The special technical and operating characteristics of rapido trawl makes it very effective in sole fishery and less harmful for the sea benthos and the species inhabiting it. This study aimed the estimation of spatial distribution of common sole and its biomass in the Albanian coast using rapido trawl gear.

  2. Effects of drilling fluids on marine organisms

    International Nuclear Information System (INIS)

    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 LC50s 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

  3. 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.

  4. The impact of the Braer oil spill on the macrobenthic infauna of the sediments off the Shetland Islands

    International Nuclear Information System (INIS)

    Following the wreck of the oil tanker Braer, a study of the benthic fauna in areas of sea-bed contaminated by oil was carried out. The results showed that no significant changes in benthic community structure, as characterized by species richness, individual abundance and diversity could be related to the areas of sea-bed affected by the Braer oil spill. The major factors determining the distribution of species in the affected areas appeared to be primarily related to the nature of the sediments, and not the degree of oil contamination. However, the levels of petroleum hydrocarbons in the most heavily contaminated sediments were sufficiently high to have eliminated sensitive groups such as the Amphipoda and encourage species associated with oil pollution, but the overall numbers of species involved and their abundances were too small to significantly affect community structure. There is no evidence from the analysis of species abundance distribution that mass mortality of the benthos took place at any time after the Braer oil spill, although there are indications that a few species may have been eliminated and were recruiting at the time of the survey. The lack of evidence of major impact from the spill indicates that either the Braer oil was of such low toxicity as to not significantly disrupt benthic community structure, or that the sampling programme was carried out too soon after the spill to enable the full effects of its impact to be detected. (author)

  5. Marine biology

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    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

  7. Tunneling trilobites: Habitual infaunalism in an Ordovician carbonate seafloor

    Science.gov (United States)

    Cherns, Lesley; Wheeley, James R.; Karis, Lars

    2006-08-01

    Asaphus trilobites preserved in tunnel systems of the trace fossil Thalassinoides from the mid-Ordovician (ca. 465 Ma) Holen Limestone, Sweden, are interpreted as the trace makers, enabled by shallow carbonate firm grounds to construct open tunnel networks and develop habitual infaunal behavior. Their in situ preservation confirms an infaunal ethology inferred for some trilobite taxa from functional morphology. We suggest that predation pressure from large omnivorous nautiloid cephalopods (“Orthoceras” Limestone facies) may have triggered ecologic opportunism. In trilobites well adapted for predatory-scavenging behavior as well as excavation, the tunnel networks functioned primarily for protection, possibly assisting in feeding, breathing, and breeding strategies. Previously, “trilobite burrows” have referred to seafloor traces of locomotion, feeding, and resting (Cruziana, Rusophycus). Infaunal, tunneling trilobites provide new evidence of mid-Ordovician partitioning of the skeletal benthos, adding to an ecologic and trophic tier hitherto interpreted as occupied by soft-bodied organisms. Such trilobites also provide an identity for Thalassinoides tracemakers prior to Devonian evolution of decapod crustaceans.

  8. 长江口外海域沉积物中有机物的来源及分布%Spatial distributions of organic carbon and nitrogen and their isotopic compositions in sediments of the Changjiang Estuary and its adjacent sea area

    Institute of Scientific and Technical Information of China (English)

    高建华; 汪亚平; 潘少明; 张瑞; 李军; 白风龙

    2008-01-01

    The spatial distribution patterns of total organic carbon and total nitrogen show significant correlations with currents of the East China Sea Shelf. Corresponding to distributions of these currents, the study area could be divided into four different parts. Total organic carbon, total nitrogen, and organic carbon and nitrogen stable isotopes in sediments show linear correlations with mean grain size, respectively, thus "grain size effect" is an important factor that influences their distributions. C/N ratios can reflect source information of organic matter to a certain degree. In contrast, nitrogen stable isotope shows different spatial distribution patterns with C/N and organic carbon stable isotope, according to their relationships and regional distributions. The highest contribution (up to 50%) of terrestrial organic carbon appears near the Changjiang Estuary with isolines projecting towards northeast, indicating the influence of the Changjiang dilution water. Terrestrial particulate organic matter suffers from effects of diagenesis, benthos and incessant inputting of dead organic matter of plankton,after depositing in seabed. Therefore, the contribution of terrestrial organic carbon to particulate organic matter is obviously greater than that to organic matter in sediments in the same place.

  9. [Sponges (porifera) distribution along a depth gradient in a coral reef, Parque Nacional San Esteban, Carabobo, Venezuela].

    Science.gov (United States)

    Núñez Flores, Mónica; Rodríguez-Quintal, José Gregorio; Cristina Díaz, María

    2010-10-01

    Sponges constitute one of the most diverse and abundant animal groups in the marine tropical benthos especially in coral reefs, though poorly studied to species level. The aim of this study is to characterize the sponge community along a depth gradient at Isla Larga (Parque Nacional San Esteban, Venezuela) fringe reef. Net and total sedimentation, roughness index, sponge species richness, density and proportion of the bottom covered by sponges, were evaluated at seven depths (1, 3, 6, 9, 12, 15, 18 m), 17 species were identified grouped in 10 demosponges families. The highest densities and coverage corresponded to 6 m of depth (6.03ind/m2; 11%), that coincides with the lowest net sedimentation and highest substrate heterogeneity. Most abundant species were Desmapsamma anchorata, Amphimedon erina and Scopalina rueztleri. Principal component analysis divided this community in three zones according to depth. The shallow zone of the reef (1 and 3 m), where wave force and high irradiance exert a constant stress sponges, shows the lowest density and coverage by sponges. In contrast, medium depth (6, 9 y 12 m) and deep zone (15 y 18 m) with lower light and sedimentation levels seem to enhance sponge growth and survival that are reflected on the higher densities and coverage of sponges. PMID:21302530

  10. An annotated and revised checklist of pleurostome ciliates (Protista: Ciliophora: Litostomatea) from Slovakia, Central Europe.

    Science.gov (United States)

    Vďačný, Peter; Rajter, L'ubomír

    2014-01-01

    Pleurostomatids are predatory ciliates, living especially in the periphyton and benthos of various freshwater and marine habitats. In the present work, we provide an annotated and revised checklist of this ciliate group from the territory of Slovakia. Altogether 29 pleurostome species belonging to five genera have been reported there: Acineria incurvata, Ac. punctata, Ac. uncinata, Amphileptus claparedii, Am. falcatus, Am. fusiformis, Am. parafusidens, Am. pleurosigma, Am. procerus, Am. punctatus, A. rotundus, Litonotus alpestris, Li. anguilla, Li. carinatus, Li. crystallinus, Li. cygnus, Li. fasciola, Li. fusidens, Li. hirundo, Li. lamella, Li. minisculus, Li. muscorum, Li. obtusus, Li. triqueter, Li. varsaviensis, Loxophyllum helus, Lo. meleagris, Lo. rostratum, and Siroloxophyllum utriculariae. We have catalogued these records providing the following data for each species: (1) author(s) and date of publication; (2) name(s) of the species as appeared in the publication(s) followed by chronologically listed references including relevant page(s) in literature; (3) nomenclatural and taxonomic notes if needed; (4) main morphological characters; (5) morphological data on Slovak populations if available; and (6) all faunistic records. PMID:24870102

  11. 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. PMID:24793778

  12. Behaviour of floating pollutants in case of an accidental spillage at sea; Le comportement des polluants flottants en cas de deversement accidentel en eau de mer

    Energy Technology Data Exchange (ETDEWEB)

    Le Goff-Bucas, G.

    2002-03-01

    The effects of sea pollution by vegetable oils are not always easily noticeable. As crude oils, vegetable oils have coating properties which affect marine life, tourism and yachting. Beside, laboratory experiments, as well as flume test and sea trials carried out for this study have shown that vegetable oils are able to disperse in the water column, to form emulsions that remain in the environment and to polymerize. Those phenomena can cause less visible damage, on the benthos for instance. In the same way, floating chemical pollutants can kill marine life when dispersing in the water column, because of their toxic properties. Therefore, it seems necessary that both types of pollutants be removed quickly from the water after a spill. Recovery operations will neither be influenced by the salinity nor by the temperature of the damaged zone, because those parameters do not affect emulsification and dispersion processes. Moreover, clay particles may help bio-remediation of vegetable oils. On the contrary, U.V. rays cause the polymerisation of the oils and, as a result, increase their residence time. However, since those types of pollutants float on the sea surface, common recovery devices designed for crude oils may be used. (author)

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

    International Nuclear Information System (INIS)

    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 15N, 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

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

    Science.gov (United States)

    Wharton, Robert A., Jr.

    1989-01-01

    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.

  15. Ammonite habitat revealed via isotopic composition and comparisons with co-occurring benthic and planktonic organisms

    Science.gov (United States)

    Sessa, Jocelyn Anne; Larina, Ekaterina; Knoll, Katja; Garb, Matthew; Cochran, J. Kirk; Huber, Brian T.; MacLeod, Kenneth G.; Landman, Neil H.

    2015-12-01

    Ammonites are among the best-known fossils of the Phanerozoic, yet their habitat is poorly understood. Three common ammonite families (Baculitidae, Scaphitidae, and Sphenodiscidae) co-occur with well-preserved planktonic and benthic organisms at the type locality of the upper Maastrichtian Owl Creek Formation, offering an excellent opportunity to constrain their depth habitats through isotopic comparisons among taxa. Based on sedimentary evidence and the micro- and macrofauna at this site, we infer that the 9-m-thick sequence was deposited at a paleodepth of 70-150 m. Taxa present throughout the sequence include a diverse assemblage of ammonites, bivalves, and gastropods, abundant benthic foraminifera, and rare planktonic foraminifera. No stratigraphic trends are observed in the isotopic data of any taxon, and thus all of the data from each taxon are considered as replicates. Oxygen isotope-based temperature estimates from the baculites and scaphites overlap with those of the benthos and are distinct from those of the plankton. In contrast, sphenodiscid temperature estimates span a range that includes estimates of the planktonic foraminifera and of the warmer half of the benthic values. These results suggest baculites and scaphites lived close to the seafloor, whereas sphenodiscids sometimes inhabited the upper water column and/or lived closer to shore. In fact, the rarity and poorer preservation of the sphenodiscids relative to the baculites and scaphites suggests that the sphenodiscid shells may have only reached the Owl Creek locality by drifting seaward after death.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jongseong [Office of Policy Research, Korea Ocean Research and Development (KORDI), Ansan, P.O. Box 29, Seoul 425-600 (Korea, Republic of); Khim, Jong Seong, E-mail: jongseongkhim@korea.ac.kr [Division of Environmental Science and Ecological Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kang, Seong-Gil [Maritime and Ocean Engineering Research Institute (MOERI)/Korea Ocean Research and Development Institute (KORDI), Daejeon 305-600 (Korea, Republic of); Kang, Daeseok [Department of Ecological Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Lee, Chang-hee [Department of Environmental Engineering and Biotechnology, Myongji University, Yongin, Gyeonggi-do 449-728 (Korea, Republic of); Koh, Chul-hwan [School of Earth and Environmental Sciences (Oceanography), Seoul National University, Seoul 151-742 (Korea, Republic of)

    2011-10-15

    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.

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

    Institute of Scientific and Technical Information of China (English)

    Wan Yang; Dan JLehrmann

    2014-01-01

    Eustasy has commonly been invoked to explain peritidal carbonate cyclicity, but is dififcult 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 lfooding over intertidal facies and con-tain 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 carbon-ate factory. The perturbations may be driven by changes in salinity and degree of eutrophica-tion, 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 oceano-graphic 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 sub-sidence and no sea-level lfuctuation.

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

    Institute of Scientific and Technical Information of China (English)

    Wan; Yang; Dan; J.Lehrmann

    2014-01-01

    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.

  19. The effect of a natural water-movement related disturbance on the structure of meiofauna and macrofauna communities in the intertidal sand flat of Rocas Atoll (NE, Brazil)

    Science.gov (United States)

    Netto, S. A.; Attrill, M. J.; Warwick, R. M.

    1999-12-01

    Rocas, the only atoll in the South Atlantic, is located 266 km off the northeast Brazilian coast. Spatial patterns in community structure of meiofauna, particularly nematodes, and macrofauna were examined along a transect through the sediment path from windward to leeward of the Rocas Atoll sand flat. Differences in benthic community structure between four zones of the sand flat were found to be significant and related to the major local processes of carbonate-grain transport and sedimentation. Both meiobenthic and macrobenthic assemblages were significantly more diverse and abundant within the sediment inflow zone (the initial part of the detrital path of Rocas sand flat) than in the other zones, where a clear impoverishment of benthic invertebrates occurred. This first study of the benthos of an intertidal sand flat over a reef island in the Atlantic showed that the meiofauna is numerically dominated by the nematodes Metoncholainus sp. 1 (Oncholaimidae) and Epsilonema sp. 1 (Epsilonematidade), whilst the macrofauna is largely dominated by oligochaetes and large Oncholaimidae nematodes. Analysis of the species composition, trophic structure and abundance of both the meiobenthos and the macrobenthos revealed an impoverished community subjected to an intense water-movement disturbance.

  20. Hypothesis carbon flow through the deepwater Lake Ontario foodweb

    International Nuclear Information System (INIS)

    Several accounts in recent years have attempted to conceptualize foodwebs in valuable fishery systems, producing useful heuristic tools to help shape research and management policy. Here a mass balance conceptual model of the Lake Ontario deepwater foodweb is developed to evaluate energy pathways and determine available nutrition for predatory salmonines. A number of different trophic links were defined from phytoplankton, through the various forage species, to the tertiary consumers. Phytoplankton photosynthesis resulted in 178 g C/m/sup 2//yr production at the base of the foodweb. Approximately 60% of primary production was counted as required support for pelagic zooplankton and benthos. Dominant forage fish (alewife, smelt and sculpin) annually appeared to consume all smaller zooplankton carbon production, 93% of mysid production, 66% of most benthic community production, and, more specifically, 94% of amphipod carbon production. The model indicated that approximately 1.22 g C/m/sup 2//yr was available for support of top level predators. Based upon historic fishery records and stocking rates, these predators required approximately half of the annual carbon available as nutritional support. Impacts of trophic rearrangements in the Lake Ontario foodweb are discussed based upon model results

  1. Studies of a contaminated brackish marsh in the Hackensack Meadowlands of northeastern New Jersey: An assessment of natural recovery

    International Nuclear Information System (INIS)

    Eight-Day Swamp is known to be contaminated with heavy metals, especially mercury. Sediment cores were collected to ∼32 cm at 17 sites on four transects and analyzed at 1 or 2 cm intervals for seven metals and organic matter. Very high metal levels were found throughout the site. Long and Morgan's 'effects range-median' (ER-M) was exceeded in more than 50% of slices for all elements except As. Hg had the highest concentration relative to ER-M; median Hg concentration was 72 times its ER-M. On the marsh plain, all metals showed enrichment at 14-20 cm depth of 10-40X over surficial sediments. 137Cs analysis showed sedimentation rates ranging from 0.33 to 0.50 cm yr-1 over the last ∼40 yr. These rates indicate that metal contamination peaks occurred in sediments deposited in the early 1960s. Thus, newer, less contaminated sediments are burying older, more contaminated layers and peak levels of contaminants are becoming less available to benthos

  2. Thaliacean distribution and abundance in the northern part of the Levantine Sea (Crete and Cyprus) during the eastern Mediterranean climatic transient, and a comparison with the western Mediterranean basin

    Science.gov (United States)

    Weikert, Horst; Godeaux, Jean E. A.

    2008-12-01

    First results are presented on the composition, abundance and vertical distribution of the thaliacean fauna in the Levantine basin obtained from stratified tows at three deep-sea sites in 1993: SE off Crete, and SW and NE off Cyprus. Samples with a 10 m2-MOCNESS (mesh size 1.67 mm) were poor in species and specimens as compared to samples with a 1 m2-double-MOCNESS (0.333 mm). Of the 12 species identified, six species belonged to the most abundant Doliolida, predominated by the phorozooids of Doliolum nationalis, five species belonged to the Salpida and one to the Pyrosomatida. Thaliaceans, most abundant by species and numbers SE off Crete, comprised ≤0.2% of the local mesozooplankton standing stocks. Presumably, they did not contribute substantially to the vertical flux generating the locally increased biomass and activity of the microbial benthos at the 4,300 m deep Cretean site. Most doliolids and salps were collected from the epipelagic and upper mesopelagic layers, and appeared to be most abundant close to the deep maximum of chlorophyll- a. Samples below 150 m were rarely rich in specimens, although two species performed diel migrations from the mesopelagic zone into the surface layers where some vertical segregation was evidenced. The aspect of niche separation is discussed.

  3. Abundant box jellyfish, Chironex sp. (Cnidaria: Cubozoa: Chirodropidae), discovered at depths of over 50 m on western Australian coastal reefs.

    Science.gov (United States)

    Keesing, John K; Strzelecki, Joanna; Stowar, Marcus; Wakeford, Mary; Miller, Karen J; Gershwin, Lisa-Ann; Liu, Dongyan

    2016-01-01

    Box jellyfish cause human fatalities and have a life cycle and habit associated with shallow waters (tow video and epibenthic sled surveys discovered large numbers (64 in a 1500 m tow or 0.05 m(-2)) of Chironex sp. very near to the benthos (tow videos and 3 of 41 epibenthic sleds spread over 2000 km(2). All Chironex filmed or captured were on low to medium relief reefs with rich filter feeder communities. None were on soft sediment habitat despite these habitats comprising 49% of all sites. The importance of the reef habitat to Chironex remains unclear. Being associated with filter feeder communities might represent a hazard, and other studies have shown C. fleckeri avoid habitats which represent a risk of entanglement of their tentacles. Most of our observations were made during the period of lowest tidal current flow in the morning. This may represent a period favourable for active hunting for prey close to the seabed. PMID:26924604

  4. Distribution and ecological risk assessment of HCHs and DDTs in surface seawater and sediment of the mariculture area of Jincheng Bay, China

    Science.gov (United States)

    Hu, Yanbing; Sun, Shan; Song, Xiukai; Ma, Jianxin; Ru, Shaoguo

    2015-04-01

    The distribution of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in the surface seawater and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87 ng L-1 and were quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column species was low. The threshold effect concentration exceeding frequency of γ-HCH, p, p'-DDD, p, p'-DDE and p, p'-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic products, e.g., sea cucumber and benthic shellfish.

  5. Preface and brief synthesis for the FOODBANCS volume

    Science.gov (United States)

    Smith, Craig R.; DeMaster, David J.

    2008-11-01

    In this volume we present results from the FOODBANCS Project, which examined the fate and benthic community impact of summer bloom material on the West Antarctic Peninsula shelf floor. The project involved a 5-cruise, 15-month time-series program in which sediment-trap moorings, core sampling, radiochemical profiling, sediment respirometry, bottom photography, and bottom trawling were used to evaluate: (1) seafloor deposition and lability of POC, (2) patterns of labile POC consumption and sediment mixing by benthos, and (3) seasonal and inter-annual variations in biotic abundance, biomass, reproductive condition, recruitment, and sediment community respiration. We find that the seafloor flux and accumulation of particulate organic carbon on the West Antarctic Peninsula shelf exhibit intense seasonal and interannual variability. Nonetheless, many key benthic processes, including organic-matter degradation, bioturbation, deposit feeding, and faunal abundance, reproduction and recruitment, show relatively muted response to this intense seasonal and inter-annual variability in export flux. We thus hypothesize that benthic ecosystems on the Antarctic shelf act as "low-pass" filters, and may be extremely useful in resolving the impacts of climatic change over periods of years to decades in Antarctic Peninsula region.

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

    International Nuclear Information System (INIS)

    Information is limited concerning variation of the δ15N with growth in marine organisms and consequently the effect of growth of marine biota on the δ15N is not yet well understood. The δ15N 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 δ15N. The mean δ15N 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 δ15N were 13.0±0.7, 9.7±0.9, and 12.2±1.2per mille, respectively. The mean δ15N 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 δ15N significantly increased with growth in one species (Pacific cod), while not significant increase in the δ15N with growth in the remaining species. (author)

  7. 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.

  8. Standing stock of deep-sea metazoan meiofauna in the Sulu Sea and adjacent areas

    Science.gov (United States)

    Shimanaga, Motohiro; Nomaki, Hidetaka; Suetsugu, Kishiko; Murayama, Masafumi; Kitazato, Hiroshi

    2007-01-01

    Standing stocks of deep-sea metazoan meiofauna were investigated in the Sulu Sea, one of the most isolated marginal basins with comparably warm bottom-water temperatures (˜10 °C) at depths below 1000 m. A decline in the abundance and biomass of organisms with increasing water depth occurred in the basin, but the abundances at bathyal and abyssal sites in the Sulu Basin appeared to be lower than standard values worldwide when adjusted for water depth. There is no significant correlation between meiofaunal abundance and the concentration of chloroplastic pigment equivalents (CPE) in the sediment, an indicator of the amount of organic matter derived from primary production. The ratios of meiofaunal abundance to CPE concentration at the sampling sites were as small as those observed at comparable depths in the Red Sea. These suggest that the quantity of "food" is not a primary factor limiting the density of organisms in the basin. It is hypothesized that a higher respiratory activity of benthos caused by warm bottom water and a lower food quality could be important factors regulating the metazoan meiofaunal standing stocks in the Sulu Sea.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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. PMID:26961305

  14. 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.

  15. 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.

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

    International Nuclear Information System (INIS)

    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

  17. 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.

  18. Metabarcoding of benthic eukaryote communities predicts the ecological condition of estuaries

    International Nuclear Information System (INIS)

    DNA-derived measurements of biological composition have the potential to produce data covering all of life, and provide a tantalizing proposition for researchers and managers. We used metabarcoding to compare benthic eukaryote composition from five estuaries of varying condition. In contrast to traditional studies, we found biotic richness was greatest in the most disturbed estuary, with this being due to the large volume of extraneous material (i.e. run-off from aquaculture, agriculture and other catchment activities) being deposited in the system. In addition, we found strong correlations between composition and a number of environmental variables, including nutrients, pH and turbidity. A wide range of taxa responded to these environmental gradients, providing new insights into their sensitivities to natural and anthropogenic stressors. Metabarcoding has the capacity to bolster current monitoring techniques, enabling the decisions regarding ecological condition to be based on a more holistic view of biodiversity. - Highlights: • We used metabarcoding to examine the benthic eukaryote composition of five estuaries. • Biotic richness (based on MOTUs) was greater in the most impacted estuary. • Similarities among estuaries reflected their environmental condition. • Composition was strongly correlated with nutrients, turbidity and pH. • Metabarcoding can provide fast, comprehensive and ecologically informative data. - Using metabarcoding we were able discriminate benthos from five estuaries, and identify those taxa which responded negatively and positivity to the key environmental stressors

  19. 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.

  20. A New Diverse Macrofossil Lagerstatte from the Uppermost Ediacaran of Southwestern China

    Institute of Scientific and Technical Information of China (English)

    TANG Feng; YIN Chongyu; LIU Pengju; GAO Linzhi; ZHANG Wenyan

    2008-01-01

    A new macrofossil Lagerstatte was discovered from the uppermost Ediacaran Jiucheng Member at Jinning and Jiangchuan of the eastern Yunnan, yielding numerous diverse well-preserved thallophyte macrofossils. These include the previously-known representatives of vendobionts, Vendotaenia and Tyrasotaenia, and the biggish multicellular benthos such as Otuaria-like and Tawuia-like fossils, as well as Longfengshaniaceaens with diverse holdfast structures. There are still some other problematic macrofossils with peculiar configurations as well as uncertain relatives. The distinct dominance of the giant, unbranching thallophytes occasionally with holdfast structures distinguishes this assemblage from the other Ediacaran macrofossil Lagerstattes in the Doushantuo Formation at Miaohe, Wenghui and Lantian, and the contemporary assemblage in the Shibantan Member of Dengying Formation, Yangtze Gorges area. This paper outlines the characteristics of some of the multicellular macrofossils from the Jiucheng Member at Jiangchuan. They include some macrofossils with different types of holdfast structure, larger Chuaria-like and Tawuia-like morphology and questionable affinities as well. The discovery of greater diverse macrofossil assemblages from the Jiucheng Member of eastern Yunnan has further indicated that an important diversification and evolutionary radiation of metaphytes took place in the latest Ediacaran time. This radiation of large-scale, benthic metaphyte along with phytoplankton was likely important contributors to the early Cambrian explosion of metazoans.

  1. 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

    2014-04-01

    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

  2. Chronic toxicity of phenanthrene to the marine polychaete worm, Nereis (Neanthes) arenaceodentata

    Energy Technology Data Exchange (ETDEWEB)

    Emery, V.L. Jr.; Dillon, T.M. [USAE Waterways Experiment Station, Vicksburg, MS (United States)

    1996-02-01

    Polycyclic aromatic hydrocarbons (PAHs) are widely distributed in the environment. While environmental concentrations are generally below acutely, lethal levels, chronic, low level exposures may result in subtle sublethal effects. PAHs accumulate in bottom sediments and may represent a hazard to the benthos. Polychaetes are important members of this community. The objective of this study is to evaluate the chronic sublethal effects of one PAH, phenanthrene (PHN), on the polychaete worm, Nereis arenaceodentata. PHN was selected because of its high toxicity to marine invertebrates relative to other PAHs. The response of bivalves to heavy metals and other toxins has usually been determined by observing valve position. Since mussels close their valves to avoid noxious stimuli, experimental delivery of chemicals is uncertain. To obtain constant results. Preston employed plastic spacers to hold the valves apart. This obviates the observation of valve position as an index of response, and some other method is required. Electromyography of intact mussels is one such index, and is shown to be a simple, effective and quantitative measurement of activity. Experiments are reported on the effects of added mercury on salt water and fresh water species. Parts of this Nvork have appeared in brief form.

  3. 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. PMID:25942562

  4. 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.

  5. 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)

    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.

  6. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    Science.gov (United States)

    Guilini, Katja; Levin, Lisa A.; Vanreusel, Ann

    2012-04-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and δ13C evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity.

  7. Algal δ15N values detect a wastewater effluent plume in nearshore and offshore surface waters and three-dimensionally model the plume across a coral reef on Maui, Hawai‘i, USA

    International Nuclear Information System (INIS)

    Highlights: ► The Lahaina WWRF effluent plume affects most of the shallow region at Kahekili. ► The Lahaina WWRF effluent plume rises to the surface waters in the Kahekili area. ► The Lahaina WWRF effluent plume flows south with the most predominant current. - Abstract: The coral reef at Kahekili, Maui is located ∼300 m south of the Lahaina Wastewater Reclamation Facility which uses four Class V injection wells to dispose of 3–5 million gallons of wastewater effluent daily. Prior research documented that the wastewater effluent percolates into the nearshore region of Kahekili. To determine if the wastewater effluent was detectable in the surface waters offshore, we used algal bioassays from the nearshore region to 100 m offshore and throughout the water column from the surface to the benthos. These algal bioassays documented that significantly more wastewater effluent was detected in the surface rather than the benthic waters and allowed us to generate a three-dimensional model of the wastewater plume in the Kahekili coastal region. Samples located over freshwater seeps had the highest δ15N values (∼30–35‰) and the effluent was detected in surface samples 500 m south and 100 m offshore of the freshwater seeps (∼8–11‰).

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

    International Nuclear Information System (INIS)

    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.

  9. Environmental drivers of phototrophic biofilms in an Alpine show cave (SW-Italian Alps).

    Science.gov (United States)

    Piano, E; Bona, F; Falasco, E; La Morgia, V; Badino, G; Isaia, M

    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. PMID:26112916

  10. 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.

  11. A process-driven sedimentary habitat modelling approach, explaining seafloor integrity and biodiversity assessment within the European Marine Strategy Framework Directive

    Science.gov (United States)

    Galparsoro, Ibon; Borja, Ángel; Kostylev, Vladimir E.; Rodríguez, J. Germán; Pascual, Marta; Muxika, Iñigo

    2013-10-01

    The Marine Strategy Framework Directive (MSFD) seeks to achieve good environmental status, by 2020, for European seas. This study analyses the applicability of a process-driven benthic sedimentary habitat model, to be used in the implementation of the MSFD in relation to biodiversity and seafloor integrity descriptors for sedimentary habitats. Our approach maps the major environmental factors influencing soft-bottom macrobenthic community structure and the life-history traits of species. Among the 16 environmental variables considered, a combination of water depth, mean grain size, a wave-induced sediment resuspension index and annual bottom maximum temperature, are the most significant factors explaining the variability in the structure of benthic communities in the study area. These variables are classified into those representing the ‘Disturbance' and ‘Scope for Growth' components of the environment. It was observed that the habitat classes defined in the process-driven model reflected different structural and functional characteristics of the benthos. Moreover, benthic community structure anomalies due to human pressures could also be detected within the model produced. Thus, the final process-driven habitat map can be considered as being highly useful for seafloor integrity and biodiversity assessment, within the European MSFD as well as for conservation, environmental status assessment and managing human activities, especially within the marine spatial planning process.

  12. 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

  13. Comparative analysis of the mobility of uranium and artificial radionuclides in the ecosystem of the Yenisei River

    International Nuclear Information System (INIS)

    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 both artificial

  14. Arctic spring awakening - Steering principles behind the phenology of vernal ice algal blooms

    Science.gov (United States)

    Leu, E.; Mundy, C. J.; Assmy, P.; Campbell, K.; Gabrielsen, T. M.; Gosselin, M.; Juul-Pedersen, T.; Gradinger, R.

    2015-12-01

    Marine ecosystems at high latitudes are characterized by extreme seasonal changes in light conditions, as well as a limited period of high primary production during spring and early summer. As light returns at the end of winter to Arctic ice-covered seas, a first algal bloom takes place in the bottom layer of the sea ice. This bottom ice algae community develops through three distinct phases in the transition from winter to spring, starting with phase I, a predominantly net heterotroph community that has limited interaction with the pelagic or benthic realms. Phase II begins in the spring once light for photosynthesis becomes available at the ice bottom, although interaction with the water column and benthos remains limited. The transition to the final phase III is then mainly driven by a balance of atmospheric and oceanographic forcing that induce structural changes in the sea ice and ultimately the removal of algal biomass from the ice. Due to limited data availability an incomplete understanding exists of all the processes determining ice algal bloom phenology and the considerable geographic differences in sympagic algal standing stocks and primary production. We present here the first pan-Arctic compilation of available time-series data on vernal sea ice algal bloom development and identify the most important factors controlling its development and termination. Using data from the area surrounding Resolute Bay (Nunavut, Canada) as an example, we support previous investigations that snow cover on top of the ice influences sea ice algal phenology, with highest biomass development, but also earliest termination of blooms, under low snow cover. We also provide a pan-Arctic overview of sea ice algae standing stocks and primary production, and discuss the pertinent processes behind the geographic differences we observed. Finally, we assess potential future changes in vernal algal bloom phenology as a consequence of climate change, including their importance to

  15. Does feeding behavior facilitate trophic niche partitioning in two sympatric sucker species from the American Southwest?

    Science.gov (United States)

    O'Neill, Matthew W; Gibb, Alice C

    2014-01-01

    We examined two sympatric desert fishes, Sonora suckers (Catostomus insignis) and desert suckers (Pantosteus clarkii), and asked, does feeding behavior facilitate trophic niche partitioning? To answer this question, we conducted laboratory-based feeding trials to determine whether morphology alone facilitates the diet separation between the relatively unspecialized, omnivorous Sonora sucker and the more morphologically specialized, algivorous desert sucker or whether behavioral differences accompany morphological specialization. We predicted that (1) algivorous desert suckers would maximize contact between jaws and substrate and produce a large mouth-gape to facilitate scraping attached food-material; (2) omnivorous Sonora suckers would be more effective suction feeders when consuming unattached food items from the benthos; and (3) because they are anatomically specialized for scraping, desert suckers could not alter their feeding behavior when presented with different prey types, whereas relatively unspecialized Sonora suckers could vary behavior with prey type. We found that both species maximized jaw contact when feeding on benthic-attached food, although desert suckers produced a greater gape area. We also found that Sonora suckers were more effective suction feeders when feeding on benthic-unattached prey. Counter to our initial predictions, both species altered key aspects of feeding behavior in response to different prey types/locations. It appears that both sucker species can function as generalist feeders to exploit a variety of prey types within their natural habitat; indeed, this behavioral versatility may allow desert and Sonora suckers to respond to the cyclic environmental changes that are characteristic of the aquatic habitats of the American Southwest. PMID:24457922

  16. Survival, movement, and health of hatchery-raised juvenile Lost River suckers within a mesocosm in Upper Klamath Lake, Oregon

    Science.gov (United States)

    Hereford, Danielle M.; Burdick, Summer M.; Elliott, Diane G.; Dolan-Caret, Amari; Conway, Carla M.; Harris, Alta C.

    2016-01-01

    The recovery of endangered Lost River suckers (Deltistes luxatus) in Upper Klamath Lake is limited by poor juvenile survival and failure to recruit into the adult population. Poor water quality, degradation of rearing habitat, and toxic levels of microcystin are hypothesized to contribute to low juvenile survival. Studies of wild juvenile suckers are limited in that capture rates are low and compromised individuals are rarely captured in passive nets. The goal of this study was to assess the use of a mesocosm for learning about juvenile survival, movement, and health. Hatchery-raised juvenile Lost River suckers were PIT (passive integrated transponder) tagged and monitored by three vertically stratified antennas. Fish locations within the mesocosm were recorded at least every 30 minutes and were assessed in relation to vertically stratified water-quality conditions. Vertical movement patterns were analyzed to identify the timing of mortality for each fish. Most mortality occurred from July 28 to August 16, 2014. Juvenile suckers spent daylight hours near the benthos and moved throughout the entire water column during dark hours. Diel movements were not in response to dissolved-oxygen concentrations, temperature, or pH. Furthermore, low dissolved-oxygen concentrations, high temperatures, high pH, high un-ionized ammonia, or high microcystin levels did not directly cause mortality, although indirect effects may have occurred. However, water-quality conditions known to be lethal to juvenile Lost River suckers did not occur during the study period. Histological assessment revealed severe gill hyperplasia and Ichthyobodo sp. infestations in most moribund fish. For these fish, Ichthyobodo sp. was likely the cause of mortality, although it is unclear if this parasite originated in the rearing facility because fish were not screened for this parasite prior to introduction. This study has demonstrated that we can effectively use a mesocosm equipped with antennas to learn

  17. Integrating Ecosystem Engineering and Food Web Ecology: Testing the Effect of Biogenic Reefs on the Food Web of a Soft-Bottom Intertidal Area.

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    Bart De Smet

    Full Text Available 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.

  18. 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

    Background 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. Methodology/Principal Findings 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. Conclusions/Significance 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

  19. Benthic ecology of the northeastern Chukchi Sea. Part II. Spatial variation of megafaunal community structure, 2009-2010

    Science.gov (United States)

    Blanchard, Arny L.; Parris, Carrie L.; Knowlton, Ann L.; Wade, Nicole R.

    2013-09-01

    Sources for spatial variability of benthic megafaunal communities in the northeastern Chukchi Sea are poorly documented and may include altered water circulation patterns, as noted for macrofauna. Spatial variability of megafauna was investigated by sampling with a plumb-staff beam trawl in three petroleum leases, the Klondike, Burger, and Statoil study areas, as part of a multi-disciplinary research program in the northeastern Chukchi Sea ecosystem. Trawling occurred during two sampling periods from 2009 and one in 2010 with a total of 81 trawls from 38 stations. A total of 99 discrete taxonomic categories were identified in 2009 and 2010 which were expanded to 239 taxa in the laboratory. Biomass in the three study areas ranged from ∼15,500 to ∼96,000 g 1000 m-2 and numerical density ranged from ∼8500 to ∼134,000 individuals 1000 m-2. Although the megabenthic species-assemblages in all three study areas were similar in composition, average biomass values were higher in Burger (ranging from ∼54,000 to ∼96,000 g 1000 m-2) where altered water circulation occurs, than in Klondike (ranging from ∼15,500 to ∼31,000 g 1000 m-2) or Statoil (∼15,000 g 1000 m-2). The brittle star Ophiura sarsi was the numerically dominant megafauna (70% of total biomass) followed by the snow crab Chionoecetes opilio (7% total biomass), as noted in prior investigations in the region. Biomass and density of benthic megafauna in this region reflected the high quantities of seasonal production reaching the benthos in the shallow waters of the Chukchi Sea. Differences in benthic communities among study areas were associated with variations in bottom-water temperature and latitude, and to a lesser extent, water depth and percent mud. We believe these associations arise from effects of topography on northward-flowing water, that create regions of slower currents, and consequently, higher organic deposition.

  20. 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.

  1. 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. PMID:26734732

  2. 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 BACKGROUND: 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. METHODOLOGY/PRINCIPAL FINDINGS: 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. CONCLUSIONS/SIGNIFICANCE: 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

  3. How well do we know the infaunal biomass of the continental shelf?

    Science.gov (United States)

    Powell, Eric N.; Mann, Roger

    2016-03-01

    Benthic infauna comprise a wide range of taxa of varying abundances and sizes, but large infaunal taxa are infrequently recorded in community surveys of the shelf benthos. These larger, but numerically rare, species may contribute disproportionately to biomass, however. We examine the degree to which standard benthic sampling gear and survey design provide an adequate estimate of the biomass of large infauna using the Atlantic surfclam, Spisula solidissima, on the continental shelf off the northeastern coast of the United States as a test organism. We develop a numerical model that simulates standard survey designs, gear types, and sampling densities to evaluate the effectiveness of vertically-dropped sampling gear (e.g., boxcores, grabs) for estimating density of large species. Simulations of randomly distributed clams at a density of 0.5-1 m-2 within an 0.25-km2 domain show that lower sampling densities (1-5 samples per sampling event) resulted in highly inaccurate estimates of clam density with the presence of clams detected in less than 25% of the sampling events. In all cases in which patchiness was present in the simulated clam population, surveys were prone to very large errors (survey availability events) unless a dense (e.g., 100-sample) sampling protocol was imposed. Thus, commercial quantities of surfclams could easily go completely undetected by any standard benthic community survey protocol using vertically-dropped gear. Without recourse to modern high-volume sampling gear capable of sampling many meters at a swath, such as hydraulic dredges, biomass of the continental shelf will be grievously underestimated if large infauna are present even at moderate densities.

  4. Heavy metals associated with reduced sulfur in sediments from different deposition environments in the Pearl River estuary, China.

    Science.gov (United States)

    Chen, Fanrong; Yang, Yongqiang; Zhang, Derong; Zhang, Ling

    2006-06-01

    Distribution of acid volatile sulfur (AVS) and the simultaneously extracted metals (SEM: Cu, Pb, Zn, Cd, Ni) in sediment profiles has been studied at five sites in Pearl River estuary, China. Of the five sampling locations, Nos.1 and 2 are in the middle shoal, Nos.3 and 4 in the west shoal and No. 5 locates to the south of the estuary. The AVS content in the sediments of the middle shoal varies in a small range (0.25-4.06 micromol g(-1)), while that of west shoal increases with depth from 0 to ultimately 26.09 micromol g(-1). The SEM concentration in the sediment profiles at location Nos. 1, 2 and 5 is generally in the range of 0.95+/-0.2 micromol g(-1) with a slight upward increase, while that in the sediment of west shallows are much higher (1.43-2.42 micromol g(-1)) with a significant upward increase, especially in the upper layer of ca. 15 cm. The observed upward increase of SEM content at all the sites implies that heavy metal contamination of sediment in the Pearl River estuary is increasing. Calculations of the excess heavy metal content which is defined by SEM-AVS molar difference suggests that the upper sediment in the Pearl River estuary, especially on the west shallows, could be a source of heavy metal contaminants and may cause toxicity to the benthos. The site-specific distribution patterns in the AVS and SEM profiles were interpreted according to the hydrogeochemistry of deposition environments. PMID:16767564

  5. Maternal food provisioning in a substrate-brooding African cichlid.

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    Kazutaka Ota

    Full Text Available Fish demonstrate the greatest variety of parental care strategies within the animal kingdom. Fish parents seldom provision food for offspring, with some exceptions predominantly found in substrate-brooding Central American cichlids and mouth-brooding African cichlids. Here, we provide the first evidence of food provisioning in a substrate-brooding African cichlid Neolamprologus mondabu. This fish is a maternal substrate-brooding cichlid endemic to Lake Tanganyika, and feeds on benthic animals using unique techniques-individuals typically feed on the surface of sandy substrates, but also expose prey by digging up substrates with vigorous wriggling of their body and fins. Young also feed on benthos on the substrate surface, but only using the first technique. We observed that feeding induced by digging accounted for 30% of total feeding bouts in adult females, demonstrating that digging is an important foraging tactic. However, parental females fed less frequently after digging than non-parental females, although both females stayed in pits created by digging for approximately 30 s. Instead, young gathered in the pit and fed intensively, suggesting that parental females provision food for young by means of digging. We tested this hypothesis by comparing the feeding frequency of young before and after digging that was simulated by hand, and observed that young doubled their feeding frequency after the simulated digging. This suggests that parental females engage in digging to uncover food items that are otherwise unavailable to young, and provision food for them at the expense of their own foraging. This behavior was similar to what has been observed in Central American cichlids.

  6. Bioavailability of surface dissolved organic matter to aphotic bacterial communities in the Amundsen Sea Polynya, Antarctica

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    Rachel E. Sipler

    2015-07-01

    Full Text Available Abstract Antarctic seas, and particularly the Amundsen Sea Polynya, are some of the most productive oceanic regions on Earth. Ice-algal production during austral spring is followed by open-water pelagic production later in the season. Although ice-free growth accounts for a greater percentage of the annual net primary production, ice algae provide an important source of nutrients to organisms throughout the water column and benthos in areas and seasons when open-water production is insignificant. The objectives of this study were to assess the bioavailability of dissolved organic matter (DOM, sourced from ice algae or the chlorophyll maximum (chl max, to marine bacterioplankton and to determine the fate of carbon within these different DOM pools, including loss to respiration, incorporation into bacterial biomass and retention within the DOM pool itself. Nutrient concentrations and bacterial abundance, production, and cell volume were monitored during a 7-day bioassay study involving four treatments conducted shipboard in the Amundsen Sea Polynya, Antarctica. The greatest response in bacterial abundance and activity was observed when ice-algal meltwater was supplied to aphotic zone bacterioplankton collected from 170-m depth. However, bacterial growth efficiency was higher (24% when chl max water was supplied to the same aphotic zone bacterial community compared to the bacterial growth efficiency of the ice-algal treatment (15%. Approximately 15% of dissolved organic carbon (DOC from the ice-algal source and 18% from the chl max was consumed by aphotic bacterial communities over the relatively short, one-week incubation. In contrast, 65% of the dissolved organic nitrogen (DON added as an integral part of the ice-algal DOM was consumed, but none of the DON supplied with chl max water was labile. This study underscores the importance of considering DOM sources when investigating or predicting changes in carbon and nitrogen cycling within the

  7. 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.

  8. The seasonal use of small-scale space by benthic species in a transiently hypoxic area

    Science.gov (United States)

    Doya, Carolina; Aguzzi, Jacopo; Chatzievangelou, Damianos; Costa, Corrado; Company, Joan Baptista; Tunnicliffe, Verena

    2016-02-01

    The use of small-scale space by benthos and its variation over the seasons in transiently hypoxic zones is poorly known. In this study, we examined the reciprocal spatial dispersion of the squat lobster (Munida quadrispina) and the slender sole (Lyopsetta exilis) according to oxygen concentrations at a VENUS platform of Ocean Networks Canada (ONC). This platform is located in a seasonally hypoxic zone at 96 m depth in the fjord of Saanich Inlet (British Columbia, Canada). We counted and located small as well as large squat lobsters and slender soles in digital still images during 1 year (2012-2013) also concomitantly obtained oxygen data. Images were subdivided in a squared grid to obtain relative density maps as a proxy for surface occupation and spatial autocorrelation. Pearson's chi-squared tests at a yearly scale, along with Dixon's spatial segregation index (S) for each possible pair among the studied groups, showed a significant absence of overlap. The same analyses by month and cross-correlation between oxygen and S showed that while the dispersion patterns of the large squat lobsters seemed to be driven mainly by the morphology of the seafloor, an effect of hypoxia was found in the small squat lobsters and the slender soles levels of aggregation. Small squat lobster sought seabed protrusions, such as sponges, to reach more oxygenated water. The slender sole's space occupation decreased significantly, being forced to retreat when the squat lobsters' abundance peaked as a result of what appeared to be a seasonal reproduction event in early summer. Our results contribute to the understanding of the ways in which oxygen levels modulate substrate use by benthic species in the framework of a global expansion of hypoxia in coastal and ocean areas.

  9. Biological vs. physical mixing effects on benthic food web dynamics.

    Directory of Open Access Journals (Sweden)

    Ulrike Braeckman

    Full Text Available Biological particle mixing (bioturbation and solute transfer (bio-irrigation contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator and Abra alba (bioturbator compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13C labelled diatom Skeletonema costatum was added to 4 treatments: (1 microcosms containing the bioturbator, (2 microcosms containing the bio-irrigator, (3 control microcosms and (4 microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ(13C of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2, which included TO(13C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food

  10. Biological vs. physical mixing effects on benthic food web dynamics.

    Science.gov (United States)

    Braeckman, Ulrike; Provoost, Pieter; Moens, Tom; Soetaert, Karline; Middelburg, Jack J; Vincx, Magda; Vanaverbeke, Jan

    2011-01-01

    Biological particle mixing (bioturbation) and solute transfer (bio-irrigation) contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria) and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering) or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator) and Abra alba (bioturbator) compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13)C labelled diatom Skeletonema costatum was added to 4 treatments: (1) microcosms containing the bioturbator, (2) microcosms containing the bio-irrigator, (3) control microcosms and (4) microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ(13)C) of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13)C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2)), which included TO(13)C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food source

  11. Benthic Oxygen Demand in Three Former Salt Ponds Adjacent to South San Francisco Bay, California

    Science.gov (United States)

    Topping, Brent R.; Kuwabara, James S.; Athearn, Nicole D.; Takekawa, John Y.; Parcheso, Francis; Henderson, Kathleen D.; Piotter, Sara

    2009-01-01

    Sampling trips were coordinated in the second half of 2008 to examine the interstitial water in the sediment and the overlying bottom waters of three shallow (average depth 2 meters). The water column at all deployment sites was monitored with dataloggers for ancillary water-quality parameters (including dissolved oxygen, salinity, specific conductance, temperature, and pH) to facilitate the interpretation of benthic-flux results. Calculated diffusive benthic flux of dissolved (0.2-micron filtered) oxygen was consistently negative (that is, drawn from the water column into the sediment) and ranged between -0.5 x 10-6 and -37 x 10-6 micromoles per square centimeter per second (site averages depicted in table 2). Assuming pond areas of 1.0, 1.4, and 2.3 square kilometers for ponds A16, A14, and A3W, respectively, this converts to an oxygen mass flux into the ponds' sediment ranging from -1 to -72 kilograms per day. Diffusive oxygen flux into the benthos (listed as negative) was lowest in pond A14 (-0.5 x 10-6 to -1.8 x 10-6 micromoles per square centimeter per second) compared with diffusive flux estimates for ponds A16 and A3W (site averages -26 x 10-6 to -35 x 10-6 and -34 x 10-6 to -37 x 10-6 micromoles per square centimeter per second, respectively). These initial diffusive-flux estimates are of the order of magnitude of those measured in the South Bay using core-incubation experiments (Topping and others, 2004), which include bioturbation and bioirrigation effects. Estimates of benthic oxygen demand reported herein, based on molecular diffusion, serve as conservative estimates of benthic flux because solute transport across the sediment-water interface can be enhanced by multidisciplinary processes including bioturbation, bioirrigation, ground-water advection, and wind resuspension (Kuwabara and others, 2009).

  12. Use of man-made impoundment in mitigating acid mine drainage in the North Branch Potomac River

    International Nuclear Information System (INIS)

    The US Department of the Army, Baltimore District Corps of Engineers, oversees a long-term monitoring study to assess and evaluate effects of the Jennings-Randolph reservoir on biota in the North Branch Potomac River. The reservoir was intended, in part, to mitigate effects of acid mine drainage originating in upstream and headwater area. The present study assessed recovery of benthos and fish in this system, six years after completion of the reservoir. Higher pH and lower iron and sulfate concentrations were observed upstream of the reservoir compared to preimpoundment conditions, suggesting better overall water quality in the upper North Branch. Water quality improved slightly directly downstream of the reservoir. However, the reservoir itself was poorly colonized by macrophytes and benthic organisms, and plankton composition suggested either metal toxicity and/or nutrient limitation. One large tributary to the North Branch and the reservoir (Stony River) was shown to have high (and possibly toxic) levels of manganese, iron, zinc, and aluminum due to subsurface coal mine drainage. Macroinvertebrate diversity and number of taxa were higher in sites downstream of the reservoir in the present study. Compared with previous years, the present study suggested relatively rapid recovery in the lower North Branch due to colonization from two major unimpacted tributaries in this system: Savage River and South Branch Potomac. Fish data were consistent with macroinvertebrate results, but site-to-site variation in species composition was greater. Results show that recovery of biota in the North Branch Potomac was attributed to decreased acid inputs from mining operations and dilution from the Savage River, which contributed better water quality. Continued improvement of North Branch Potomac biota may not be expected unless additional mitigation attempts, either within the reservoir or upstream, are undertaken

  13. Field experiments on the role of epibenthic predators in determining prey densities in an estuarine mudflat

    Science.gov (United States)

    Gee, J. M.; Warwick, R. M.; Davey, J. T.; George, C. L.

    1985-09-01

    A series of caging experiments was performed on an estuarine mudflat at three seasons of the year, in which Carcinus maenas L. and Pomatoschistus microps (Kroyer) were either excluded from, or allowed to prey upon, the benthos in order to determine to what extent infaunal abundance and mortality was a result of predation by epibenthic predators. The difficulties of conducting and interpreting the results of such experiments are recognized. The benthic macrofauna of this mudflat is dominated numerically by small annelids and there is evidence that adult C. maenas can cause significant increases in the oligochaete component of this assemblage, probably as a result of disturbance caused by its burrowing activity. Juvenile C. maenas on the other hand significantly reduced the abundance of small annelids, particularly the dominant polychaete Manayunkia aestuarina (Bourne) and could be responsible for year-to-year variations in abundance of this species. The role of fish predators (in this case P. microps) is more problematical but it is suggested that in the densities at which they occur naturally on the mudflat they have little direct effect on the abundance of prey species. There is no evidence that seasonal mortality of small annelids is reduced in the absence of predation and this is taken to indicate that not all mortality is due to epibenthic predation. Certain changes in relative abundance of the component species of the harpacticoid copepod community were discerned but it is suggested that the plasticity of their reproductive potential is such that the effect of predation on the group as a whole is usually masked.

  14. Decadal reanalysis of biogeochemical indicators and fluxes in the North West European shelf-sea ecosystem

    Science.gov (United States)

    Ciavatta, S.; Kay, S.; Saux-Picart, S.; Butenschön, M.; Allen, J. I.

    2016-03-01

    This paper presents the first decadal reanalysis simulation of the biogeochemistry of the North West European shelf, along with a full evaluation of its skill, confidence, and value. An error-characterized satellite product for chlorophyll was assimilated into a physical-biogeochemical model of the North East Atlantic, applying a localized Ensemble Kalman filter. The results showed that the reanalysis improved the model simulation of assimilated chlorophyll in 60% of the study region. Model validation metrics showed that the reanalysis had skill in matching a large data set of in situ observations for 10 ecosystem variables. Spearman rank correlations were significant and higher than 0.7 for physical-chemical variables (temperature, salinity, and oxygen), ˜0.6 for chlorophyll and nutrients (phosphate, nitrate, and silicate), and significant, though lower in value, for partial pressure of dissolved carbon dioxide (˜0.4). The reanalysis captured the magnitude of pH and ammonia observations, but not their variability. The value of the reanalysis for assessing environmental status and variability has been exemplified in two case studies. The first shows that between 325,000 and 365,000 km2 of shelf bottom waters were vulnerable to oxygen deficiency potentially threatening bottom fishes and benthos. The second application confirmed that the shelf is a net sink of atmospheric carbon dioxide, but the total amount of uptake varies between 36 and 46 Tg C yr-1 at a 90% confidence level. These results indicate that the reanalysis output data set can inform the management of the North West European shelf ecosystem, in relation to eutrophication, fishery, and variability of the carbon cycle.

  15. The role of the hydrological cycle on the temporal patterns of macroinvertebrate assemblages in an Andean foothill stream in Colombia

    Directory of Open Access Journals (Sweden)

    María I. Ríos-Pulgarín

    2016-03-01

    Full Text Available The seasonal and interannual changes in the structure, composition and functional feeding groups of the macroinvertebrate assemblage of the Guarinó River, a torrential system located in the Colombian Andean foothills, were examined in relation to the physical and chemical environmental changes associated with the hydrological cycle and the El Niño-Niña/Southern Oscillation (ENSO between 2007 and 2010. Benthic samples were collected at three sites in the lower sections of the river. A total of 127 taxa were collected in the study, with the total taxonomic richness per site ranging from 82 to 96 taxa and benthos density averaging 5.41 ind. m-2. The density showed a tendency to decrease in periods of maximum river level and flow, particularly during La Niña phenomena, and to increase in dry periods, especially in the third year (2009-2010 during El Niño phenomena. The presence and abundance of taxa, functional feeding groups and life habits were regulated by environmental parameters associated with hydrological variability, derived of ENSO phenomena, especially flow rate values. The assemblage showed high taxonomic and functional diversity, which is characteristic of ecosystems affected by recurrent hydrological disturbances, exhibiting differentiated responses based on adaptive strategies against the local hydrologic regime that allow fast recovery under conditions like ENSO phenomena. Such responses include composition changes according to adaptations to different hydrological scenarios, the predominance of generalist trophic guilds and taxa with plasticity in their habits and range of environmental tolerance.

  16. Linking manipulative experiments to field data to test the dilution effect.

    Science.gov (United States)

    Venesky, Matthew D; Liu, Xuan; Sauer, Erin L; Rohr, Jason R

    2014-05-01

    The dilution effect, the hypothesis that biodiversity reduces disease risk, has received support in many systems. However, few dilution effect studies have linked mechanistic experiments to field patterns to establish both causality and ecological relevance. We conducted a series of laboratory experiments and tested the dilution effect hypothesis in an amphibian-Batrachochytrium dendrobatidis (Bd) system and tested for consistency between our laboratory experiments and field patterns of amphibian species richness, host identity and Bd prevalence. In our laboratory experiments, we show that tadpoles can filter feed Bd zoospores and that the degree of suspension feeding was positively associated with their dilution potential. The obligate suspension feeder, Gastrophryne carolinensis, generally diluted the risk of chytridiomycosis for tadpoles of Bufo terrestris and Hyla cinerea, whereas tadpoles of B. terrestris (an obligate benthos feeder) generally amplified infections for the other species. In addition, G. carolinensis reduced Bd abundance on H. cinerea more so in the presence than absence of B. terrestris and B. terrestris amplified Bd abundance on H. cinerea more so in the absence than presence of G. carolinensis. Also, when ignoring species identity, species richness was a significant negative predictor of Bd abundance. In our analysis of field data, the presence of Bufo spp. and Gastrophryne spp. were significant positive and negative predictors of Bd prevalence, respectively, even after controlling for climate, vegetation, anthropogenic factors (human footprint), species richness and sampling effort. These patterns of dilution and amplification supported our laboratory findings, demonstrating that the results are likely ecologically relevant. The results from our laboratory and field data support the dilution effect hypothesis and also suggest that dilution and amplification are predictable based on host traits. Our study is among the first to link

  17. Environmental effects monitoring for exploration drilling

    International Nuclear Information System (INIS)

    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

  18. Contribution of allochthonous organic carbon across the Serrano River Basin and the adjacent fjord system in Southern Chilean Patagonia: Insights from the combined use of stable isotope and fatty acid biomarkers

    Science.gov (United States)

    Lafon, Alejandra; Silva, Nelson; Vargas, Cristian A.

    2014-12-01

    Chilean Patagonia is characterized by an irregular geography involving many islands, peninsulas, channels, sounds and fjords, that prevent direct interaction between oceanic water masses and freshwater river discharges at the head of the continental fjords. In this paper, we evaluate the potential sources and composition of organic matter along the Serrano River basin and the adjacent channels and fjords in Southern Chilean Patagonia (51-52°S), as well as their importance for marine planktonic organisms. In spring of 2009, evidence of C:N ratio, δ13C, δ15N and fatty acids composition in particulate organic carbon (POC), surface sediment, soil, plankton, and vegetal tissue, as well some physical and chemical characteristics (i.e. salinity, dissolved oxygen, NO3-, NH4+, PO4-3, Si(OH)4), were measured in samples collected during the CIMAR 14 Fiordos oceanographic cruise. Significant differences in δ13C-POC were found between the terrestrial and marine environments but not within fjord stations. Along the fjord region, the high C:N ratio and depleted δ13C values in POC samples suggest that particulate organic matter (POM) in the upper level of the water column (0-10 m depth) is supported by different sources. Terrestrial organic carbon exported by rivers may constitute a significant subsidy, up to 70% based on two end-member mixing model, to the fjord ecosystem. Furthermore, terrestrial carbon might account for a significant percentage of the zooplankton body carbon, estimated both by using isotopic (∼24-61%) and fatty acid analysis (∼14-61%). Isotopic analyses in marine sediment samples suggest that POC seems to be decoupled from terrestrial-influenced surface sources at the fjord stations, and the contribution of surrounding vegetation seemingly unimportant for carbon export to the benthos. Local hydrographic and geomorphological characteristics might determine the presence of oceanographic frontal zones, which in turn might explain differences in carbon

  19. Trophic structure and pathways of biogenic carbon flow in the eastern North Water Polynya

    Science.gov (United States)

    Tremblay, Jean-Éric; Hattori, Hiroshi; Michel, Christine; Ringuette, Marc; Mei, Zhi-Ping; Lovejoy, Connie; Fortier, Louis; Hobson, Keith A.; Amiel, David; Cochran, Kirk

    2006-10-01

    In the eastern North Water, most of the estimated annual new and net production of carbon (C) occurred during the main diatom bloom in 1998. During the bloom, at least 30% of total and new phytoplankton production occurred as dissolved organic carbon (DOC) and was unavailable for short-term assimilation into the herbivorous food web or sinking export. Based on particle interceptor traps and 234Th deficits, 27% of the particulate primary production (PP) sank out of the upper 50 m, with only 7% and 1% of PP reaching the benthos at shallow (≈200 m) and deep (≈500 m) sites, respectively. Mass balance calculations and grazing estimates agree that ≈79% of PP was ingested by pelagic consumers between April and July. During this period, the vertical flux of biogenic silica (BioSi) at 50 m was equivalent to the total BioSi produced, indicating that all of the diatom production was removed from the euphotic zone as intact cells (direct sinking) or empty frustules (grazing or lysis). The estimated flux of empty frustules was consistent with rates of herbivory by the large, dominant copepods and appendicularians during incubations. Since the carbon demand of the dominant planktivorous bird, Alle alle, amounted to ≈2% of the biomass synthesized by its main prey, the large copepod Calanus hyperboreus, most of the secondary carbon production was available to pelagic carnivores. Stable isotopes indicated that the biomass of predatory amphipods, polar cod and marine mammals was derived from these herbivores, but corresponding carbon fluxes were not quantified. Our analysis shows that a large fraction of PP in the eastern North Water was ingested by consumers in the upper 50 m, leading to substantial carbon respiration and DOC accumulation in surface waters. An increasingly early and prolonged opening of the Artic Ocean is likely to promote the productivity of the herbivorous food web, but not the short-term efficiency of the particulate, biological CO 2 pump.

  20. 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. PMID:26733008

  1. 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.

  2. Correlation of resource plays and biodiversity patterns: accumulation of organic-rich shale tracks taxonomic turnover

    Science.gov (United States)

    Eoff, Jennifer D.

    2012-01-01

    Similar paleogeographic and paleotectonic settings characterize most self-sourced shale hydrocarbon plays. Their deposition occurred within similar orders of magnitude of eustatic events and during geologic periods characterized by “warm” (or transitional) climates and calcitic seas. In addition, the stratigraphic occurrence of shale plays parallels certain historical patterns of marine metazoan biodiversity. Such strong agreement among several correlation tools elucidates why these resources may be limited to discrete intervals of geological time. Correlation of self-sourced shale with biodiversity trends indicates that the factors controlling the deposition of marine organic matter may not be independent of those that induced taxonomic turnover. Paleoecological changes promoted accumulation and preservation of Type II kerogen. Deposition of self-sourced shale appears to correspond to reductions in absolute biodiversity and declining percentages of bioturbating taxa, with concomitant increases in proportions of pelagic taxa relative to infaunal and epifaunal organisms. Whereas upwelling and anoxia may have contributed to the deposition of kerogen in source rocks throughout much of the sedimentary record, diminished consumption of biomass by benthic metazoans likely augmented the preservation of organic carbon during deposition of this shale type. Rapid tectonic-plate reconfiguration induced coeval events, creating basins with sufficiently high rates of accommodation creation necessary to preserve additional organic material accumulating as the heterotrophic benthos suffered in response to rapidly changing environments. Combining sea-level curves, paleogeography, climate, and seawater chemistry provides a first-order approximation of the distribution of potential self-sourced shale in the geologic record. A model that predicts the stratigraphic distribution of self-sourced-shale deposition can aid in exploration of continuous hydrocarbon accumulations in self

  3. Biological effects of anthropogenic contaminants in the San Francisco Estuary

    Science.gov (United States)

    Thompson, B.; Adelsbach, T.; Brown, C.; Hunt, J.; Kuwabara, J.; Neale, J.; Ohlendorf, H.; Schwarzbach, S.; Spies, R.; Taberski, K.

    2007-01-01

    Concentrations of many anthropogenic contaminants in the San Francisco Estuary exist at levels that have been associated with biological effects elsewhere, so there is a potential for them to cause biological effects in the Estuary. The purpose of this paper is to summarize information about biological effects on the Estuary's plankton, benthos, fish, birds, and mammals, gathered since the early 1990s, focusing on key accomplishments. These studies have been conducted at all levels of biological organization (sub-cellular through communities), but have included only a small fraction of the organisms and contaminants of concern in the region. The studies summarized provide a body of evidence that some contaminants are causing biological impacts in some biological resources in the Estuary. However, no general patterns of effects were apparent in space and time, and no single contaminant was consistently related to effects among the biota considered. These conclusions reflect the difficulty in demonstrating biological effects due specifically to contamination because there is a wide range of sensitivity to contaminants among the Estuary's many organisms. Additionally, the spatial and temporal distribution of contamination in the Estuary is highly variable, and levels of contamination covary with other environmental factors, such as freshwater inflow or sediment-type. Federal and State regulatory agencies desire to develop biological criteria to protect the Estuary's biological resources. Future studies of biological effects in San Francisco Estuary should focus on the development of meaningful indicators of biological effects, and on key organism and contaminants of concern in long-term, multifaceted studies that include laboratory and field experiments to determine cause and effect to adequately inform management and regulatory decisions. ?? 2006 Elsevier Inc. All rights reserved.

  4. Dietary assimilation of cadmium associated with bacterial exopolymer sediment coatings by the estuarine amphipod Leptocheirus plumulosus: Effects of Cd concentration and salinity

    Science.gov (United States)

    Schlekat, C.E.; Decho, Alan W.; Chandler, G.T.

    1999-01-01

    Bacterial extracellular substances (also known as exopolysaccharides, or EPS) may serve as vectors for trophic transfer of metals in benthic systems because these ubiquitous sediment coatings can sorb high concentrations of toxic metals, and because many benthic invertebrates assimilate EPS sediment coatings upon ingestion. We conducted 3 sets of experiments to determine the assimilative bioavailability of EPS-associated Cd to the benthic amphipod Leptocheirus plumulosus as a function of Cd concentration and salinity. Bioavailability was measured as L. plumulosus Cd assimilation efficiency (AE) from EPS-coated silica (EPS-Si) and from uncoated silica (NC-Si) using modified pulse-chase methods with the gamma-emitting radioisotope 109Cd. Cd AE was significantly greater from NC-Si than from EPS-Si at 7.5???, but not at 2.5 or 25???. Overall, Cd AE from EPS-Si was between 15.1 and 21.5%. Because EPS-Si sorbed more Cd than NC-Si, EPS coatings magnified the amount of Cd amphipods accumulated at each salinity by up to a factor of 10. Salinity did not directly affect Cd AE from EPS-Si, but because Cd-EPS partitioning increased with decreasing salinity, amphipods accumulated more Cd from EPS at the lowest Cd-EPS incubation salinity (2.5 ???) than at higher salinities (7.5 and 25 ???). Finally, Cd concentration in EPS exhibited an inverse relationship with Cd AE at 2.5 ???, but not at 25 ???. Specifically, Cd AE was 12 times greater at 1 compared with 10 ??g Cd ??g-1 EPS. Together, these results show that estuarine benthos can accumulate Cd from EPS sediment coatings, but that the degree to which this phenomenon occurs is dependent upon seawater salinity and Cd concentration in EPS.

  5. The application of plant tests for sediment evaluation; Der Einsatz von Pflanzentests bei der Sedimentbewertung

    Energy Technology Data Exchange (ETDEWEB)

    Feiler, U. [Bundesanstalt fuer Gewaesserkunde, Koblenz (Germany); Claus, E. [Bundesanstalt fuer Gewaesserkunde, Berlin (Germany); Heininger, P. [Bundesanstalt fuer Gewaesserkunde, Koblenz (Germany); Bundesanstalt fuer Gewaesserkunde, Berlin (Germany)

    2002-07-01

    The aim of the present study is to demonstrate that the use of higher plants in biotests for analyses of anthropogenically contaminated sediments yields valuable results, which may be included in a concept for the integrated assessment of waters. The results of this study prove that the selected aquatic plant, Lemna minor, is basically able to indicate contamination. In the aquatic test of the sediment extracts, it showed weak, but very selective, responses to certain classes of contaminants. Fractionating of the sample and subsequent chemical analysis combined with toxicity tests allow to narrow down the groups of substances causing toxic effects. This toxicity was confirmed by analyses of the pore waters and whole sediment samples. Together with other toxicity tests (e.g. standardized bioassays) and combined with biological benthos examinations, an overall judgment can be given for the integrated assessment of waters. (orig.) [German] Ziel der hier vorgestellten Untersuchungen war es zu zeigen, dass der Einsatz von hoeheren Pflanzen in Biotests zur Untersuchung anthropogenen belasteter Sedimente wertvolle Ergebnisse liefert, die in einem Konzept zur integrierten Gewaesserbewertung verwendet werden koennen. Die Ergebnisse dieser Arbeit machen deutlich, dass die ausgewaehlte Wasserpflanze Lemna minor Schadstoffbelastungen grundsaetzlich anzeigt. Im aquatischen Test der Sedimentextrakte weist sie eine zwar schwache, aber sehr selektive Reaktion auf bestimmte Schadstoffklassen auf. Die Fraktionierung der Probe mit anschliessender Stoffanlayse kombiniert mit Toxizitaetstests erlaubt die Eingrenzung der toxisch wirksamen Stoffgruppen. Diese toxische Belastung wurde durch die Porenwasser- und Gesamtsedimentuntersuchung bestaetigt. Zusammen mit weiteren Toxizitaetstests (z.B. standardisierte Biotests) und in Kombination mit benthosbiologischen Untersuchngen ergibt sich eine Gesamtaussage zur integrierten Gewaesserbewertung. (orig.)

  6. 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

  7. 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.

  8. The middle Eocene climatic optimum (MECO): A multiproxy record of paleoceanographic changes in the southeast Atlantic (ODP Site 1263, Walvis Ridge)

    Science.gov (United States)

    Boscolo Galazzo, F.; Thomas, E.; Pagani, M.; Warren, C.; Luciani, V.; Giusberti, L.

    2014-12-01

    The middle Eocene climatic optimum (MECO, ~40 Ma) was a transient period of global warming that interrupted the secular Cenozoic cooling trend. We investigated the paleoceanographic, paleoenvironmental, and paleoecological repercussions of the MECO in the southeast Atlantic subtropical gyre (Ocean Drilling Program Site 1263). TEX86 and δ18O records support an ~4°C increase in surface and deepwater temperatures during the MECO. There is no long-term negative carbon isotope excursion (CIE) associated with the early warming, consistent with other sites, and there is no short-term negative CIE (~50 kyr) during the peak of the MECO, in contrast to what has been observed at some sites. This lack of a CIE during the peak of the MECO at Site 1263 could be due to poor sediment recovery or geographic heterogeneity of the δ13C signal. Benthic and planktic foraminiferal mass accumulation rates markedly declined during MECO, indicating a reduction of planktic foraminiferal production and export productivity. Vertical δ13C gradients do not indicate major changes in water column stratification, and there is no biomarker or micropaleontological evidence that hypoxia developed. We suggest that temperature dependency of metabolic rates could explain the observed decrease in foraminiferal productivity during warming. The kinetics of biochemical reactions increase with temperature, more so for heterotrophs than for autotrophs. Steady warming during MECO may have enhanced heterotroph (i.e., foraminiferal) metabolic rates, so that they required more nutrients. These additional nutrients were not available because of the oligotrophic conditions in the region and the lesser response of primary producers to warming. The combination of warming and heterotroph starvation altered pelagic food webs, increased water column recycling of organic carbon, and decreased the amount of organic carbon available to the benthos.

  9. 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.

  10. Carbon fate in a large temperate human-impacted river system: focus on benthic dynamics

    Science.gov (United States)

    Vilmin, Lauriane; Flipo, Nicolas; Escoffier, Nicolas; Rocher, Vincent; Groleau, Alexis

    2016-04-01

    During the last decade, several studies highlighted the important role of fluvial networks in regional and global carbon (C) budgets. Therefore, for sustainable C management, in-river C processing needs to be well understood. The Seine River from the Paris urban area to the entrance of its estuary (220 km) is studied here as a pertinent example of a large human impacted river system subject to temperate climatic conditions. We assess organic C (OC) budgets up- and downstream one of the world's largest waste water treatment plants and for different hydrological conditions through hydro-biogeochemical distributed modelling. The fine representation of sediment accumulation on the river bed allows the quantification of the effect of pelagic and benthic processes on OC export towards the estuary and on river metabolism (i.e. net CO2 emission). OC export is significantly affected by benthic dynamics during the driest periods, when 25 % of the inputs to the system is transformed or stored in the sediment layer. River metabolism is also significantly affected by benthic processes, whatever the hydrological conditions. On average, benthic respiration accounts for one third of the total ecosystem respiration along the studied stretch (0.23 out of 0.86 gC.m-2.d-1). These results stress the major influence of benthic dynamics, and thus of physical processes such as sedimentation and re-suspension on C cycling, in large human-impacted temperate river systems and on C export to the estuaries. Even though the importance of benthos processes was already acknowledged by the scientific community for headwater streams, this work highlights its importance for downstream river systems and opens the door to new developments in the quantification of C emissions by global models, in which biogeochemical processing and benthic dynamics must be taken into account.

  11. 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.

  12. 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

  13. Evolutionary pathways among shallow and deep-sea echinoids of the genus Sterechinus in the Southern Ocean

    Science.gov (United States)

    Díaz, A.; Féral, J.-P.; David, B.; Saucède, T.; Poulin, E.

    2011-03-01

    Antarctica is structured by a narrow and deep continental shelf that sustains a remarkable number of benthic species. The origin of these species and their affinities with the deep-sea fauna that borders the continent shelf are not clear. To date, two main hypotheses have been considered to account for the evolutionary connection between the faunas: (1) either shallow taxa moved down to deep waters (submergence) or (2) deep-sea taxa colonized the continental shelf (emergence). The regular sea urchin genus Sterechinus is a good model to explore the evolutionary relationships among these faunas because its five nominal species include Antarctic and Subantarctic distributions and different bathymetric ranges. Phylogenetic relationships and divergence times among Sterechinus species were established using the COI mitochondrial gene by assuming a molecular clock hypothesis. The results showed the existence of two genetically distinct main groups. The first corresponds exclusively to the shallow-water Antarctic species S. neumayeri, while the second includes all the other nominal species, either deep or shallow, Antarctic or Subantarctic. Within the latter group, S. dentifer specimens all formed a monophyletic cluster, slightly divergent from all other specimens, which were mixed in a second cluster that included S. agassizi from the continental shelf of Argentina, S. diadema from the Kerguelen Plateau and S. antarcticus from the deep Antarctic shelf. These results suggest that the deeper-water species S. dentifer and S. antarcticus are more closely related to Subantarctic species than to the shallow Antarctic species S. neumayeri. Thus, for this genus, neither the submergence nor emergence scenario explains the relationships between Antarctic and deep-sea benthos. At least in the Weddell quadrant, the observed genetic pattern suggests an initial separation between Antarctic and Subantarctic shallow species, and a much later colonization of deep water from the

  14. Rapid Smothering of Coral Reef Organisms by Muddy Marine Snow

    Science.gov (United States)

    Fabricius, K. E.; Wolanski, E.

    2000-01-01

    Estuarine mud, when resuspended in nutrient-rich near-shore water, aggregates to marine snow, and within minutes to hours can exert detrimental or even lethal effects on small coral reef organisms. In a pilot study, estuarine mud was suspended in near-shore and off-shore waters of the Great Barrier Reef to a final concentration of 170 mg l -1. The short-term responses of a coral ( Acropora sp.) and coral-inhabiting barnacles (subfamily Pyrgomatidae), exposed to either near-shore or off-shore water, were microscopically observed and video recorded. In the off-shore water treatment, flocculation was minor, and aggregate sizes were c. 50 μm. The organisms were able to clean themselves from these small settling aggregates at low siltation (mucus only at high siltation (4-5 mg cm -2). In contrast, in near-shore, nutrient-enriched waters, the suspended mud aggregated into large sticky flocs of marine snow (200-2000 μm diameter). The organisms responded to a thin coat of deposited flocs with vigorous cleaning by cirri and tentacle beating. After 5 min struggle, the barnacle stopped moving, calanoid copepods were entangled in the aggregates, and thick layers of mucus were exuded by the coral polyps. Both barnacle and copepods died after coral reefs. Enhanced nutrient concentrations are known to contribute to enhance biologically mediated flocculation. This pilot study suggests that the concentration of suspended mud, and extent of stickiness and flocculation, can synergistically affect reef benthos organisms after short exposure. The enclosed macro video recordings clearly visualize these effects, and help convey the important implications for managers: that inshore reefs of the Great Barrier Reef cannot be sustainably managed without managing the adjacent land.

  15. Biodiversity of Spongosorites coralliophaga (Stephens, 1915) on coral rubble at two contrasting cold-water coral reef settings

    Science.gov (United States)

    Kazanidis, Georgios; Henry, Lea-Anne; Roberts, J. Murray; Witte, Ursula F. M.

    2016-03-01

    Cold-water coral reefs (CWRs) in the northeast Atlantic harbor diverse sponge communities. Knowledge of deep-sea sponge ecology is limited and this leaves us with a fragmented understanding of the ecological roles that sponges play in CWR ecosystems. We present the first study of faunal biodiversity associated with the massive demosponge Spongosorites coralliophaga (Stephens, 1915) that typically colonizes coral debris fields of CWRs. Our study focused on the sessile fauna inhabiting sponges mixed with coral rubble at two contrasting settings in the northeast Atlantic: the shallow inshore (120-190 m water depth) Mingulay Reef Complex (MRC) and the deep offshore (500-1200 m) Logachev Mound (LM) coral province. MRC is dominated by the scleractinian Lophelia pertusa, while LM is dominated by L. pertusa and Madrepora oculata. Nine sponge-coral rubble associations were collected from MRC and four from LM. Measurements of abundance, species richness, diversity, evenness, dry biomass, and composition of sessile fauna on sponge and coral rubble microhabitats were undertaken. Differences in community composition between the two regions were mainly a response to changes in fauna with depth. Fauna composition was also different between sponge and coral rubble within each region. Infauna constituted a minor component of the sponge-associated fauna in MRC but had a higher contribution in LM. Sponge and coral rubble sessile fauna in both regions was mainly composed of cnidarians and molluscs, similarly to some previous studies. Sponges' outer surfaces at MRC were colonized by a species-rich community with high abundance and biomass suggesting that S. coralliophaga at MRC acts as a settlement surface for various organisms but such a role is not the case at LM. This difference in the role of S. coralliophaga as a biological structure is probably related to differences in fauna composition with depth, bottom current speed, and the quantity/quality of food supplied to the benthos.

  16. 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.

  17. Coral reef monitoring in the Iles Eparses, Mozambique Channel (2011-2013)

    Science.gov (United States)

    Chabanet, P.; Bigot, L.; Nicet, J.-B.; Durville, P.; Massé, L.; Mulochau, T.; Russo, C.; Tessier, E.; Obura, D.

    2016-04-01

    Monitoring of coral reefs has become a major tool for understanding how they are changing, and for managing them in a context of increasing degradation of coastal ecosystems. The Global Coral Reef Monitoring Network (GCRMN) has near-global coverage, but there are few remote sites free of direct human impact that can serve as reference sites. This study provides baseline data for the French Iles Eparses in the Mozambique Channel, Western Indian Ocean (WIO), whose coral reefs are little known owing to their limited accessibility, and have been free from fishing pressure for over 20 years. Surveys of coral reef health and fish community structure were undertaken at four of the islands (Europa, Bassas da India, Juan de Nova and Glorieuses) in 2011-2013. Monitoring was conducted using standardized GCRMN methods for benthos and fish communities, at the highest taxonomic level. Benthic cover showed a latitudinal gradient, with higher coral cover and conversely lower algae cover (60% and 14% respectively) in the south of the Mozambique Channel. This could be due to the geomorphology of the islands, the latitudinal temperature gradient, and/or the history of chronic stress and bleaching events during the last decades. Fish also showed a latitudinal gradient with higher diversity in the north, in a center of diversity for the western Indian Ocean already recognized for corals. An exceptional biomass fish was recorded (approximately 3500 kg/ha excluding sharks, compared to a maximum of 1400 kg/ha elsewhere in the WIO). The presence of large predators and sharks in all the islands as well as the absence of fleshy benthic algae were indicators of the good health of the reef systems. Nevertheless, these islands are beginning to experience illegal fishing, particularly in the north of the Mozambique Channel, demonstrating their vulnerability to exploitation and the need to protect them as reference sites for coral reef studies, including of climate change impacts, for the region

  18. 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.

  19. 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

  20. Indirect effects of overfishing on Caribbean reefs: sponges overgrow reef-building corals

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    Tse-Lynn Loh

    2015-04-01

    Full Text Available 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.

  1. 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.

  2. Ecotoxicological response of marine organisms to inorganic and organic sediment amendments in laboratory exposures.

    Science.gov (United States)

    Rosen, Gunther; Leather, James; Kan, Jinjun; Arias-Thode, Yolanda Meriah

    2011-10-01

    Experimental materials currently being investigated for use as amendments for the in situ remediation of contaminated sediments were assessed for their potential impacts on marine benthos. Laboratory toxicity tests involving lethal and sublethal endpoints were conducted on sediments amended with apatite, organoclay, chitin, or acetate, with the polychaete Neanthes arenaceodentata, the amphipod Eohaustorius estuarius, and the larval sheepshead minnow Cyprinodon variegatus. Amendments were mixed loosely into uncontaminated or metal-contaminated sediments, and also added inside experimental geotextile mats, at sediment dry weight (dw) concentrations ranging from 0.5% to 10%. The geotextile mats, containing apatite (5 or 10% dw), and/or organoclay (5%) did not result in adverse effects on any of the test organisms. Chitin and acetate, however, repetitively resulted in adverse effects on survival and/or adverse or positive effects on organism growth at concentrations of ≤ 2.5% dw. The adverse effects were attributed to water quality degradation in the exposure vessels (notably ammonia and dissolved oxygen concentration, for chitin and acetate, respectively) as a result of the microbial breakdown of the amendments. For N. arenaceodentata, growth was enhanced in the presence of chitin at concentrations as low as 0.5% sediment dw, which stimulated bacterial growth that may have provided an additional food source for the polychaete. Sediment chitin concentrations of 0.5% resulted in a statistically significant reduction in N. arenaceodentata body burdens of 61%, 29%, and 54%, relative to unamended contaminated sediment, for Cu, Zn, and Cd, respectively. The studies suggest a lack of inherent toxicity of these materials on the experimental organisms, as the adverse or positive responses observed are likely related to artifacts associated with laboratory exposure. Assessments in field settings are needed to verify this conclusion. PMID:21840599

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

    Science.gov (United States)

    Beare, Doug; Rijnsdorp, Adriaan D.; Blaesberg, Mette; Damm, Ulrich; Egekvist, Josefine; Fock, Heino; Kloppmann, Matthias; Röckmann, Christine; Schroeder, Alexander; Schulze, Torsten; Tulp, Ingrid; Ulrich, Clara; van Hal, Ralf; van Kooten, Tobias; Verweij, Marieke

    2013-11-01

    To reduce discarding of plaice Pleuronectes platessa in the North Sea flatfish fisheries, the major nursery areas were closed to large trawlers in 1995. The area closed was named the ‘Plaice Box’ (PB) and beam trawl effort fell by over 90%,while the exemption fleets of small flatfish beam trawlers, gill netters targeting sole (Solea solea) and shrimp (Crangon crangon) trawlers increased their effort. Contrary to the expectation, plaice landings and biomass declined. The initial support for the PB from the fisheries was lost, whereas other stakeholder groups claimed that any failure was due 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 analyzed to test whether the observed changes are due to the PB or to changes in the environment unrelated to the PB. Juvenile growth rate of plaice decreased and juveniles moved to deeper waters outside the PB. Demersal fish biomass decreased, whereas the abundance of epibenthic predators (Asterias rubens and Cancer pagurus) increased in the PB. Endobenthos, in particular the main food items of plaice (polychaetes and small bivalves) remained stable or decreased both inside and outside the PB. Currently catches of both plaice and sole from within the PB are lower than in the late 1980s and the exemption fleet often prefers to fish outside the Plaice Box alongside much larger competitors. 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 of setting testable objectives and an appropriate evaluation framework including both ecological and socio-economic indicators when implementing closed areas.

  4. South Arne field development: an environmental impact assessment of oil spills

    International Nuclear Information System (INIS)

    The South Arne field being developed by Amerada Hess A/S is located in 60 m water depth approximately 200 km from the Danish mainland, in block 5604/29 of the Danish sector of the North Sea. As part of the development of the field, a comprehensive environmental impact assessment has been carried out, including the assessment of the impact from oil spills. The Danish authorities required that a 'worst case' oil spill be chosen as the basis for the assessment on birds and aquatic organisms including plankton, fish eggs and larvae and benthos. A well blow-out at the surface was chosen as the worst case for the impact on birds, and a seabed blow-out for aquatic organisms. The oil spill modelling was carried out with the DEEPBLOW, SLIKMAP and OSCAR models from SINTEF. The modelling identified environmentally sensitive areas which could potentially be influenced by an oil spill. These included the Dogger Bank, western Skagerrak, south-western Norwegian Trench, the eastern German Bight and the Wadden Sea. Historical meteorological and hydrodynamic scenarios were chosen from a long period of records to ensure that the plume passed through the environmentally sensitive resource areas. For birds, a scan of the literature and available databases was made to determine the numbers and species of birds in the areas swept by the surface slick, the number of fatalities was estimated and finally the recovery time for each species population was estimated. The impact on aquatic organisms was estimated using the predicted environmental concentration/predicted no effect concentration (PEC/PNEC) method of the CHARM model. This method is normally applied to continuous discharges, but here has been used to estimate the impact of a transient pollution cloud resulting from an oil spill. (Author)

  5. Ciliated protists from the nepheloid layer and water column of sites affected by the Deepwater Horizon oil spill in the Northeastern Gulf of Mexico

    Science.gov (United States)

    Moss, Joseph A.; McCurry, Chelsea; Tominack, Sarah; Romero, Isabel C.; Hollander, David; Jeffrey, Wade H.; Snyder, Richard A.

    2015-12-01

    Benthic marine protists have been well documented from shallow marine benthic habitats but remain understudied in deeper habitats on continental shelves and slopes, particularly in the Northeastern Gulf of Mexico (NEGOM). This region was affected by a deep water oil well failure (BP-Deepwater Horizon, 2010). The combination of a lack of information on deep sea microbenthic communities and the potential for benthic microbial petroleum mineralization prompted this investigation. Water column and nepheloid layer samples were obtained via Niskin bottles and a multicorer respectively at stations across the NEGOM to: (1) determine whether nepheloid and water column communities are distinct and (2) assess benthic species richness relative to sediment PAH contamination. Phylum specific 18S rRNA gene amplification was used to construct clone libraries of ciliate assemblages. BLAST searches in the NCBI database indicated that a majority (~75%) of the clone sequences corresponded (94-100% similarity) with listed, yet unclassified sequences. Several putative species were common at most site locations and depths. Many known benthic ciliates, such as Uronychia transfuga, Uronychia setigera, and Spirotrachelostyla tani, were common in the nepheloid layer samples and not recovered in water column samples. Ciliated protist species richness increased with PAH levels found in surface sediments, suggesting a positive microbial response to petroleum enrichment of the benthos. The presence of previously unknown microbenthic communites in the nephaloid layer over oceanic clay-silt muds alters our view of microbial processes in the deep sea and merits investigation of the microbial processes and rates of microbial mineralization and biomass production important to global biogeochemistry.

  6. 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.

  7. 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

  8. Strategies for baseline/environmental impact studies in Nigeria

    International Nuclear Information System (INIS)

    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

  9. The use of biotopes in assessing the environmental quality of tidal estuaries in Europe

    Science.gov (United States)

    Ducrotoy, Jean-Paul

    2010-02-01

    In Europe, the Water Framework Directive (WFD) (European Commission 2000) - and the recently proposed EU Marine Strategy Directive - have established a framework for the protection of groundwater, inland surface waters, estuarine (transitional) waters and coastal waters. TheWFD has several objectives: to prevent water ecosystem deterioration, to protect and to enhance the status of water resources but the most important aspect is to achieve a 'Good Ecological Status' (GES) for all waters, by 2015. In essence, the WFD requires a water body to be compared against a reference condition and then its ecological status designated - if the water body does not meet good or high ecological status, i.e. it is in moderate, poor or bad ecological status, then remedial measures have to be taken (e.g. pollution has to be removed). Many indices were developed from benthic work and are often thought fit for purpose. Based on the successional model proposed by Pearson and Rosenberg (1978), most of these indices were effectively established for soft sediment benthos. However, those developed in the framework of the WFD were derived from work on the subtidal. They are difficult to use in the intertidal and in transitional waters. As they were derived from work on organic pollution, there is no or little evident link with chemical and physical pollution. Ecomorphology brings together a biological approach and a sedimentological approach to estuarine ecology. It considers the use of the biotope and related concepts (biocenosis, bio-facies, ecotone, habitat…) as a basis to a novel approach to environmental quality assessment. It addresses the problem of the estuarine quality paradox in recognising the role of nutrients and organic matter in biogeochemical cycles. The discussion shows the complementarity of biotopes with the Sato-Umi and the ecohydrolgy approaches.

  10. Fish Food in the Deep Sea: Revisiting the Role of Large Food-Falls

    Science.gov (United States)

    Higgs, Nicholas D.; Gates, Andrew R.; Jones, Daniel O. B.

    2014-01-01

    The carcasses of large pelagic vertebrates that sink to the seafloor represent a bounty of food to the deep-sea benthos, but natural food-falls have been rarely observed. Here were report on the first observations of three large ‘fish-falls’ on the deep-sea floor: a whale shark (Rhincodon typus) and three mobulid rays (genus Mobula). These observations come from industrial remotely operated vehicle video surveys of the seafloor on the Angola continental margin. The carcasses supported moderate communities of scavenging fish (up to 50 individuals per carcass), mostly from the family Zoarcidae, which appeared to be resident on or around the remains. Based on a global dataset of scavenging rates, we estimate that the elasmobranch carcasses provided food for mobile scavengers over extended time periods from weeks to months. No evidence of whale-fall type communities was observed on or around the carcasses, with the exception of putative sulphide-oxidising bacterial mats that outlined one of the mobulid carcasses. Using best estimates of carcass mass, we calculate that the carcasses reported here represent an average supply of carbon to the local seafloor of 0.4 mg m−2d−1, equivalent to ∼4% of the normal particulate organic carbon flux. Rapid flux of high-quality labile organic carbon in fish carcasses increases the transfer efficiency of the biological pump of carbon from the surface oceans to the deep sea. We postulate that these food-falls are the result of a local concentration of large marine vertebrates, linked to the high surface primary productivity in the study area. PMID:24804731

  11. Fish food in the deep sea: revisiting the role of large food-falls.

    Directory of Open Access Journals (Sweden)

    Nicholas D Higgs

    Full Text Available The carcasses of large pelagic vertebrates that sink to the seafloor represent a bounty of food to the deep-sea benthos, but natural food-falls have been rarely observed. Here were report on the first observations of three large 'fish-falls' on the deep-sea floor: a whale shark (Rhincodon typus and three mobulid rays (genus Mobula. These observations come from industrial remotely operated vehicle video surveys of the seafloor on the Angola continental margin. The carcasses supported moderate communities of scavenging fish (up to 50 individuals per carcass, mostly from the family Zoarcidae, which appeared to be resident on or around the remains. Based on a global dataset of scavenging rates, we estimate that the elasmobranch carcasses provided food for mobile scavengers over extended time periods from weeks to months. No evidence of whale-fall type communities was observed on or around the carcasses, with the exception of putative sulphide-oxidising bacterial mats that outlined one of the mobulid carcasses. Using best estimates of carcass mass, we calculate that the carcasses reported here represent an average supply of carbon to the local seafloor of 0.4 mg m(-2d(-1, equivalent to ∼ 4% of the normal particulate organic carbon flux. Rapid flux of high-quality labile organic carbon in fish carcasses increases the transfer efficiency of the biological pump of carbon from the surface oceans to the deep sea. We postulate that these food-falls are the result of a local concentration of large marine vertebrates, linked to the high surface primary productivity in the study area.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. Brown trout and food web interactions in a Minnesota stream

    Science.gov (United States)

    Zimmerman, J.K.H.; Vondracek, B.

    2007-01-01

    1. We examined indirect, community-level interactions in a stream that contained non-native brown trout (Salmo trutta Linnaeus), native brook trout (Salvelinus fontinalis Mitchill) and native slimy sculpin (Cottus cognatus Richardson). Our objectives were to examine benthic invertebrate composition and prey selection of fishes (measured by total invertebrate dry mass, dry mass of individual invertebrate taxa and relative proportion of invertebrate taxa in the benthos and diet) among treatments (no fish, juvenile brook trout alone, juvenile brown trout alone, sculpin with brook trout and sculpin with brown trout). 2. We assigned treatments to 1 m2 enclosures/exclosures placed in riffles in Valley Creek, Minnesota, and conducted six experimental trials. We used three designs of fish densities (addition of trout to a constant number of sculpin with unequal numbers of trout and sculpin; addition of trout to a constant number of sculpin with equal numbers of trout and sculpin; and replacement of half the sculpin with an equal number of trout) to investigate the relative strength of interspecific versus intraspecific interactions. 3. Presence of fish (all three species, alone or in combined-species treatments) was not associated with changes in total dry mass of benthic invertebrates or shifts in relative abundance of benthic invertebrate taxa, regardless of fish density design. 4. Brook trout and sculpin diets did not change when each species was alone compared with treatments of both species together. Likewise, we did not find evidence for shifts in brown trout or sculpin diets when each species was alone or together. 5. We suggest that native brook trout and non-native brown trout fill similar niches in Valley Creek. We did not find evidence that either species had an effect on stream communities, potentially due to high invertebrate productivity in Valley Creek. ?? 2007 Blackwell Publishing Ltd.

  17. Estimating natural mortality rates and simulating fishing scenarios for Gulf of Mexico red grouper (Epinephelus morio) using the ecosystem model OSMOSE-WFS

    Science.gov (United States)

    Grüss, Arnaud; Schirripa, Michael J.; Chagaris, David; Velez, Laure; Shin, Yunne-Jai; Verley, Philippe; Oliveros-Ramos, Ricardo; Ainsworth, Cameron H.

    2016-02-01

    The ecosystem model OSMOSE-WFS was employed to evaluate natural mortality rates and fishing scenarios for Gulf of Mexico (GOM) red grouper (Epinephelus morio). OSMOSE-WFS represents major high trophic level (HTL) groups of species of the West Florida Shelf, is forced by the biomass of plankton and benthos groups, and has a monthly time step. The present application of the model uses a recently developed 'stochastic mortality algorithm' to resolve the mortality processes of HTL groups. OSMOSE-WFS predictions suggest that the natural mortality rate of juveniles of GOM red grouper is high and essentially due to predation, while the bulk of the natural mortality of adult red grouper results from causes not represented in OSMOSE-WFS such as, presumably, red tides. These results were communicated to GOM red grouper stock assessments. Moreover, OSMOSE-WFS indicate that altering the fishing mortality of GOM red grouper may have no global impact on the biomass of the major prey of red grouper, due to the high complexity and high redundancy of the modeled system. By contrast, altering the fishing mortality of GOM red grouper may have a large impact on the biomass of its major competitors. Increasing the fishing mortality of red grouper would increase the biomass of major competitors, due to reduced competition for food. Conversely, decreasing the fishing mortality of red grouper would diminish the biomass of major competitors, due to increased predation pressure on the juveniles of the major competitors by red grouper. The fishing scenarios that we evaluated may have slightly different impacts in the real world, due to some discrepancies between the diets of red grouper and its major competitors predicted by OSMOSE-WFS and the observed ones. Modifications in OSMOSE-WFS are suggested to reduce these discrepancies.

  18. Evaluation of changes in macrobenthic standing stock and polychaete community structure along the south eastern Arabian Sea shelf during the monsoon trawl-ban

    Science.gov (United States)

    Abdul Jaleel, K. U.; Parameswaran, Usha V.; Gopal, Aiswarya; Khader, Chippy; Ganesh, T.; Sanjeevan, V. N.; Shunmugaraj, T.; Vijayan, Anil Kumar; Gupta, G. V. M.

    2015-07-01

    The south eastern Arabian Sea is characterized by moderate coastal upwelling, high biological production and subsurface oxygen depletion during the southwest monsoon (June-September). Concurrently, a seasonal closure to trawling activities (15th June-31st July) is implemented here, as a sustainable ecosystem management practise. The effects of monsoon driven environmental changes and consequences of trawling cessation on macrofauna were assessed, based on surveys at 12 sites (30-200 m) preceding and during different phases of the southwest monsoon. Macrofaunal density and biomass increased considerably towards the mid and late monsoon along the inner shelf (30-50 m) where trawling is intense, while no temporal changes were observed along the outer shelf (100-200 m). Density increased four-folds at the 30 m contour and three-folds at 50 m, while biomass nearly doubled at both depths, reflecting a marked increase in density of polychaetes (61-87% of macrofauna). The disproportionate increase in faunal density and biomass along the inner shelf (30-50 m) was due to abundance of juvenile polychaetes and dominance of small-sized opportunists towards late monsoon (August-September). A concurrent hike in nominal species count of polychaetes was also observed in the study area. The increase in polychaete standing stock and high density of planktonic larvae during onset and peak monsoon, coupled with occurrence of juveniles as well as gamete-bearing adults in sediments, indicates that the southwest monsoon is a peak breeding season for the dominant polychaetes in the region. The trawl-ban during this period facilitates the recoupment of benthos by maximising spawning success and larval settlement, thereby enhancing overall ecosystem integrity.

  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. Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea.

    Science.gov (United States)

    Enge, Annekatrin J; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F M; Hunter, William R; Heinz, Petra

    2016-01-01

    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 (13)C and (15)N) by calcareous 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 phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant 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 species. 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 conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing 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 boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels. PMID:26903959

  1. Ecosystem characteristics and processes facilitating persistent macrobenthic biomass hotspots and associated benthivory in the Pacific Arctic

    Science.gov (United States)

    Grebmeier, Jacqueline M.; Bluhm, Bodil A.; Cooper, Lee W.; Danielson, Seth L.; Arrigo, Kevin R.; Blanchard, Arny L.; Clarke, Janet T.; Day, Robert H.; Frey, Karen E.; Gradinger, Rolf R.; Kędra, Monika; Konar, Brenda; Kuletz, Kathy J.; Lee, Sang H.; Lovvorn, James R.; Norcross, Brenda L.; Okkonen, Stephen R.

    2015-08-01

    The northern Bering and Chukchi Seas are areas in the Pacific Arctic characterized by high northward advection of Pacific Ocean water, with seasonal variability in sea ice cover, water mass characteristics, and benthic processes. In this review, we evaluate the biological and environmental factors that support communities of benthic prey on the continental shelves, with a focus on four macrofaunal biomass "hotspots." For the purpose of this study, we define hotspots as macrofaunal benthic communities with high biomass that support a corresponding ecological guild of benthivorous seabird and marine mammal populations. These four benthic hotspots are regions within the influence of the St. Lawrence Island Polynya (SLIP), the Chirikov Basin between St. Lawrence Island and Bering Strait (Chirikov), north of Bering Strait in the southeast Chukchi Sea (SECS), and in the northeast Chukchi Sea (NECS). Detailed benthic macrofaunal sampling indicates that these hotspot regions have been persistent over four decades of sampling due to annual reoccurrence of seasonally consistent, moderate-to-high water column production with significant export of carbon to the underlying sediments. We also evaluate the usage of the four benthic hotspot regions by benthic prey consumers to illuminate predator-prey connectivity. In the SLIP hotspot, spectacled eiders and walruses are important winter consumers of infaunal bivalves and polychaetes, along with epibenthic gastropods and crabs. In the Chirikov hotspot, gray whales have historically been the largest summer consumers of benthic macrofauna, primarily feeding on ampeliscid amphipods in the summer, but they are also foraging further northward in the SECS and NECS hotspots. Areas of concentrated walrus foraging occur in the SLIP hotspot in winter and early spring, the NECS hotspot in summer, and the SECS hotspot in fall. Bottom up forcing by hydrography and food supply to the benthos influences persistence and composition of benthic prey

  2. 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.

  3. Twenty-year changes in coral near Muscat, Oman estimated from manta board tow observations.

    Science.gov (United States)

    Coles, Steve L; Looker, Elayne; Burt, John A

    2015-02-01

    The coastline of Muscat, Oman, contains some of the most extensive and diverse coral reefs in the northeastern Arabian Peninsula. In the past two decades this region has been impacted by expanding coastal development, the largest cyclone ever recorded in the Arabian Sea, and a large-scale harmful algal bloom which resulted in mass mortality of reefs elsewhere in the Gulf of Oman. In 2012 we estimated live and dead coral using manta tow observations on 370 transects at 13 locations along the coastline and nearshore islands of Muscat Oman. We compared these estimates against observations made on 389 transects at the same 13 locations two decades earlier (1993-94) in order to determine long-term changes in benthos along the Muscat coast. Results were mapped and differences in categorical mean values for transect locations were statistically compared between survey years. Live hard and soft coral decreased over the past two decades at most survey sites, and decreases were significant at three exposed coastline sites and one semi-enclosed embayment. One sheltered embayment site showed a significant increase in live hard coral over the study period. Declines in live hard coral were associated with increases in dead coral framework at 8 of the 13 sites, but these changes were non-significant. We attribute these changes primarily to long-term effects of Cyclone Gonu, which struck the Oman coast in June 2007. The study results suggest that the manta tow method can be an effective way to detect long-term changes in coral and other benthic parameters over large areas, despite limitations on its precision. PMID:25460063

  4. 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

  5. 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.

  6. 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.

  7. Factors influencing the distribution of epibenthic megafauna across the Peruvian oxygen minimum zone

    Science.gov (United States)

    Mosch, Thomas; Sommer, Stefan; Dengler, Marcus; Noffke, Anna; Bohlen, Lisa; Pfannkuche, Olaf; Liebetrau, Volker; Wallmann, Klaus

    2012-10-01

    Current de-oxygenation of the oceans is associated with severe habitat loss and distinct changes in the species composition of bentho-pelagic communities. We investigated the distributions of epibenthic megafauna across the Peruvian OMZ (11°S) at water depths ranging from ˜80 to 1000 m water depth using sea floor images. Likely controls of distributions were adressed by combining the abundances of major groups with geochemical parameters and sea-floor topography. In addition to bottom-water oxygen levels and organic-carbon availability, particular emphasis is laid on the effects of local hydrodynamics. Beside the occurrence of microbial mats at the shelf and upper slope, distinct zones of highly abundant megafauna, dominated by gastropods (900 ind. m-2), ophiuroids (140 ind. m-2), and pennatulaceans (20 ind. m-2), were observed at the lower boundary of the OMZ. Their distribution extended from 460 m water depth (O2 levels local hydrodynamics caused by the energy dissipation of incipient internal M2 tides affecting the suspension, transport and deposition of food particles. This was particularly evident in certain sections of the investigated transect. At these potentially critical sites, energy dissipation of internal tides is associated with high bottom shear stress and high turbulences and coincides with elevated turbidity levels in the benthic boundary layer, increased Zr/Al-ratios, low sedimentation rates as well as a shift in the grain size towards coarser particles. In or near such areas, abundant suspension-feeding organisms, such as ophiuroids, pennatulaceans, and tunicates were present, whereas deposit-feeding gastropods were absent. The influence of local hydrodynamic conditions on the distribution of epibenthic organisms has been neglected in OMZ studies, although it has been considered in other settings.

  8. Fish food in the deep sea: revisiting the role of large food-falls.

    Science.gov (United States)

    Higgs, Nicholas D; Gates, Andrew R; Jones, Daniel O B

    2014-01-01

    The carcasses of large pelagic vertebrates that sink to the seafloor represent a bounty of food to the deep-sea benthos, but natural food-falls have been rarely observed. Here were report on the first observations of three large 'fish-falls' on the deep-sea floor: a whale shark (Rhincodon typus) and three mobulid rays (genus Mobula). These observations come from industrial remotely operated vehicle video surveys of the seafloor on the Angola continental margin. The carcasses supported moderate communities of scavenging fish (up to 50 individuals per carcass), mostly from the family Zoarcidae, which appeared to be resident on or around the remains. Based on a global dataset of scavenging rates, we estimate that the elasmobranch carcasses provided food for mobile scavengers over extended time periods from weeks to months. No evidence of whale-fall type communities was observed on or around the carcasses, with the exception of putative sulphide-oxidising bacterial mats that outlined one of the mobulid carcasses. Using best estimates of carcass mass, we calculate that the carcasses reported here represent an average supply of carbon to the local seafloor of 0.4 mg m(-2)d(-1), equivalent to ∼ 4% of the normal particulate organic carbon flux. Rapid flux of high-quality labile organic carbon in fish carcasses increases the transfer efficiency of the biological pump of carbon from the surface oceans to the deep sea. We postulate that these food-falls are the result of a local concentration of large marine vertebrates, linked to the high surface primary productivity in the study area. PMID:24804731

  9. Seasonal changes in the δ13C and δ15N signatures of the Lago Maggiore pelagic food web

    Directory of Open Access Journals (Sweden)

    Marina MANCA

    2011-08-01

    Full Text Available Seasonal variation in the relative contributions of littoral and pelagic food sources to the diets of open-water zooplankton and subsequent changes in their trophic positions were investigated with carbon and nitrogen Stable Isotope Analysis (SIA. We selected three open water stations as truly pelagic, but also influenced by littoral and riverine carbon sources. During each of the four seasons, integrated pelagic zooplankton samples were collected over 0-50 m depth intervals at each site along with seston in the size range 1.2-76 μm. In addition, vertical temperature profiles were measured. Littoral benthos from three sites along the main longitudinal axis of the lake was sampled to serve as a reference for tracing Lago Maggiore's littoral carbon isotopic signature. Among stations differences in δ13C and δ15N signatures of the different components of the pelagic food web, from seston to predatory zooplankton, were statistically non significant, thus confirming that allochthonous input may become important only after exceptional rainfall events. Changes in the δ13C pelagic baseline mirrored mean water temperature (0-50 m seasonal changes. Similarly to Lake Geneva, they were likely driven by changes in carbon sources for phytoplankton growth during stratification and vertical water mixing. Differently from what observed for the other taxa, the role of littoral food sources was far from negligible (>50% for diaptomids during winter and spring. We do not know however, whether such a result could be at least partially attributed to the heavy infestation by algal epibionts, or was consequent to the fact that these zooplankters may carry littoral carbon to the pelagial via horizontal migration. In winter, Bythotrephes longimanus was able to prey on Cyclops, thus occupying a trophic position comparable to that of planktivorous fish. Such a result confirms an ability of this visual, invertebrate predator to compete with young zooplanktivorous fish

  10. 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.

  11. 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. PMID:26682944

  12. The interplay between the surface and bottom water environment within the Benguela Upwelling System over the last 70 ka

    Science.gov (United States)

    McKay, C. L.; Filipsson, H. L.; Romero, O. E.; Stuut, J.-B. W.; Björck, S.

    2016-02-01

    The Benguela Upwelling System (BUS), located between 30 and 20°S, is one of the fundamental high-productivity systems of the world ocean. The BUS has previously been studied in terms of primary productivity and ecology over glacial-interglacial timescales; however, the response and coupling with the benthic environment have received little attention. Here, for the first time, we present a high-resolution reconstruction of the BUS highlighting the link between surface and benthic productivity and their response to climatic and oceanographic changes over the last 70 ka. The study is based on benthic foraminiferal faunal analysis together with analyses of diatom assemblages, grain size of the terrigenous fraction, and stable O and C isotopic and bulk biogenic components of core GeoB3606-1. We reveal significant shifts in benthic foraminiferal assemblage composition. Tight coupling existed between the surface and bottom water environment especially throughout marine isotope stages 4 and 3 (MIS4 and MIS3). Due to the high export production, the site has essentially experienced continuous low oxygen conditions; however, there are time periods where the hypoxic conditions were even more notable. Two of these severe hypoxic periods were during parts of MIS4 and MIS3 where we find an inverse relationship between diatom and benthic foraminifera accumulation, meaning that during times of extremely high phytodetritus export we note strongly suppressed benthic productivity. We also stress the importance of food source for the benthos throughout the record. Shifts in export productivity are attributed not only to upwelling intensity and filament front position, but also, regional-global climatic and oceanographic changes had significant impact on the BUS dynamics.

  13. 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

  14. 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. PMID:25945305

  15. Coral Reef Color: Remote and In-Situ Imaging Spectroscopy of Reef Structure and Function

    Science.gov (United States)

    Hochberg, E. J.

    2015-12-01

    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.

  16. 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.

  17. Biogenic reefs affect multiple components of intertidal soft-bottom benthic assemblages: the Lanice conchilega case study

    Science.gov (United States)

    De Smet, Bart; D'Hondt, An-Sofie; Verhelst, Pieterjan; Fournier, Jérôme; Godet, Laurent; Desroy, Nicolas; Rabaut, Marijn; Vincx, Magda; Vanaverbeke, Jan

    2015-01-01

    Biogenic reefs composed of the tube-building polychaete Lanice conchilega are important from a conservation point of view because they noticeably increase the biodiversity in otherwise species poor environments. However, up to now, little or no attention has been paid to the intertidal epi- and hyperbenthic communities associated with the reefs. Therefore, this is the first study which focuses on the effect of L. conchilega reefs on the entire bentho-pelagic community at two different locations. Environmental variables were measured and macro-, epi- and hyperbenthic communities were sampled within a L. conchilega reef and a control area at two locations in France: the bay of the Mont Saint-Michel (BMSM) and Boulogne-sur-Mer (Boulogne). The effect of the reef presence on the benthic community was studied with a 3-factor (Reef, Location and Period) Permanova. In addition, the relationship between the benthic community and the environmental variables was investigated using Distance-based linear models (DistLM). Most collected organisms were sampled in the reef area (macrobenthos: 91%, epibenthos: 81% and hyperbenthos: 78.5%) indicating that, independent of the location, the L. conchilega reefs positively affect all three associated benthic communities. However, the extent of the effect seems to be most pronounced for the macrobenthos and less distinct in case of the hyperbenthos. The macro-, and epibenthos are mainly structured by biotic variables (L. conchilega density and macrobenthic food availability respectively), while the hyperbenthos is rather structured by environmental variables. In general, L. conchilega reefs do not only affect abundances and diversity but they substantially steer the structure of the intertidal benthic sandy beach ecosystem.

  18. Environmental drivers of phototrophic biofilms in an Alpine show cave (SW-Italian Alps)

    International Nuclear Information System (INIS)

    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

  19. Seston Dynamics and Food Availability on Mussel and Cockle Beds

    Science.gov (United States)

    Smaal, A. C.; Haas, H. A.

    1997-08-01

    To provide a better understanding of seston dynamics in relation to food supply to the benthos, a series of 13-h tidal cycle sampling programmes was executed in the Oosterschelde estuary (The Netherlands). Samples were taken near the surface and near the bottom on two subtidal mussel cultivation plots and on two intertidal cockle beds. Long-term annual variablity of seston concentrations was lower than coefficients of variance of the short-term tidal cycle seston data at the intertidal stations, and higher than at the subtidal stations. Near-bottom relative to surface concentrations were highest for suspended particulate matter (SPM), followed by particulate organic carbon (POC), and chlorophyll. There was no food depletion near the bottom but food quality was lower, presumably due to re-suspension of sediment, including low-quality biodeposits. Chlorophyll concentrations were lower in ebb than flood water at all stations, which was ascribed to feeding activity of the bivalves. At the subtidal stations, SPM and POC concentrations were also lower during low water, owing to sedimentation. There was a positive correlation at the intertidal stations of seston quantity with wind speed and wave action. At a wave length exceeding twice the water depth, re-suspension of low quality bottom material was observed and seston quality decreased. It was concluded that food availability for benthic suspension feeders was lower than suggested by routine monitoring data. At the intertidal stations, food quality was further reduced during periods of increased wind velocities and wave action. The low near-bottom food quality can partly be considered as an effect of the feeding activity of the benthic suspension feeders.

  20. A spatially resolved model of seasonal variations in phytoplankton and clam ( Tapes philippinarum) biomass in Barbamarco Lagoon, Italy

    Science.gov (United States)

    Spillman, C. M.; Hamilton, D. P.; Hipsey, M. R.; Imberger, J.

    2008-08-01

    Barbamarco Lagoon (area = 7 km 2) is in the Po River Delta, adjoining the Northern Adriatic Sea, and supports a commercially valuable clam ( Tapes philippinarum) fishery. This study investigated interactions of the lagoon with adjacent coastal waters and inland riverine inputs by modelling both the lagoon and the Northern Adriatic Sea, using a coupled three-dimensional (3D) hydrodynamic-ecological model (ELCOM-CAEDYM) adapted to include the clam population. The clam model accounted for carbon (C), nitrogen (N) and phosphorus (P) biomass in the benthos through parameterisations for filtration, excretion, egestion, respiration, mortality, and harvesting. Multiple clam size classes were included in a new population dynamics sub-model. Output from the coupled model was validated against hydrodynamic and water quality data from intensive field sampling and routine monitoring. Time scales of tidal flushing, primary production and clam grazing were investigated with the model to demonstrate that food supply to clam populations is dominated by phytoplankton inputs from the Northern Adriatic Sea. Effects of clam cultivation on nutrient concentrations and phytoplankton biomass in Barbamarco Lagoon were primarily localised, with strong tidal flushing minimising impacts of clam filtration on lagoon-wide nutrient concentrations at current clam stocking levels. Clam populations were found to alter the cycling of nutrients in the system, causing the lagoon to become a net sink for particulate organic matter and to export dissolved organic matter to the adjacent sea via tidal flushing. Ecosystem health and sensitivity of nutrient cycles to clam cultivation are important considerations for the long term sustainable management and potential expansion of the fishery.

  1. 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

  2. Historical Distribution of Polycyclic Aromatic Hydrocarbons in Shallow Sediments from Lake Chapala, Mexico

    Science.gov (United States)

    Zárate-Del Valle, P. F.; Macías-Pérez, M. P.; Barajas-Martínez, C. D.; Gómez-Hermosillo, C. M.

    2008-12-01

    The incomplete combustion of fossil fuels and burning of vegetation and other organic materials release into the environment pollutants like polycyclic aromatic hydrocarbons (PAHs) which are ubiquitous pollutants. The environmental behavior of PAHs is characterized by very low solubility, high hydrophobic sorptive capacity (kow), low volatility and general chemical stability. These characteristics mean, in practice, that PAHs are environmentally persistent compounds that in aquatic systems, are strongly held to solid surfaces present as both suspended particles and bottom sediment. Additionally, because of their high partition to organic carbon, PAHs show a high rate of bioconcentration and an easy way to enter the food chain. A benthos type sediment core was collected (CHA-C: N20° 15.105'; W103° 03.104') from the depocenter of lake Chapala. The first 40 cm of the sedimentary column representing an ecological history of ~ 150 years (210Pb dating) were cutted every 2 cm (n=20). For each core sectioned, the presence of PAHs was evaluated by GC-MS following methods from the USEPA (EPA 3540C, EPA 3620C, EPA 8270C). For the first 30 cm deep only products resulting of PAHs degradation were identified, namely: Butilisobutilphtalate, 1,2-benzenedicarboxaldehyde, phenol and, cinnamaldehyde; we attibute the presence of these products to a faster transformation of PAHs by photo and metabolic degradation as well as to chemical oxydation. For the 30-40 cm deep, the presence of the follwing PAHs was detected: 1H-indene, 1,2- difluor-3,4,5-trimetylbenzenethylnaphthalene, naphthalene, anthracene, and phenantren. A study is in progress to determine the presence of PAHs in other sites of the lake. We conclude that shallow sediment (40 cm deep) from Lake Chapala could constitute a potentially large pool of PAHs.

  3. Rhythmic behaviour of marine benthopelagic species and the synchronous dynamics of benthic communities

    Science.gov (United States)

    Aguzzi, Jacopo; Sbragaglia, Valerio; Tecchio, Samuele; Navarro, Joan; Company, Joan B.

    2015-01-01

    Light-intensity cycles drive the relentless motion of species in the oceans, and water column migrants may cyclically make contact with the seabed, hence influencing the temporal dynamism of benthic ecosystems. The influence of light on this process remains largely unknown to date. In this study, we focus on the occurrence of day-night changes in benthic communities on the western Mediterranean continental shelf (100 m depth) and slope (400 m depth) as a potential result of a behaviourally sustained benthopelagic coupling. We analysed fluctuations in species abundance based on trawling at hourly intervals over a 4-day period as a proxy of activity rhythms at the seabed. We also measured light in situ to assess how the depth-related decrease of its intensity influences species rhythms and the occurrence of the putative benthopelagic synchronisation. Temporal similarities in the catch patterns for different species were screened by dendrogram analysis. On the continental shelf, species performing diel migrations (i.e., over a 24 h period) that were either vertical (i.e., benthopelagic) or horizontal across depths (i.e., nektobenthic) clustered together separately from the more sedentary endobenthic and epibenthic species. At the same depth, waveform analysis showed a significant diurnal increase in the catch of water column species and benthic species at night. Such coupling was absent on the continental slope, where light intensity was several orders of magnitude lower than that on the shelf. Our data indicate that diel activity rhythms, which are well known for vertical pelagic migrators, are also evident in the benthos. We discuss the role of light as a major evolutionary driver shaping the composition and biodiversity of benthic communities via visual predation.

  4. Effects of houseboats on organisms of the La Parguera Reserve, Puerto Rico.

    Science.gov (United States)

    Hertler, Heidi; Spotila, James; Kreeger, Danielle A

    2004-11-01

    As coastal development increases so too does the number of artificial floating and permanent structures. It has been postulated that because of their size, many houseboats are similar to permanent structures in that they shade a significant portion of the benthos and thereby limit production by benthic flora. On the other hand, these structures can benefit biotic communities by providing sites for attachment of organisms in a substrate-limited environment and both habitat and food sources for fish. In this study, we examined whether houseboats benefit or harm the ecological integrity of a typical seagrass dominated system, at La Parguera, Puerto Rico. We performed a benthic survey to compare the diversity and health of seagrasses under houseboats to that at control locations. Species diversity (0-0.79) varied significantly among sites, but this variability was not attributed to the houseboats. Rather, the variability appeared related to the proximity of the study locations to new development along the shoreline. Average seagrass blade density and length were 52.7 blades/m(-2) and 23.6 cm, respectively. Neither parameter differed between houseboat and control areas; however, both varied significantly among sites. In addition, boat hulls were heavily encrusted with invertebrates. The overall averages of species diversity and richness of sessile organisms on hulls of the houseboats were 1.13 and 4.83, respectively. Fish also utilized these structures. Our results indicate that houseboats did not directly harm the seagrass communities at La Parguera primarily because of sound environmental management of wastes and mooring techniques. PMID:15473548

  5. 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

  6. Empirical relationships among resilience indicators on Micronesian reefs

    Science.gov (United States)

    Mumby, P.J.; Bejarano, S.; Golbuu, Y.; Steneck, R.S.; Arnold, S.N.; van Woesik, R.; Friedlander, A.M.

    2013-01-01

    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

  7. Dynamic processes observed at a gas hydrate outcropping on the continental slope of the Gulf of Mexico

    Science.gov (United States)

    Vardaro, Michael F.; MacDonald, Ian R.; Bender, Leslie C.; Guinasso, Norman L.

    2006-03-01

    A deep-sea time-lapse camera and several temperature probes were deployed on the Gulf of Mexico continental shelf at a biological community associated with a gas hydrate outcropping to study topographic and hydrologic changes over time. The deployment site, Bush Hill (GC-185), is located at 27°47.5' N and 91°15.0' W at depths of ˜540 m. The digital camera recorded one still image every 6 h for July-October in 2001, every 2 h for the month of June 2002, and every 6 h for the month of July 2002. Temperature probes were in place at the site for the entire experimental period. The data recovered provide a record of processes that occur at gas hydrate mounds. Sediment resuspension over the mound causes significant variation in luminosity of the time-lapse photographs. A marked diurnal pattern can be seen in the temperature and luminosity records. No major change in shape or size of the gas hydrate outcrop at this site was observed during this study. Stable topography of the gas hydrate mound, combined with high bacterial activity and sediment turnover, appears to focus biological activity in the mound area. Frequency and recurrence of sediment resuspension indicate that short-term change in the depth and distribution of surface sediments is a feature of the benthos at the site. Because the sediment interface is a critical environment for hydrocarbon oxidation and chemosynthesis, short-term variability and heterogeneity may be important characteristics of these settings.

  8. A dynamic box model to predict the radionuclide behaviour in river for average and long-term periods

    International Nuclear Information System (INIS)

    This paper presents a dynamic box model to predict, for average and long time periods, the radionuclide behaviour in the main abiotic and biotic compartments of rivers. It is integrated in the operational code CASTEAUR, aiming to increase its application domain, limited, up to now, to short-term periods. The retained approach for this tool describes the river as a succession of elementary boxes representative of its different reaches. Two media are considered, the water column and the bottom sediment, through their biotic and abiotic components. In the water column, the abiotic components are the water and different classes of suspended particles classified according their deposit kinetics. The biotic components are plankton, divided into phytoplankton and zooplankton, and fish, distributed in planktonivorous and omnivorous species. The bottom sediment is represented according two layers. The first one, which can exchange with the water column, is called the reactive layer. Its abiotic components are the interstitial water and the different classes of deposit matter. It also includes a biotic component called macro-benthos. The second layer, i.e. the permanent layer, contains only the different classes of deposit matter transferred from the previous layer by consolidation process. The main processes linking all these components are modelled to assess in each reach the average radionuclide concentrations in the abiotic and biotic targets (components) describing the river ecosystem. The calculation are made with a minimum daily time step and for periods from several days to several years, taken possibly into account several releases distributed in time and space, and characterized by daily kinetics. After the model, an application on a real case is presented. (author)

  9. Following a foraging fish-finder: diel habitat use of Blainville's beaked whales revealed by echolocation.

    Directory of Open Access Journals (Sweden)

    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.

  10. 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

  11. MARINE LIFE OF URUGUAY: CRITICAL UPDATE AND PRIORITIES FOR FUTURE RESEARCH LA VIDA MARINA DE URUGUAY: REVISION CRITICA Y PRIORIDADES PARA INVESTIGACIONES FUTURAS

    Directory of Open Access Journals (Sweden)

    Danilo Calliari

    2003-01-01

    Full Text Available The marine areas of Uruguay consist of the Río de la Plata estuary and the adjacent shelf and slope, part of the Subtropical Convergence Ecosystem. In this paper, the main advances in the knowledge of marine life in these areas (the known are reviewed in order to discuss future lines of research (the unknown. Information has been separately analysed for the plankton, nekton, and benthos in each of 3 areas-the littoral, the shelfs and the "open ocean". Current knowledge of marine life is uneven among the groups and areas. In the case of the plankton, research has concentrated on the near-shore waters and focused on taxonomy and distribution. Little is known about the responses of organisms to environmental variability and about biological processes. The nekton of coastal and estuarine areas is better known, but, with shelf and slope assemblages, research has focused on exploited species. The main unknowns for the nekton are how trophodynamics, reproduction, and recruitment processes are linked to environmental variability and the effect of fisheries on community structure. Littoral benthos, in particular the macroinfauna of sandy beaches, is much better studied and spatial patterns of community distribution have been identified at different scales and in relation to environmental variables. Also, at the population level, there is information about distribution, responses to disturbances, dynamics, and the roles of biotic and abiotic factors in modulating population variability. Information is mainly lacking for the sub-tidal fringe and regarding the macro-ecology of population dynamics, the dispersive abilities of larval phases, and the effects of toxic blooms on suspension feeders. Knowledge of the benthos of estuaries and more so of the shelf and slope environments is rather scarce. For the latter two, faunal inventories are far from complete. Topics identified for future research include taxonomy, macro-scale community structure and its

  12. 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

  13. Radiocesium distribution on sea sediment and in benthic organisms in the north-east Japan coast

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Tsuneo; Ambe, Daisuke; Kaeriyama, Hideki; Shigenobu, Yuya; Fujimoto, Ken; Saito, Hajime; Miki, Shiduho; Setou, Takashi; Morita, Takami; Watanabe, Tomowo [National Research Institute of Fisheries Sciences, Fisheries Research Agency, 2-12-4, Fukuura, Kanazawaward, Yokohama, Kanagawa, 236-8648 (Japan); Sawada, Hideki [National Resarch Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7, Hasaki, Kamisu-shi, Ibaraki, 314-0408 (Japan)

    2014-07-01

    seawater) and hence radiocesium are mainly absorbed on organic materials as exchangeable form. High radiocesium concentration in sedimental organic compound makes us fear for the affection to benthic organisms. However, our investigation showed that radiocesium concentration of benthic food organisms (polychaetes, crandons, hermit crabs, etc) for demersal fishes are less than 30 Bq/kg-wet even where organic component of bottom sediment has several tens hundreds Bq/kg-wet. This finding suggests that benthos, as most of which are the osmoconfomers, easily emit their radiocesium to the ambient seawater and do not hold radiocesium derived from their food. (authors)

  14. Histamine is a modulator of metamorphic competence in Strongylocentrotus purpuratus (Echinodermata: Echinoidea

    Directory of Open Access Journals (Sweden)

    Sutherby Josh

    2012-04-01

    Full Text Available Abstract Background A metamorphic life-history is present in the majority of animal phyla. This developmental mode is particularly prominent among marine invertebrates with a bentho-planktonic life cycle, where a pelagic larval form transforms into a benthic adult. Metamorphic competence (the stage at which a larva is capable to undergo the metamorphic transformation and settlement is an important adaptation both ecologically and physiologically. The competence period maintains the larval state until suitable settlement sites are encountered, at which point the larvae settle in response to settlement cues. The mechanistic basis for metamorphosis (the morphogenetic transition from a larva to a juvenile including settlement, i.e. the molecular and cellular processes underlying metamorphosis in marine invertebrate species, is poorly understood. Histamine (HA, a neurotransmitter used for various physiological and developmental functions among animals, has a critical role in sea urchin fertilization and in the induction of metamorphosis. Here we test the premise that HA functions as a developmental modulator of metamorphic competence in the sea urchin Strongylocentrotus purpuratus. Results Our results provide strong evidence that HA leads to the acquisition of metamorphic competence in S. purpuratus larvae. Pharmacological analysis of several HA receptor antagonists and an inhibitor of HA synthesis indicates a function of HA in metamorphic competence as well as programmed cell death (PCD during arm retraction. Furthermore we identified an extensive network of histaminergic neurons in pre-metamorphic and metamorphically competent larvae. Analysis of this network throughout larval development indicates that the maturation of specific neuronal clusters correlates with the acquisition of metamorphic competence. Moreover, histamine receptor antagonist treatment leads to the induction of caspase mediated apoptosis in competent larvae. Conclusions We

  15. Comparative analysis of morphometric characteristics of bivalves Anodonta piscinalis from the reservoirs of techa cascade of Mayak Production Association

    Energy Technology Data Exchange (ETDEWEB)

    Yegoreichenkov, E.; Pryakhin, E.; Akleyev, A. [Urals Research Center for Radiation Medicine - URCRM (Russian Federation)

    2014-07-01

    The reservoirs R-11, R-10 and R-4 of the Techa cascade (Chelyabinsk region) are used as low-active radioactive wastes storages, and are separated from open hydrographical network by a system of dams and by-pass channels. The values of specific activity of radionuclides in water and bottom sediments increases in the row: R-11, R-10, R-4, and at the same time the dose rate for zoo-benthos is increased on an order from reservoir to reservoir. Bivalves, which are obligate filter feeders and produce a significant part of water community biomass, are an important part of energy and matter transformation chain inside the hydro-biocenosis. Among this group of animals, the Anodonta piscinalis, a massive bivalve, takes the most part in biomass of Techa reservoirs cascade. Several studies show that in polluted environment the shell morphology changes are possible: the ratio of most morphometric values changes; the level of fluctuated asymmetry and shell polymorphism increases. For morphological studies of bivalves populations, 34 specimens of Anodonta were taken from R-11, 43 specimens from R-10 and 4 specimens from R-4. The specimens selection was arranged in May 2013, using hydro-biological drag. The shell shape was analyzed using TPS DIG software. Besides the measurements of maximal shell length, shell height, and the distance between shell's top and maximally distant point of front edge of the shell were measured. The ratio between the length and the height of the shell, between the length and the distance from the top to the front edge were calculated. The data analysis was arranged using R statistics. As a result of the data analysis the significant difference between shell's length to height ratios were registered between populations of R-4 and R-10 (p = 0.002). The ratio of maximal length of the shell to the distance from the top to the front edge also significantly differs between the animals of the R-4 and R-10 reservoirs (?= 0.03). Between the animals of

  16. Benthic buffers and boosters of ocean acidification on coral reefs

    Directory of Open Access Journals (Sweden)

    K. R. N. Anthony

    2013-02-01

    Full Text Available Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (pn and calcification (gn. Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia contribute to changes in seawater aragonite saturation state (Ωa. Results of flume studies showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm, macroalgae (Chnoospora implexa, turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm and high flow (35 compared to 8 cm s−1. In contrast, branching corals (Acropora aspera increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1 and exacerbated by acidification. Calcifying macroalgae (Halimeda spp. raised Ωa by day (by around 0.13 h−1, but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from four different benthic compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water residence times in neighbouring areas dominated by turfs, macroalgae and potentially sand.

  17. Benthic buffers and boosters of ocean acidification on coral reefs

    Directory of Open Access Journals (Sweden)

    K. R. N. Anthony

    2013-07-01

    Full Text Available Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP and calcification (NCC. Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia contribute to changes in the seawater aragonite saturation state (Ωa. Results of flume studies using intact reef habitats (1.2 m by 0.4 m, showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm, macroalgae (Chnoospora implexa, turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm and high flow (35 compared to 8 cm s−1. In contrast, branching corals (Acropora aspera increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1 and exacerbated by acidification. Calcifying macroalgae (Halimeda spp. raised Ωa by day (by around 0.13 h−1, but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from benthic communities with four different compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water-residence times in neighbouring areas dominated by turfs, macroalgae and carbonate sand.

  18. The feeding and diet of the deep-sea shrimp Aristeus antennatus off the Balearic Islands (Western Mediterranean): Influence of environmental factors and relationship with the biological cycle

    Science.gov (United States)

    Cartes, Joan E.; Papiol, Vanesa; Guijarro, Beatriz

    2008-10-01

    reproductive processes in a deep-sea species such as the shrimp Aristeus antennatus, situated near the top of the trophic web, suggests a rapid energy flow via mesopelagic fauna between surface primary production and bathyal megabenthic communities at oligotrophic insular areas. In contrast to mainland areas off the Catalan coasts submitted to the influence of submarine canyons, around the island of Mallorca the empoverishment of benthos biomass may enhance consumption of micronektonic prey and a possible accumulation of pre-reproductive females of A. antennatus in areas (e.g., steep slopes and persistent frontal systems found off Sóller) with high zooplankton aggregations.

  19. The biogeochemistry of carbon in continental slope sediments: The North Carolina margin

    Energy Technology Data Exchange (ETDEWEB)

    Blair, N.; Levin, L.; DeMaster, D.; Plaia, G.; Martin, C.; Fornes, W.; Thomas, C.; Pope, R.

    1999-12-01

    The responses of the continental slope benthos to organic detritus deposition were studied with a multiple trace approach. Study sites were offshore of Cape Fear (I) and Cape Hatteras (III), N.C. (both 850 m water depth) and were characterized by different organic C deposition rates, macrofaunal densities (III>I in both cases) and taxa. Natural abundances of {sup 13}C and {sup 12}C in particulate organic carbon (POC), dissolved inorganic carbon (DIC) and macrofauna indicate that the reactive organic detritus is marine in origin. Natural abundance levels of {sup 14}C and uptake of {sup 13}C-labeled diatoms by benthic animals indicate that they incorporate a relatively young component of carbon into their biomass. {sup 13}C-labeled diatoms (Thalassiorsira pseudonana) tagged with {sup 210}Pb, slope sediment tagged with {sup 113}Sn and {sup 228}Th-labeled glass beads were emplaced in plots on the seafloor at both locations and the plots were sampled after 30 min., 1-1.5 d and 14 mo. At Site I, tracer diatom was intercepted at the surface primarily by protozoans and surface-feeding annelids. Little of the diatom C penetrated below 2 cm even after 14 months. Oxidation of organic carbon appeared to be largely aerobic. At Site III, annelids were primarily responsible for the initial uptake of tracer. On the time scale of days, diatom C was transported to a depth of 12 cm and was found in animals collected between 5-10 cm. The hoeing of tracer from the surface by the maldanid Praxillela sp. may have been responsible for some of the rapid nonlocal transport. Oxidation of the diatom organic carbon was evident to at least 10 cm depth. Anaerobic breakdown of organic matter is more important at Site III. Horizontal transport, which was probably biologically mediated, was an order of magnitude more rapid than vertical displacement over a year time scale. If the horizontal transport was associated with biochemical transformations of the organic matter, it may represent an

  20. Transcriptome profiling of the demosponge Amphimedon queenslandica reveals genome-wide events that accompany major life cycle transitions

    Directory of Open Access Journals (Sweden)

    Conaco Cecilia

    2012-05-01

    Full Text Available Abstract Background The biphasic life cycle with pelagic larva and benthic adult stages is widely observed in the animal kingdom, including the Porifera (sponges, which are the earliest branching metazoans. The demosponge, Amphimedon queenslandica, undergoes metamorphosis from a free-swimming larva into a sessile adult that bears no morphological resemblance to other animals. While the genome of A. queenslandica contains an extensive repertoire of genes very similar to that of complex bilaterians, it is as yet unclear how this is drawn upon to coordinate changing morphological features and ecological demands throughout the sponge life cycle. Results To identify genome-wide events that accompany the pelagobenthic transition in A. queenslandica, we compared global gene expression profiles at four key developmental stages by sequencing the poly(A transcriptome using SOLiD technology. Large-scale changes in transcription were observed as sponge larvae settled on the benthos and began metamorphosis. Although previous systematics suggest that the only clear homology between Porifera and other animals is in the embryonic and larval stages, we observed extensive use of genes involved in metazoan-associated cellular processes throughout the sponge life cycle. Sponge-specific transcripts are not over-represented in the morphologically distinct adult; rather, many genes that encode typical metazoan features, such as cell adhesion and immunity, are upregulated. Our analysis further revealed gene families with candidate roles in competence, settlement, and metamorphosis in the sponge, including transcription factors, G-protein coupled receptors and other signaling molecules. Conclusions This first genome-wide study of the developmental transcriptome in an early branching metazoan highlights major transcriptional events that accompany the pelagobenthic transition and point to a network of regulatory mechanisms that coordinate changes in morphology with

  1. 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.

  2. The Fecal Pellet fraction of biogeochemical particle fluxes to the deep sea

    Science.gov (United States)

    Pilskaln, Cynthia H.; Honjo, Susumu

    1987-03-01

    important source of organic carbon for the deep-sea benthos. Rapid remineralization of the organic-rich pellets must occur at the deep-sea sediment/water interface, as these biogenic aggregates were completely absent from all site core tops.

  3. Sampling benthic macroinvertebrates in a large flood-plain river: Considerations of study design, sample size, and cost

    Science.gov (United States)

    Bartsch, L.A.; Richardson, W.B.; Naimo, T.J.

    1998-01-01

    Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37 km reach of the Upper Mississippi River. We sampled benthos at 36 sites within each of two strata, contiguous backwater and channel border. Three standard ponar (525 cm(2)) grab samples were obtained at each site ('Original Design'). Analysis of variance and sampling cost of strata-wide estimates for abundance of Oligochaeta, Chironomidae, and total invertebrates showed that only one ponar sample per site ('Reduced Design') yielded essentially the same abundance estimates as the Original Design, while reducing the overall cost by 63%. A posteriori statistical power analysis (alpha = 0.05, beta = 0.20) on the Reduced Design estimated that at least 18 sites per stratum were needed to detect differences in mean abundance between contiguous backwater and channel border areas for Oligochaeta, Chironomidae, and total invertebrates. Statistical power was nearly identical for the three taxonomic groups. The abundances of several taxa of concern (e.g., Hexagenia mayflies and Musculium fingernail clams) were too spatially variable to estimate power with our method. Resampling simulations indicated that to achieve adequate sampling precision for Oligochaeta, at least 36 sample sites per stratum would be required, whereas a sampling precision of 0.2 would not be attained with any sample size for Hexagenia in channel border areas, or Chironomidae and Musculium in both strata given the variance structure of the original samples. Community-wide diversity indices (Brillouin and 1-Simpsons) increased as sample area per site increased. The backwater area had higher diversity than the channel border area. The number of sampling sites

  4. Infauna monitoring Horns Rev offshore wind farm. Annual status report 2003

    International Nuclear Information System (INIS)

    ELSAM and ELTRA have established an offshore wind farm with an output of 160 MW in the waters of Horns Rev 1420 km off Blaevands Huk, which is the most westerly point of Denmark. The first phase of construction of the wind farm started in spring 2002. Before the construction activities took place, a baseline description of the benthos was conducted as a part of an environmental monitoring programme for the establishment of the Horns Rev Offshore Wind Farm. The baseline surveys for the present monitoring programme were conducted in the wind farm area on three occasions: spring 1999, spring 2001 and September 2001. In designated reference areas, surveys were conducted in spring 1999 and September 2001. The reference areas in 1999 and September 2001 were placed at two different geographical locations because the survey in September 2001 was planned to be a part of a fish monitoring programme. A comparison between the baseline study in spring 2001 and the baseline study in autumn 2001 clearly revealed that the biomass of most species increased considerably from spring to September. Despite the increase in biomass, the overall distribution of the species and their relative abundance did not change. In order to use the baseline data to investigate a possible impact after the construction of the wind farm, it was essential to arrange the monitoring programme either in spring or in September 2003, because the baseline studies were conducted in these periods. The monitoring programme was conducted in September 2003 after the wind farm had become operational, parallel with the survey on hard bottom substrates. The impacts of the wind farm on the benthic fauna (infauna) in the area were mainly expected to be due to the alteration of the local currents. As the changes in the currents are only minor, impacts on the water chemistry and on the benthic fauna resulting from hydrodynamic causes were expected to be limited or non-existent. The main objective of the present monitoring

  5. Synthetic polymers in the marine environment: a rapidly increasing, long-term threat.

    Science.gov (United States)

    Moore, Charles James

    2008-10-01

    Shearwaters was positively correlated with PCBs in their fat and eggs. Colonization of plastic marine debris by sessile organisms provides a vector for transport of alien species in the ocean environment and may threaten marine biodiversity. There is also potential danger to marine ecosystems from the accumulation of plastic debris on the sea floor. The accumulation of such debris can inhibit gas exchange between the overlying waters and the pore waters of the sediments, and disrupt or smother inhabitants of the benthos. The extent of this problem and its effects have recently begun to be investigated. A little more than half of all thermoplastics will sink in seawater. PMID:18949831

  6. Partitioning the contributions of mega-, macro- and meiofauna to benthic metabolism on the upper continental slope of New Zealand: Potential links with environmental factors and trawling intensity

    Science.gov (United States)

    Leduc, Daniel; Pilditch, Conrad A.; Nodder, Scott D.

    2016-02-01

    Understanding and predicting change in deep-sea benthic ecosystem function remains a major challenge. Here, we conducted analyses combining data on the abundance and biomass of benthic fauna and sediment community oxygen consumption (SCOC) on New Zealand's continental margin to estimate and compare the contributions of meio-, macro-, and megafauna to total benthic metabolism and identify potential links with environmental factors and trawling intensity. We focussed on two regions in close proximity-the high surface primary productivity Chatham Rise and low surface productivity Challenger Plateau. Mean megafauna biomass was twenty times greater on Chatham Rise than Challenger Plateau, likely reflecting differences in food supply between the two regions; this contrast in megafaunal biomass was mainly due to differences in mean body weight rather than abundance. Meio- and macrofauna made similar contributions to SCOC and together accounted for 12% of benthic metabolism on average. In contrast, the estimated contribution of megafauna never exceeded 1.5%. Significant positive correlations between faunal respiration and food availability indicate a link between food supply and benthic community function. Our analyses also show that fauna made a greater contribution to SCOC in conditions of high food availability, and that microorganisms (i.e., the proportion of SCOC not accounted for by the fauna) tended to be more dominant at sites with low food availability. These findings provide support for the concept that large organisms are more strongly affected by a reduction in food resources than small organisms, which in turn underlies one of the most widely described patterns in the deep-sea benthos, i.e., the reduction in organism body size with depth. Because metabolism in deep-sea sediments is typically dominated by microorganisms and small fauna, the absence of a relationship between bottom trawling intensity and the respiration of benthic fauna in the present study may

  7. Biogenic carbon flows through the planktonic food web of the Amundsen Gulf (Arctic Ocean): A synthesis of field measurements and inverse modeling analyses

    Science.gov (United States)

    Forest, Alexandre; Tremblay, Jean-Éric; Gratton, Yves; Martin, Johannie; Gagnon, Jonathan; Darnis, Gérald; Sampei, Makoto; Fortier, Louis; Ardyna, Mathieu; Gosselin, Michel; Hattori, Hiroshi; Nguyen, Dan; Maranger, Roxane; Vaqué, Dolors; Marrasé, Cèlia; Pedrós-Alió, Carlos; Sallon, Amélie; Michel, Christine; Kellogg, Colleen; Deming, Jody; Shadwick, Elizabeth; Thomas, Helmuth; Link, Heike; Archambault, Philippe; Piepenburg, Dieter

    2011-12-01

    Major pathways of biogenic carbon (C) flow are resolved for the planktonic food web of the flaw lead polynya system of the Amundsen Gulf (southeast Beaufort Sea, Arctic Ocean) in spring-summer 2008. This period was relevant to study the effect of climate change on Arctic marine ecosystems as it was characterized by unusually low ice cover and warm sea surface temperature. Our synthesis relied on a mass balance estimate of gross primary production (GPP) of 52.5 ± 12.5 g C m -2 calculated using the drawdown of nitrate and dissolved inorganic C, and a seasonal f-ratio of 0.64. Based on chlorophyll a biomass, we estimated that GPP was dominated by phytoplankton (93.6%) over ice algae (6.4%) and by large cells (>5 μm, 67.6%) over small cells (functioning of the planktonic food web was elucidated through inverse analysis using the mean GPP and the 95% confidence limits of every other field measurement as lower and upper constraints. The model computed a net primary production of 49.2 g C m -2, which was directly channeled toward dominant calanoid copepods (i.e. Calanus hyperboreus 20%, Calanus glacialis 10%, and Metridia longa 10%), other mesozooplankton (12%), microzooplankton (14%), detrital POC (18%), and DOC (16%). Bacteria required 29.9 g C m -2, a demand met entirely by the DOC derived from local biological activities. The ultimate C outflow comprised respiration fluxes (82% of the initial GPP), a small sedimentation (3%), and a modest residual C flow (15%) resulting from NCP, dilution and accumulation. The sinking C flux at the model limit depth (395 m) supplied 60% of the estimated benthic C demand (2.8 g C m -2), suggesting that the benthos relied partly on other C sources within the bottom boundary layer to fuel its activity. In summary, our results illustrate that the ongoing decline in Arctic sea ice promotes the growth of pelagic communities in the Amundsen Gulf, which benefited from a ∼80% increase in GPP in spring-summer 2008 when compared to 2004 - a

  8. Sources of organic matter for flatfish juveniles in coastal and estuarine nursery grounds: A meta-analysis for the common sole (Solea solea) in contrasted systems of Western Europe

    Science.gov (United States)

    Le Pape, O.; Modéran, J.; Beaunée, G.; Riera, P.; Nicolas, D.; Savoye, N.; Harmelin-Vivien, M.; Darnaude, A. M.; Brind'Amour, A.; Le Bris, H.; Cabral, H.; Vinagre, C.; Pasquaud, S.; França, S.; Kostecki, C.

    2013-01-01

    Coastal and estuarine nursery grounds are essential habitats for sustaining flatfish stocks since only these shallow and productive areas provide the high food supply that allows maximizing juvenile growth and survival in most flatfish species. However, the main organic matter sources at the basis of benthic food webs might differ drastically between estuarine nursery grounds under strong freshwater influences, where food webs are mainly supported by continental organic matter, and coastal ecosystems under limited freshwater influence, where the local marine primary production is the main source of carbon for the benthos. To better understand the links between continental inputs to the coastal zone and stock maintenance in the highly prized common sole, Solea solea (L.), we investigated the variability in the organic matter sources supporting the growth of its young-of-the-year (YoY) in five contrasted estuarine and coastal nursery grounds under varying freshwater influence. Stable isotopes of carbon and nitrogen allowed tracing the origin of the organic matter exploited by YoY soles in the very first months following their benthic settlement, i.e. when most of the juvenile mortality occurs in the species. A mixing model was run to unravel and quantify the contribution of all major potential sources of organic matter to sole food webs, with a sensitivity analysis allowing assessment of the impact of various trophic enrichment factors on model outputs. This meta-analysis demonstrated a relative robustness of the estimation of the respective contributions of the various organic matter sources. At the nursery scale, the upstream increase in freshwater organic matter exploitation by YoY soles and its positive correlation with inter-annual variations in the river flow confirmed previous conclusions about the importance of organic matter from continental origin for juvenile production. However, inter-site differences in the organic matter sources exploited for growth

  9. A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia

    Directory of Open Access Journals (Sweden)

    Z. M. Easton

    2010-10-01

    Full Text Available A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT model was developed to predict runoff and sediment losses from the Ethiopian Blue Nile Basin. The model simulates saturation excess runoff from the landscape using a simple daily water balance coupled to a topographic wetness index in ways that are consistent with observed runoff processes in the basin. The spatial distribution of landscape erosion is thus simulated more correctly. The model was parameterized in a nested design for flow at eight and sediment at three locations in the basin. Subbasins ranged in size from 1.3 to 174 000 km2, and interestingly, the partitioning of runoff and infiltrating flow could be predicted by topographic information. Model predictions showed reasonable accuracy (Nash Sutcliffe Efficiencies ranged from 0.53–0.92 with measured data across all sites except Kessie, where the water budget could not be closed; however, the timing of flow was well captured. Runoff losses increased with rainfall during the monsoonal season and were greatest from areas with shallow soils and large contributing areas. Analysis of model results indicate that upland landscape erosion dominated sediment delivery to the main stem of the Blue Nile in the early part of the growing season when tillage occurs and before the soil was wetted up and plant cover was established. Once plant cover was established in mid August landscape erosion was negligible and sediment export was dominated by channel processes and re-suspension of landscape sediment deposited early in the growing season. These results imply that targeting small

  10. A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia

    Directory of Open Access Journals (Sweden)

    Z. M. Easton

    2010-06-01

    Full Text Available A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT model was developed to predict runoff and sediment losses from the Ethiopian Blue Nile Basin. The model simulates saturation excess runoff from the landscape using a simple daily water balance coupled to a wetness index in ways that are consistent with observed runoff processes in the basin. The spatial distribution of landscape erosion is thus simulated more correctly. The model was parameterized in a nested design for flow at eight and sediment at two subbasin locations in the basin. Subbasins ranged in size from 4.8 to 174 000 km2, and interestingly, the partitioning of runoff and infiltrating flow could be predicted by topographic information. Model predictions showed reasonable accuracy (Nash Sutcliffe Efficiencies ranged from 0.53–0.92 with measured data across all sites except Kessie, where the water budget could not be closed; however, the timing of flow was well captured. Runoff losses increased with rainfall during the monsoonal season and were greatest from shallow soils. Analysis of model results indicate that upland landscape erosion dominated sediment delivery to the main stem of the Blue Nile in the early part of the growing season before the soil was wetted up and plant cover was established. Once plant cover was established in mid August landscape erosion was negligible and sediment export was dominated by channel processes and re-suspension of landscape sediment deposited early in the growing season. These results imply that targeting small areas of the landscape where runoff is produced can be the most

  11. Couplerlib: a metadata-driven library for the integration of multiple models of higher and lower trophic level marine systems with inexact functional group matching

    Science.gov (United States)

    Beecham, Jonathan; Bruggeman, Jorn; Aldridge, John; Mackinson, Steven

    2016-03-01

    were more stable (although the benthic linkage modelled was purely at the detritus level, so this stability reflects the stability of the Ecosim model). The coupled model was used to examine long-term effects of environmental change, and showed the system to be nutrient limited and relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long-term environmental change than short-term perturbations.

  12. Effect of zinc-enriched natural sediments, in isolated and microcosm models, on three species of benthic invertebrates

    International Nuclear Information System (INIS)

    Availability of toxic in aquatic bodies is limited by the physicochemical characteristics of sediments and water, as well as by the interactions between the different xenobiotics and inhabits species. The aim of this work was to relate the effect produced by zinc (Zn) spiked in sediments of the Ignacio Ramirez dam (PIR), in isolated and microcosm models, on ATP concentration of three benthic organisms with the metal biodisponibility. The selected species were a crustacean, an annelid and a mollusk: Hyalella azteca (Amphipoda: Hyalellidae), Limnodrilus hoffmeisteri (Oligochaeta: Tubificidae) and Stagnicola attenuata (Basommatophora: Lymnaeidae), species that are found at high proportions in the reservoir and use different spaces in the benthos. Samples of sediments and organisms were collected from the PIR during the dry season (February of 1999). Metal concentration (Zn, Fe, Cu and Ni), pH, texture, particle size, total nitrogen and organic matter were determined in sediments. Sublethal studies were carried out using two types of static systems (isolated and in microcosm organisms). Both models contained PIR sediments enriched with Zn (nominal concentration of 0.8129 mg/kg) and synthetic water in a proportion of 1:4. The test organisms were added to the systems once the equilibrium was reached (2 hr) considering the biomass quantity with respect to volume (1.0 g of organism by each 100 ml of water:sediment). After 0, 12, 24, 36, 48 and 72 hr of exposure, samples of sediment and hydrobionts were taken, and Zn content was quantified by atomic absorption. ATP concentration was also determined in organisms. The effect produced by natural sediments spiked with Zn is increased by the presence of more than one specie in the system (microcosm). With respect to Zn levels, two of the organisms (L. hoffmeisteri y S. attenuata) tend to lose this metal in isolated and microcosm models, probably as a regulation strategy in its accumulation, as well as Fe presence in the

  13. Extending Hydrologic Information Systems to accommodate Arctic marine observations data

    Science.gov (United States)

    Hersh, Eric S.; Maidment, David R.

    2014-04-01

    The Chukchi Sea Offshore Monitoring in Drilling Area - Chemical and Benthos (COMIDA CAB) project characterizes the biota and chemistry of the continental shelf ecosystem of a region of the Chukchi Sea to form a baseline survey of environmental conditions before drilling for oil commences. This paper describes the COMIDA CAB project data and processing methods, which provide a novel approach to data tracking and archiving from marine sampling cruises. This approach features an adaptation of the Consortium of Universities for the Advancement of Hydrologic Science. Observations Data Model for application with physical, chemical, and biological oceanographic data - a new extension of the CUAHSI Hydrologic Information System - thus bringing hydroinformatics into the oceanographic realm. Environmental sampling has been carried out by five separate scientific teams who characterize particular classes of physical, chemical and biological variables, and who each have their own methods of processing samples in their laboratories following the two sampling cruises made to the Chukchi Sea in the summers of 2009 and 2010. The results of their observations and analyses are stored in data files, mostly in Excel format, whose structure is defined differently by each scientific team. In all, the 2009 and 2010 COMIDA CAB field efforts yielded a database of 510,405 data values. Of these, 474,129 were derived from continuous in-situ data sonde profiles and 36,276 were derived from non-sonde extracted samples of the sediment, epibenthos, and water column. These data values represent 301 variables measured at 65 sites and originated from 26 different source files. The biological observations represented 519 distinct taxa. The data from these files are transformed and synthesized into a comprehensive project database in which a set of standardized descriptors of each observed data value are specified and each data value is linked to the data file from which it was created to establish a

  14. Radioecological consequences of Chernobyl accident for Lake ecosystems within 10 km exclusion zone

    International Nuclear Information System (INIS)

    During 1997-2005 we studied distribution and dynamics of 90Sr, 137Cs, 238Pu, 239+240Pu and 241Am in the main components of the aquatic ecosystems within exclusion zone, defined as a roughly circular area of 30-km radius around the destroyed unit of the Chernobyl NPP. Our special attention was given to bottom sediments, water, seston, higher aquatic plants, molluscs and fish of lake ecosystems within inner (10-km) exclusion zone: Azbuchin Lake, Dalekoye Lake and Glubokoye Lake. The data analysis has shown that about 98-99% of 137Cs and more than 99% of transuranic elements of the total radionuclide content has deposited in the bottom sediments. The content of 90Sr in sediments of lakes, due to higher solubility, amounts to 89-95%. About 2-10% of radionuclides concentrated in water and only about 1% - in biota. In this percent a prevailing value for different radionuclides has the macro benthos species (especially bivalve molluscs) and higher aquatic plants. The average specific activity of radionuclides in fish tissue more than in 100 times exceeds a maximum permissible level for fish production in Ukraine. The absorbed dose rate for hydrobionts, living within littoral zone of the researched lakes, due to external irradiation and radionuclides incorporated in tissue was in a range from 0.2 to 3.4 Gy year-1. The highest value was found for hydrobionts from lakes within embankment territory on left-bank flood plain of the Pripyat River with high density of radionuclide contamination (Dalekoye Lake and Glubokoye Lake). The numerous effects of irradiation on hydrobionts within the exclusion zone are revealed. Some of these effects required for the short period of time for their formation, however it is supposed that an increasing importance will be got by the remote consequences - genetic damages induced by a long-term irradiation. The molluscs embryos from Dalekoye-1 Lake and Glubokoye Lake were characterised by the highest rate of chromosome aberration - about 20

  15. Development and validation of hydroacoustic monitoring concepts for the coastal German Bight (SE North Sea)

    Science.gov (United States)

    Mielck, Finn; Hass, H. Christian; Holler, Peter; Bartholomä, Alexander; Neumann, Andreas; Kröncke, Ingrid; Reimers, Hans-Christian; Capperucci, Ruggero

    2016-04-01

    The joint research project WIMO (Wissenschaftliche Monitoringkonzepte für die Deutsche Bucht/Scientific Monitoring Concepts for the German Bight, NE North Sea) aims at providing methods for detection and analysis of seabed habitats using modern remote sensing techniques. Our subproject focuses on hydroacoustic techniques in order to gain information about seafloor environments and sediment dynamics. In a timeframe of four years, several key areas in the German Bight were repeatedly observed using different hydroacoustic gear (i. e. sidescan sonars, single/multibeam echo sounders and sub-bottom profilers). In order to ground-truth the acoustic data, hundreds of grab samples and underwater videos were taken. With these techniques it is possible to distinguish between different seafloor habitats, which range from muddy to sandy seafloors (esp. near the barrier islands) to rugged or vegetated/populated reefs around Helgoland. The conducted monitoring program revealed seasonal changes regarding the abundance of the sand mason worm (Lanice conchilega) and the brittle star (Amphiora filiformis) as well as ongoing sedimentary processes driven by tidal currents and wind/storms. It was also possible to determine relationships between sediment characteristics and benthos in some key areas. An essential part of our project included a comparison between the datasets obtained with different hydroacoustic devices, configurations, and evaluation methods in the same study areas. The investigation reveals that there could be distinct differences in interpreting the data and hence in the determination of prevailing seafloor habitats, especially in very heterogeneous areas and at transition zones between the habitats. Therefore, it is recommended to employ more than one hydroacoustic system (preferably a singlebeam device combined with a wide-swath sonar system) synchronously during a survey in order to gain more reliable and detailed information about the seafloor environments. The

  16. Assessing the impact of the Tunoe Knob wind park on sea ducks: the influence of food resources

    International Nuclear Information System (INIS)

    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 baseline

  17. An approach for coupling higher and lower levels in marine ecosystem models and its application to the North Sea

    Directory of Open Access Journals (Sweden)

    J. A. Beecham

    2015-07-01

    modelled was purely at the detritus level. The coupled model was used to examine long term effects of environmental change, and showed the system to be nutrient limited, relatively unaffected by forecast climate change, especially in the benthos. The stability of an Ecosim formulation for large higher tropic level food webs is discussed and it is concluded that this kind of coupled model formulation is better for examining the effects of long term environmental change than short term perturbations.

  18. The northeast US application of ATLANTIS: A full system model exploring marine ecosystem dynamics in a living marine resource management context

    Science.gov (United States)

    Link, Jason S.; Fulton, Elizabeth A.; Gamble, Robert J.

    2010-10-01

    Understanding marine ecosystem dynamics is a key challenge and opportunity facing us. One of the ways we can continue to unravel and understand marine ecosystem dynamics is via ecosystem modeling. We used one such model, ATLANTIS, to help explore the dynamics of the Northeast United States (NEUS) Continental Shelf Large Marine Ecosystem (LME). We have parameterized ATLANTIS for the NEUS LME by including major functional groups across a range of biota, the physiographic dynamics of the ecosystem, and the major fishing fleets. The objectives of this work were to describe the application of this ATLANTIS NEUS model; briefly highlight modeling skill; note areas for further improvement, data gaps, major lessons learned, and how our understanding of the ecosystem was enhanced as we executed the modeling process; and note how these model outputs could inform living marine resource management in this region. The preliminary results we show here describe outputs from a multivariate, multispecies, multifactorial modeling approach. Our modeling skill is reasonable, as determined by the fact that over 90% of our fleet effort estimates, nearly 80% of our functional group catches, and 100% of our main functional group biomasses were within limits of tolerance. Moreover, the general patterns and phenology of major events were replicated consistently, both in space and time across a broad suite of physical, chemical, biological and human factors. These include several taxa groups such as primary producers, zooplankton, benthos, fishes, marine mammals, as well as nutrients, landings, and fishing effort. Conversely, as expected, there were some groups or fleets that did exceed levels of tolerance. These were mostly invertebrate groups such as shrimp, squid or gelatinous zooplankton, groups which are notorious for being difficult to model. Yet the major taxa groups and main fishing fleets were all well within levels of tolerance. Thus, we assert that with the majority of all main

  19. Assessing the impact of the Tunoe Knob wind park on sea ducks: the influence of food resources

    Energy Technology Data Exchange (ETDEWEB)

    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{sup -2} in 1997-98 compared to 11,111 individuals m{sup -2} during the baseline year and only 100 individuals m{sup -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

  20. TOXIC EFFECT OF PESTICIDES ON THE BIOTA OF FRESHWATER RESERVOIRS OF UKRAINE (A REVIEW

    Directory of Open Access Journals (Sweden)

    N. Kolesnyk

    2015-12-01

    Full Text Available Purpose. To analyze scientific sources on the studies of toxic and lethal concentrations of pesticides on phytoplankton, zooplankton, zoobenthos and fish in current conditions of Ukraine. Findings. A review of works of a variety of scientists showed that pesticides with different chemical origins have disastrous effects on everyone without the exception of freshwater biota organisms. The article highlights the peculiarities of the toxic effects of pesticides of major chemical groups, which are used or stored in Ukraine. Their toxic and lethal concentrations for the major species of phytoplankton, zooplankton, zoobenthos and ichthyofauna reservoirs are considered. The data on basic features of behavioral reactions of aquatic organisms on poisoning by pesticides are provided. The basic structural and systemic diosrders of homeostasis of the organisms of aquatic biota are described. The effect of pesticides on phytoplankton needs further research, however, is was found that they have common feature as the disturbace of photosynthesis process and accumulation. In turn, this provoques kills in water bodies and poisoning of phytoplanctivorous fish. Zooplanktonic organisms are highly sensitive to pesticides; hence they can be used as an indicator of the state of fresh water. It was found that, pesticides depending on their concentration have different toxic effects on zooplankton organisms. The effect of pesticides on benthic organisms was little investigated. It is known that benthic communities respond to the presence of pesticide by changes in species composition, number of species, abundance and biomass of benthos in general and individual taxonomic groups of benthic invertebrates. The toxicity of pesticides for fish depends on their chemical nature, the form of the preparation, dose, fish species and age, water temperature and the content of oxygen and salts. In particular, juvenile fish are much more sensitive to the chemicals, and an increase in