A simple mixing explanation for late Pleistocene changes in the Pacific-South Atlantic benthic δ13C gradient

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L. E. Lisiecki

2010-05-01

Full Text Available The fact that the deep-ocean benthic δ13C minimum shifted from the North Pacific to the South Atlantic during the Last Glacial Maximum is often interpretted as evidence of a change in deep water circulation, such as the development of deep water ventilation in the North Pacific or a decrease in Southern Ocean overturning. This study re-evaluates the implications of changes in benthic δ13C gradients by comparing Pacific Deep Water (PDW δ13C measurements with the values expected for the null hypothesis that PDW ventilation sources remained unchanged throughout the Late Pleistocene. The δ13C compositions of PDW, Northern Component Water (NCW and Southern Component Water (SCW are estimated from regional benthic δ13C stacks of 3–6 sites. Changes in PDW δ13C and PDW-SCW δ13C gradients over the past 800 kyr are found to be well described by a constant mixture of 60% NCW and 40% SCW plus a constant Pacific remineralization offset of −0.5‰. Thus, a change in PDW ventilation cannot be inferred solely on the basis of changes in the Pacific-South Atlantic benthic δ13C gradient.

Temperature tracking by North Sea benthic invertebrates in response to climate change.

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Hiddink, Jan G; Burrows, Michael T; García Molinos, Jorge

2015-01-01

Climate change is a major threat to biodiversity and distributions shifts are one of the most significant threats to global warming, but the extent to which these shifts keep pace with a changing climate is yet uncertain. Understanding the factors governing range shifts is crucial for conservation management to anticipate patterns of biodiversity distribution under future anthropogenic climate change. Soft-sediment invertebrates are a key faunal group because of their role in marine biogeochemistry and as a food source for commercial fish species. However, little information exists on their response to climate change. Here, we evaluate changes in the distribution of 65 North Sea benthic invertebrate species between 1986 and 2000 by examining their geographic, bathymetric and thermal niche shifts and test whether species are tracking their thermal niche as defined by minimum, mean or maximum sea bottom (SBT) and surface (SST) temperatures. Temperatures increased in the whole North Sea with many benthic invertebrates showing north-westerly range shifts (leading/trailing edges as well as distribution centroids) and deepening. Nevertheless, distribution shifts for most species (3.8-7.3 km yr(-1) interquantile range) lagged behind shifts in both SBT and SST (mean 8.1 km yr(-1)), resulting in many species experiencing increasing temperatures. The velocity of climate change (VoCC) of mean SST accurately predicted both the direction and magnitude of distribution centroid shifts, while maximum SST did the same for contraction of the trailing edge. The VoCC of SBT was not a good predictor of range shifts. No good predictor of expansions of the leading edge was found. Our results show that invertebrates need to shift at different rates and directions to track the climate velocities of different temperature measures, and are therefore lagging behind most temperature measures. If these species cannot withstand a change in thermal habitat, this could ultimately lead to a drop in

Benthic macroinvertebrates as bioindicators of water quality in Billings Reservoir fishing sites (SP, Brazil

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José Ricardo Baroldi Ciqueto Gargiulo

Full Text Available Abastract: Aim The Billings Reservoir is the largest reservoir in the metropolitan region of São Paulo and has multiple uses, including artisanal fishing. Its surroundings present intense occupation, resulting in various environmental impacts. Although the water is degraded, affecting the composition and quality of the fish, this reservoir supports artisanal fishermen who survive through this activity. This study aimed to analyze the water quality in the main sites of artisanal fishing activity, with an emphasis on the benthic community as a bioindicator. Methods Three sampling sites were selected, in which water and zoobenthos samples were collected monthly from April 2012 to March 2013. Water analyses consisted of the determination of pH, temperature, conductivity, turbidity, total dissolved solids, dissolved oxygen, total nitrogen, total phosphorus, and trophic state as well as a principal components analysis. The zoobenthos analysis consisted of determining the relative abundance and total density of taxa, the Shannon-Weaver diversity index, taxa richness, uniformity, Simpson’s dominance index, and the benthic community index and conducting a canonical correspondence analysis. The non-parametric Kruskal-Wallis test followed by the Student-Newman-Keuls test were used to investigate the existence of significant differences in the abiotic and biotic variables among the sites. Results The studied sites showed a high degree of eutrophication, with nitrogen and phosphorus totals levels above the limits defined by current Brazilian legislation. Taquacetuba (P1 showed the best environmental conditions for the development of fishing activity, with the presence of sensitive organisms (Polymitarcyidae and higher levels of dissolved oxygen. Alvarenga (P2 had the worst water quality, with a predominance of tolerant organisms (Oligochaeta and lower levels of dissolved oxygen. Conclusion In conclusion, the benthic community in association with abiotic

Upwelling and Other Environmental Influences on Growth of a Nearshore Benthic Fish

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von Biela, V. R.; Zimmerman, C. E.; Kruse, G. H.; Mueter, F. J.; Black, B.; Douglas, D. C.; Bodkin, J. L.

2016-02-01

The role of upwelling in nearshore benthic systems is more uncertain compared to the relatively strong positive associations with pelagic production. To understand how upwelling and other environmental conditions influence nearshore benthic production, we developed an annual index of production from growth increments recorded in otoliths of kelp greenling (Hexagrammos decagrammus) at nine sites in the seasonally-upwelling California Current and downwelling Alaska Coastal currents. Kelp greenling are a benthic-feeding fish common in kelp forests with food webs sustained by both kelp and phytoplankton primary production. We explored the influence of basin- and local-scale conditions, including upwelling, across all seasons at lags up to two years taken to represent changes in the quantity and quality of prey. Upwelling strength was positively related to fish growth in both current systems, although relationships in the Alaska Coastal Current were indicative of faster growth with relaxed downwelling, rather than upwelling. Looking across a suite of basin- and local-scale environmental indicators, complex relationships emerged in the California Current, with faster growth related to within-year warm conditions and lagged-year cool conditions. In contrast, fish in the downwelling system grew faster both during and subsequent to warm conditions. The complex lag-dependent dynamics in the upwelling system may reflect differences in conditions that promote quantity versus quality of benthic invertebrate prey. Thus, we hypothesize that benthic production is maximized when cool and warm years alternate during periods of high frequency climate variability in the California Current. Such a pattern is consistent with previous findings suggesting that benthic invertebrate abundance (e.g., recruitment) is food-limited during warm years with reduced upwelling, while quality (e.g., energy content) is temperature-limited during cool years.

WATER QUALITY ANALYSIS OF LOTIC ECOSYSTEMS OF NERA AND CARAS RIVERS CATCHMENTS USING BENTHIC INVERTEBRATES AS BIOINDICATORS

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CLAUDIA PETRUCEAN

2009-01-01

Full Text Available The study of the two watersheds involved the collection of twenty-four benthic samples from the main tributaries of Nera and Caras rivers, but also from the Nera river. The samples were collected in august 2009 with a benthic net, which had the mesh size of 250 μm, by disturbing the substrate upstream for three minutes, being thus qualitative samples. The next stage, working in the laboratory, consisted in separating the invertebrates from the substrate, sorting them to taxonomic categories and counting them. The data was statistically analized and interpreted. It led to the conclusion that the water quality in the two watersheds is good. In most of the sampling points the major groups of benthic macroinvertebrates were found, some of the sampling points were dominated by the EPT groups (Ephemeroptera, Plecoptera, Trichoptera which is known as a clean freshwater group, sensitive to pollution and human impact.

The role of pelagic-benthic coupling in structuring littoral benthic communities at Terra Nova Bay (Ross Sea and in the Straits of Magellan

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Riccardo Cattaneo-Vietti

1999-12-01

Full Text Available In Antarctic and peri-Antarctic regions, benthic communities are persistent in time and show high biomass and large numbers of individuals, mainly consisting of suspension and deposit feeders. In fact, apart from recruitment, the major factor structuring these communities is the high flow of organic matter from the pelagic domain to the bottom, representing an important energy source for the benthic organisms. The aim of this paper is to review, compile and compare the data from earlier investigations in Terra Nova Bay (Ross Sea and the Straits of Magellan, in order to come to a more general conclusion about the role of the pelagic-benthic coupling in structuring littoral benthic communities in southern coastal areas. Few measurements of flux rates and the biochemical composition of the sinking particles occurring in Antarctic and peri-Antarctic shallow waters are available, but a compilation of our own data and others allows a comparison of these two systems. The different environmental conditions between Antarctica and the Straits of Magellan lead to differences in the origin of the particulate organic matter and in its biochemical composition, and consequently in the coupling between pelagic and benthic domains. At Terra Nova Bay the summer particulate matter shows a high labile fraction of a good food value: its flux has been evaluated at about 0.67 g m-2d-1. Conversely, the Straits of Magellan show multi-structured ecosystems where the quality and quantity of the organic matter flux towards the bottom change according to the local geomorphology and current dynamics. Moreover, the three-dimensional assemblages of suspension-feeders, so common in Antarctic shallow waters, seem to be absent in the Magellan area. In particular sponges, gorgonarians and bryozoans play a secondary role inside the Straits of Magellan, where polychaetes (60% and molluscs (9-10% are dominant on soft bottoms, and where they reach high values in density and biomass

THE STUDY OF WATER QUALITY USING BENTHIC MACROINVERTEBRATES AS BIOINDICATORS IN THE CATCHMENT AREAS OF THE RIVERS JIU, OLT AND IALOMIŢA

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Elena Daniela MITITELU

2012-01-01

Full Text Available The wide distribution of benthic invertebrates and their different sensitivity shown upon modifying the qualitative parameters of aquatic ecosystems led to a frequent use of these group as bioindicators in different studies. The present study aims at presenting a list concerning the different macroinvertebrates identified in the larva stage in three watersheds (Jiu, Olt, Ialomiţa and establishing the water quality of the monitored sections using this benthic macroinvertebrates. The sample collecting points were represented by 23 stations. The abundance and frequency values recorded for benthic communities varied according to the physical-chemical conditions specific to each sample collecting station. There were identified 15 groups in total. The most frequent were Ephemeroptera, Plecoptera, Trichoptera, Diptera (Chironomidae and others. The deterioration of water quality is marked by the decrease in the biotic index EPT/Ch value.

Analysis of Benthic Foraminiferal Size Change During the Eocene-Oligocene Transition

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Zachary, W.; Keating-Bitonti, C.

2017-12-01

The Eocene-Oligocene transition is a significant global cooling event with the first growth of continental ice on Antarctica. In the geologic record, the size of fossils can be used to indirectly observe how organisms respond to climate change. For example, organisms tend to be larger in cooler environments as a physiological response to temperature. This major global cooling event should influence organism physiology, resulting in significant size trends observed in the fossil record. Benthic foraminifera are protists and those that grow a carbonate shell are both well-preserved and abundant in marine sediments. Here, we used the foraminiferal fossil record to study the relationship between their size and global cooling. We hypothesize that cooler temperatures across the Eocene-Oligocene boundary promoted shell size increase. To test this hypothesis, we studied benthic foraminifera from 10 deep-sea cores drilled at Ocean Drilling Program Site 744, located in the southern Indian Ocean. We washed sediment samples over a 63-micron sieve and picked foraminifera from a 125-micron sieve. We studied the benthic foraminiferal genus Cibicidoides and its size change across this cooling event. Picked specimens were imaged and we measured the diameter of their shells using "imageJ". Overall, we find that Cibicidoides shows a general trend of increasing size during this transition. In particular, both the median and maximum sizes of Cibicidoides increase from the Eocene into the Oligocene. We also analyzed C. pachyderma and C. mundulus for size trends. Although both species increase in median size across the boundary, only C. pachyderma shows a consistent trend of increasing maximum, median, and minimum shell diameter. After the Eocene-Oligocene boundary, we observe that shell diameter decreases following peak cooling and that foraminiferal sizes remain stable into the early Oligocene. Therefore, the Eocene-Oligocene cooling event appears to have strong influence on shell size.

Annual changes in Arctic fjord environment and modern benthic foraminiferal fauna: Evidence from Kongsfjorden, Svalbard

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Jernas, Patrycja; Klitgaard-Kristensen, Dorthe; Husum, Katrine; Koç, Nalan; Tverberg, Vigdis; Loubere, Paul; Prins, Maarten; Dijkstra, Noortje; Gluchowska, Marta

2018-04-01

The relationships between modern Arctic benthic foraminifera and their ecological controls, along with their sensitivity to rapid environmental changes, is still poorly understood. This study examines how modern benthic foraminifera respond to annual environmental changes in the glaciated Arctic fjord Kongsfjorden, western Svalbard. Large environmental gradients due to the inflow of warm and saline Atlantic Water and the influence of tidewater glaciers characterise the fjord hydrography. A transect of six multi-corer stations, from the inner to the outer fjord, was sampled in the late summers of 2005 to 2008 to study the distribution of living (rose Bengal stained) benthic foraminifera. Physical properties of the water masses were measured concurrently. In general, nearly the entire Kongsfjorden region was dominated by ubiquitous N. labradorica foraminiferal assemblage that successfully exploited the local food resources and thrived particularly well in the presence of Atlantic-derived Transformed Atlantic Water (TAW). Further, the annual investigation revealed that Kongsfjorden underwent large interannual hydrological changes during the studied years related to variable inflow of warm and saline Atlantic Water. This led to a strong fauna variability particularly at the two marginal sites: the glacially influenced inner fjord and marine influenced shelf region. We also observed significant species shift from the 'cold' to 'warm' years and an expansion of widespread and sub-arctic to boreal species into the fjord.

Benthic N2 fixation in coral reefs and the potential effects of human-induced environmental change

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Cardini, Ulisse; Bednarz, Vanessa N; Foster, Rachel A; Wild, Christian

2014-01-01

Tropical coral reefs are among the most productive and diverse ecosystems, despite being surrounded by ocean waters where nutrients are in short supply. Benthic dinitrogen (N2) fixation is a significant internal source of “new” nitrogen (N) in reef ecosystems, but related information appears to be sparse. Here, we review the current state (and gaps) of knowledge on N2 fixation associated with coral reef organisms and their ecosystems. By summarizing the existing literature, we show that benthic N2 fixation is an omnipresent process in tropical reef environments. Highest N2 fixation rates are detected in reef-associated cyanobacterial mats and sea grass meadows, clearly showing the significance of these functional groups, if present, to the input of new N in reef ecosystems. Nonetheless, key benthic organisms such as hard corals also importantly contribute to benthic N2 fixation in the reef. Given the usually high coral coverage of healthy reef systems, these results indicate that benthic symbiotic associations may be more important than previously thought. In fact, mutualisms between carbon (C) and N2 fixers have likely evolved that may enable reef communities to mitigate N limitation. We then explore the potential effects of the increasing human interferences on the process of benthic reef N2 fixation via changes in diazotrophic populations, enzymatic activities, or availability of benthic substrates favorable to these microorganisms. Current knowledge indicates positive effects of ocean acidification, warming, and deoxygenation and negative effects of increased ultraviolet radiation on the amount of N fixed in coral reefs. Eutrophication may either boost or suppress N2 fixation, depending on the nutrient becoming limiting. As N2 fixation appears to play a fundamental role in nutrient-limited reef ecosystems, these assumptions need to be expanded and confirmed by future research efforts addressing the knowledge gaps identified in this review. PMID:24967086

The continental shelf benthic ecosystem: Current status, agents for change and future prospects

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Hall, S.J.

2002-01-01

Metadata only record Continental shelf benthic ecosystems play an important role in the economy of many coastal states through the provision of food, non-living resources and through control of climate. Changes in the status of these ecosystems, through either natural or human-induced environmental drivers can be expected to have important economic and social consequences. Agents that could induce change include climate and oceanography, hydrology (river discharge), land-use and waste disp...

Benthic Foraminifera as ecological indicators for water quality on the Great Barrier Reef

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Uthicke, Sven; Nobes, Kristie

2008-07-01

Benthic foraminifera are established indicators for Water Quality (WQ) in Florida and the Caribbean. However, nearshore coral reefs of the Great Barrier Reef (GBR) and other Pacific regions are also subjected to increased nutrient and sediment loads. Here, we investigate the use of benthic foraminifera as indicators to assess status and trends of WQ on GBR reefs. We quantified several sediment parameters and the foraminiferan assemblage composition on 20 reefs in four geographic regions of the GBR, and along a water column nutrient and turbidity gradient. Twenty-seven easily recognisable benthic foraminiferan taxa (>63 μm) were distinguished. All four geographic regions differed significantly ( p turbid inner shelf towards clearer outer shelf reefs. A RDA separated symbiotic and aposymbiotic (heterotrophic) taxa. In addition, total suspended solid and water column chlorophyll a concentrations were negatively correlated, and optical depth and distance to the mainland were positively correlated, with the abundance of symbiont-bearing taxa. Several large foraminifera were identified as indicators for offshore, clear water conditions. In contrast, heterotrophic rotaliids and a species retaining plastids ( Elphidium sp.) where highly characteristic for low light, higher nutrient conditions. Application of the FORAM index to GBR assemblage composition showed a significant increase in the value of this index with increased distance from the mainland in the Whitsunday region ( r2 = 0.75, p < 0.001), and therefore with increasing light and decreased nutrient availability. We conclude that it will be possible to apply this index to GBR and possibly other Pacific reefs after some adaptations and additional experimental work on species-specific limiting factors.

Louisiana waterthrush and benthic macroinvertebrate response to shale gas development

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Wood, Petra; Frantz, Mack W.; Becker, Douglas A.

2016-01-01

Because shale gas development is occurring over large landscapes and consequently is affecting many headwater streams, an understanding of its effects on headwater-stream faunal communities is needed. We examined effects of shale gas development (well pads and associated infrastructure) on Louisiana waterthrush Parkesia motacilla and benthic macroinvertebrate communities in 12 West Virginia headwater streams in 2011. Streams were classed as impacted (n = 6) or unimpacted (n = 6) by shale gas development. We quantified waterthrush demography (nest success, clutch size, number of fledglings, territory density), a waterthrush Habitat Suitability Index, a Rapid Bioassessment Protocol habitat index, and benthic macroinvertebrate metrics including a genus-level stream-quality index for each stream. We compared each benthic metric between impacted and unimpacted streams with a Student's t-test that incorporated adjustments for normalizing data. Impacted streams had lower genus-level stream-quality index scores; lower overall and Ephemeroptera, Plecoptera, and Trichoptera richness; fewer intolerant taxa, more tolerant taxa, and greater density of 0–3-mm individuals (P ≤ 0.10). We then used Pearson correlation to relate waterthrush metrics to benthic metrics across the 12 streams. Territory density (no. of territories/km of stream) was greater on streams with higher genus-level stream-quality index scores; greater density of all taxa and Ephemeroptera, Plecoptera, and Trichoptera taxa; and greater biomass. Clutch size was greater on streams with higher genus-level stream-quality index scores. Nest survival analyses (n = 43 nests) completed with Program MARK suggested minimal influence of benthic metrics compared with nest stage and Habitat Suitability Index score. Although our study spanned only one season, our results suggest that shale gas development affected waterthrush and benthic communities in the headwater streams we studied. Thus, these ecological effects of

The offshore benthic fish community

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Lantry, Brian F.; Lantry, Jana R.; Weidel, Brian C.; Walsh, Maureen; Hoyle, James A.; Schaner, Teodore; Neave, Fraser B.; Keir, Michael

2014-01-01

Lake Ontario’s offshore benthic fish community includes primarily slimy sculpin, lake whitefish, rainbow smelt, lake trout, burbot, and sea lamprey. Of these, lake trout have been the focus of an international restoration effort for more than three decades (Elrod et al. 1995; Lantry and Lantry 2008). The deepwater sculpin and three species of deepwater ciscoes (Coregonus spp.) that were historically important in the offshore benthic zone became rare or were extirpated by the 1960s (Christie 1973; Owens et al. 2003; Lantry et al. 2007b; Roth et al. 2013). Ecosystem changes continue to influence the offshore benthic fish community, including the effects of dreissenid mussels, the near disappearance of burrowing amphipods (Diporeia spp.) (Dermott et al. 2005; Watkins et al. 2007), and the increased abundance and expanded geographic distribution of round goby (see Nearshore Fish Community chapter) (Lantry et al. 2007b). The fish-community objectives for the offshore benthic fish community, as described by Stewart et al. (1999), are:

Regeneration and abnormality in benthic foraminifer Rosalina leei: Implications in reconstructing past salinity changes

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Kurtarkar, S.R.; Nigam, R.; Saraswat, R.; Linshy, V.N.

water, especially in regions where rivers meet the ocean. Benthic foraminifera, preferentially marine microorganisms with a hard calcareous or agglutinated exoskeleton known as the test, are one of the most abundant groups of microorganisms... temperature under incubators and under 12 hour light -12 hour dark condition throughout the experiment. In order to avoid evaporation, culture trays were wrapped in thin polythene film, immediately after changing the culture media. Culture media was changed...

Six decades of change in pollution and benthic invertebrate biodiversity in a southern New England estuary

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Pollution has led to a decline of benthic invertebrate biodiversity of Narragansett Bay, raising questions about effects on ecosystem functions and services including shellfish production, energy flow to fishes, and biogeochemical cycles. Changes in community composition and taxo...

Bathymetric and regional changes in benthic macrofaunal assemblages on the deep Eastern Brazilian margin, SW Atlantic

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Bernardino, Angelo Fraga; Berenguer, Vanessa; Ribeiro-Ferreira, Venina P.

2016-05-01

Deep-sea continental slopes have valuable mineral and biological resources in close proximity to diverse, undersampled and fragile marine benthic ecosystems. The eastern Brazilian Continental Margin (19.01°S to 21.06°S, 37.88°W to 40.22°W) is an important economic region for both fishing and oil industries, but is poorly understood with respect to the structure of the soft-sediment benthic fauna, their regional distribution and their bathymetric patterns. To identify spatial and temporal patterns of benthic macrofaunal assemblages on the slope (400 to 3000 m), the Espirito Santo Basin Assessment Project (AMBES, coordinated by Cenpes-Petrobras) sampled 42 stations across the Brazilian Eastern Slope during both Summer 2012 and Winter 2013. We found a significant decrease in macrofaunal abundance at the 400 m isobath along the slope near the northern region of the Espirito Santo Basin, suggesting benthic responses to upwelling events towards the south in Campos Basin and southern Espirito Santo Basin. The taxonomic diversity and assemblage composition also changed significantly across depth zones with mid-slope peaks of diversity at 1000-1300 m. In general, macrofaunal assemblages were strongly related to slope depth, suggesting a strong influence of productivity gradients and water mass distribution on this oligotrophic margin. Sediment grain size was marginally important to macrofaunal composition on the upper slope. In general, macrofaunal assemblages on the slope of Espirito Santo Basin are similar to other areas of the SE Brazilian margin, but regional changes in response to productivity and depth need to be considered for management strategies in the face of increasing economic activities off-shore.

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

Modeling Benthic Sediment Processes to Predict Water Quality and Ecology in Narragansett Bay

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The benthic sediment acts as a huge reservoir of particulate and dissolved material (within interstitial water) which can contribute to loading of contaminants and nutrients to the water column. A benthic sediment model is presented in this report to predict spatial and temporal ...

Benthic foraminiferal biocoenoses in the estuarine regimes of Goa

Digital Repository Service at National Institute of Oceanography (India)

Setty, M.G.A.P.

Benthic Foraminifera are highly responsive to subtle changes in the estuarine environment. Keeping this in view, a qualitative analysis of living benthic Foraminifera was made of the samples collected from the Mandovi-Zuari estuaries...

Historical changes in the structure and functioning of the benthic community in the lagoon of Venice

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Pranovi, Fabio; Da Ponte, Filippo; Torricelli, Patrizia

2008-03-01

One of the main challenges in environmental management is how to manage the dynamics of natural environments. In this context, having information about historical changes of the structure of the biological communities could represent a useful tool to improve management strategies, contributing to refine the policy objectives, since it gives reference states with which to compare the present. The Venice lagoon represents an interesting case study, since it is a highly dynamic, but sensitive, environment which requires the adoption of prudent management. In its recent history the lagoon ecosystem has been exposed to different kinds of disturbance, from the discharge of pollutants and nutrients, to the invasion of alien species and the exploitation of its biological resources by using highly impacting fishing gears. The analysis of available data about the macro-benthic community, from 1935 to 2004, allows the description of changes of the community structure over almost 70 years, showing a sharp decrease in its diversity. In order to obtain information about its functioning, it is necessary to know how these changes have affected processes at the community and system level. In shallow water ecosystems, as the control is mainly due to the benthic compartment, variations in the structure of the benthic community can induce modifications in processes at different hierarchical levels. The trophic structure analysis has revealed major changes during the period; from a well-assorted structure in 1935, to an herbivore-detritivore dominated one in the 1990s, and finally to a filter feeder dominated structure during the last decade. This has produced variations in the secondary production and it has induced modifications in the type of the ecosystem control. These changes are discussed in the light of the dynamics of the main driving forces.

Ecological attributes of the benthic community and indices of water quality in urban, rural and preserved environments

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Claudia Eiko Yoshida

Full Text Available INTRODUCTION: Reference streams are pristine streams, untouched or unaltered by man, it being possible to use their environmental characteristics as quality threshold values. Besides the organic impacts measured via water quality biological monitoring programs, it has become necessary to evaluate the relationship between alterations in the landscape of streams and surrounding areas and changes in the structure of the macroinvertebrate community; AIM: The objective of the present study was to correlate the changes in the landscape with the ecological attributes of the community and indices of water quality, and to recommend reference condition values for the integrity of streams in the region of Jundiai (SP; METHODS: The benthic fauna were sampled in three urban streams, three rural streams and three preserved streams during July 2010, using a Surber-type sampler. The characteristics of the landscape were evaluated by means of Diversity of Habitat; the community, analyzed for several biodiversity indices, and; the water quality assessed using the indices River-BCI, BMWP-CETEC (CETEC - Science and Technology Center, ASPT and SOMI (SOMI - Serra dos Órgãos Multimetric Index (Serra dos Órgãos is a mountain range national park in the state of Rio de Janeiro; RESULTS: The structure and the composition of the communities varied according to the stream and this was reflected in the values of the biological and environmental quality indices. The best conditions were found in preserved streams, intermediate streams and rural streams while the worst conditions were found in the urban streams. The significant Pearson correlations (r > 0.73 and P < 0.05 between the diversity of habitat index and the ecological and water quality index attributes in the streams of Jundiai demonstrated that diversity of habitat may be a good predictor of the environmental characteristics evaluated.

Ecosystem responses to extreme natural events: impacts of three sequential hurricanes in fall 1999 on sediment quality and condition of benthic fauna in the Neuse River Estuary, North Carolina.

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Balthis, W Leonard; Hyland, Jeffrey L; Bearden, Daniel W

2006-08-01

A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km2 (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissolved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia.

WATER QUALITY EVALUATION OF CRIŞUL ALB AND CRIŞUL NEGRU RIVERS CATCHMENTS, FROM CODRU-MOMA MOUNTAINS (WEST OF ROMANIA, USING BENTHIC INVERTEBRATES COMMUNITIES

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Andreea VARGA

2010-01-01

Full Text Available Water quality evaluation of the two watersheds involved the collection of thirteen samples from the tributaries of Crişul Alb and Crişul Negru rivers. The samples were collected in june 2010 with a benthic net, which had the mesh size of 250 µm, by disturbing the substrate, being thus qualitative samples. To get an overview, a series of physical-chemical parameters (water temperature, pH, oxygen, conductivity, cyanide, nitrates, nitrites, phosphates was studied in parallel with the study of benthic community. In most of the sampling points the major group of benthic macroinvertebrates were found and in some EPT group (Ephemeroptera, Plecoptera, Trichoptera prevailed even, which is known as a clean freshwater group, sensitive to pollution and human impact.

Species diversity variations in Neogene deep-sea benthic

Indian Academy of Sciences (India)

Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is ...

Multivariate Analysis of Water Quality and Benthic Macrophyte Communities in Florida Bay, USA Reveals Hurricane Effects and Susceptibility to Seagrass Die-Off

Directory of Open Access Journals (Sweden)

Amanda M. Cole

2018-05-01

Full Text Available Seagrass communities, dominated by Thalassia testudinum, form the principal benthic ecosystem within Florida Bay, Florida USA. The bay has had several large-scale seagrass die-offs in recent decades associated with drought and hypersaline conditions. In addition, three category-5 hurricanes passed in close proximity to the bay during the fall of 2005. This study investigated temporal and spatial trends in macrophyte abundance and water quality from 2006 to 2013 at 15 permanent transect sites, which were co-located with long-term water quality stations. Relationships, by year and by transect location (basin, between antecedent water quality (mean, minimum and maximum for a 6-month period and benthic macrophyte communities were examined using multivariate analyses. Total phosphorus, salinity, pH, turbidity, dissolved inorganic nitrogen (DIN, DIN to phosphate ratio (DIN:PO4-3, chlorophyll a, and dissolved oxygen correlated with temporal and spatial variations in the macrophyte communities. Temporal analysis (MDS and LINKTREE indicated that the fall 2005 hurricanes affected both water quality and macrophyte communities for approximately a 2-year period. Spatial analysis revealed that five basins, which subsequently exhibited a major seagrass die-off during summer 2015, significantly differed from the other ten basins in macrophyte community structure and water quality more than 2 years before this die-off event. High total phosphorus, high pH, low DIN, and low DIN:PO4-3, in combination with deep sediments and high seagrass cover were characteristic of sites that subsequently exhibited severe die-off. Our results indicate basins with more mixed seagrass communities and higher macroalgae abundance are less susceptible to die-off, which is consistent with the management goals of promoting more heterogeneous benthic macrophyte communities.

Water Quality Assessment Using Benthic Macroinvertebrates in Saigon River and Its Tributaries, Vietnam

Directory of Open Access Journals (Sweden)

Duc Pham Anh

2016-06-01

Full Text Available This study to enhance the discussion about the usefulness of benthic macroinvertebrates for water quality assessment in Saigon River and its tributaries. Data from 16 sites were used as a representative example for Saigon River and its tributaries in the area of basin over 4,500 km2, the length through provinces of Tay Ninh, Binh Phuoc, Binh Duong, and Ho Chi Minh City of about 280 km. The data covered the period of dry and rainy seasons in 2015, the survey sampled 16 sites (32 events of the Saigon River and its tributaries selected. To implement this evaluation, the analyses were based on MRC methods and classifications these improved by the scientific group.

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.

[Effects of cascading hydropower dams operation on the structure and distribution pattern of benthic macroinvertebrate assemblages in Manwan Reservoir, Southwest China].

Science.gov (United States)

Li, Jin Peng; Dong, Shi Kui; Peng, Ming Chun; Wu, Xuan; Zhou, Fang; Yu, Yin

2017-12-01

Benthic macroinvertebrate assemblages are one of the biological groups in aquatic ecosystem most sensitive to the habitat change and degradation, and can be a biological indicator for the aquatic ecosystem change and succession in cascading hydropower dam reservoir. The middle and lower reaches of the Lancang River are key spot for international biodiversity conservation and ecological studies on the effects of cascading hydropower dam exploitation. In this study, the reservoir of Manwan hydropower dam, the first dam in Lancang-Mekong river main stream, was selected as the study site. The benthic macroinvertebrate assemblages were sampled in 2011 and 2016 respectively. Meanwhile, the survey data before impounding (natural river, 1996) and early stage of single dam (1997) were collected to conduct the overall analysis for structure, distribution pattern and evolution of benthic macroinvertebrate assemblages. The results showed that the dominant biological group was gradually changed from the Oligochaeta and Insecta to the Mollusca. Along the longitudinal gradient, the density and biomass of the benthic macroinvertebrate assemblages were remarkably increased in reservoir, especially in the lacustrine zone. As for the functional feeding group, the predator and gatherer-collector changed into filter-collector predominantly in lacustrine zone. With the cascading dams operation, the biotic index indicated that the water quality of reservoir in 2016 was better than in 2011. The evolution of benthic macroinvertebrate assemblages in the Manwan Reservoir was related to the operation of Xiaowan dam in the upper reach, the hydrological regime and siltation in the reservoir, and would continue with dynamic changes with the operation of the cascading hydropower dam.

Late Glacial–Holocene record of benthic foraminiferal ...

Indian Academy of Sciences (India)

K Verma

2018-03-06

Mar 6, 2018 ... influence of oxygen-rich Antarctic Intermediate Water (AAIW). Keywords. Paleontology; benthic ..... nent changes at millennial scale are noticed during certain intervals ...... become environmental change? The proxy record of ...

A preliminary study of an eastern Mediterranean coastal ecosystem: Summer Resorts and Benthic ecosystems

Directory of Open Access Journals (Sweden)

S. REIZOPOULOU

2006-06-01

Full Text Available The present study investigates whether coastal benthic communities are affected by tourist activities along the coast, which persist for a limited time period. The analysis of benthic macrofauna is based on the ecological parameters (quantitative analyses as well as on the ecological identity of the species (qualitative analyses. Microbial contamination and some population statistics are correlated with ecological parameters. The disturbance of benthic communities in the vicinity of summer resorts is summarized by a reduction in species number and dominance of opportunistic species characteristic of disturbed and polluted environments. It is found that community diversity and evenness of distribution decrease with the deterioration of water quality, expressed as grade of microbial contamination, which implies that benthic community is also a significant element in assessing the quality of coastal waters. The above parameters were statistically negatively correlated with the number of tourists.

Benthic-pelagic coupling: effects on nematode communities along southern European continental margins.

Directory of Open Access Journals (Sweden)

Ellen Pape

Full Text Available Along a west-to-east axis spanning the Galicia Bank region (Iberian margin and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m. Nematode standing stock (abundance and biomass and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter. Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes.

Benthic Foraminiferal Stable Isotope and Dinocyst Assemblages in Sediments of the Trondheimfjord Area (Mid-Norway): Proxies for Regional Oceanographic and Climate Changes?

Science.gov (United States)

Milzer, G.; Giraudeau, J.; Faust, J.; Knies, J.; Schmidt, S.; Rühlemann, C.

2012-04-01

The Trondheimfjord is located at the west coast of Mid-Norway and is characterized by local environmental and hydrological changes that are linked to regional oceanographic and atmospheric processes in the Norwegian Sea. The North Atlantic Current (NAC) and the Norwegian Coastal Current (NCC), two major northward flowing sea surface/intermediate currents, strongly contribute to the oceanography of the Norwegian Sea and thus, to the hydrological settings of the fjord. Instrumental records indicate that the renewal of the fjord water by Atlantic-derived water masses occurs twice a year and that bottom water temperature and salinity changes reflect NAC variability. Sedimentation rates in the fjord basin exceed several mm/yr. Hence, the Trondheimfjord is an ideal location for high resolution studies of important climate-sensitive parameters such as characteristics of Atlantic-derived waters, freshwater discharge and sedimentary patterns. We measured stable isotope ratios in tests of the benthic foraminifera Melonis barleanus from surface sediments of the Trondheimfjord; δ18O ratios vary according to circulation and stratification patterns in the fjord which are linked to the topography. Based on these surface sediment measurements, as well as previous sediment core studies (Milzer et al, unpublished), we assume that benthic δ18O ratios in sedimentary archives from the Trondheimfjord reflect ocean circulation changes in the Norwegian Sea. In order to examine to which extent physico-chemical characteristics of the prevailing water masses are affecting the benthic signal in the Trondheimfjord, and how these findings can be related to oceanographic changes in the Norwegian Sea, we analyze benthic δ18O ratios from three multi-cores distributed along the fjord axis. According to 210Pb and 137Cs chronology these multi-cores contain undisturbed sedimentary records for the last 10 to 50 years, with sedimentation rates ranging from 2.5 to 7 mm/yr. We perform this analysis by

Recent changes in estuarine benthic and suprabenthic communities resulting from the development of harbour infrastructure.

Science.gov (United States)

Dauvin, J C; Desroy, N; Janson, A L; Vallet, C; Duhamel, S

2006-01-01

Using a Before/During/After sampling protocol, the effects of the Le Havre harbour extension, which was started at the end of 2001, on the macrobenthic and suprabenthic communities in the eastern Bay of Seine (English Channel) were examined. As the construction phase has not yet been completed, the results presented here reflect only the data collected before and during the operations (September 2000 and 2002 for benthos sampling and March 2001, September 2001, October 2002 and March 2003 for suprabenthos sampling). Although bio-sedimentary changes did occur at the mouth of the Seine river, an analysis of benthic assemblages reveals that the dredging and construction operations do not seem to have influenced assemblage structure or the spatial distribution of organisms. Comparisons of the suprabenthic assemblages at each sampling date indicate that seasonal dynamics was mainly responsible for determining species distribution. We conclude that, 1 year into the harbour management plan, the observed changes in benthic and suprabenthic assemblage abundance do not exceed the range of spatial variability that exists naturally in the Seine estuary. Despite this compensatory actions designed to protect the aquatic habitats and to preserve a sustainable and healthy ecosystem have been added to the infrastructure development plan.

The intriguing relationship between coiling direction and reproductive mode in benthic foraminifera

Digital Repository Service at National Institute of Oceanography (India)

Nigam, R.; Rao, A

direction changes. The relationship between mode of reproduction and coiling directions in benthic foraminifera is explored. Benthic foraminiferal species Cavarotalia annectens (Paarker & Jones) in 58 samples obtained from a core off Karwar, west coast...

Evaluation of some Physicochemical Parameters and Benthic ...

African Journals Online (AJOL)

ADOWIE PERE

studied to assess the impact of anthropogenic activities on this man-made lake by collecting surface water and benthic samples. ... activities like domestic and industrial (Banetti and. Garrido, 2010). ... of organic matter and also in assessing the quality of ... Ogun River. ... wastes waters from washing of clothes, sewage.

Phanerozoic changes in hardpart availability and utilization in benthic communities: evolutionary ecology or evolutionary stratigraphy

Energy Technology Data Exchange (ETDEWEB)

Kidwell, S.M.

1985-01-01

Published experiments on modern communities and quantitative data from Miocene assemblages indicate that the accumulation of dead hardparts can drive specific changes in the composition of benthic communities (taphonomic feedback). Both opportunities and pathways of taphonomic feedback have changed over the Phanerozoic, however, owing to the evolution and environmental expansion of hardpart producers, utilizers, and destroyers. These changes were tracked using semi-quantitative estimates of hardpart availability based on familial diversity of the most abundant taxa, scored according to preservation potential at or near the seafloor. The data suggest a dramatic increase in hardpart availability from the Cambrian into the later Paleozoic, with a decline through the Mesozoic and Cenozoic related to the loss or dramatic reduction in calcitic epifauna, recliners on soft substrata, and large shelled nekton/plankton. The reduction in opportunities for taphonomic feedback among epifauna was accompanied by an increase in levels of infaunal interactions in the Cenozoic, which is characterized by fully three-dimensional shell gravels. In addition to evolutionary change in body sizes of hardpart producers and biotically-driven declines in certain benthic life habits, the change in pathways of taphonomic feedback was also a consequence of the large-scale shift from predominantly carbonate sedimentation in the Paleozoic to predominantly terrigenous sedimentation in the Cenozoic. For example, the waning of epifauna-dominated communities is closely associated with the restriction of level-bottom carbonate environments through the late Mesozoic and Cenozoic. The global evolution of sedimentary environments and their relative representation is important not only in its consequences for sampling but as a driving mechanism of evolutionary ecology of marine benthos.

Benthic status of near-shore fishing grounds in the central Philippines and associated seahorse densities.

Science.gov (United States)

Marcus, J E; Samoilys, M A; Meeuwig, J J; Villongco, Z A D; Vincent, A C J

2007-09-01

Benthic status of 28 near-shore, artisanal, coral reef fishing grounds in the central Philippines was assessed (2000-2002) together with surveys of the seahorse, Hippocampus comes. Our measures of benthic quality and seahorse densities reveal some of the most degraded coral reefs in the world. Abiotic structure dominated the fishing grounds: 69% of the benthos comprised rubble (32%), sand/silt (28%) and dead coral (9%). Predominant biotic structure included live coral (12%) and Sargassum (11%). Rubble cover increased with increasing distance from municipal enforcement centers and coincided with substantial blast fishing in this region of the Philippines. Over 2 years, we measured a significant decrease in benthic 'heterogeneity' and a 16% increase in rubble cover. Poor benthic quality was concomitant with extremely low seahorse densities (524 fish per km(2)). Spatial management, such as marine reserves, may help to minimize habitat damage and to rebuild depleted populations of seahorses and other reef fauna.

Benthic cyanobacteria: A source of cylindrospermopsin and microcystin in Australian drinking water reservoirs.

Science.gov (United States)

Gaget, Virginie; Humpage, Andrew R; Huang, Qiong; Monis, Paul; Brookes, Justin D

2017-11-01

Cyanobacteria represent a health hazard worldwide due to their production of a range of highly potent toxins in diverse aquatic environments. While planktonic species have been the subject of many investigations in terms of risk assessment, little is known about benthic forms and their impact on water quality or human and animal health. This study aimed to purify isolates from environmental benthic biofilms sampled from three different drinking water reservoirs and to assess their toxin production by using the following methods: Enzyme-Linked Immunosorbent Assay (ELISA), High-Performance Liquid Chromatography (HPLC), Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) and quantitative PCR (qPCR). Microscopic observation of the isolates allowed the identification of various filamentous cyanobacterial genera: Anabaena (benthic form), Calothrix and Nostoc from the Nostocales and Geitlerinema, Leptolyngbya, Limnothrix, Lyngbya, Oxynema, Phormidium and Pseudanabaena representing non-heterocystous filamentous cyanobacteria. The Phormidium ambiguum strain AWQC-PHO021 was found to produce 739 ng/mg of dry weight (d/w) of cylindrospermopsin and 107 ng/mg (d/w) of deoxy-cylindrospermopsin. The Nostoc linckia strain AWQC-NOS001 produced 400 ng/mg (d/w) of a microcystin analogue. This is the first report of hepatotoxin production by benthic cyanobacteria in temperate Australian drinking water reservoirs. These findings indicate that water quality monitoring programs need to consider benthic cyanobacteria as a potential source of toxins. Copyright © 2017 Elsevier Ltd. All rights reserved.

Changes in benthic fish assemblages as a consequence of coastal works in a coastal lagoon: The Mar Menor (Spain, Western Mediterranean).

Science.gov (United States)

Pérez-Ruzafa, A; García-Charton, J A; Barcala, E; Marcos, C

2006-01-01

The benthic fish assemblage of the Mar Menor consisted of 37 species. Dominant species are: Gobius cobitis, Lipophrys pavo and Tripterygion tripteronotus on infralittoral rocks; Pomatoschistus marmoratus, Callionymus pussillus, Callionymus risso and Solea vulgaris on sandy bottoms and Gobius niger, Syngnathus abaster, Hippocampus ramulosus and Symphodus cinereus on Cymodocea nodosa-Caulerpa prolifera mixed beds. From 1985 to 1989 tourist development has led to the creation of new beaches and the installation of artificial rocky structures for retaining sediments. Dredging for the extraction of sand and subsequent pumping altered sediment characteristics causing a real stress leading to the substitution of typical sandy bottoms communities with Cymodocea nodosa by Caulerpa prolifera communities on mud. Soft bottom fish assemblages responded to changes in vegetation cover and substratum characteristics mainly changing the species composition, while artificial hard substrata contain a similar fish community than natural ones, harbouring even richer and more diverse assemblages. This positive effect of breakwaters should not obscure their likely negative effects on hydrodynamics and the subsequent changes of sediment quality and vegetation cover on the breakwaters' area of influence.

Benthic monitoring of salmon farms in Norway using foraminiferal metabarcoding

DEFF Research Database (Denmark)

Pawlowski, Jan; Esling, Philippe; Lejzerowicz, Franck

2016-01-01

The rapid growth of the salmon industry necessitates the development of fast and accurate tools to assess its environmental impact. Macrobenthic monitoring is commonly used to measure the impact of organic enrichment associated with salmon farm activities. However, classical benthic monitoring can...... of macrofauna-based benthic monitoring. Here, we tested the application of foraminiferal metabarcoding to benthic monitoring of salmon farms in Norway. We analysed 140 samples of eDNA and environmental RNA (eRNA) extracted from surface sediment samples collected at 4 salmon farming sites in Norway. We sequenced...... of Foraminifera as bioindicators of organic enrichment associated with salmon farming. The foraminiferal diversity increased with the distance to fish cages, and metabarcoding provides an assessment of the ecological quality comparable to the morphological analyses. The foraminiferal metabarcoding approach...

Downstream impacts of dams: shifts in benthic invertivorous fish assemblages

Science.gov (United States)

Granzotti, Rafaela Vendrametto; Miranda, Leandro E.; Agostinho, Angelo A.; Gomes, Luiz Carlos

2018-01-01

Impoundments alter connectivity, sediment transport and water discharge in rivers and floodplains, affecting recruitment, habitat and resource availability for fish including benthic invertivorous fish, which represent an important link between primary producers and higher trophic levels in tropical aquatic ecosystems. We investigated long-term changes to water regime, water quality, and invertivorous fish assemblages pre and post impoundment in three rivers downstream of Porto Primavera Reservoir in south Brazil: Paraná, Baía and Ivinhema rivers. Impacts were distinct in the Paraná River, which is fully obstructed by the dam, less evident in the Baía River which is partially obstructed by the dam, but absent in the unimpounded Ivinhema River. Changes in water regime were reflected mainly as changes in water-level fluctuation with little effect on timing. Water transparency increased in the Paraná River post impoundment but did not change in the Baía and Ivinhema rivers. Changes in fish assemblages included a decrease in benthic invertivorous fish in the Paraná River and a shift in invertivorous fish assemblage structure in the Baía and Paraná rivers but not in the unimpounded Ivinhema River. Changes in water regime and water transparency, caused by impoundment, directly or indirectly impacted invertivorous fish assemblages. Alterations of fish assemblages following environmental changes have consequences over the entire ecosystem, including a potential decrease in the diversity of mechanisms for energy flow. We suggest that keeping existing unimpounded tributaries free of dams, engineering artificial floods, and intensive management of fish habitat within the floodplain may preserve native fish assemblages and help maintain functionality and ecosystem services in highly impounded rivers.

A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

Science.gov (United States)

Schwing, Patrick T; Romero, Isabel C; Brooks, Gregg R; Hastings, David W; Larson, Rebekka A; Hollander, David J

2015-01-01

Sediment cores were collected from three sites (1000-1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background) in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long

Influence of land-use patterns on benthic diatom communities and ...

African Journals Online (AJOL)

The objective of this study was to determine the effects of land-use patterns on both diatom community composition and water quality in tropical streams during the dry season. Benthic diatom collections and water quality sampling were done 4 times at 10 sites. A suite of environmental variables that varied with human ...

Benthic foraminifera baseline assemblages from a coastal nearshore reef complex on the central Great Barrier Reef

Science.gov (United States)

Johnson, Jamie; Perry, Chris; Smithers, Scott; Morgan, Kyle

2016-04-01

Declining water quality due to river catchment modification since European settlement (c. 1850 A.D.) represents a major threat to the health of coral reefs on Australia's Great Barrier Reef (GBR), particularly for those located in the coastal waters of the GBR's inner-shelf. These nearshore reefs are widely perceived to be most susceptible to declining water quality owing to their close proximity to river point sources. Despite this, nearshore reefs have been relatively poorly studied with the impacts and magnitudes of environmental degradation still remaining unclear. This is largely due to ongoing debates concerning the significance of increased sediment yields against naturally high background sedimentary regimes. Benthic foraminifera are increasingly used as tools for monitoring environmental and ecological change on coral reefs. On the GBR, the majority of studies have focussed on the spatial distributions of contemporary benthic foraminiferal assemblages. While baseline assemblages from other environments (e.g. inshore reefs and mangroves) have been described, very few records exist for nearshore reefs. Here, we present preliminary results from the first palaeoecological study of foraminiferal assemblages of nearshore reefs on the central GBR. Cores were recovered from the nearshore reef complex at Paluma Shoals using percussion techniques. Recovery was 100%, capturing the entire Holocene reef sequence of the selected reef structures. Radiocarbon dating and subsequent age-depth modelling techniques were used to identify reef sequences pre-dating European settlement. Benthic foraminifera assemblages were reconstructed from the identified sequences to establish pre-European ecological baselines with the aim of providing a record of foraminiferal distribution during vertical reef accretion and against which contemporary ecological change may be assessed.

Changes of benthic fauna in the Kattegat - An indication of climate change at mid-latitudes?

Science.gov (United States)

Göransson, Peter

2017-07-01

Several predictions point to changes in the marine benthic macrofauna associated with climate change, but so far only a few and minor changes have been reported. This study relates observed changes in the species composition to climate change by looking on the past decades in the Kattegat between Denmark and Sweden. A reduction of the total number species and a reduction of species with a northern range parallel to an increase of species with a southern range have been observed. The most likely explanation of the changes is the increase in temperature of the bottom water. Increased temperature could change the species distributions but also decrease primary production which impacts recruitment and growth. Hypoxia and bottom trawling could also act synergistic in this process. A sparse occurrence of previously encountered Arctic-Boreal species and critical foundation species, which gives the area its special character, suggests a change in biodiversity and might therefore be designated as early warning signals of a warmer climate. The northern fauna below the halocline with limited capacity of dispersal and low reproduction potential, can be considered as sensitive with low adaptive capacity to climate change. Therefore, not only tropical and high-latitude species, but also benthos on deep bottoms at mid-latitudes, could be vulnerable to warming. As many species live at the edge of their range in the Kattegat, and also are dependent of distant recruitment, large scale changes will probably be detected here at an early stage. It is important to protect relatively undisturbed reference areas in the Kattegat for future studies, but also for preserving a large number of ecosystem services, biotopes, habitats, and fish species.

Benthic foraminifera

Digital Repository Service at National Institute of Oceanography (India)

Saraswat, R.; Nigam, R.

(Nolet and Corliss, 1990). Differences in the abundance of oxygen-sensitive and dissolution-prone benthic foraminiferal species between the Last Glacial Maximum (LGM) and the Holocene in the abyssal waters of the southwestern Gulf of Mexico were used... (2009) Deep-sea benthic diversity linked to seasonality of pelagic productivity. Deep Sea Research Part I: Oceanographic Research Papers 56: 835-841. Culver S (1988) New foraminiferal depth zonation of the northwestern Gulf of Mexico. Palaios 3: 69...

Assessment of water chemistry, habitat, and benthic macroinvertebrates at selected stream-quality monitoring sites in Chester County, Pennsylvania, 1998-2000

Science.gov (United States)

Reif, Andrew G.

2004-01-01

Biological, chemical, and habitat data have been collected from a network of sites in Chester County, Pa., from 1970 to 2003 to assess stream quality. Forty sites in 6 major stream basins were sampled between 1998 and 2000. Biological data were used to determine levels of impairment in the benthic-macroinvertebrate community in Chester County streams and relate the impairment, in conjunction with chemical and habitat data, to overall stream quality. Biological data consisted of benthic-macroinvertebrate samples that were collected annually in the fall. Water-chemistry samples were collected and instream habitat was assessed in support of the biological sampling.Most sites in the network were designated as nonimpacted or slightly impacted by human activities or extreme climatic conditions on the basis of biological-metric analysis of benthic-macroinvertebrate data. Impacted sites were affected by factors, such as nutrient enrichment, erosion and sedimentation, point discharges, and droughts and floods. Streams in the Schuylkill River, Delaware River, and East Branch Brandywine Creek Basins in Chester County generally had low nutrient concentrations, except in areas affected by wastewater-treatment discharges, and stream habitat that was affected by erosion. Streams in the West Branch Brandywine, Christina, Big Elk, and Octoraro Creek Basins in Chester County generally had elevated nutrient concentrations and streambottom habitat that was affected by sediment deposition.Macroinvertebrate communities identified in samples from French Creek, Pigeon Creek (Schuylkill River Basin), and East Branch Brandywine Creek at Glenmoore consistently indicate good stream conditions and were the best conditions measured in the network. Macroinvertebrate communities identified in samples from Trout Creek (site 61), West Branch Red Clay Creek (site 55) (Christina River Basin), and Valley Creek near Atglen (site 34) (Octoraro Creek Basin) indicated fair to poor stream conditions and

History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

Science.gov (United States)

Dauvin, Jean-Claude

2015-06-01

Benthic studies in the English Channel (EC), a shallow megatidal and epicontinental sea, began in the 1960s and 1970s with the work of teams led by Norman Holme (UK) and Louis Cabioch (F). During this period, benthic sampling was mainly qualitative, i.e. using a device such as the 'Rallier du Baty' dredge in the case of the French team and a modified anchor dredge in the case of the British team. Studies were focused on acquiring knowledge of the main distributions of benthic communities and species. Surveys on the scale of the whole EC led to the recognition of general features and two main patterns were identified: 1) the role of hydrodynamics on the spatial distribution of sediment, benthic species and communities; 2) the presence of a west-east climatic gradient of faunal impoverishment. Benthic studies in the 1980s-1990s were focused on the beginning of the implementation of long-term survey at a limited number of sites to identify seasonal and multi-annual changes. In the first decade of the 2000s, the implementation of the European Water Framework Directive and the Marine Strategy Framework Directive to define the Ecological Quality Status of marine environments increased the need to acquire better information of the structure and functioning of benthic communities, since benthic species and habitats were recognised as good indicators of human pressure on marine ecosystems. Faced with the increase of human maritime activities, the appearance of invasive species and the need to preserve sensitive marine habitats, benthic studies have been focused on developing a 'toolkit' to help in the decision-making and planning for both sound governance and sustainable management of marine resources and human activities in the English Channel. Multidisciplinary approaches were used to differentiate habitats in a more precise detail. Both indirect (side-scan sonar, ROV) and direct (grab sampling with benthos identification and grain-size analyses) approaches were used and

Benthic indicators to use in Ecological Quality classification of Mediterranean soft bottom marine ecosystems, including a new Biotic Index

Directory of Open Access Journals (Sweden)

N. SIMBOURA

2002-12-01

Full Text Available A general scheme for approaching the objective of Ecological Quality Status (EcoQ classification of zoobenthic marine ecosystems is presented. A system based on soft bottom benthic indicator species and related habitat types is suggested to be used for testing the typological definition of a given water body in the Mediterranean. Benthic indices including the Shannon-Wiener diversity index and the species richness are re-evaluated for use in classification. Ranges of values and of ecological quality categories are given for the diversity and species richness in different habitat types. A new biotic index (BENTIX is proposed based on the relative percentages of three ecological groups of species grouped according to their sensitivity or tolerance to disturbance factors and weighted proportionately to obtain a formula rendering a five step numerical scale of ecological quality classification. Its advantage against former biotic indices lies in the fact that it reduces the number of the ecological groups involved which makes it simpler and easier in its use. The Bentix index proposed is tested and validated with data from Greek and western Mediterranean ecosystems and examples are presented. Indicator species associated with specific habitat types and pollution indicator species, scored according to their degree of tolerance to pollution, are listed in a table. The Bentix index is compared and evaluated against the indices of diversity and species richness for use in classification. The advantages of the BENTIX index as a classification tool for ECoQ include independence from habitat type, sample size and taxonomic effort, high discriminative power and simplicity in its use which make it a robust, simple and effective tool for application in the Mediterranean Sea.

Biodiversity of benthic macroinvertebrates in Air Terjun Asahan, Asahan, Melaka, Malaysia

Science.gov (United States)

Nurhafizah-Azwa, S.; Ahmad A., K.

2016-11-01

A study on benthic macroinvertebrate diversity was conducted at Air Terjun Asahan, Asahan, Melaka. Five stations were selected with distance intervals of approximately 500 metres. Three replicates of benthic macroinvertebrate and water samples were taken. Results classified Air Terjun Asahan in class II, which indicated good water quality based on WQI recommended by the Department of Environment. A total of 1 phylum, 2 classes, 6 order, 30 families, and 2183 individuals were successfully sampled and recorded. The analysis showed that the average value of Shannon Diversity Index, H' (2.19), Pielou Evenness Index, J' (0.30), and Margaleff Richness Index, DMG (3.77) described that Air Terjun Asahan was in moderate condition and the distribution of macroinvertebrates was uniform between stations. Correlation test showed that the WQI had a strong relationship with the diversity indices involved. BMWP, and FBI showed that Air Terjun Asahan was in good water quality. CCA test was conducted to show environmental factors towards benthic macroinvertebrate distribution. The presence of Leptophlebiidae, Baetidae, Heptageniidae and Chironomidae with high abundance of the families showed the potential as biological indicators of a clean ecosystem.

Benthic macrofaunal structure and secondary production in tropical estuaries on the Eastern Marine Ecoregion of Brazil.

Science.gov (United States)

Bissoli, Lorena B; Bernardino, Angelo F

2018-01-01

Tropical estuaries are highly productive and support diverse benthic assemblages within mangroves and tidal flats habitats. Determining differences and similarities of benthic assemblages within estuarine habitats and between regional ecosystems may provide scientific support for management of those ecosystems. Here we studied three tropical estuaries in the Eastern Marine Ecoregion of Brazil to assess the spatial variability of benthic assemblages from vegetated (mangroves) and unvegetated (tidal flats) habitats. A nested sampling design was used to determine spatial scales of variability in benthic macrofaunal density, biomass and secondary production. Habitat differences in benthic assemblage composition were evident, with mangrove forests being dominated by annelids (Oligochaeta and Capitellidae) whereas peracarid crustaceans were also abundant on tidal flats. Macrofaunal biomass, density and secondary production also differed between habitats and among estuaries. Those differences were related both to the composition of benthic assemblages and to random spatial variability, underscoring the importance of hierarchical sampling in estuarine ecological studies. Given variable levels of human impacts and predicted climate change effects on tropical estuarine assemblages in Eastern Brazil, our data support the use of benthic secondary production to address long-term changes and improved management of estuaries in Eastern Brazil.

Metal contamination in benthic macroinvertebrates in a sub-basin in the southeast of Brazil

Directory of Open Access Journals (Sweden)

WAC Chiba

Full Text Available Benthic macroinvertebrates have many useful properties that make possible the use of these organisms as sentinel in biomonitoring programmes in freshwater. Combined with the characteristics of the water and sediment, benthic macroinvertebrates are potential indicators of environmental quality. Thus, the spatial occurrence of potentially toxic metals (Al, Zn, Cr, Co, Cu, Fe, Mn and Ni in the water, sediment and benthic macroinvertebrates samples were investigated in a sub-basin in the southeast of Brazil in the city of São Carlos, São Paulo state, with the aim of verifying the metals and environment interaction with benthic communities regarding bioaccumulation. Hypothetically, there can be contamination by metals in the aquatic environment in the city due to lack of industrial effluent treatment. All samples were analysed by the USEPA adapted method and processed in an atomic absorption spectrophotometer. The sub-basin studied is contaminated by toxic metals in superficial water, sediment and benthic macroinvertebrates. The Bioaccumulation Factor showed a tendency for metal bioaccumulation by the benthic organisms for almost all the metal species. The results show a potential human and ecosystem health risk, contributing to metal contamination studies in aquatic environments in urban areas.

Benthic protists: the under-charted majority.

Science.gov (United States)

Forster, Dominik; Dunthorn, Micah; Mahé, Fréderic; Dolan, John R; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Edvardsen, Bente; Egge, Elianne; Eikrem, Wenche; Gobet, Angélique; Kooistra, Wiebe H C F; Logares, Ramiro; Massana, Ramon; Montresor, Marina; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Romac, Sarah; Shalchian-Tabrizi, Kamran; Simon, Nathalie; Richards, Thomas A; Santini, Sébastien; Sarno, Diana; Siano, Raffaele; Vaulot, Daniel; Wincker, Patrick; Zingone, Adriana; de Vargas, Colomban; Stoeck, Thorsten

2016-08-01

Marine protist diversity inventories have largely focused on planktonic environments, while benthic protists have received relatively little attention. We therefore hypothesize that current diversity surveys have only skimmed the surface of protist diversity in marine sediments, which may harbor greater diversity than planktonic environments. We tested this by analyzing sequences of the hypervariable V4 18S rRNA from benthic and planktonic protist communities sampled in European coastal regions. Despite a similar number of OTUs in both realms, richness estimations indicated that we recovered at least 70% of the diversity in planktonic protist communities, but only 33% in benthic communities. There was also little overlap of OTUs between planktonic and benthic communities, as well as between separate benthic communities. We argue that these patterns reflect the heterogeneity and diversity of benthic habitats. A comparison of all OTUs against the Protist Ribosomal Reference database showed that a higher proportion of benthic than planktonic protist diversity is missing from public databases; similar results were obtained by comparing all OTUs against environmental references from NCBI's Short Read Archive. We suggest that the benthic realm may therefore be the world's largest reservoir of marine protist diversity, with most taxa at present undescribed. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Regulation of nitrous oxide emission associated with benthic invertebrates

DEFF Research Database (Denmark)

Stief, Peter; Schramm, Andreas

2010-01-01

1. A number of freshwater invertebrate species emit N2O, a greenhouse gas that is produced in their gut by denitrifying bacteria (direct N2O emission). Additionally, benthic invertebrate species may contribute to N2O emission from sediments by stimulating denitrification because of their bioirrig......1. A number of freshwater invertebrate species emit N2O, a greenhouse gas that is produced in their gut by denitrifying bacteria (direct N2O emission). Additionally, benthic invertebrate species may contribute to N2O emission from sediments by stimulating denitrification because...... of their bioirrigation behaviour (indirect N2O emission). 2. Two benthic invertebrate species were studied to determine (i) the dependence of direct N2O emission on the preferred diet of the animals, (ii) the regulation of direct N2O emission by seasonally changing factors, such as body size, temperature and NO3...... emitted by benthic invertebrates can be partially consumed in the sediment (E. danica), non-emitting species can still indirectly contribute to total N2O emission from sediment (S. lutaria)....

Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments.

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Rénald Belley

Full Text Available The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen, quality of organic matter (chl a:phaeo and C:N ratios and sediment characteristics (mean grain size and porosity explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and

Fertilization of Earth Ponds. III: Effects on Benthic Macro ...

African Journals Online (AJOL)

Organic fertilizers in form of cow and chicken manure were applied in oligotrophic or unproductive pond water over a period of one year to stimulate the production of benthic macro invertebrates for the benefit of trout culture, while maintaining adequate water quality. Development of aquatic macrophytes during both ...

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

Science.gov (United States)

Wu, Bin; Song, Jinming; Li, Xuegang

2014-10-15

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

Effects of Management Legacies on Stream Fish and Aquatic Benthic Macroinvertebrate Assemblages

Science.gov (United States)

Quist, Michael C.; Schultz, Randall D.

2014-09-01

Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly

Benthic ecology of tropical coastal lagoons: Environmental changes over the last decades in the Términos Lagoon, Mexico

Science.gov (United States)

Grenz, Christian; Fichez, Renaud; Silva, Carlos Álvarez; Benítez, Laura Calva; Conan, Pascal; Esparza, Adolfo Contreras Ruiz; Denis, Lionel; Ruiz, Silvia Díaz; Douillet, Pascal; Martinez, Margarita E. Gallegos; Ghiglione, Jean-François; Mendieta, Francisco José Gutiérrez; Origel-Moreno, Montserrat; Garcia, Antonio Zoilo Marquez; Caravaca, Alain Muñoz; Pujo-Pay, Mireille; Alvarado, Rocío Torres; Zavala-Hidalgo, Jorge

2017-10-01

The Términos Lagoon is a 2000-km2 wide coastal lagoon linked to the largest river catchment in Mesoamerica. Economic development, together with its ecological importance, led the Mexican government to pronounce the Términos Lagoon and its surrounding wetlands as a Federal protected area for flora and fauna in 1994. It is characterized by small temperature fluctuations, but with two distinct seasons (wet and dry) that control the biological, geochemical, and physical processes and components. This paper presents a review of the available information about the Términos Lagoon. The review shows that the diversity of benthic communities is structured by the balance between marine and riverine inputs and that this structuration strongly influences the benthic metabolism and its coupling with the biogeochemistry of the water column. The paper also presents many specific drivers and recommendations for a long-term environmental survey strategy in the context of the expected Global Change in the Central American region.

Composition and dynamic of benthic macroinvertebrates community ...

African Journals Online (AJOL)

the purpose to analyze the taxonomic composition, the structure of benthic macroinvertebrates community and the composite ... differences relative to the spatial and temporal variation in the taxonomic composition. ... changes in the structure of macroinvertebrates community ... 2007) with an annual growth rate of 2.4% rely.

The Bering Strait Region: A Window into Changing Benthic Populations in Response to Varying Subarctic-Arctic Connectivity and Ecosystem Dynamics

Science.gov (United States)

Grebmeier, J. M.; Cooper, L. W.; Moore, S. E.

2016-02-01

A key ecological organizing principle for the northern Bering Sea and the adjoining southern Chukchi Sea just north of Bering Strait is that the shallow, seasonally productive waters lead to strong pelagic-benthic coupling to the sea floor, with deposition of fresh chlorophyll coinciding with the spring bloom as sea ice retreats. Both in situ production and advection of upstream phytodetritus to these regions support persistent biological hotspots that connect benthic prey to upper trophic benthivores. This northern marine ecosystem is dominated by marine macroinvertebrates (e.g. clams, polychaetes, sipunculids, and amphipods) that feed on the high production deposited rapidly to the seafloor, which in turn serve as food resources for diving mammals and seabirds, such as gray whales, bearded seals, eiders, and walruses. Between St. Lawrence Island and Bering Strait and northwards into the Chukchi Sea, the persistence of seasonal sea ice has significantly declined over the past two decades, and along with warming seawater temperatures, these changes have potential ramifications to ecosystem structure. Times-series data over the last 25 years indicate that these regions have experienced a northward shift in macrofaunal composition and a decline in core benthic biomass that matches patterns of reduced sea ice, warming seawater, and changing sediment grain size that relates to varying current patterns. This presentation will discuss these data in the context of both process studies from the region and results from the Distributed Biological Observatory (DBO), an international network of time series transects that is providing a framework to evaluate status and trends on a latitudinal bases in the Pacific Arctic region.

Do benthic biofilters contribute to sustainability and restoration of the benthic environment impacted by offshore cage finfish aquaculture?

International Nuclear Information System (INIS)

Aguado-Gimenez, F.; Piedecausa, M.A.; Carrasco, C.; Gutierrez, J.M.; Aliaga, V.; Garcia-Garcia, B.

2011-01-01

Highlights: → Benthic biofilters were deployed under an offshore fish farm and in control locations. → We checked the farm influence on fouling, wild fish and sediment near the biofilters. → Fouling under the cages used fish farm-derived wastes, but at low efficiency. → Wild fish were more abundant in the biofilters located below the cages. → Despite these clear benefits, sediment quality around the biofilters did not improve. - Abstract: Benthic biofilters were deployed under a cage fish farm and in two reference locations to assess the influence of the farm on the biofilters and the surroundings, as well as to verify the usefulness of this technology as a mitigation tool. The biofilters underneath the farm recruited a fouling community practically identical to that of the control biofilters, which included a variety of trophic strategies. The former showed a higher 15 N enrichment, indicating that fouling beneath the farm was benefiting from the farm waste. The waste retention efficiency was low (0.02 g N m -2 month -1 ) beneath the farm. Benthic biofilters aggregated demersal wild fish around and within them. Pelagic wild fish also frequently used the biofilters beneath the farm, forming compact shoals around them. The increased complexity of the habitat below the fish farm enhanced biodiversity, but this improvement did not lead to the recovery of the sediments around the biofilters.

Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels

Science.gov (United States)

Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

2010-01-01

Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

Assessment of sediment quality in dredged and undredged areas of the Trenton Channel of the Detroit River, Michigan USA, using the sediment quality triad

Science.gov (United States)

Besser, John M.; Giesy, John P.; Kubitz, Jody A.; Verbrugge, David A.; Coon, Thomas G.; Braselton, W. Emmett

1996-01-01

The “sediment quality triad” approach was used to assess the effects of dredging on the sediment quality of a new marina in the Trenton Channel of the Detroit River, and to evaluate spatial and temporal variation in sediment quality in the Trenton Channel. Samples were collected in November of 1993 (10 months after dredging) and characterized by chemical analysis, sediment bioassays, and assessment of benthic invertebrate communities. The three study components indicated little difference in sediment quality at dredged sites in the marina relative to nearby areas in the Trenton Channel, and little change in sediment quality of Trenton Channel sites relative to conditions reported in the mid-1980s. These results suggest that improvement in sediment quality in the Trenton Channel, due to dredging or natural processes, will depend on elimination of sediment “hot spots” and other upstream contaminant sources. Concentrations of chemical contaminants, especially metals and polycyclic aromatic hydrocarbons, exceeded concentrations associated with effects on biota and were significantly correlated with results of sediment bioassays and characteristics of benthic communities. Laboratory sediment bioassays with Hyalella azteca andChironomus tentans produced better discrimination among sites with differing degrees of contamination than did characterization of benthic communities, which were dominated by oligochaetes at all sites in the marina and the Trenton Channel.

Hexabromocyclododecane affects benthic-pelagic coupling in an experimental ecosystem

International Nuclear Information System (INIS)

Bradshaw, Clare; Näslund, Johan; Hansen, Joakim; Kozlowsky-Suzuki, Betina; Sundström, Bo; Gustafsson, Kerstin

2015-01-01

Hexabromocyclododecane (HBCDD) is an additive brominated flame retardant and a recognized PBT chemical. However, little is known about its effects on coastal species, and even less on ecosystem effects. We investigated the dose–response effects of HBCDD over 8 months in 1000 L experimental mesocosms assembled from coastal Baltic Sea ecosystem components. HBCDD was added via spiked plankton material and a range of structural and functional endpoints were measured during the experiment. Increasing HBCDD concentration decreased the biomass of large Macoma balthica, resulting in a decreased recirculation of nutrients to the water. Changes in plankton communities were also observed, either due to direct toxic HBCDD effects or indirect via changes in benthic-pelagic coupling of nutrients. Such complex ecosystem responses can only be quantified and understood by using realistic experimental set-ups, and including knowledge of system-specific ecological interactions. This is the first study of HBCDD effects on ecosystem level. - Graphical abstract: HBCDD caused direct effects on the population structure of sediment-dwelling Macoma balthica and on the plankton community. Indirect HBCDD effects via reduced nutrient remineralization by M. balthica affected nutrient levels in the water, likely leading to additional changes in plankton community structure. Seasonal effects were large and affected the whole system including nutrient dynamics as well as plankton community structure. Display Omitted - Highlights: • HBCDD caused effects on benthic population structure and ecosystem function. • Large seasonal effects highlight the importance of using relevant experimental conditions. • A realistic exposure pathway was applied by using HBCDD enriched plankton material. • This is the first study of HBCDD effects on ecosystem level, coupling benthic and pelagic communities. - HBCDD has a dose-dependent effect on benthic-pelagic coupling.

Monitoring of coastal coral reefs near Dahab (Gulf of Aqaba, Red Sea) indicates local eutrophication as potential cause for change in benthic communities.

Science.gov (United States)

Naumann, Malik S; Bednarz, Vanessa N; Ferse, Sebastian C A; Niggl, Wolfgang; Wild, Christian

2015-02-01

Coral reef ecosystems fringing the coastline of Dahab (South Sinai, Egypt) have experienced increasing anthropogenic disturbance as an emergent international tourism destination. Previous reports covering tourism-related impacts on coastal environments, particularly mechanical damage and destructive fishing, have highlighted the vital necessity for regular ecosystem monitoring of coral reefs near Dahab. However, a continuous scientific monitoring programme of permanent survey sites has not been established to date. Thus, this study conducted in situ monitoring surveys to investigate spatio-temporal variability of benthic reef communities and selected reef-associated herbivores along with reef health indicator organisms by revisiting three of the locally most frequented dive sites during expeditions in March 2010, September 2011 and February 2013. In addition, inorganic nutrient concentrations in reef-surrounding waters were determined to evaluate bottom-up effects of key environmental parameters on benthic reef community shifts in relation to grazer-induced top-down control. Findings revealed that from 2010 to 2013, live hard coral cover declined significantly by 12 % at the current-sheltered site Three Pools (TP), while showing negative trends for the Blue Hole (BH) and Lighthouse (LH) sites. Hard coral cover decline was significantly and highly correlated to a substantial increase in turf algae cover (up to 57 % at TP) at all sites, replacing hard corals as dominant benthic space occupiers in 2013. These changes were correlated to ambient phosphate and ammonium concentrations that exhibited highest values (0.64 ± 0.07 μmol PO4 (3-) l(-1), 1.05 ± 0.07 μmol NH4 (+) l(-1)) at the degraded site TP. While macroalgae appeared to respond to both bottom-up and top-down factors, change in turf algae was consistent with expected indications for bottom-up control. Temporal variability measured in herbivorous reef fish stocks reflected seasonal impacts by

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

Survival under stress : benthic foraminiferal patterns and Cenozoic biotic crises

NARCIS (Netherlands)

Kouwenhoven, T.J.

2000-01-01

A principal conclusion of this thesis is, that benthic foraminifera are excellent recorders of paleoenvironments and paleoenvironmental change. Insight in their community structure, and changes in this through time, is still increasing and will add to their usefulness in the reconstruction of past

Survival under stress : benthic foraminiferal patterns and Cenozoic biotic crises

NARCIS (Netherlands)

Kouwenhoven, T.J.

2000-01-01

A principal conclusion of this thesis is, that benthic foraminifera are excellent recorders of paleoenvironments and paleoenvironmental change. Insight in their community structure, and changes in this through time, is still increasing and will add to their usefulness in the reconstruction of

Benthic macroinvertebrate community and chlorophyll a (chl-a ...

African Journals Online (AJOL)

ADOWIE PERE

consequences of climate change are some of the most visible warning signals ... present; spatial and temporal mobility of species is quite restricted, hence .... taxonomic groups using suitable identification manuals ... describe the structure and composition of benthic .... pollution respond to polluted environment by increase.

Residual concentrations of micropollutants in benthic mussels in the coastal areas of Bohai Sea, North China

International Nuclear Information System (INIS)

Liu Wenxin; Chen Jianglin; Lin Xiumei; Fan Yongsheng; Tao Shu

2007-01-01

Studies of heavy metals and organic pollutants in different benthic mussel species from Bohai Sea show that concentrations of Cd in mussels commonly exceed national biological quality standards. In addition, a site located in Laizhou Bay exhibits higher average concentrations of As, Hg and Pb with respect to the other sites. Residual levels of petroleum hydrocarbons at several sites in Liaodong Bay also exceed quality guidelines. Contents and compositional characteristics of DDT and its metabolites in mussels suggest the probability of recent inputs and potential ecological risks to the local benthic environment. - Residual Cd contents of mussels at many sites in Bohai Sea exceed national marine biological quality standard and compositions of DDT metabolites indicate recent inputs and potential risk

Streamflow characteristics and benthic invertebrate assemblages in streams across the western United States

Science.gov (United States)

Brasher, Anne M.D.; Konrad, Chris P.; May, Jason T.; Edmiston, C. Scott; Close, Rebecca N.

2010-01-01

Hydrographic characteristics of streamflow, such as high-flow pulses, base flow (background discharge between floods), extreme low flows, and floods, significantly influence aquatic organisms. Streamflow can be described in terms of magnitude, timing, duration, frequency, and variation (hydrologic regime). These characteristics have broad effects on ecosystem productivity, habitat structure, and ultimately on resident fish, invertebrate, and algae communities. Increasing human use of limited water resources has modified hydrologic regimes worldwide. Identifying the most ecologically significant hydrographic characteristics would facilitate the development of water-management strategies.Benthic invertebrates include insects, mollusks (snails and clams), worms, and crustaceans (shrimp) that live on the streambed. Invertebrates play an important role in the food web, consuming other invertebrates and algae and being consumed by fish and birds. Hydrologic alteration associated with land and water use can change the natural hydrologic regime and may affect benthic invertebrate assemblage composition and structure through changes in density of invertebrates or taxa richness (number of different species).This study examined associations between the hydrologic regime and characteristics of benthic invertebrate assemblages across the western United States and developed tools to identify streamflow characteristics that are likely to affect benthic invertebrate assemblages.

Phytoplankton community indicators of changes associated with dredging in the Tagus estuary (Portugal)

International Nuclear Information System (INIS)

Cabrita, Maria Teresa

2014-01-01

This work reports changes in suspended particulate matter, turbidity, dissolved Cr, Ni, Cu, Cd, Hg and Pb concentrations, and phytoplankton biomass and composition during a 5-month period dredging operation, in a trace element contaminated area of the Tagus estuary (Portugal). Phytoplankton biomass, diatom:other groups ratio, benthic:pelagic diatom ratio, Margalef's, Simpson's diversity, Shannon–Wiever's, and Warwick and Clarke's taxonomic diversity and distinctness indices, and individual taxa were investigated as indicators of dredging induced changes. Significant rise in sediment resuspension and trace element mobilisation caused by dredging influenced the community structure but not the overall biomass. Benthic diatom displacement into the water column maintained species diversity, and therefore, none of the indices highlighted community changes. Contrastingly, diatom:other groups ratio and benthic:pelagic diatom ratio were reliable indicators for the assessment of dredging induced changes. A shift in composition towards species less susceptible to trace elements was observed, disclosing some individual taxa as potential indicators. - Highlights: • Phytoplankton community indicators of dredging induced changes were investigated. • Increased resuspension and trace element mobilisation changed community structure. • Diversity indices unsuitable to detect changes because species richness was maintained. • Diatom:other groups and benthic:pelagic diatom ratios were efficient indicators. • Individual taxa may be potential indicators but require site-specific validation. - Diatom:other groups ratio, benthic:pelagic diatom ratio and individual taxa were identified as efficient indicators for the assessment of water quality changes associated with dredging

Influence of benthic macrofauna community shifts on ecosystem functioning in shallow estuaries

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Erik eKristensen

2014-09-01

Full Text Available We identify how ecosystem functioning in shallow estuaries is affected by shifts in benthic fauna communities. We use the shallow estuary, Odense Fjord, Denmark, as a case study to test our hypotheses that (1 shifts in benthic fauna composition and species functional traits affect biogeochemical cycling with cascading effects on ecological functioning, which may (2 modulate pelagic primary productivity with feedbacks to the benthic system. Odense Fjord is suitable because it experienced dramatic shifts in benthic fauna community structure from 1998 to 2008. We focused on infaunal species with emphasis on three dominating burrow-dwelling polychaetes: the native Nereis (Hediste diversicolor and Arenicola marina, and the invasive Marenzelleria viridis. The impact of functional traits in the form of particle reworking and ventilation on biogeochemical cycles, i.e. sediment metabolism and nutrient dynamics, was determined from literature data. Historical records of summer nutrient levels in the water column of the inner Odense Fjord show elevated concentrations of NH4+ and NO3- (DIN during the years 2004-2006, exactly when the N. diversicolor population declined and A. marina and M. viridis populations expanded dramatically. In support of our first hypothesis, we show that excess NH4+ delivery from the benthic system during the A. marina and M. viridis expansion period enriched the overlying water in DIN and stimulated phytoplankton concentration. The altered benthic-pelagic coupling and stimulated pelagic production may, in support of our second hypothesis, have feedback to the benthic system by changing the deposition of organic material. We therefore advice to identify the exact functional traits of the species involved in a community shift before studying its impact on ecosystem functioning. We also suggest studying benthic community shifts in shallow environments to obtain knowledge about the drivers and controls before exploring deep

Trawling disturbance on benthic ecosystems and consequences on commercial species: a northwestern Mediterranean case study

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Alba Muntadas

2014-03-01

Full Text Available Trawling is known to disturb benthic communities and habitats, which may in turn indirectly affect populations of commercial species that live in close association with the seabed. The degree of impact on both benthic communities and demersal species depends on the fishing effort level. This may vary over the year because of the fleet dynamics, which are in turn normally driven by the main target species’ life cycle. In this study we describe changes in benthic functional components of a northwestern Mediterranean fishing ground that represents a recruitment area for an important target species (red mullet, Mullus barbatus. This fishing ground experiences a varying intensity of fishing effort over the year and benthic functional components under different levels of trawling were compared with an unfished, control area. Traits related to sexual maturity and life span for infauna and body size and life span for epifauna were found to vary with fishing activity. Potential effects of these changes on ecological functioning and the impact on red mullet population are discussed. The development of fisheries management plans under an ecosystem based fisheries management (EBFM requires the links between target species and benthic communities’ disturbance due to fishing practices to be explicitly considered.

Short-term versus long-term changes in the benthic communities of a small coastal lagoon: implications for ecological status assessment

OpenAIRE

Félix, PM; Chainho, P; Costa, Jl; Correia, MJ; Chaves, ML; Medeiros, JP; Cabral, HN; Wouters, N; Bernardo, J; Costa, AM; Cristo, M; Silva, G; Azeda, C; Tavares, P; Costa, MJ

2013-01-01

The characteristic high variability and low predictability of coastal lagoons, due to strong changes in marine and freshwater inputs, make these ecosystems an interesting casestudy. The small Melides landlocked coastal lagoon in SW Portugal is a paradigmatic example, with a biological community highly stressed by these phenomena. Benthic macroinvertebrate samples were collected in 1998/99 and 2009 and each year, in different seasons and addressing different environmental conditions i...

Does proximity to urban centres affect the dietary regime of marine benthic filter feeders?

Science.gov (United States)

Puccinelli, Eleonora; Noyon, Margaux; McQuaid, Christopher D.

2016-02-01

Threats to marine ecosystems include habitat destruction and degradation of water quality, resulting from land- and ocean-based human activities. Anthropogenic input causing modification of water quality, can affect primary productivity and thus food availability and quality for higher trophic levels. This is especially important for sedentary benthic intertidal communities, which rely on local food availability. We investigated the effect of urbanization on the dietary regime of four species of intertidal filter feeders (three barnacles and one mussel) at sites close to high-density cities and at sites far from heavily urbanized areas using fatty acid and stable isotope techniques. δ15N was significantly higher at urbanized sites compared to their corresponding control sites for all species with few exceptions, while no effect on δ13C was recorded. Barnacle fatty acid profiles were not affected by cities, while mussels from sites close to cities had fatty acid signatures with a higher proportion of polyunsaturated fatty acids (PUFA). We suggest that the enrichment in δ15N at urbanised sites reflects the influence of anthropogenically derived nitrogen directly linked to wastewater input from domestic and industrial sewage. Linked to this, the high proportion of PUFA in mussels at urbanized sites may reflect the influence of increased nitrogen concentrations on primary production and enhanced growth of large phytoplankton cells. The results indicate that anthropogenic effects can strongly influence the diets of benthic organisms, but these effects differ among taxa. Changes in the diet of such habitat forming species can affect their fitness and survival with potential effects on the populations associated with them.

Temporal change in deep-sea benthic ecosystems: a review of the evidence from recent time-series studies.

Science.gov (United States)

Glover, A G; Gooday, A J; Bailey, D M; Billett, D S M; Chevaldonné, P; Colaço, A; Copley, J; Cuvelier, D; Desbruyères, D; Kalogeropoulou, V; Klages, M; Lampadariou, N; Lejeusne, C; Mestre, N C; Paterson, G L J; Perez, T; Ruhl, H; Sarrazin, J; Soltwedel, T; Soto, E H; Thatje, S; Tselepides, A; Van Gaever, S; Vanreusel, A

2010-01-01

by stochastic events such as volcanic eruptions, with associated fauna showing complex patterns of community succession. For the slow-spreading centres such as the Mid-Atlantic Ridge, vent sites appear to be stable over the time periods measured, with no discernable long-term trend. At cold seeps, inferences based on spatial studies in the Gulf of Mexico, and data on organism longevity, suggest that these sites are stable over many hundreds of years. However, at the Haakon Mosby mud volcano, a large, well-studied seep in the Barents Sea, periodic mud slides associated with gas and fluid venting may disrupt benthic communities, leading to successional sequences over time. For chemosynthetic ecosystems of biogenic origin (e.g. whale-falls), it is likely that the longevity of the habitat depends mainly on the size of the carcass and the ecological setting, with large remains persisting as a distinct seafloor habitat for up to 100 years. Studies of shallow-water analogs of deep-sea ecosystems such as marine caves may also yield insights into temporal processes. Although it is obvious from the geological record that past climate change has impacted deep-sea faunas, the evidence that recent climate change or climate variability has altered deep-sea benthic communities is extremely limited. This mainly reflects the lack of remote sensing of this vast seafloor habitat. Current and future advances in deep-ocean benthic science involve new remote observing technologies that combine a high temporal resolution (e.g. cabled observatories) with spatial capabilities (e.g. autonomous vehicles undertaking image surveys of the seabed). Copyright © 2010 Elsevier Ltd. All rights reserved.

Relationship between benthic foraminifera and sediment in the estuarine complex of Goa

Digital Repository Service at National Institute of Oceanography (India)

Dalal, S.G.

Two indices of community association were used to elucidate the relationship between changes in species composition of benthic foraminifera and changes in the grain size composition of the sediment in estuarine complex of Goa. The degree...

Multivariate benthic ecosystem functioning in the Arctic – benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea

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H. Link

2013-09-01

Full Text Available The effects of climate change on Arctic marine ecosystems and their biogeochemical cycles are difficult to predict given the complex physical, biological and chemical interactions among the ecosystem components. We studied benthic biogeochemical fluxes in the Arctic and the influence of short-term (seasonal to annual, long-term (annual to decadal and other environmental variability on their spatial distribution to provide a baseline for estimates of the impact of future changes. In summer 2009, we measured fluxes of dissolved oxygen, nitrate, nitrite, ammonia, soluble reactive phosphate and silicic acid at the sediment–water interface at eight sites in the southeastern Beaufort Sea at water depths from 45 to 580 m. The spatial pattern of the measured benthic boundary fluxes was heterogeneous. Multivariate analysis of flux data showed that no single or reduced combination of fluxes could explain the majority of spatial variation, indicating that oxygen flux is not representative of other nutrient sink–source dynamics. We tested the influence of eight environmental parameters on single benthic fluxes. Short-term environmental parameters (sinking flux of particulate organic carbon above the bottom, sediment surface Chl a were most important for explaining oxygen, ammonium and nitrate fluxes. Long-term parameters (porosity, surface manganese and iron concentration, bottom water oxygen concentrations together with δ13Corg signature explained most of the spatial variation in phosphate, nitrate and nitrite fluxes. Variation in pigments at the sediment surface was most important to explain variation in fluxes of silicic acid. In a model including all fluxes synchronously, the overall spatial distribution could be best explained (57% by the combination of sediment Chl a, phaeopigments, δ13Corg, surficial manganese and bottom water oxygen concentration. We conclude that it is necessary to consider long-term environmental variability along with

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

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Karen M Chong-Seng

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

Assessment of stream quality using biological indices at selected sites in the Schuylkill River basin, Chester County, Pennsylvania, 1981-97

Science.gov (United States)

Reif, Andrew G.

2002-01-01

IntroductionIn 1970, the Chester County Water Resources Authority (Pennsylvania) and the U.S. Geological Survey (USGS) established a long-term water-quality network with the goal of assessing the quality of streams in the county and understanding stream changes in response to urbanization using benthic-macroinvertebrate data. This database represents one of the longest continuous water-quality data sets in the country. Benthic macroinvertebrates are aquatic insects, such as mayflies, caddisflies, riffle beetles, and midges, and other invertebrates that live on the stream bottom. Benthic macroinvertebrates are useful in evaluating stream quality because their habitat preferences and low motility cause them to be affected directly by substances that enter the aquatic system. By evaluating the diversity and community structure of benthic-macroinvertebrate populations, a determination of stream quality can be made.Between 1981 and 1997, the network consisted of 43 sites in 5 major basins in Chester County—Delaware, Schuylkill, Brandywine, Big Elk and Octoraro, and Red and White Clay. Benthic-macroinvertebrate, water-chemistry, and habitat data were collected each year in October or November during base-flow conditions. Using these data, Reif evaluated the overall water-quality condition of Chester County streams. This Fact Sheet summarizes the key findings from Reif for streams in the Schuylkill River Basin. These streams include Pigeon Creek (site 10), Stony Run (site 6), French Creek (sites 12-16), Pickering Creek (sites 1-5), Little Valley Creek (site 49), and Valley Creek (site 50). This summary includes an analysis of stream conditions based on benthic-macroinvertebrate samples and an analysis of trends in stream conditions for the 17-year study period.

Benthic Cover

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic cover (habitat) maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. Shallow to moderate-depth...

Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

Science.gov (United States)

Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

2014-01-01

We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

Field experiments on responses of a freshwater, benthic macroinvertebrate community to vertebrate predators

International Nuclear Information System (INIS)

Thorp, J.H.; Bergey, E.A.

1981-01-01

The seasonal importance of vertebrate predators in potentially regulating the abundance and diversity of the benthic macroinvertebrates in the littoral zone of a soft-bottom reservoir that receives thermal effluent from a nuclear production reactor was examined. Thirty-six predator (fish and turtle) exclusion cages (4 m 2 ) were placed in shallow water at six locations along a thermal gradient in Par Pond, a 1100-ha cooling reservoir on the Savannah River Plant near Aiken, South Carolina, USA. An additional 36 control plots (4 m 2 ) were also set up. Cages were in place during three, 3-mo test periods beginning in September 1977. Estimates of benthic density, taxon richness, and distribution within functional groups (defined by feeding mechanism) were calculated for each test period. Effects of temperature on predator-prey relationships were also determined. Experimental results of this study suggest that vertebrate predation was not the fundamental parameter organizing the benthic macroinvertebrate community in the littoral zone of this reservoir. Neither taxon richness nor density of total macroinvertebrates was conclusively related to predator treatment. Relationships between predator treatment and community response (changes in density and taxon richness) were generally unaffected by either plot locality, temperature fluctuations from thermal effluent, or seasonal changes. When data from caged and control plots were pooled, however, both location and water temperature individually had direct impacts on the benthic community. From these results and other field studies it is hypothesized that individual species of keystone benthic predators do not occur in the littoral zone of freshwater lentic environments with soft bottoms

Biodiversity in Benthic Ecology

DEFF Research Database (Denmark)

Friberg, Nikolai; Carl, J. D.

Foreword: This proceeding is based on a set of papers presented at the second Nordic Benthological Meeting held in Silkeborg, November 13-14, 1997. The main theme of the meeting was biodiversity in benthic ecology and the majority of contributions touch on this subject. In addition, the proceeding...... contains papers which cover other themes thus continuing with the spirit of the meetings in the Nordic Benthological Society (NORBS) by being an open forum for exchanging knowledge on all aspects of benthic ecology. Overall, we feel the proceeding contains a wide selection of very interesting papers...... representing the state-of-the-art of benthic ecology research within, and to a lesser degree, outside the Nordic countries. We wish to thank all the authors for their inspirational contributions to the proceeding, but we feel that a special thanks is due to the invited speakers for their readiness to produce...

Benthic fluxes of mercury during redox changes in pristine coastal marine sediments from the Gulf of Trieste (northern Adriatic Sea)

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Koron, Neza [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Faganeli, Jadran [National Institute of Biology, Piran (Slovenia). Marine Biological Section; Jozef Stefan Institute, Ljubljana (Slovenia). Dept. of Environmental Sciences

2012-12-15

Purpose: The Gulf of Trieste (northern Adriatic Sea) is an example of a coastal environment contaminated with mercury (Hg). Contamination is a consequence of nearly 500 years of activity at the Idrija Mine (western Slovenia), which is the second largest Hg mine in the world. Oxygen depletion can be common in the Gulf of Trieste due to late summer stratification of the water column and accumulation of labile organic matter. Since changing redox conditions can have an impact on Hg transformations, we studied the effect of oxygen depletion, in parallel with sulphide, iron (Fe), manganese (Mn), fluorescent dissolved organic matter (FDOM) and nitrogen (N) and phosphorus (P) availability, on total Hg and methylmercury (MeHg) fluxes from sediments. Materials and methods: Pore water concentrations and benthic fluxes of total dissolved Hg and MeHg were studied in situ and in microcosm laboratory experiments using flux chambers encompassing three different stages: oxic, anoxic and reoxidation. Results and discussion: Our experiments showed that in the oxic stage there were small effluxes of MeHg to the water column, which increased in the anoxic stage and dropped rapidly in a subsequent reoxic stage, showing influx. Our results support the hypothesis that MeHg desorption from reduced metal hydroxides under anoxic conditions, and co-precipitation with Fe-oxides and MeHg demethylation in the reoxidation stage, may play a major role in determining MeHg benthic fluxes. For Hg and MeHg, it appears that there is little relationship between their pore water distribution and flux and that of FDOM, i.e. humics. Conclusions: The results indicate that there was no significant difference in Hg and MeHg pore water levels and their benthic fluxes between the contaminated northern and central parts of the Gulf of Trieste and the pristine southern part. This suggests that shallow and stratified coastal marine environments, in general, represent areas with a risk of high benthic release of

Historical data reveal 30-year persistence of benthic fauna associations in heavily modified waterbody

Directory of Open Access Journals (Sweden)

Ruth Callaway

2016-08-01

Full Text Available Baseline surveys form the cornerstone of coastal impact studies where altered conditions, for example through new infrastructure development, are assessed against a temporal reference state. They are snapshots taken before construction. Due to scarcity of relevant data prior to baseline surveys long-term trends can often not be taken into account. Particularly in heavily modified waterbodies this would however be desirable to control for changes in anthropogenic use over time as well as natural ecological variation. Here, the benthic environment of an industrialized embayment was investigated (Swansea Bay, Wales, UK where it is proposed to build a tidal lagoon that would generate marine renewable energy from the tidal range. Since robust long-term baseline data was not available, the value of unpublished historical benthos information from 1984 by a regional water company was assessed with the aim to improve certainty about the persistence of current benthic community patterns. A survey of 101 positions in 2014 identified spatially discrete benthic communities with areas of high and low diversity. Habitat characteristics including sediment properties and the proximity to a sewage outfall explained 17-35% of the variation in the community structure. Comparing the historical information from 1984 with 2014 revealed striking similarity in the benthic communities between those years, not just in their spatial distribution but also to a large extent in the species composition. The 30-year-old information confirmed spatial boundaries of discrete species associations and pinpointed a similar diversity hotspot. A group of five common species was found to be particularly persistent over time (Nucula nitidosa, Spisula elliptica, Spiophanes bombyx, Nephtys hombergii, Diastylis rathkei. According to the Infauna Quality Index (IQI linked to the EU Water Framework Directive (WFD the average ecological status for 2014 was ‘moderate’, but eleven samples

Response of benthic macroinvertebrate communities to highway construction in an Appalachian watershed

Science.gov (United States)

Hedrick, Lara B.; Welsh, S.A.; Anderson, James T.; Lin, L.-S.; Chen, Y.; Wei, X.

2010-01-01

Highway construction in mountainous areas can result in sedimentation of streams, negatively impacting stream habitat, water quality, and biotic communities. We assessed the impacts of construction of a segment of Corridor H, a four-lane highway, in the Lost River watershed, West Virginia, by monitoring benthic macroinvertebrate communities and water quality, before, during, and after highway construction and prior to highway use at upstream and downstream sites from 1997 through 2007. Data analysis of temporal impacts of highway construction followed a Before-After-Control-Impact (BACI) study design. Highway construction impacts included an increase in stream sedimentation during the construction phase. This was indicated by an increase in turbidity and total suspended solids. Benthic macroinvertebrate metrics indicated a community more tolerant during and after construction than in the period before construction. The percent of Chironomidae and the Hilsenhoff Biotic Index (HBI) increased, while percent of Ephemeroptera, Plecoptera, and Trichoptera (EPT) decreased. Our 10-year study addressed short-term impacts of highway construction and found that impacts were relatively minimal. A recovery of the number of EPT taxa collected after construction indicated that the benthic macroinvertebrate community may be recovering from impacts of highway construction. However, this study only addressed a period of 3 years before, 3 years during, and 4 years post construction. Inferences cannot be made concerning the long-term impacts of the highway, highway traffic, runoff, and other factors associated with highway use. Continual monitoring of the watershed is necessary to determine if the highway has a continual impact on stream habitat, water quality, and biotic integrity. ?? 2010 Springer Science+Business Media B.V.

Seafloor Mapping and Benthic Habitats off Assateague Island National Seashore: can we Resolve any Effects of Superstorm Sandy?

Science.gov (United States)

Miller, D.; Trembanis, A. C.; Kennedy, E.; Rusch, H.; Rothermel, E.

2016-02-01

The National Park Service has partnered with faculty and students at the University of Delaware to map the length of Assateague Island and sample benthic communities there for two purposes: (1) to provide a complete inventory of benthic habitats and their biota, and (2) to determine if any changes from a pre-storm survey can be ascribed to Superstorm Sandy in 2012. During the 2014 and 2015 field seasons over 75 km2 of high-resolution ( 50 cm/pixel) side-scan sonar and collocated bathymetry were collected with a surface vessel mounted bathy side-scan sonar (EdgeTech 6205), spanning the shore from depths of less than 2 m out to a distance of approximately 1 nautical mile and depths of 10-12 m. Furthermore, we have resampled using standard methodology (modified Young grab and 0.5-mm sieve) a subset of the previously sampled benthic stations that represent all sediment classes identified in prior studies. Additionally, we have obtained novel data with our ROV and AUV assets, including finer scale bottom video and multibeam bathymetry, at specifically chosen locations in order to enhance understanding of the benthic habitat and bottom type changes. In addition to providing a habitat and faunal inventory for resource management purposes, we will compare our side scan and benthic survey data to the pre-storm 2011 data products with comparable coverage. To date we have found that ArcGIS and ENVI sediment classifications agree well with those from the 2011 study, but spatially we note more areas of finer sediments and less of gravel. As was expected, 2014 benthic assemblages differ significantly among sediment classes (PRIMER ANOSIM), and sediment class is the best predictor of the benthic community (PERMANOVA+ distance-based RDA). Our goal here is to use consistent analytical approaches to characterize changes that occur over season and inter-annual time scales. This is a critical step toward attributing sediment, habitat and biological changes to Superstorm Sandy.

Benthic macroinvertebrate community structure and distribution in the Ayeyarwady continental shelf, Andaman Sea

Digital Repository Service at National Institute of Oceanography (India)

Ansari Z.A.; Furtado, R.; Badesab, S.; Mehta, P.; Thwin, S.

water, Myanmar] Introduction Abundance of benthic fauna is one of the biological indices that support the food chain hypothesis of overall productivity in marine ecosystem1. Changes in benthic community may occur on different spatial scale..., biomass and species diversity of macrobenthos was more in the inshore waters than in the offshore areas of Malaysia and Gulf of Thailand. As indicated earlier, a significant amount of the variation in faunal abundances, not unexpectedly, is a function...

Long-term (1998 vs. 2010) large-scale comparison of soft-bottom benthic macrofauna composition in the Gulf of Lions, NW Mediterranean Sea

Science.gov (United States)

Bonifácio, Paulo; Grémare, Antoine; Gauthier, Olivier; Romero-Ramirez, Alicia; Bichon, Sabrina; Amouroux, Jean-Michel; Labrune, Céline

2018-01-01

We achieved a long term (i.e., 1998 vs. 2010) large scale (i.e., whole Gulf of Lions) study of benthic macrofauna composition in the Gulf of Lions based on the resampling of 91 stations located along 21 inshore-offshore transects. Results show that the 3 main benthic communities identified in 1998 were still present in 2010 although their composition changed. Using only year and station of sampling we found a significant space-time interaction explaining changes in macrofaunal community composition, and, in this study, stations differ primarily in terms of depth and distance to the Rhône river mouth. Temporal changes in benthic macrofauna composition were clearly most important at shallow stations (i.e., in the Littoral Fine Sand community) than at deep ones (i.e., Terrigenous Coastal Mud community). These results are in good agreement with the current paradigm according to which climatic oscillations such as NAO (North Atlantic Oscillation) and WeMO (Western Mediterranean Oscillation) are indirectly (i.e., through changes in the frequency of occurrence and the intensity of storms) controlling benthic macrofauna composition in the Gulf of Lions. This hypothesis is further supported by a meta-analysis of changes in the average and maximal yearly abundances of the polychaete Ditrupa arietina. At last, the spatial modelling of 1998 and 2010 benthic macrofauna compositions both suggested a significant effect of Rhône River inputs on the spatial distribution of benthic macrofauna in the Gulf of Lions.

Food and disturbance effects on Arctic benthic biomass and production size spectra

Science.gov (United States)

Górska, Barbara; Włodarska-Kowalczuk, Maria

2017-03-01

Body size is a fundamental biological unit that is closely coupled to key ecological properties and processes. At the community level, changes in size distributions may influence energy transfer pathways in benthic food webs and ecosystem carbon cycling; nevertheless they remain poorly explored in benthic systems, particularly in the polar regions. Here, we present the first assessment of the patterns of benthic biomass size spectra in Arctic coastal sediments and explore the effects of glacial disturbance and food availability on the partitioning of biomass and secondary productivity among size-defined components of benthic communities. The samples were collected in two Arctic fjords off west Spitsbergen (76 and 79°N), at 6 stations that represent three regimes of varying food availability (indicated by chlorophyll a concentration in the sediments) and glacial sedimentation disturbance intensity (indicated by sediment accumulation rates). The organisms were measured using image analysis to assess the biovolume, biomass and the annual production of each individual. The shape of benthic biomass size spectra at most stations was bimodal, with the location of a trough and peaks similar to those previously reported in lower latitudes. In undisturbed sediments macrofauna comprised 89% of the total benthic biomass and 56% of the total production. The lower availability of food resources seemed to suppress the biomass and secondary production across the whole size spectra (a 6-fold decrease in biomass and a 4-fold decrease in production in total) rather than reshape the spectrum. At locations where poor nutritional conditions were coupled with disturbance, the biomass was strongly reduced in selected macrofaunal size classes (class 10 and 11), while meiofaunal biomass and production were much higher, most likely due to a release from macrofaunal predation and competition pressure. As a result, the partitioning of benthic biomass and production shifted towards meiofauna

URBAN GROWTH AND WATER QUALITY IN THIMPHU, BHUTAN

Directory of Open Access Journals (Sweden)

Nandu Giri

2013-01-01

Full Text Available Detailed study was undertaken in 2008 and 2009 on assessment of water quality of River Wang Chhu which flows through Thimphu urban area, the capital city of Bhutan. The water samples were examined at upstream of urban area, within the urban area and its downstream. The water quality was analyzed by studying the physico-chemical, biological and benthic macro-invertebrates. The water quality data obtained during present study are discussed in relation to land use/land cover changes (LULC and various ongoing human activities at upstream, within the each activity areas and it’s downstream. Analyses of satellite imagery of 1990 and 2008 using GIS revealed that over a period of eighteen years the forest, scrub and agricultural areas have decreased whereas urban area and road network have increased considerably. The forest cover, agriculture area and scrub decreased from 43.3% to 42.57%, 6.88% to 5.33% and 42.55% to 29.42%, respectively. The LULC changes effect water quality in many ways. The water temperature, pH, conductivity, total dissolved solids, turbidity, nitrate, phosphate, chloride, total coliform, and biological oxygen demand were lower at upstream and higher in urban area. On the other hand dissolved oxygen was found higher at upstream and lower in urban area. The pollution sensitive benthic macro- invertebrates population were dominant at upstream sampling sites whereas pollution tolerant benthic macro-invertebrates were found abundant in urban area and its immediate downstream. The rapid development of urban infrastructure in Thimphu city may be posing serious threats to water regime in terms of its quality. Though the deterioration of water quality is restricted to a few localized areas, the trend is serious and needs proper attention of policy planners and decision makers. Proper treatment of effluents from urban areas is urgently needed to reduce water pollution in such affected areas to check further deterioration of water quality

The influence of multiple chemical and non-chemical stressors on benthic communities in a mid-west agricultural stream.

Science.gov (United States)

Hall, Lenwood W; Killen, Willian D; Anderson, Ronald D; Alden, Raymond W

2017-08-24

The objective of this 3-year study was to characterize benthic communities and physical habitat in an agricultural stream in the mid-west area of the United States (Big Bureau Creek, Illinois). Concurrent basic water quality parameters and seven nutrients were measured in the water column. Sediment measurements from depositional areas were conducted for bifenthrin, Total Organic Carbon, grain size, polychlorinated biphenyls (PCBs) and eight metals. All parameters were measured at 12 sites annually during the late summer for a 3-year period (2014, 2015 and 2016). Univariate regressions, stepwise multiple regressions and canonical correlation statistical analyses were used to determine the relationship between various benthic metrics (i.e., taxa richness and abundance) and all the measured parameters for the 3-year database. Benthic communities comprising 108-110 taxa were collected annually, and were generally dominated by sensitive caddisflies and mayflies. These communities were rated as good to exceptional using the Ohio Invertebrate Community Index. Physical habitat for the various sites was rated as good using the Ohio Qualitative Habitat Evaluation Index, thus suggesting that habitat is not a significant stressor that would likely impact resident benthic communities. Based on a comparison of measured in-stream total nitrogen and total phosphorus concentrations and criterion value exceedances, it appears that the in-stream nutrient concentrations could be potentially stressful to resident benthic biota. Metal concentrations were below established NOAA Threshold Effects Levels at all sites. Measured PCB concentrations were below levels of detection at all sites. Toxic units' (TUs) calculations based on using sensitive laboratory strains of Hyalella were less than 0.1 for bifenthrin, thus suggesting that bifenthrin sediment toxicity was unlikely. Thirty significant relationships reported between benthic metrics and the various environmental variables based on the

Modelling benthic oxygen consumption and benthic-pelagic coupling at a shallow station in the southern North Sea

NARCIS (Netherlands)

Provoost, P.; Braeckman, U.; Van Gansbeke, D.; Moodley, L.; Soetaert, K.; Middelburg, J.J.; Vanaverbeke, J.

2013-01-01

A time-series of benthic oxygen consumption, water-column and sediment chlorophyll concentrations, and temperature in the southern North Sea was subjected to inverse modelling in order to study benthic-pelagic coupling in this coastal marine system. The application of a Markov Chain Monte Carlo

Effects of Exposed Artificial Substrate on the Competition between Phytoplankton and Benthic Algae: Implications for Shallow Lake Restoration

Directory of Open Access Journals (Sweden)

Hu He

2017-01-01

Full Text Available Phytoplankton and benthic algae coexist in shallow lakes and the outcome of the competition between these two photoautotrophs can markedly influence water clarity. It is well established that exposed artificial substrate in eutrophic waters can remove nutrients and fine particles from the water column via the attached periphyton canopy. However, the effects of the introduction of artificial substrate on the competition between planktonic and benthic primary producers remain to be elucidated. We conducted a short-term outdoor mesocosm experiment to test the hypothesis that the nutrient and light changes induced by exposed artificial substrate (polythene nets would benefit the benthic algae. Artificial substrate significantly reduced total nitrogen and phosphorus concentrations and water clarity improved, the latter due to the substrate-induced reduction of both organic and inorganic suspended solids. Consequently, as judged from changes in chlorophyll a (Chl-a concentrations in water and sediment, respectively, exposed artificial substrate significantly reduced the phytoplankton biomass, while benthic algae biomass increased. Our results thus indicate that exposed artificial substrate may be used as a tool to re-establish benthic primary production in eutrophic shallow lakes after an external nutrient loading reduction, paving the way for a benthic- or a macrophyte-dominated system. Longer term and larger scale experiments are, however, needed before any firm conclusions can be drawn on this.

Benthic Foraminifera as bio-indicators of anthropogenic impacts in coastal environments: Acqua dei Corsari area case study (Palermo, Italy).

Science.gov (United States)

Musco, Marianna; Cuttitta, Angela; Bicchi, Erica; Quinci, Enza Maria; Sprovieri, Mario; Tranchida, Giorgio; Giaramita, Luigi; Traina, Anna; Salvagio Manta, Daniela; Gherardi, Serena; Mercurio, Pietro; Siragusa, Angelo; Mazzola, Salvatore

2017-04-15

This study investigates living benthic foraminiferal assemblages as bio-indicators of anthropogenic activities in a coastal area within the Gulf of Palermo (Sicily, Italy), affected by industrial and urban activities, and evaluates the environmental quality through the calibration of a Tolerant Species index (%TS std ). Sediments from 6 stations were sampled along a bathymetric transect from the coast to offshore. Sediment grain size, TOC, major, minor and trace elements and polycyclic aromatic hydrocarbons (PAHs) were compared to benthic foraminiferal assemblages and species at each station. Diversity and density of benthic foraminiferal assemblages were not affected by the presence of pollutants, while tolerant species increased with organic (TOC and PAHs) or chemical (As and Pb) concentrations. Moreover, the calibration of the %TS std formula to >125μm foraminiferal assemblage, gives a detailed description of environmental quality along the transect, representing a good and sensitive tool to evaluate marine coastal environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Global occurrence of pyrethroid insecticides in sediment and the associated toxicological effects on benthic invertebrates: An overview.

Science.gov (United States)

Li, Huizhen; Cheng, Fei; Wei, Yanli; Lydy, Michael J; You, Jing

2017-02-15

Pyrethroids are the third most applied group of insecticides worldwide and are extensively used in agricultural and non-agricultural applications. Pyrethroids exhibit low toxicity to mammals, but have extremely high toxicity to fish and non-target invertebrates. Their high hydrophobicity, along with pseudo-persistence due to continuous input, indicates that pyrethroids will accumulate in sediment, pose long-term exposure concerns to benthic invertebrates and ultimately cause significant risk to benthic communities and aquatic ecosystems. The current review synthesizes the reported sediment concentrations of pyrethroids and associated toxicity to benthic invertebrates on a global scale. Geographically, the most studied area was North America, followed by Asia, Europe, Australia and Africa. Pyrethroids were frequently detected in both agricultural and urban sediments, and bifenthrin and cypermethrin were identified as the main contributors to toxicity in benthic invertebrates. Simulated hazard quotients (HQ) for sediment-associated pyrethroids to benthic organisms ranged from 10.5±31.1 (bifenthrin) to 41.7±204 (cypermethrin), suggesting significant risk. The current study has provided evidence that pyrethroids are not only commonly detected in the aquatic environment, but also can cause toxic effects to benthic invertebrates, and calls for better development of accurate sediment quality criteria and effective ecological risk assessment methods for this emerging class of insecticides. Copyright © 2016 Elsevier B.V. All rights reserved.

Assessment of water quality, benthic invertebrates, and periphyton in the Threemile Creek basin, Mobile, Alabama, 1999-2003

Science.gov (United States)

McPherson, Ann K.; Gill, Amy C.; Moreland, Richard S.

2005-01-01

The U.S. Geological Survey conducted a 4-year investigation of water quality and aquatic-community structure in Threemile Creek, an urban stream that drains residential areas in Mobile, Alabama. Water-quality samples were collected between March 2000 and September 2003 at four sites on Threemile Creek, and between March 2000 and October 2001 at two tributary sites that drain heavily urbanized areas in the watershed. Stream samples were analyzed for major ions, nutrients, fecal-indicator bacteria, and selected organic wastewater compounds. Continuous measurements of dissolved-oxygen concentrations, water temperature, specific conductance, and turbidity were recorded at three sites on Threemile Creek during 1999?2003. Aquatic-community structure was evaluated by conducting one survey of the benthic invertebrate community and multiple surveys of the algal community (periphyton). Benthic invertebrate samples were collected in July 2000 at four sites on Threemile Creek; periphyton samples were collected at four sites on Threemile Creek and the two tributary sites during 2000 ?2003. The occurrence and distribution of chemical constituents in the water column provided an initial assessment of water quality in the streams; the structure of the benthic invertebrate and algal communities provided an indication of the cumulative effects of water quality on the aquatic biota. Information contained in this report can be used by planners and resource managers in the evaluation of proposed total maximum daily loads and other restoration efforts that may be implemented on Threemile Creek. The three most upstream sites on Threemile Creek had similar water chemistry, characterized by a strong calcium-bicarbonate component; the most downstream site on Threemile Creek was affected by tidal fluctuations and mixing from Mobile Bay and had a strong sodium-chloride component. The water chemistry at the tributary site on Center Street was characterized by a strong sodium-chloride component

URBAN GROWTH AND WATER QUALITY IN THIMPHU, BHUTAN

Directory of Open Access Journals (Sweden)

Nandu Giri

2013-06-01

Full Text Available Detailed study was undertaken in 2008 and 2009 on assessment of water quality of River Wang Chhu which flows through Thimphu urban area, the capital city of Bhutan. The water samples were examined at upstream of urban area, within the urban area and its downstream. The water samples were analyzed by studying the physico-chemical, biological and benthic macro-invertebrates. The water quality data obtained during present study are discussed in relation to land use/land cover changes(LULC and various ongoing human activities at upstream, within the each activity areas and it’s downstream. Analyses of satellite imagery of 1990 and 2008 using GIS revealed that over a period of eighteen years the forest, scrub and agricultural areas have decreased whereas urban area and road network have increased considerably. The forest cover, agriculture area and scrub decreased from 43.3% to 42.57%, 6.88% to 5.33% and 42.55% to 29.42%, respectively. The LULC changes effect water quality in many ways. The water temperature, pH, conductivity, total dissolved solids, turbidity, nitrate, phosphate, chloride, total coliform, and biological oxygen demand were lower at upstream and higher in urban area. On the other hand dissolved oxygen was found higher at upstream and lower in urban area. The pollution sensitive benthic macro-invertebrates population were dominant at upstream sampling sites whereas pollution tolerant benthic macro-invertebrates were found abundant in urban area and its immediate downstream. The rapid development of urban infrastructure in Thimphu city may be posing serious threats to water regime in terms of its quality. Though the deterioration of water quality is restricted to a few localized areas, the trend is serious and needs proper attention of policy planners and decision makers. Proper treatment of effluents from urban areas is urgently needed to reduce water pollution in such affected areas to check further deterioration of water quality

Benthic meiofaunal community response to the cascading effects of herbivory within an algal halo system of the Great Barrier Reef.

Science.gov (United States)

Ollivier, Quinn R; Hammill, Edward; Booth, David J; Madin, Elizabeth M P; Hinchliffe, Charles; Harborne, Alastair R; Lovelock, Catherine E; Macreadie, Peter I; Atwood, Trisha B

2018-01-01

Benthic fauna play a crucial role in organic matter decomposition and nutrient cycling at the sediment-water boundary in aquatic ecosystems. In terrestrial systems, grazing herbivores have been shown to influence below-ground communities through alterations to plant distribution and composition, however whether similar cascading effects occur in aquatic systems is unknown. Here, we assess the relationship between benthic invertebrates and above-ground fish grazing across the 'grazing halos' of Heron Island lagoon, Australia. Grazing halos, which occur around patch reefs globally, are caused by removal of seagrass or benthic macroalgae by herbivorous fish that results in distinct bands of unvegetated sediments surrounding patch reefs. We found that benthic algal canopy height significantly increased with distance from patch reef, and that algal canopy height was positively correlated with the abundances of only one invertebrate taxon (Nematoda). Both sediment carbon to nitrogen ratios (C:N) and mean sediment particle size (μm) demonstrated a positive correlation with Nematoda and Arthropoda (predominantly copepod) abundances, respectively. These positive correlations indicate that environmental conditions are a major contributor to benthic invertebrate community distribution, acting on benthic communities in conjunction with the cascading effects of above-ground algal grazing. These results suggest that benthic communities, and the ecosystem functions they perform in this system, may be less responsive to changes in above-ground herbivorous processes than those previously studied in terrestrial systems. Understanding how above-ground organisms, and processes, affect their benthic invertebrate counterparts can shed light on how changes in aquatic communities may affect ecosystem function in previously unknown ways.

Effectiveness of benthic foraminiferal and coral assemblages as water quality indicators on inshore reefs of the Great Barrier Reef, Australia

Science.gov (United States)

Uthicke, S.; Thompson, A.; Schaffelke, B.

2010-03-01

Although the debate about coral reef decline focuses on global disturbances (e.g., increasing temperatures and acidification), local stressors (nutrient runoff and overfishing) continue to affect reef health and resilience. The effectiveness of foraminiferal and hard-coral assemblages as indicators of changes in water quality was assessed on 27 inshore reefs along the Great Barrier Reef. Environmental variables (i.e., several water quality and sediment parameters) and the composition of both benthic foraminiferal and hard-coral assemblages differed significantly between four regions (Whitsunday, Burdekin, Fitzroy, and the Wet Tropics). Grain size and organic carbon and nitrogen content of sediments, and a composite water column parameter (based on turbidity and concentrations of particulate matter) explained a significant amount of variation in the data (tested by redundancy analyses) in both assemblages. Heterotrophic species of foraminifera were dominant in sediments with high organic content and in localities with low light availability, whereas symbiont-bearing mixotrophic species were dominant elsewhere. A similar suite of parameters explained 89% of the variation in the FORAM index (a Caribbean coral reef health indicator) and 61% in foraminiferal species richness. Coral richness was not related to environmental setting. Coral assemblages varied in response to environmental variables, but were strongly shaped by acute disturbances (e.g., cyclones, Acanthaster planci outbreaks, and bleaching), thus different coral assemblages may be found at sites with the same environmental conditions. Disturbances also affect foraminiferal assemblages, but they appeared to recover more rapidly than corals. Foraminiferal assemblages are effective bioindicators of turbidity/light regimes and organic enrichment of sediments on coral reefs.

Environmental drivers of the benthic macroinvertebrates community in a hypersaline estuary (Northeastern Brazil

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Carlinda Railly Ferreira Medeiros

Full Text Available Abstract Introduction The estuarine community of benthic macroinvertebrates spatially varies in response to changes in environmental variables in these ecosystems. Understanding this variability helps our understanding the mechanisms structuring these communities. Aim Assess the structural aspects of the benthic macroinvertebrate community in a hypersaline estuary, and to relate to environmental variables that influence the community structure along the estuary. Methods The study was conducted at Tubarão river estuary in May 2015. We sampled two estuarine areas (upper and lower, and in each zone were sampled six points composed of two replicas, one sampled in sandy bottom and the other in muddy bottom. Samples of benthic macroinvertebrates and estuarine environmental variables were collected. Environmental drivers of the benthic macroinvertebrate community were determined by Distance-based Linear Models analysis. The contribution of individual species to the dissimilarity between the areas and substrate types were determined by analysis of the percentage of similarity. Results The composition of benthic macroinvertebrate community differed between the upper and lower areas, although it was similar between the muddy and sandy bottoms. The variation in the benthic community between areas was mainly related to the influence of salinity in the upper area. In the lower area, the variation of the macroinvertebrates was related to salinity, associated with other variables in the sandy (temperature, turbidity and dissolved oxygen and muddy (temperature, total dissolved solids and dissolved oxygen substrates. Taxa which contributed most to the dissimilarity between the upper and lower areas were Nereididae (17.89%, Anomalocardia brasiliana (15% and Cirratulidae (10.43%. Conclusions Salinity was the main driver of the structural aspects of the benthic macroinvertebrate community in the upper area of the estuary, although in the lower area a set of

Assessment of benthic macroinvertebrates at Nile tilapia production using artificial substrate samplers

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M. S. G. Moura e Silva

Full Text Available Abstract Biomonitoring is a cheap and effective tool for evaluation of water quality, and infer on the balance of aquatic ecosystems. The benthic macroinvertebrates are bioindicators sensitive to environmental changes, and can assist in detecting and preventing impacts such as organic enrichment and imbalance in the food chain. We compared the structure of benthic communities on artificial substrate samplers located in places near and far from net cages for production of Nile tilapia (Oreochromis niloticus. Samplers were manufactured with nylon net, using substrates such as crushed stone, gravel, loofah and cattail leaves. Samples were collected after 30 days of colonization, rinsed and then the specimens were identified and quantified. The following metrics were calculated: richness of Operational Taxonomic Units, Margalef richness, abundance of individuals, Shannon index and evenness index. The macrobenthic community structure was strongly modified according to the proximity of the net cages. Metrics showed significant differences (p < 0.05 between near and distant sites, for both periods (dry and rainy seasons. The position of the samplers significantly affected the structure of macroinvertebrate community, as near sites showed higher values for the community metrics, such as richness and diversity. Near sites presented a larger number of individuals, observed both in the dry and rainy seasons, with a predominance of Chironomidae (Diptera in the dry season and Tubificidae (Oligochaeta in the rainy season.

A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers.

Science.gov (United States)

Li, Fengqing; Sundermann, Andrea; Stoll, Stefan; Haase, Peter

2016-11-01

Dispersal capacity plays a fundamental role in the riverine benthic invertebrate colonization of new habitats that emerges following flash floods or restoration. However, an appropriate measure of dispersal capacity for benthic invertebrates is still lacking. The dispersal of benthic invertebrates occurs mainly during the aquatic (larval) and aerial (adult) life stages, and the dispersal of each stage can be further subdivided into active and passive modes. Based on these four possible dispersal modes, we first developed a metric (which is very similar to the well-known and widely used saprobic index) to estimate the dispersal capacity for 802 benthic invertebrate taxa by incorporating a weight for each mode. Second, we tested this metric using benthic invertebrate community data from a) 23 large restored river sites with substantial improvements of river bottom habitats dating back 1 to 10years, b) 23 unrestored sites very close to the restored sites, and c) 298 adjacent surrounding sites (mean±standard deviation: 13.0±9.5 per site) within a distance of up to 5km for each restored site in the low mountain and lowland areas of Germany. We hypothesize that our metric will reflect the temporal succession process of benthic invertebrate communities colonizing the restored sites, whereas no temporal changes are expected in the unrestored and surrounding sites. By applying our metric to these three river treatment categories, we found that the average dispersal capacity of benthic invertebrate communities in the restored sites significantly decreased in the early years following restoration, whereas there were no changes in either the unrestored or the surrounding sites. After all taxa had been divided into quartiles representing weak to strong dispersers, this pattern became even more obvious; strong dispersers colonized the restored sites during the first year after restoration and then significantly decreased over time, whereas weak dispersers continued to increase

A review of current knowledge on toxic benthic freshwater cyanobacteria--ecology, toxin production and risk management.

Science.gov (United States)

Catherine, Quiblier; Susanna, Wood; Isidora, Echenique-Subiabre; Mark, Heath; Aurélie, Villeneuve; Jean-François, Humbert

2013-10-01

Benthic cyanobacteria are found globally in plethora of environments. Although they have received less attention than their planktonic freshwater counterparts, it is now well established that they produce toxins and reports of their involvement in animal poisonings have increased markedly during the last decade. Most of the known cyanotoxins have been identified from benthic cyanobacteria including: the hepatotoxic microcystins, nodularins and cylindrospermopsins, the neurotoxic saxitoxins, anatoxin-a and homoanatoxin-a and dermatotoxins, such as lyngbyatoxin. In most countries, observations of toxic benthic cyanobacteria are fragmented, descriptive and in response to animal toxicosis events. Only a limited number of long-term studies have aimed to understand why benthic proliferations occur, and/or how toxin production is regulated. These studies have shown that benthic cyanobacterial blooms are commonly a mixture of toxic and non-toxic genotypes and that toxin concentrations can be highly variable spatially and temporally. Physiochemical parameters responsible for benthic proliferation vary among habitat type with physical disturbance (e.g., flow regimes, wave action) and nutrients commonly identified as important. As climatic conditions change and anthropogenic pressures on waterways increase, it seems likely that the prevalence of blooms of benthic cyanobacteria will increase. In this article we review current knowledge on benthic cyanobacteria: ecology, toxin-producing species, variables that regulate toxin production and bloom formation, their impact on aquatic and terrestrial organisms and current monitoring and management strategies. We suggest research needs that will assist in filling knowledge gaps and ultimately allow more robust monitoring and management protocols to be developed. Copyright © 2013 Elsevier Ltd. All rights reserved.

Benthic macroinvertebrate assemblages in mangroves and open ...

African Journals Online (AJOL)

Benthic macroinvertebrate assemblages in mangroves and open intertidal areas on the Dar es Salaam coast, Tanzania. ... it is recommended that conservation efforts along the Tanzanian coast should focus here. Keywords: benthic macrofauna, community structure, littoral zone, Tanganyika, Western Indian Ocean ...

Response of deep-sea benthic foraminifera to Miocene paleoclimatic events, DSDP site 289

International Nuclear Information System (INIS)

Woodruff, F.; Douglas, R.G.

1981-01-01

Changes in the Miocene deep-sea benthic foraminifera at DSDP Site 289 closely correlate to the climatically induced variations in deep and bottom waters in the Pacific Ocean. In early Miocene time, oxygen and carbon isotopes indicate that bottom waters were relatively warm and poorly oxygenated. Benthic foraminiferal assemblages are characterized by various species inherited from the Oligocene. Expansion of the Antarctic icecap in the early middle Miocene, 14-16 m.y. ago, increased oxygen isotope values, produced cold, more oxygenated bottom waters and lead to a turnover in the benthic foraminifera. An Oligocene-early Miocene assemblage was replaced by a cibicidoid-dominated assemblage. Some species became extinct and benthic faunas became more bathymetrically restricted with the increased stratification of deep waters in the ocean. In mid-Miocene time, Epistominella exigua and E. umbonifera, indicative of young, oxygenated bottom waters, are relatively common at DSDP Site 289. Further glacial expansion 5-9 m.y. ago lowered sealevel, increased oceanic upwelling and associated biological productivity and intensified the oxygen minima. Abundant hispid and costate uvigerines become a dominant faunal element at shallow depths above 2500 m as E. umbonifera becomes common to abundant below 2500 m. By late Miocene time, benthic faunas similar in species composition and proportion to modern faunas on the Ontong-Java plateau, had become established. (Auth.)

Classification of threespine stickleback along the benthic-limnetic axis.

Science.gov (United States)

Willacker, James J; von Hippel, Frank A; Wilton, Peter R; Walton, Kelly M

2010-11-01

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have been studied because identifying additional populations as either benthic or limnetic requires detailed dietary or observational studies. Here we develop a Fisher's linear discriminant function based on the skull morphology of known benthic and limnetic stickleback populations from the Cook Inlet Basin of Alaska and test the feasibility of using this function to identify other morphologically divergent populations. Benthic and limnetic morphotypes were separable using this technique and of 45 populations classified, three were identified as morphologically extreme (two benthic and one limnetic), nine as moderately divergent (three benthic and six limnetic) and the remaining 33 populations as morphologically intermediate. Classification scores were found to correlate with eye size, the depth profile of lakes, and the presence of invasive northern pike (Esox lucius). This type of classification function provides a means of integrating the complex morphological differences between morphotypes into a single score that reflects the position of a population along the benthic-limnetic axis and can be used to relate that position to other aspects of stickleback biology.

Biological control of trace metal and organometal benthic fluxes in a eutrophic lagoon (Thau Lagoon, Mediterranean Sea, France)

Science.gov (United States)

Point, D.; Monperrus, M.; Tessier, E.; Amouroux, D.; Chauvaud, L.; Thouzeau, G.; Jean, F.; Amice, E.; Grall, J.; Leynaert, A.; Clavier, J.; Donard, O. F. X.

2007-04-01

In situ benthic chamber experiments were conducted in the Thau Lagoon that allowed the simultaneous determination of the benthic exchanges of trace metals (Cd, Co, Cu, Mn, Pb and U) and mercury species (iHg and MMHg). Fluxes of organotin compounds (MBT, DBT and TBT) were also investigated for the first time. The benthic incubations were performed during two campaigns at four stations that presented different macrobenthic and macrophytic species distribution and abundance (see [Thouzeau, G., Grall, J., Clavier, J., Chauvaud, L., Jean, F., Leynaert, A., Longpuirt, S., Amice, E., Amouroux, D., 2007. Spatial and temporal variability of benthic biogeochemical fluxes associated with macrophytic and macrofaunal distributions in the Thau lagoon (France). Estuarine, Coastal and Shelf Science 72 (3), 432 446.]). The results indicate that most of the flux intensity as well as the temporal and spatial variability can be explained by the combined influence of microscale and macroscale processes. Microscale changes were identified using Mn flux as a good indicator of the redox conditions at the sediment water interface, and by extension, as an accurate proxy of benthic fluxes for most trace metals and mercury species. We also observed that the redox gradient at the interface is promoted by both microbial and macrobenthic species activity that governs O2 budgets. Macroscale processes have been investigated considering macrobenthic organisms activity (macrofauna and macroalgal cover). The density of such macroorganisms is able to explain most of the spatial and temporal variability of the benthic metal fluxes within a specific site. A tentative estimation of the flux of metals and organometals associated with deposit feeder and suspension feeder activity was found to be in the range of the flux determined within the chambers for most considered elements. Furthermore, a light/dark incubation investigating a dense macroalgal cover present at the sediment surface illustrates the role

Using sediment profile imagery to quantify water quality and benthic condition relationships in Pensacola Bay

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We present results from a monthly study in the Pensacola Bay estuary (FL) designed to evaluate the response and recovery in benthic habitats to intermittent, seasonal hypoxia (DO < 2 mg L-1). Samples were collected monthly from June 2015 through October 2017 at seven to nine s...

Reorganization of a marine trophic network along an inshore-offshore gradient due to stronger pelagic-benthic coupling in coastal areas

Science.gov (United States)

Kopp, Dorothée; Lefebvre, Sébastien; Cachera, Marie; Villanueva, Maria Ching; Ernande, Bruno

2015-01-01

Recent theoretical considerations have highlighted the importance of the pelagic-benthic coupling in marine food webs. In continental shelf seas, it was hypothesized that the trophic network structure may change along an inshore-offshore gradient due to weakening of the pelagic-benthic coupling from coastal to offshore areas. We tested this assumption empirically using the eastern English Channel (EEC) as a case study. We sampled organisms from particulate organic matter to predatory fishes and used baseline-corrected carbon and nitrogen stable isotope ratios (δ13C and δ15N) to determine their trophic position. First, hierarchical clustering on δ13C and δ15N coupled to bootstrapping and estimates of the relative contribution of pelagic and benthic carbon sources to consumers' diet showed that, at mesoscale, the EEC food web forms a continuum of four trophic levels with trophic groups spread across a pelagic and a benthic trophic pathway. Second, based on the same methods, a discrete approach examined changes in the local food web structure across three depth strata in order to investigate the inshore-offshore gradient. It showed stronger pelagic-benthic coupling in shallow coastal areas mostly due to a reorganization of the upper consumers relative to the two trophic pathways, benthic carbon sources being available to pelagic consumers and, reciprocally, pelagic sources becoming accessible to benthic species. Third a continuous approach examined changes in the mean and variance of upper consumers' δ13C and δ15N with depth. It detected a significant decrease in δ13C variance and a significant increase in δ15N variance as depth increases. A theoretical two-source mixing model showed that an inshore-offshore decrease in the pelagic-benthic coupling was a sufficient condition to produce the δ13C variance pattern, thus supporting the conclusions of the discrete approach. These results suggest that environmental gradients such as the inshore-offshore one should

Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

International Nuclear Information System (INIS)

Serrano, Alberto . E-mail aserrano@st.ieo.es; Sanchez, Francisco; Preciado, Izaskun; Parra, Santiago; Frutos, Inmaculada

2006-01-01

Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts

Spatial and temporal changes in benthic communities of the Galician continental shelf after the Prestige oil spill

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Serrano, Alberto [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain)]. E-mail aserrano@st.ieo.es; Sanchez, Francisco [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Preciado, Izaskun [Instituto Espanol de Oceanografia, P.O. Box 240, 39080 Santander (Spain); Parra, Santiago [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain); Frutos, Inmaculada [Instituto Espanol de Oceanografia, P.O. Box 130, 15080 La Coruna (Spain)

2006-07-01

Two years after the Prestige oil spill (POS) an assessment of the effects on benthic fauna was carried out using the data obtained in five multidisciplinary surveys. Otter trawl, beam trawl, suprabenthic sled and box corer were used to study the main benthic compartments, along eight transects perpendicular to the coastline. Beam trawl was also employed to quantify the amount of tar aggregates on the continental shelf. No significant correlations between tar aggregates and species richness, biomass and diversity of benthic communities were found. This result was corroborated when the role of depth, season, latitude and sediment characteristics was examined by canonical ordination, in which POS-related variables had low influence on spatial distribution patterns. Depth and sediment grain diameter profoundly influence epibenthic communities. Sediment organic content is a third key variable for the infaunal, suprabenthic and lower-sized epibenthic communities, but not for the larger epibenthic communities. Nevertheless, a decrease in the densities of several epibenthic indicators was detected the first year after spill, followed by a noteworthy recovery in 2004. Non-macroscopic toxicity and some oceanographic agents are suggested as possible causes of these shifts.

Biomonitoring polluted sediments in Arctic regions - possibilities and challenges using benthic foraminifera. Case studies from northern Norway

Science.gov (United States)

Skirbekk, Kari; Dijkstra, Noortje; Junttila, Juho; Sternal, Beata; Pedersen, Kristine Bondo; Forwick, Matthias; Carroll, JoLynn

2016-04-01

Biomonitoring pollution in marine environments using benthic foraminifera assemblages have proven to be a valid method for many regions. Two important reasons for their suitability are their sensitivity to changes in the environment and their rapid response time due to short life cycles. In addition, they are preserved in the sedimentary record, allowing for baseline studies of conditions prior to introduction of contaminants. Species of benthic foraminifera that appear to tolerate polluted sediments are referred to as opportunistic species. This notion is in general used for species able to dominate environments that are too stressful for most species. The high latitude setting of the northern Norwegian coastal zone experience high seasonality and, hence, largely changing conditions throughout a year: variations in water mass domination, freshwater influence, temperature and current velocity. It is possible that an environment like this is inhibited by a higher amount of opportunistic species generally thriving under high stress conditions. This might make the use of benthic foraminifera for biomonitoring more challenging, as the faunal compositions may be a result of a complex set of processes. Consequently, large datasets are necessary in order to make reliable conclusions, which in time may be used as generalized guidelines for biomonitoring in this geographical area. Here, we present preliminary results of benthic foraminiferal assemblages from two sites in Finnmark, northern Norway, which have been exposed to pollution. The main site is Repparfjorden, where the inner parts of the fjord were used as a submarine waste deposal site for mine tailings from a local copper mine during the 1970´s. Results from four marine sediment cores (10-20 cm long) containing sediments classified to be in moderate to very bad state (according to Norwegian sediment quality criteria) are presented. The contamination is seen in intervals of elevated copper content dated to the 1970

Carbon isotopic changes in benthic foraminifera from the western South Atlantic: Reconstruction of glacial abyssal circulation patterns

Science.gov (United States)

Curry, W. B.; Lohmann, G. P.

1982-09-01

Oxygen- and carbon-isotopic analyses have been performed on the benthic foraminifer Planulina wuellerstorfi in seven Late Quaternary cores from the Vema Channel-Rio Grande Rise region. The cores are distributed over the water-depth interval of 2340 to 3939 m, which includes the present transition from North Atlantic Deep Water (NADW) to Antarctic Bottom Water (AABW). The carbon-isotopic records in the cores vary as a function of water depth. The shallowest and deepest cores show no significant glacial-interglacial difference in δ 13C. Four of the five cores presently located in the NADW have benthic foraminiferal δ 13C that is lower during glacial isotopic stages. Based on bathymetric gradients in δ 13C, we conclude that, like today, there were two water masses present in the Vema Channel during glacial intervals: a water mass enriched in 13C overlying another water mass depleted in 13C. The largest gradient of change of δ 13C with depth, however, occurred at 2.7 km, ˜ 1 km shallower than the present position of this gradient. On the basis of paleontologic and sedimentologic evidence, we consider it unlikely that the NADW:AABW transition shallowed to this level. Reduced carbon-isotopic gradients between the deep basins of the North Atlantic and Pacific Oceans during the last glaciation suggest that production of NADW was reduced. Lower production of NADW may have modified the local abyssal circulation pattern in the Vema Channel region.

Subtidal Benthic Invertebrates Shifting Northward Along the U.S. Atlantic Coast

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Numerous marine and terrestrial species have shifted their ranges poleward in response to warming from global climate change. However, few studies have examined range shifts of subtidal benthic communities in estuarine and nearshore waters. This study examined 20 years (1990–2010...

EFFECTS OF HURRICANE KATRINA ON BENTHIC MACROINVERTEBRATE COMMUNITIES ALONG THE NORTHERN GULF OF MEXICO COAST

Science.gov (United States)

A study was initiated in fall 2005 to assess potential effects on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama following Hurricane Katrina, which struck the coast of Louisiana, between New Orleans and Bioloxi, Mississippi on August 29...

Benthic faunal sampling adjacent to the Barbers Point ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900098)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size...

Benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and sediment...

Microphytobenthos in ecotoxicology: a review of the use of marine benthic diatoms in bioassays.

Science.gov (United States)

Araújo, Cristiano V M; Blasco, Julián; Moreno-Garrido, Ignacio

2010-08-01

Contamination in coastal zones is an increasing problem that adversely affects biological diversity and the functioning of coastal ecosystems. Sediment is an important compartment of these zones since large quantities of diverse contaminants can accumulate there. Whole-sediment toxicity assays are of increasing importance, and several assay methods using mainly invertebrates have been developed. However, an important part of the benthic community, the microphytobenthos (represented principally by benthic diatoms and cyanobacteria), has surprisingly been neglected. Recently, comprehensive studies have been conducted using benthic marine microalgae with the object of establishing a toxicity assay method for sediment samples. The main results published to date in the literature and obtained by our own team have been compiled and are discussed in this review. The value and feasibility of using certain organisms of the microphytobenthos group in ecotoxicology studies are also discussed, and a sediment quality guideline based on multivariate procedure has been derived from data obtained in previous studies. Finally, future perspectives for research in this field are discussed. Copyright 2010 Elsevier Ltd. All rights reserved.

Thirty-Three Years of Ocean Benthic Warming Along the U.S. Northeast Continental Shelf and Slope: Patterns, Drivers, and Ecological Consequences

Science.gov (United States)

Kavanaugh, Maria T.; Rheuban, Jennie E.; Luis, Kelly M. A.; Doney, Scott C.

2017-12-01

The U.S. Northeast Continental Shelf is experiencing rapid warming, with potentially profound consequences to marine ecosystems. While satellites document multiple scales of spatial and temporal variability on the surface, our understanding of the status, trends, and drivers of the benthic environmental change remains limited. We interpolated sparse benthic temperature data along the New England Shelf and upper Slope using a seasonally dynamic, regionally specific multiple linear regression model that merged in situ and remote sensing data. The statistical model predicted nearly 90% of the variability of the data, resulting in a synoptic time series spanning over three decades from 1982 to 2014. Benthic temperatures increased throughout the domain, including in the Gulf of Maine. Rates of benthic warming ranged from 0.1 to 0.4°C per decade, with fastest rates occurring in shallow, nearshore regions and on Georges Bank, the latter exceeding rates observed in the surface. Rates of benthic warming were up to 1.6 times faster in winter than the rest of the year in many regions, with important implications for disease occurrence and energetics of overwintering species. Drivers of warming varied over the domain. In southern New England and the mid-Atlantic shallow Shelf regions, benthic warming was tightly coupled to changes in SST, whereas both regional and basin-scale changes in ocean circulation affect temperatures in the Gulf of Maine, the Continental Shelf, and Georges Banks. These results highlight data gaps, the current feasibility of prediction from remotely sensed variables, and the need for improved understanding on how climate may affect seasonally specific ecological processes.

Lake Malawi cichlid evolution along a benthic/limnetic axis.

Science.gov (United States)

Hulsey, C D; Roberts, R J; Loh, Y-H E; Rupp, M F; Streelman, J T

2013-07-01

Divergence along a benthic to limnetic habitat axis is ubiquitous in aquatic systems. However, this type of habitat divergence has largely been examined in low diversity, high latitude lake systems. In this study, we examined the importance of benthic and limnetic divergence within the incredibly species-rich radiation of Lake Malawi cichlid fishes. Using novel phylogenetic reconstructions, we provided a series of hypotheses regarding the evolutionary relationships among 24 benthic and limnetic species that suggests divergence along this axis has occurred multiple times within Lake Malawi cichlids. Because pectoral fin morphology is often associated with divergence along this habitat axis in other fish groups, we investigated divergence in pectoral fin muscles in these benthic and limnetic cichlid species. We showed that the eight pectoral fin muscles and fin area generally tended to evolve in a tightly correlated manner in the Lake Malawi cichlids. Additionally, we found that larger pectoral fin muscles are strongly associated with the independent evolution of the benthic feeding habit across this group of fish. Evolutionary specialization along a benthic/limnetic axis has occurred multiple times within this tropical lake radiation and has produced repeated convergent matching between exploitation of water column habitats and locomotory morphology.

A Benthic Macroinvertebrate Multimetric Index for Assessment of the Ecological Integrity of Northeast Streams, Thailand

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Nantiya Rattanachan

2016-07-01

Full Text Available This study aims to develop a benthic macroinvertebrate multimetric index for assessing the ecological quality of streams in Northeastern Thailand. ANOSIM indicated that the benthic macroinvertebrate assemblage in both of each basin and each season were not significantly different (R = 0.09, p = 0.24 and R = 0.07, p = 0.35, respectively. The efficacy metrics of each basin consisting of the Mekong II, the Chi, and the Mun basins were integrated and calibrated. A total of 255 data sets of water physico-chemical and benthic macroinvertebrates during the dry period (cool and hot seasons were obtained. The stream classification could be divided into three groups: the reference group (48 stations, the stressed group (42 stations, and the intermediate group (165 stations. Twelve out of 56 metrics have been considered as a core metric for the development of a biological index for quality streams in the Northeast, including Total taxa, EPT taxa, Ephemeroptera taxa, Coleoptera taxa, % EPT, % Chironomidae, % Tolerant individuals, % Intolerant individuals, Beck's index, HBI, Predator taxa, and Clinger taxa. Moreover, this metric set covered the structure and function of organisms including the diversity of species, community structure, tolerance/intolerance measures, functional feeding group, and habit. From the efficacy validation of the biological index, the results of stream assessment corresponded to the classification sites with the physico-chemical characteristics.

Measurement of changes in marine benthic ecosystem function following physical disturbance by dredging

OpenAIRE

Wan Hussin, Wan Mohd Rauhan

2012-01-01

Measuring the impact of physical disturbance on macrofaunal communities and sediment composition is important given the increased demand for the exploitation and disturbance of marine ecosystems. The aim of the present investigation was to provide a comprehensive study about the extent to which the disturbance (especially aggregate dredging) may affect benthic ecosystem function. The first part of the thesis concerns a field investigation of the impacts of dredging on the be...

Seasonal variation in accumulation of persistent organic pollutants in an Arctic marine benthic food web

Energy Technology Data Exchange (ETDEWEB)

Evenset, A., E-mail: anita.evenset@akvaplan.niva.no [Akvaplan-niva. Fram Centre, Tromsø (Norway); University of Tromsø, The Arctic University of Norway, Tromsø (Norway); Hallanger, I.G. [University of Tromsø, The Arctic University of Norway, Tromsø (Norway); Tessmann, M. [Akvaplan-niva. Fram Centre, Tromsø (Norway); Institute for Hydrobiology and Fisheries Research, University of Hamburg (Germany); Warner, N. [Norwegian Institute for Air Research, Fram Centre, Tromsø (Norway); Ruus, A. [Norwegian Institute for Water Research, Oslo (Norway); Borgå, K. [Norwegian Institute for Water Research, Oslo (Norway); Department of Biosciences, P.O. Box 1066, Blindern 0316, Oslo (Norway); Gabrielsen, G.W. [Norwegian Polar Institute, Fram Centre, Tromsø (Norway); Christensen, G. [Akvaplan-niva. Fram Centre, Tromsø (Norway); Renaud, P.E. [Akvaplan-niva. Fram Centre, Tromsø (Norway); University Centre in Svalbard, Longyearbyen (Norway)

2016-01-15

The aim of the present study was to investigate seasonal variation in persistent organic pollutant (POP) concentrations, as well as food-web biomagnification, in an Arctic, benthic marine community. Macrozoobenthos, demersal fish and common eiders were collected both inside and outside of Kongsfjorden, Svalbard, during May, July and October 2007. The samples were analysed for a selection of legacy chlorinated POPs. Overall, low levels of POPs were measured in all samples. Although POP levels and accumulation patterns showed some seasonal variation, the magnitude and direction of change was not consistent among species. Overall, seasonality in bioaccumulation in benthic biota was less pronounced than in the pelagic system in Kongsfjorden. In addition, the results indicate that δ{sup 15}N is not a good predictor for POP-levels in benthic food chains. Other factors, such as feeding strategy (omnivory, necrophagy versus herbivory), degree of contact with the sediment, and a high dependence on particulate organic matter (POM), with low POP-levels and high δ{sup 15}N-values (due to bacterial isotope enrichment), seem to govern the uptake of the different POPs and result in loads deviating from what would be expected consulting the trophic position alone. - Highlights: • Seasonal variation in POP biomagnification was investigated in a benthic food web. • Levels of POPs are generally low in benthic species from Kongsfjorden, Svalbard. • POP-concentrations varied with season, but direction of change varied among taxa. • No POP-biomagnification, except for cis-nonachlor, was detected in this study. • δ{sup 15}N-values does not seem to be a good proxy for trophic level in macrozoobenthos.

Seasonal variation in accumulation of persistent organic pollutants in an Arctic marine benthic food web

International Nuclear Information System (INIS)

Evenset, A.; Hallanger, I.G.; Tessmann, M.; Warner, N.; Ruus, A.; Borgå, K.; Gabrielsen, G.W.; Christensen, G.; Renaud, P.E.

2016-01-01

The aim of the present study was to investigate seasonal variation in persistent organic pollutant (POP) concentrations, as well as food-web biomagnification, in an Arctic, benthic marine community. Macrozoobenthos, demersal fish and common eiders were collected both inside and outside of Kongsfjorden, Svalbard, during May, July and October 2007. The samples were analysed for a selection of legacy chlorinated POPs. Overall, low levels of POPs were measured in all samples. Although POP levels and accumulation patterns showed some seasonal variation, the magnitude and direction of change was not consistent among species. Overall, seasonality in bioaccumulation in benthic biota was less pronounced than in the pelagic system in Kongsfjorden. In addition, the results indicate that δ"1"5N is not a good predictor for POP-levels in benthic food chains. Other factors, such as feeding strategy (omnivory, necrophagy versus herbivory), degree of contact with the sediment, and a high dependence on particulate organic matter (POM), with low POP-levels and high δ"1"5N-values (due to bacterial isotope enrichment), seem to govern the uptake of the different POPs and result in loads deviating from what would be expected consulting the trophic position alone. - Highlights: • Seasonal variation in POP biomagnification was investigated in a benthic food web. • Levels of POPs are generally low in benthic species from Kongsfjorden, Svalbard. • POP-concentrations varied with season, but direction of change varied among taxa. • No POP-biomagnification, except for cis-nonachlor, was detected in this study. • δ"1"5N-values does not seem to be a good proxy for trophic level in macrozoobenthos.

Benthic percent cover derived from analysis of benthic images collected at coral reef sites in Timor-Leste in 2013 and 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The benthic cover data described here result from benthic photo-quadrat surveys conducted by the NOAA Coral Reef Ecosystem Program (CREP) in hard bottom shallow...

Distribution and habitat use of the Missouri River and Lower Yellowstone River benthic fishes from 1996 to 1998: A baseline for fish community recovery

Science.gov (United States)

Wildhaber, M.L.; Gladish, D.W.; Arab, A.

2011-01-01

Past and present Missouri River management practices have resulted in native fishes being identified as in jeopardy. In 1995, the Missouri River Benthic Fishes Study was initiated to provide improved information on Missouri River fish populations and how alterations might affect them. The study produced a baseline against which to evaluate future changes in Missouri River operating criteria. The objective was to evaluate population structure and habitat use of benthic fishes along the entire mainstem Missouri River, exclusive of reservoirs. Here we use the data from this study to provide a recent-past baseline for on-going Missouri River fish population monitoring programmes along with a more powerful method for analysing data containing large percentages of zero values. This is carried out by describing the distribution and habitat use of 21 species of Missouri River benthic fishes based on catch-per-unit area data from multiple gears. We employ a Bayesian zero-inflated Poisson model expanded to include continuous measures of habitat quality (i.e. substrate composition, depth, velocity, temperature, turbidity and conductivity). Along with presenting the method, we provide a relatively complete picture of the Missouri River benthic fish community and the relationship between their relative population numbers and habitat conditions. We demonstrate that our single model provides all the information that is often obtained by a myriad of analytical techniques. An important advantage of the present approach is reliable inference for patterns of relative abundance using multiple gears without using gear efficiencies.

Benthic Foraminifera, Food in the Deep Sea, and Limits to Bentho-Pelagic Coupling

Science.gov (United States)

Thomas, E.; Boscolo-Galazzo, F.; Arreguin-Rodrigu, G. J.; Ortiz, S.; Alegret, L.

2015-12-01

The deep-sea is the largest habitat on Earth, contains highly diverse biota, but is very little known. Many of its abundant benthic biota (e.g., nematodes) are not preserved in the fossil record. Calcareous and agglutinated benthic foraminifera (unicellular eukaryotes, Rhizaria; efficient dispersers) and ostracodes (Animalia, Crustacea; non-efficient dispersers) are the most common organisms providing a fossil record of deep-sea environments. Very little food is supplied to the deep-sea, because organic matter produced by photosynthesis is largely degraded before it arrives at the seafloor. Only a few % of organic matter is carried to the ocean bottom by 'marine snow', with its particle size and behavior in the water column controlled by surface ecosystem structure, including type of dominant primary producers (diatoms, cyanobacteria). Food supply and its seasonality are generally seen as the dominant control on benthic assemblages (combined with oxygenation), providing bentho-pelagic coupling between primary and benthic productivity. Benthic foraminiferal assemblages (composition and density) thus are used widely to estimate past productivity, especially during episodes of global climate change, ocean acidification, and mass extinction of primary producers. We show that some environmental circumstances may result in interrupting bentho-pelagic coupling, e.g. through lateral supply of organic matter along continental margins (adding more refractory organic matter), through trophic focusing and/or fine particle winnowing on seamounts (giving an advantage to suspension feeders), and through carbonate undersaturation (giving advantage to infaunal over epifaunal calcifyers). In addition, increased remineralization of organic matter combined with increased metabolic rates may cause assemblages to reflect more oligotrophic conditions at stable primary productivity during periods of global warming. As a result, benthic foraminiferal accumulation rates must be carefully

Water quality and benthic macroinvertebrate bioassessment of Gallinas Creek, San Miguel County, New Mexico, 1987-90

Science.gov (United States)

Garn, H.S.; Jacobi, G.Z.

1996-01-01

Upper Gallinas Creek in north-central New Mexico serves as the public water supply for the City of Las Vegas. The majority of this 84-square-mile watershed is within national forest lands managed by the U.S. Forest Service. In 1985, the Forest Service planned to conduct timber harvesting in the headwaters of Gallinas Creek. The City of Las Vegas was concerned about possible effects from logging on water quality and on water-supply treatment costs. The U.S. Geological Survey began a cooperative study in 1987 to (1) assess the baseline water-quality characteristics of Gallinas Creek upstream from the Las Vegas water-supply diversion, (2) relate water quality to State water- quality standards, and (3) determine possible causes for spatial differences in quality. During 1987-90, water-quality constituents and aquatic benthic macroinvertebrates were collected and analyzed at five sampling sites in the watershed. Specific conductance, pH, total hardness, total alkalinity, and calcium concentrations increased in a downstream direction, probably in response to differences in geology in the watershed. The water-quality standard for temperature was exceeded at the two most downstream sites probably due to a lack of riparian vegetation and low streamflow conditions. The standards for pH and turbidity were exceeded at all sites except the most upstream one. Concentrations of nitrogen species and phosphorus generally were small at all sites. The maximum total nitrogen concentration of 2.1 milligrams per liter was at the mouth of Porvenir Canyon; only one sample at this site exceeded the water-quality standard for total inorganic nitrogen. At each of the sites, 10 to 15 percent of the samples exceeded the total phosphorus standard of less than 0.1 milligram per liter. Except for aluminum and iron, almost all samples tested for trace elements contained concentrations less than the laboratory detection limit. No trace-element concentrations exceeded the State standard for domestic

Eutrophication induced changes in benthic community structure of a flow-restricted tropical estuary (Cochin backwaters), India

Digital Repository Service at National Institute of Oceanography (India)

Martin, G.D.; Nisha, P.A.; Balachandran, K.K.; Madhu, N.V.; Nair, M.; Shaiju, P.; Joseph, T.; Srinivas, K.; Gupta, G.V.M.

The influence of anthropogenic loading on the distribution of soft bottom benthic organisms of a tropical estuary (Cochin backwaters) was examined. The industrial activities were found to be high in the northern and central part of the estuary...

Nutrient reduction and climate change cause a potential shift from pelagic to benthic pathways in a eutrophic marine ecosystem

DEFF Research Database (Denmark)

Lindegren, Martin; Blenckner, T.; Stenseth, N.C.

2012-01-01

The degree to which marine ecosystems may support the pelagic or benthic food chain has been shown to vary across natural and anthropogenic gradients for e.g., in temperature and nutrient availability. Moreover, such external forcing may not only affect the flux of organic matter but could trigger...... variables across all trophic levels, we here propose a potential regime shift from pelagic to benthic regulatory pathways; a possible first sign of recovery from eutrophication likely triggered by drastic nutrient reductions (involving both nitrogen and phosphorus), in combination with climate...

Mangrove clearing impacts on macrofaunal assemblages and benthic food webs in a tropical estuary.

Science.gov (United States)

Bernardino, Angelo Fraga; Gomes, Luiz Eduardo de Oliveira; Hadlich, Heliatrice Louise; Andrades, Ryan; Correa, Lucas Barreto

2018-01-01

Despite over 21,000ha of mangrove forests being removed per year in Brazil, ecological changes following mangrove deforestation have been overlooked. Here we evaluated changes in benthic macrofaunal assemblages and food-webs at a mangrove removal and natural sites in a tropical estuary in Eastern Brazil. The impacted site had coarser sediment particle sizes suggesting significant changes in sedimentation processes after forest clearing. Spatial differences in macrofaunal abundance, biomass and diversity were not directly associated with the removal of mangrove forests, supporting recolonization of impacted areas by estuarine fauna. However, benthic assemblage composition, infaunal δ 13 C signatures and food-web diversity markedly differed at the impacted site being strongly related to sedimentary changes. The loss of infaunal trophic diversity that followed mangrove removal suggests that large-scale forest clearing may impact estuarine food webs, with potential consequences to nearby coastal ecosystems given the high clearing rate of mangrove forests in Brazil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Lake Ontario benthic prey fish assessment, 2015

Science.gov (United States)

Weidel, Brian C.; Walsh, Maureen; Holden, Jeremy P.; Connerton, Michael J.

2016-01-01

Benthic prey fishes are a critical component of the Lake Ontario food web, serving as energy vectors from benthic invertebrates to native and introduced piscivores. Since the late 1970’s, Lake Ontario benthic prey fish status was primarily assessed using bottom trawl observations confined to the lake’s south shore, in waters from 8 – 150 m (26 – 492 ft). In 2015, the Benthic Prey Fish Survey was cooperatively adjusted and expanded to address resource management information needs including lake-wide benthic prey fish population dynamics. Effort increased from 55 bottom trawl sites to 135 trawl sites collected in depths from 8 - 225m (26 – 738 ft). The spatial coverage of sampling was also expanded and occurred in all major lake basins. The resulting distribution of tow depths more closely matched the available lake depth distribution. The additional effort illustrated how previous surveys were underestimating lake-wide Deepwater Sculpin, Myoxocephalus thompsonii, abundance by not sampling in areas of highest density. We also found species richness was greater in the new sampling sites relative to the historic sites with 11 new fish species caught in the new sites including juvenile Round Whitefish, Prosopium cylindraceum, and Mottled sculpin, Cottus bairdii. Species-specific assessments found Slimy Sculpin, Cottus cognatus abundance increased slightly in 2015 relative to 2014, while Deepwater Sculpin and Round Goby, Neogobius melanostomus, dramatically increased in 2015, relative to 2014. The cooperative, lake-wide Benthic Prey Fish Survey expanded our understanding of benthic fish population dynamics and habitat use in Lake Ontario. This survey’s data and interpretations influence international resource management decision making, such as informing the Deepwater Sculpin conservation status and assessing the balance between sport fish consumption and prey fish populations. Additionally a significant Lake Ontario event occurred in May 2015 when a single

Distributions of Benthic Foraminifera in the Salisbury Embayment before and after the PETM Onset

Science.gov (United States)

Range, M. M.; Robinson, M. M.

2017-12-01

Abrupt climatic perturbations associated with the onset of the Paleocene-Eocene Thermal Maximum (PETM) caused major disruptions to the shallow shelf ecology along the U.S. Atlantic Coastal Plain. Several studies examine the changes in benthic foraminiferal assemblages across the PETM in neritic sediments in New Jersey, Maryland, and Virginia and describe a hydrological and sedimentological paradigm shift that marks the Paleocene-Eocene boundary. In the Salisbury Embayment, a flexural low between the South Jersey High and the Norfolk Arch, this shift is seen in the transition between the upper Paleocene Aquia Formation and the lower Eocene Marlboro Clay. Here we map the abundance of seven benthic foraminifera species from five sites within the Salisbury Embayment from both the uppermost Aquia Formation and the lowermost Marlboro Clay. In addition to the benthic foraminiferal turnover at the PETM onset, we show a geographic distribution of species that highlights a past latitudinal biogeographic zonation not unlike what is found on the modern shelf in this region. Sites document a change in the abundance of species between the late Paleocene and early Eocene, showing a decrease in biodiversity of benthic species along the U.S. Atlantic Coast. Spatial extent of the different species also changed across the Paleocene-Eocene boundary. On the modern Atlantic shelf, a biogeographic zonation is due to the path of the Gulf Stream marking a boundary between relatively cold sea-surface temperatures to the north and warmer temperatures to the south, guided by the geomorphic expression of the mid-Atlantic coastline. During the Paleocene-Eocene transition, we suspect a similar boundary likely existed between the New Jersey sites and the Maryland and Virginia sites. We speculate that with the addition of more assemblage data, we will be able to partially reconstruct the geomorphic expression of the PETM coastline and/or the path of major coastal ocean currents.

Effects of sediment organic matter quality on bioaccumulation, degradation, and distribution of pyrene in two macrofaunal species and their surrounding sediment

DEFF Research Database (Denmark)

Granberg, M. E.; Selck, H.

2007-01-01

Sediment dwelling macrofauna (infauna) are important vectors for the transfer of sediment-associated contaminants to higher trophic levels. Sedimenting organic matter constitutes an important food source for all benthic organisms and changes seasonally in terms of quantity and quality. Sediment...... organic matter (SOM) quality affects organism activity and feeding behaviour, and is therefore also likely to affect contaminant fate in benthic systems. We investigated the impact of SOM quality (enrichment with either labile Tetraselmis sp. or refractory lignin) on the accumulation and metabolism...... imply that bioaccumulation and trophic transfer of sediment-associated PAH should increase following fresh organic matter input, e.g. after sedimentation of phytoplankton blooms. We stress the importance of considering behavioural characteristics of infauna and the trophic situation of the system when...

Benthic ecological status of Algerian harbours.

Science.gov (United States)

Dauvin, J C; Bakalem, A; Baffreau, A; Grimes, S

2017-12-15

This work is an overview of all available benthic data collected in the Algerian harbours between 1983 and 2001. So, total of 571 stations were reported in the 10 major Algerian harbours along the Algerian coast (1200km). Two main categories of harbours were distinguished according to their hydrodynamic regime and volume of water exchange between inner harbour basins and the entrance of the harbours. Univariate, multivariate, benthic indices and Biological Traits of Life approaches were applied on stations sampled in the late 1990s and long-term observations in six out of these ten harbours. These approaches assessed the main characteristics and ecological statuses from these south Mediterranean harbours. One of the main characteristics of the Algerian harbours was the very high species diversity (847 species). Although all the fauna was dominated by pollution-tolerant species; some harbours such as Bethioua and Djendjen hosted normal benthic communities as found in the open sea, but also included some pollution indicator species typical of a slight polluted system. On the contrary, the newly constructed port of Skikda showed perturbed benthic communities in relation to hydrocarbon pollution. Biological Traits of Life analysis reinforced the separation of benthic species along a gradient reflecting their sensitivity or tolerance to pollution. This response was related to an increase in organic matter content, probably associated with a general organic and metal contamination, from the entrance of the harbour to the innermost basins in areas with weak circulation, high sedimentation rate and concentrations of pollutants. Except for Oran harbour, where the poor to moderate ecological status remained unchanged with time, the other harbours showed an improvement or a slight degradation. A strategy of long-term monitoring should be promoted, based on a restricted and selected number of stations characteristic of the different basins and water masses occupying the

Variations of the paleo-productivity in benthic foraminifera records in MIS 3 from western South China Sea

Science.gov (United States)

Niu, Y.; Du, J.; Huang, B.; Chen, M.

2010-12-01

Understanding climate change of last glacial age as the background information of climate forecasting is particularly important in climate research. Marine Isotope Stage 3 (MIS 3, 61-24 ka B.P.) is a relative warm and unstable period in the last glacial. Millennium scale abrupt climate changes, such as Heinrich events and Dansgaard-Oeschger (D-O) cycles, are identified in this period. Research topic on the variations of monsoon during the glacial cycles, especially in MIS 3, is critical for understanding low latitude climatic change and the global paleo-environment as a whole. Fortunately, high resolution sedimentary records in western South China Sea provide us valuable materials to uncover how East Asia Summer Monsoon (EASM) system acts in a highly fluctuating climate ambient like MIS 3. Core 17954 is located in the modern summer upwelling area off the Vietnam coast in western South China Sea (SCS), its sediments record the variations of upwelling generated by EASM. In this work, we carry out paleo-ecological analyses on planktonic ( Neogloboquadrina dutertrei, Globigerina bulloides) and benthic foraminifera (Bulimina aculeate, Uvigerina peregrina, Cibicidoides wuellerstorfi, ect.) sampled from Core 17954 to investigate paleo-productivity and nutrition change of western SCS and its relation to EASM. The results show that benthic and planktonic foraminifera have similar responses to nutrition change. Various indicators of productivity on the basis of benthic foraminiferal analyses reflect an overall three stage change trend: productivity gradually increases from the beginning of MIS 3 (60-40 ka) to its maximum during 35-30 ka, and finally declines after 30 ka. There is also another important discovery, if we observe the climate change in MIS 3 as a whole, we can also find western SCS and Northern Hemisphere High latitude have strong correspondences in such changes: Heinrich events coincided with high productivity events in the western SCS. Further, the result of

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

Assessing the ecological status of the Cisadane River’s headwaters using benthic macroinvertebrates

Science.gov (United States)

Krisanti, M.; Wardiatno, Y.; Anzani, Y. M.

2017-01-01

Benthic macroinvertebrates are commonly used in river health biomonitoring. In monitoring program biotic indices are now widely established in water quality monitoring around the world, including in the tropical countries. The aim of this study was to reveal the ecological status of Cisadane River’s headwaters in inside and outside of Mount Halimun-Salak National Park by using benthic macroinvertebrates. The research was conducted in the headwaters of Cisadane River located in Mount Halimun-Salak National Park. Macroinvertebrates were collected from four sites, i.e. inside the park (station 1, 2, 3, and 4) and from two sites outside the park (station 5 and 6). Collections were made twice a month, starting from April to June 2015 by means of Surber sampler (frame area 30x30 cm). A total of 65 genera from 38 families and 11 orders were found in the river. The results showed that based on diversity index, Lincoln Quality Index (LQI), Family Biotic Index (FBI), and Stream Invertebrate Grade Number Average Level 2 (SIGNAL 2), stations located within national park were ecologically better than those outside national park. Rivers with well-preserved riverside vegetation, as in the national park area have greater ecological status.

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, and Marine Debris Sightings of the Marianas since 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, and Marine Debris Sightings of American Samoa in 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Long-Term Changes in the Water Quality and Macroinvertebrate Communities of a Subtropical River in South China

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Kun Li

2014-12-01

Full Text Available Subtropical rivers support a highly diverse array of benthic macroinvertebrates. In this study, by combining historical data and new data, we identified specific changes in the Guanlan River, in South China, from 1981 to 2011, and evaluated the effectiveness of an ecological restoration project under highly polluted conditions. From 1981 to 2011, the water quality in the Guanlan River underwent three major stages. With the deterioration of water quality, there was an overall decrease in the species number of macroinvertebrates in the Guanlan River, an increase in macroinvertebrate density, and a reduction of the biodiversity, and a reduction of functional feeding groups. In 2011, after five years of comprehensive remediation, the Guanlan River was somewhat improved. Macroinvertebrate biodiversity in the middle reach of the Guanlan River, where a key ecological restoration engineering project was implemented, did not differ significantly from other sites. This finding indicates that the effectiveness of ecological restoration measures in highly polluted rivers, particularly at the reach-scale, is very limited and even ineffective.

Seasonal rates of benthic primary production in a Greenland fjord measured by aquatic eddy correlation

DEFF Research Database (Denmark)

M. Attard, Karl; Glud, Ronnie; McGinnis, Daniel F.

2014-01-01

-quality multiple-day EC data sets document the presence of a year-round productive benthic phototrophic community. The shallow-water sites were on average autotrophic during the spring and summer months, up to 43.6 mmol O2 m22 d21, and heterotrophic or close to metabolic balance during the autumn and winter....... Substantial benthic gross primary production (GPP) was measured year-round. The highest GPP rates were measured during the spring, up to 5.7 mmol O2 m22 h21 (136.8 mmol O2 m22 d21), and even at low light levels (, 80 mmol quanta m22 s21) during late autumn and winter we measured rates of up to 1.8 mmol O2 m22...

Leachates and elemental ratios of macrophytes and benthic algae of an Andean high altitude wetland

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Beatriz MODENUTTI

2011-08-01

Full Text Available In wetlands, macrophytes and filamentous algae constitute an important carbon source for the total content of Dissolved Organic Matter (DOM of the environment. Mallín wetland meadows are highly diverse and rare habitats in Patagonia, that can be characterized as wet meadows with a dense cover mainly dominated by herbaceous plants. We carried out a field study comparing elemental composition (C:N:P of benthic algae (Spirogyra sp. and Zygnema sp. and the submerged macrophyte (Myriophyllum quitense from a high latitude wetland (local name: mallín. Besides we performed laboratory experiments in order to study the effect of ultraviolet radiation (UVR on the optical properties and nutrient release of DOM from leachates of these benthic algae and submerged macrophyte. The obtained results indicated that macrophyte leachates could contribute significantly to changes in the optical characteristics of the wetlands while benthic algae contribute with leachates with low photoreactivity. Finally, nutrient release differs among plant species and season: benthic algae leachates release more P in spring, while M. quitense releases more of this nutrient in autumn. These results suggested that the different colonization may contribute differentially to the chemical environment of the wetland.

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

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Kalinkina Nataliya Michailovna

2016-06-01

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

Deposition and benthic mineralization of organic carbon: A seasonal study from Faroe Islands

Science.gov (United States)

á Norði, Gunnvør; Glud, Ronnie N.; Simonsen, Knud; Gaard, Eilif

2018-01-01

Seasonal variations in sedimentation and benthic mineralization of organic carbon (OC) were investigated in a Faroese fjord. Deposited particulate organic carbon (POC) was mainly of marine origin, with terrestrial material only accounting for rates were associated to the spring bloom. The dynamics in the benthic solute exchange were governed by stratification that isolated the bottom water during summer and intensified sediment resuspension during winter. The POC export from the euphotic zone could not sustain the benthic mineralization rate (10.8 mol C m- 2 yr- 1) and the calculated burial rate (9.8 mol C m- 2 yr- 1) of organic material in the central basin. This indicated considerable focusing of material in the central part of the fjord. This was supported by the fact that the measured benthic mineralization rate - in contrast to most investigations - actually increased with increasing water depth. In August, when mineralization was at its maximum, the dissolved inorganic carbon (DIC) release from the sediment increased by 2.2 mmol m- 2 d- 1 for every m increase in water depth at 30-60 m depth. Due to sediment focusing, the OC burial in the deepest part of the fjord was 9.8 mol C m- 2 yr- 1. This was 2.4 times higher than the average OC burial in the fjord, estimated from the total sedimentation, and benthic mineralization accounting for the water depth related changes in activity. The study in Kaldbaksfjørður underscore that fjords are important sites for long time OC burial, but emphasize the need for accounting for spatial variations when extrapolating results from a single or few stations to the scale of the entire fjord.

Quantifying tidally driven benthic oxygen exchange across permeable sediments

DEFF Research Database (Denmark)

McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas

2014-01-01

Continental shelves are predominately (approximate to 70%) covered with permeable, sandy sediments. While identified as critical sites for intense oxygen, carbon, and nutrient turnover, constituent exchange across permeable sediments remains poorly quantified. The central North Sea largely consists...... of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O-2 exchange across the permeable North Sea sediments using a combination of in situ microprofiles, a benthic chamber, and aquatic eddy correlation. Tidal bottom currents drive...... the variable sediment O-2 penetration depth (from approximate to 3 to 8 mm) and the concurrent turbulence-driven 25-fold variation in the benthic sediment O-2 uptake. The O-2 flux and variability were reproduced using a simple 1-D model linking the benthic turbulence to the sediment pore water exchange...

Guidelines for the processing and quality assurance of benthic invertebrate samples collected as part of the National Water-Quality Assessment Program

Science.gov (United States)

Cuffney, T.F.; Gurtz, M.E.; Meador, M.R.

1993-01-01

Benthic invertebrate samples are collected as part of the U.S. Geological Survey's National Water-Quality Assessment Program. This is a perennial, multidisciplinary program that integrates biological, physical, and chemical indicators of water quality to evaluate status and trends and to develop an understanding of the factors controlling observed water quality. The Program examines water quality in 60 study units (coupled ground- and surface-water systems) that encompass most of the conterminous United States and parts of Alaska and Hawaii. Study-unit teams collect and process qualitative and semi-quantitative invertebrate samples according to standardized procedures. These samples are processed (elutriated and subsampled) in the field to produce as many as four sample components: large-rare, main-body, elutriate, and split. Each sample component is preserved in 10-percent formalin, and two components, large-rare and main-body, are sent to contract laboratories for further processing. The large-rare component is composed of large invertebrates that are removed from the sample matrix during field processing and placed in one or more containers. The main-body sample component consists of the remaining sample materials (sediment, detritus, and invertebrates) and is subsampled in the field to achieve a volume of 750 milliliters or less. The remaining two sample components, elutriate and split, are used for quality-assurance and quality-control purposes. Contract laboratories are used to identify and quantify invertebrates from the large-rare and main-body sample components according to the procedures and guidelines specified within this document. These guidelines allow the use of subsampling techniques to reduce the volume of sample material processed and to facilitate identifications. These processing procedures and techniques may be modified if the modifications provide equal or greater levels of accuracy and precision. The intent of sample processing is to

Sediment Monitoring and Benthic Faunal Sampling Adjacent to the Barbers Point Ocean Outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900098)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Barbers Point (Honouliuli) ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment...

Impaired Short-Term Functioning of a Benthic Community from a Deep Norwegian Fjord Following Deposition of Mine Tailings and Sediments

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Lisa Mevenkamp

2017-05-01

Full Text Available The extraction of minerals from land-based mines necessitates the disposal of large amounts of mine tailings. Dumping and storage of tailings into the marine environment, such as fjords, is currently being performed without knowing the potential ecological consequences. This study investigated the effect of short-term exposure to different deposition depths of inert iron ore tailings (0.1, 0.5, and 3 cm and dead subsurface sediment (0.5 and 3 cm on a deep water (200 m fjord benthic assemblage in a microcosm experiment. Biotic and abiotic variables were measured to determine structural and functional changes of the benthic community following an 11 and 16 day exposure with tailings and dead sediment, respectively. Structural changes of macrofauna, meiofauna, and bacteria were measured in terms of biomass, density, community composition and mortality while measures of oxygen penetration depth, sediment community oxygen consumption and 13C-uptake and processing by biota revealed changes in the functioning of the system. Burial with mine tailings and natural sediments modified the structure and functioning of the benthic community albeit in a different way. Mine tailings deposition of 0.1 cm and more resulted in a reduced capacity of the benthic community to remineralize fresh 13C-labeled algal material, as evidenced by the reduced sediment community oxygen consumption and uptake rates in all biological compartments. At 3 cm of tailings deposition, it was evident that nematode mortality was higher inside the tailings layer, likely caused by reduced food availability. In contrast, dead sediment addition led to an increase in oxygen consumption and bacterial carbon uptake comparable to control conditions, thereby leaving deeper sediment layers anoxic and in turn causing nematode mortality at 3 cm deposition. This study clearly shows that even small levels (0.1 cm of instantaneous burial by mine tailings may significantly reduce benthic ecosystem

Physicochemical Constraints on the Distribution of Benthic Foraminiferal Cell Morphology in the Modern Ocean

Science.gov (United States)

Keating-Bitonti, C.; Payne, J.

2016-02-01

Patterns in the sizes and shapes of marine organisms often occur across latitude and water depth gradients as a function of metabolic constraints dictated by the physical environment. However, the environmental factors that maintain these gradients in morphology remain incompletely understood because several oceanographic variables of biological importance are intimately correlated, such as temperature, dissolved oxygen concentration, particulate organic carbon (POC) flux, and carbonate saturation. Benthic foraminifera, a diverse group of single-celled protists that occur in nearly all marine environments, provide an ideal opportunity to test statistically among the various hypothesized environmental controls on cell morphology. Here, we use over 7,000 occurrences of 541 species of recent benthic foraminifera that span more than 60 degrees of latitude and 1,600 meters of water depth around the North American continental margin to assess the relative contributions of temperature, oxygen availability, carbonate saturation, and POC flux on their size and volume-to-surface area ratio in the modern ocean. Seawater temperature and dissolved oxygen concentrations best predict both measures of benthic foraminiferal cell morphology from the North American continental margin. These same variables also explain morphological variations from the Pacific continental margin in isolation, but dissolved oxygen is absent from the best model for the Atlantic. Because our results concur with predictions from first principles of cell physiology, we interpret these findings to reflect the physiological selective pressures on cell morphology as determined by the physical environment. Moreover, these findings suggest that warming waters and the expansion of hypoxic zones associated with anthropogenic-induced climate change are more likely to impact benthic foraminiferal communities than changes in primary productivity or ocean acidification.

Aura-biomes are present in the water layer above coral reef benthic macro-organisms

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Kevin Walsh

2017-08-01

Full Text Available As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1 the coral Mussismilia braziliensis, (2 fleshy macroalgae (Stypopodium, Dictota and Canistrocarpus, (3 turf algae, and (4 the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific “aura-biome”. The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria, Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms.

Aura-biomes are present in the water layer above coral reef benthic macro-organisms.

Science.gov (United States)

Walsh, Kevin; Haggerty, J Matthew; Doane, Michael P; Hansen, John J; Morris, Megan M; Moreira, Ana Paula B; de Oliveira, Louisi; Leomil, Luciana; Garcia, Gizele D; Thompson, Fabiano; Dinsdale, Elizabeth A

2017-01-01

As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1) the coral Mussismilia braziliensis , (2) fleshy macroalgae ( Stypopodium , Dictota and Canistrocarpus ), (3) turf algae, and (4) the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific "aura-biome". The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria , Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms.

The latest Paleocene benthic extinction event: Punctuated turnover in outer neritic benthic foraminiferal faunas from Gebel Aweina, Egypt

OpenAIRE

Speijer, Robert; Schmitz, B; Aubry, MP; Charisi, SD

1995-01-01

We investigated the benthic foraminiferal record of the neritic sequence at Gebel Aweina (Nile Valley, Egypt) in relation to the latest Paleocene deep-sea benthic extinction event (BEE). At Gebel Aweina an expanded sequence, spanning calcareous nannofossil Zones NP8-NPlO, is continuously exposed and yields calcareous microfauna throughout. The BEE level is situated about halfway through Zone NP9 at 17m above the base of the Esna Formation. Detailed biostratigraphic and isotopic studies have i...

Fish stomach contents in benthic macroinvertebrate assemblage assessments

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TH. Tupinambás

Full Text Available The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil. We sampled sediments through use of a Petersen dredge (total of 216 grabs and used gill nets to sample fish (total of 36 samples. We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus. Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity. This is especially true

Influence of sediment quality on the responses of benthic invertebrates after treatment with the fungicide triphenyltin acetate

NARCIS (Netherlands)

Haas, de E.M.; Roessink, I.; Verbree, B.; Koelmans, A.A.; Kraak, M.H.S.; Admiraal, W.

2005-01-01

After decades of pollution, benthic communities in floodplain lake ecosystems are likely to be exposed to a diverse assortment of sediment-bound historical toxicants and nutrients as well as pulses of newly discharged or deposited toxicants. The aim of this study was therefore to analyze the effects

Deep-sea benthic foraminiferal record of the paleoceanography in the southern Okinawa Trough over the last 20 000 years

Institute of Scientific and Technical Information of China (English)

翦知湣; 陈荣华; 李保华

1996-01-01

Quantitative analyses have been carried out on benthic foraminifera from 66 samples of Core 255 in the southern Okinawa Trough, in combination with the stable isotopic analyses of planktonic and benthic foraminifera and AMS 14C dating, in order to reconstruct the history of change under deep water conditions and surface paleoproduclivity over the last 20 000 years. The variations in the ratio of agglutinants in benthic foraminiferal fauna and the ratio of fragments in planktonic foraminifera] fauna indicate higher carbonate dissolution during the postglacial stage than during the glacial stage. The distribution of species and the results of Q-mode factor analysis show that there are three distinctly different benthic foraminiferal assemblages during the glacial, deglacial and postglacial stages in the Okinawa Trough over the last 20000 years: the glacial Bulimina aculeata assemblage (especially the dominant species Uvigerina pereyrina) is associated with high surface primary productivity and organic mat

Predicting estuarine benthic production using functional diversity

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Marina Dolbeth

2014-05-01

Full Text Available We considered an estuarine system having naturally low levels of diversity, but attaining considerable high production levels, and being subjected to different sorts of anthropogenic impacts and climate events to investigate the relationship between diversity and secondary production. Functional diversity measures were used to predict benthic production, which is considered as a proxy of the ecosystem provisioning services. To this end, we used a 14-year dataset on benthic invertebrate community production from a seagrass and a sandflat habitat and we adopted a sequential modeling approach, where abiotic, trait community weighted means (CWM and functional diversity indices were tested by generalized linear models (GLM, and their significant variables were then combined to produce a final model. Almost 90% of variance of the benthic production could be predicted by combining the number of locomotion types, the absolute maximum atmospheric temperature (proxy of the heat waves occurrence, the type of habitat and the mean body mass, by order of importance. This result is in agreement with the mass ratio hypothesis, where ecosystem functions/services can be chiefly predicted by the dominant trait in the community, here measured as CWM. The increase of benthic production with the number of locomotion types may be seen as greater possibility of using the resources available in the system. Such greater efficiency would increase production. The other variables were also discussed in line of the previous hypothesis and taking into account the general positive relationship obtained between production and functional diversity indices. Overall, it was concluded that traits representative of wider possibilities of using available resources and higher functional diversity are related with higher benthic production.

Effects of streambank fencing of pasture land on benthic macroinvertebrates and the quality of surface water and shallow ground water in the Big Spring Run basin of Mill Creek watershed, Lancaster County, Pennsylvania, 1993-2001

Science.gov (United States)

Galeone, Daniel G.; Brightbill, Robin A.; Low, Dennis J.; O'Brien, David L.

2006-01-01

Streambank fencing along stream channels in pastured areas and the exclusion of pasture animals from the channel are best-management practices designed to reduce nutrient and suspended-sediment yields from drainage basins. Establishment of vegetation in the fenced area helps to stabilize streambanks and provides better habitat for wildlife in and near the stream. This study documented the effectiveness of a 5- to 12-foot-wide buffer strip on the quality of surface water and near-stream ground water in a 1.42-mi2 treatment basin in Lancaster County, Pa. Two miles of stream were fenced in the basin in 1997 following a 3- to 4-year pre-treatment period of monitoring surface- and ground-water variables in the treatment and control basins. Changes in surface- and ground-water quality were monitored for about 4 years after fence installation. To alleviate problems in result interpretation associated with climatic and hydrologic variation over the study period, a nested experimental design including paired-basin and upstream/downstream components was used to study the effects of fencing on surface-water quality and benthic-macroinvertebrate communities. Five surface-water sites, one at the outlet of a 1.77-mi2 control basin (C-1), two sites in the treatment basin (T-3 and T-4) that were above any fence installation, and two sites (one at an upstream tributary site (T-2) and one at the outlet (T-1)) that were treated, were sampled intensively. Low-flow samples were collected at each site (approximately 25-30 per year at each site), and stormflow was sampled with automatic samplers at all sites except T-3. For each site where stormflow was sampled, from 35 to 60 percent of the storm events were sampled over the entire study period. Surface-water sites were sampled for analyses of nutrients, suspended sediment, and fecal streptococcus (only low-flow samples), with field parameters (only low-flow samples) measured during sample collection. Benthic-macroinvertebrate samples

Benthic algae of benchmark streams in agricultural areas of eastern Wisconsin

Science.gov (United States)

Scudder, Barbara C.; Stewart, Jana S.

2001-01-01

Benthic algae were collected from 20 streams in the Western Lake Michigan Drainages by the U.S. Geological Survey in May and June of 1993 as part of the National Water-Quality Assessment program. These streams were selected to represent "benchmark" streams that were minimally affected by human activities, especially agriculture, for comparison to other streams in similar environmental settings. Streams were chosen from four relatively homogeneous units (RHU's) in agricultural areas with differing texture of surficial deposits and bedrock type.

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, and Marine Debris Sightings of the Hawaiian Archipelago in 2016

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Multi- and hyperspectral remote sensing of tropical marine benthic habitats

Science.gov (United States)

Mishra, Deepak R.

Tropical marine benthic habitats such as coral reef and associated environments are severely endangered because of the environmental degradation coupled with hurricanes, El Nino events, coastal pollution and runoff, tourism, and economic development. To monitor and protect this diverse environment it is important to not only develop baseline maps depicting their spatial distribution but also to document their changing conditions over time. Remote sensing offers an important means of delineating and monitoring coral reef ecosystems. Over the last twenty years the scientific community has been investigating the use and potential of remote sensing techniques to determine the conditions of the coral reefs by analyzing their spectral characteristics from space. One of the problems in monitoring coral reefs from space is the effect of the water column on the remotely sensed signal. When light penetrates water its intensity decreases exponentially with increasing depth. This process, known as water column attenuation, exerts a profound effect on remotely sensed data collected over water bodies. The approach presented in this research focuses on the development of semi-analytical models that resolves the confounding influence water column attenuation on substrate reflectance to characterize benthic habitats from high resolution remotely sensed imagery on a per-pixel basis. High spatial resolution satellite and airborne imagery were used as inputs in the models to derive water depth and water column optical properties (e.g., absorption and backscattering coefficients). These parameters were subsequently used in various bio-optical algorithms to deduce bottom albedo and then to classify the benthos, generating a detailed map of benthic habitats. IKONOS and QuickBird multispectral satellite data and AISA Eagle hyperspectral airborne data were used in this research for benthic habitat mapping along the north shore of Roatan Island, Honduras. The AISA Eagle classification was

Coastal Benthic Optical Properties (CoBOP): Optical Properties of Benthic Marine Organisms and Substrates

National Research Council Canada - National Science Library

Mazel, Charles

2002-01-01

...). The long-term objective of our research is to gain an understanding of the nature and significance of fluorescence and reflectance characteristics of benthic marine organisms in general, and coral...

Ecotoxicological effect of grounded MV River Princess on the intertidal benthic organisms off Goa

Digital Repository Service at National Institute of Oceanography (India)

Ingole, B.S.; Sivadas, S.; Goltekar, R.; Clemente, S.; Nanajkar, M.; Sawant, R.; DeSilva, C.; Sarkar, A.; Ansari, Z.A.

–biomass curves showed significant negative impact of TPH on macrofauna. The benthic community structure also showed measurable changes, as there was significant decrease (60%) in the number of species. Given that the microalgal counts were low in sediment...

Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia USA

Science.gov (United States)

Mountaintop removal and valley fill (MTR/VF) coal mining recountours the Appalachian landscape, buries headwater stream channels, and degrades downstream water quality. The goal of this study was to compare benthic community production estimates, based on seasonal insect emergen...

Ozone, air quality and climatic change

International Nuclear Information System (INIS)

Van Noije, T.

2008-01-01

Changes in climate due to increased greenhouse gas emissions differ per region. Regional climate changes can also be caused by regional changes in air quality, though. On the other hand, global and regional changes in climate also lead to changes in air quality without any changes in sources of pollution. This article discusses the various aspects of the interaction between air quality and climate change with extra focus on the role of ozone. [mk] [nl

Sediment monitoring and benthic faunal sampling adjacent to the Sand Island ocean outfall, Oahu, Hawaii, 1986-2010 (NODC Accession 9900088)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic fauna and sediment in the vicinity of the Sand Island ocean outfall were sampled from 1986-2010. To assess the environmental quality, sediment grain size and...

Potentiality of benthic dinoflagellate cultures and screening of their ...

African Journals Online (AJOL)

Taken together, this is the first report on the growth potential and biomass production of benthic dinoflagellate strains isolated from Jeju Island in appropriate culture medium as well as their importance in potential pharmacological applications. Key words: Amphidinium carterae, benthic dinoflagellates, biomass, bioactivities, ...

Marine benthic faunal successional stages and related sedimentary activity

Directory of Open Access Journals (Sweden)

Rutger Rosenberg

2001-12-01

Full Text Available This paper is a brief review of successional stages and activity of benthic soft-bottom communities. Benthic communities was first described by Petersen in the 1910s and further developed by Molander, Thorson and Margalef. Successional stages of benthic communities chance in a predictable way in relation to environmental disturbance and food availability. Food supply to the bottom can occur as a vertical flux, but transport through lateral advection is more important in some areas. While at the bottom, the infauna processes the food in many different ways, and the feeding modes can be categorised into more than 20 functional groups, but fewer are present in brackish water. This categorisation is based on animal mobility and where and how they ingest the food. Animal activity in the sediment, bioturbation, has a significant effect on redox conditions and diagenetic processes. Structures in the sediment due to infaunal presence and activity can be observed in situ by sediment profile imaging, and the biogenic structures and redox conditions can be parameterised and have been shown to correlate to benthic community successional stages. The largest threat to benthic faunal biodiversity is the spread of near-bottom oxygen deficiency in many enclosed are stratified coastal areas.

Gray whale distribution relative to benthic invertebrate biomass and abundance: Northeastern Chukchi Sea 2009-2012

Science.gov (United States)

Brower, Amelia A.; Ferguson, Megan C.; Schonberg, Susan V.; Jewett, Stephen C.; Clarke, Janet T.

2017-10-01

The shallow continental shelf waters of the Bering and Chukchi seas are the northernmost foraging grounds of North Pacific gray whales (Eschrichtius robustus). Benthic amphipods are considered the primary prey of gray whales in these waters, although no comprehensive quantitative analysis has been performed to support this assumption. Gray whale relative abundance, distribution, and behavior in the northeastern Chukchi Sea (69°-72°N, 155-169°W) were documented during aerial surveys in June-October 2009-2012. Concurrently, vessel-based benthic infaunal sampling was conducted in the area in July-August 2009-10, September 2011, and August 2012. Gray whales were seen in the study area each month that surveys were conducted, with the majority of whales feeding. Statistical analyses confirm that the highest densities of feeding gray whales were associated with high benthic amphipod abundance, primarily within 70 km of shore from Point Barrow to Icy Cape, in water whales were not seen in 40-km×40-km cells containing benthic sampling stations with 85 m-2 or fewer amphipods. Continuing broad-scale aerial surveys in the Chukchi Sea and prey sampling near feeding gray whales will be an important means to monitor and document ongoing and predicted ecosystem changes.

PALEOENVIRONMENTAL RECONSTRUCTION FROM BENTHIC FORAMINIFERAL ASSEMBLAGES OF EARLY HOLOCENE, SHALLOW MARINE DEPOSITS IN GOMBONG, CENTRAL JAVA

Directory of Open Access Journals (Sweden)

Luli Gustiani

2017-07-01

Full Text Available A 30m-long sediment core covering the Holocene period was taken from the area of Gombong in the southern part of Central Java. The sediments were deposited in a shallow marine to lagoonal environment that was confirmed by the dominance of Ammonia beccarii along the core intervals. In addition, the species Quinqueloculina poeyana, Miliolinella lakemacquariensis, and Miliolinella subrotunda were also found in the sediments that are typical of normal shallow marine conditions. The decrease and increase in the abundance of these species throughout the core is an expression of sea level change in the area, which results the environmental changes. Low sea level is expressed by the dominance of Ammonia beccarii, and the low abundances or absence of the other three species. In contrast, high sea level stands are reflected by the presence of all four species. The high sea level would imply favorable conditions for benthic foraminifera because it would result in normal shallow marine conditions in the area. Finally, from this benthic assemblages study, it can be assumed that the environmental transformation from the originally shallow marine environment into land was occurred at level 5.5m depths of the sediment core, when all benthic foraminifera were terminated, including Ammonia beccarii. These new results from the shallow marine deposits in the Gombong area are a new contribution to the understanding of paleoenvironmental change in the region, which in turn is important for understanding sea level change as well as climate change in the region.

Impact of exploratory offshore drilling on benthic communities in the Minerva gas field, Port Campbell, Australia

Energy Technology Data Exchange (ETDEWEB)

Currie, D.R.; Isaacs, L.R. [Central Queensland Univ., Gladstone (Australia). Centre for Environmental Management

2005-04-01

Changes to benthic infauna caused by exploratory gas drilling operations in the Minerva field were examined experimentally using a BACI (before, after, control, impact) design. Analysis of 72 x 0.1 m{sup 2} Smith-McIntyre grab samples obtained from one pre-drilling and three post-drilling periods yielded a diverse fauna consisting of 196 invertebrate species and 5035 individuals. Changes to benthic community structure were assessed using ANOVA and nonmetric multidimensional scaling (MDS). The abundances of two common species (Apseudes sp. 1 and Prionospio coorilla) decreased significantly at the well-head site immediately after drilling. The size of these reductions in abundance ranged between 71% and 88%, and persisted for less than 4 months after drilling. A third common species (Katlysia sp. 1) increased in abundance 200 m east of the well-head following drilling. Most species occurred at densities too low to be analysed individually and so were pooled at higher taxonomic levels. Changes in the abundance of species aggregated by phylum varied, but significant declines in the most abundant phyla (Crustaceans and Polychaetes) of 45-73% were observed at all sites within a 100 m radius of the well-head following drilling. In most cases these changes became undetectable four months after drilling following species recruitments. MDS ordinations confirm that drilling related changes to benthic community structure are most pronounced at stations located closest to the well-head. Additionally, the ordinations indicate that modified communities persist at the well-head for more than 11 months following exploratory drilling. (author)

High dietary quality of non-toxic cyanobacteria for a benthic grazer and its implications for the control of cyanobacterial biofilms.

Science.gov (United States)

Groendahl, Sophie; Fink, Patrick

2017-05-18

Mass occurrences of cyanobacteria frequently cause detrimental effects to the functioning of aquatic ecosystems. Consequently, attempts haven been made to control cyanobacterial blooms through naturally co-occurring herbivores. Control of cyanobacteria through herbivores often appears to be constrained by their low dietary quality, rather than by the possession of toxins, as also non-toxic cyanobacteria are hardly consumed by many herbivores. It was thus hypothesized that the consumption of non-toxic cyanobacteria may be improved when complemented with other high quality prey. We conducted a laboratory experiment in which we fed the herbivorous freshwater gastropod Lymnaea stagnalis single non-toxic cyanobacterial and unialgal diets or a mixed diet to test if diet-mixing may enable these herbivores to control non-toxic cyanobacterial mass abundances. The treatments where L. stagnalis were fed non-toxic cyanobacteria and a mixed diet provided a significantly higher shell and soft-body growth rate than the average of all single algal, but not the non-toxic cyanobacterial diets. However, the increase in growth provided by the non-toxic cyanobacteria diets could not be related to typical determinants of dietary quality such as toxicity, nutrient stoichiometry or essential fatty acid content. These results strongly contradict previous research which describes non-toxic cyanobacteria as a low quality food resource for freshwater herbivores in general. Our findings thus have strong implications to gastropod-cyanobacteria relationships and suggest that freshwater gastropods may be able to control mass occurrences of benthic non-toxic cyanobacteria, frequently observed in eutrophied water bodies worldwide.

Successional trends of the benthic macroinvertebrate community in a new southeastern cooling reservoir

International Nuclear Information System (INIS)

Griffin, M.A.; Herring, M.K.

1990-01-01

Lakes created by river impoundments provide new lentic habitats for benthic macroinvertebrates. As new lakes age, benthic macroinvertebrate succession proceeds as first colonizers are replaced and stable populations eventually become established. L Lake, a 400 ha reservoir, was constructed in 1985 on the Department of Energy's Savannah River Site in South Carolina to receive heated effluent from a nuclear production reactor. Benthic macroinvertebrates were collected in L Lake with a ponar grab sampler at 2 and 4 meters at 10 locations in 5 lake regions. Monthly collections were made from 1986 through 1989. Annual average densities of benthic macroinvertebrates increased substantially during the study (ranging from 3955.5--4471.6 organisms/m 2 in 1986 to 8948.1--11,694.1 organisms/m 2 in 1988). Annual mean biomass also increased (ranging from 0.749--0.907g AFDM/m 2 in 1986 to 2074--11,322 g AFDM/m 2 in 1988). Mean annual taxa richness ranged from 9.3--12.2 per ponar in 1986 to 11.8--15.3 per ponar in 1988. Some early colonizers (Chironomidae: Chironomini) dominated throughout the study (ranging from 60.3--79.1% of all organisms). Other chironomids (Tanytarsini and Tanypodinae) declined while slower colonizers (oligochaetes and nematodes) generally increased from 1986 through 1988. The increases in macroinvertebrate density, biomass and changes in community composition observed are typical of early reservoir succession. 14 refs., 12 figs., 1 tab

Paleoecology of benthic foraminifera from the Miocene of the San Jacinto Basin, Colombia

Science.gov (United States)

Poveda, John Sebastian; Fiorini, Flavia; Andres Trejos, Raul; Vallejo, Diego Felipe; Pardo, Andres

2015-04-01

Quantitative benthic foraminifera analysis was conducted on 34 samples collected from a borehole core (393.72m deep) drilled by Colombian Hydrocarbon Agency (ANH) on 2009 in the San Jacinto basin (Northern Colombia). The aims of the research were to define a taxonomical data-bank of Miocene benthic foraminifera for this region, to use the benthic foraminifera assemblages to interpret the paleoenvironment and to identify paleoenvironmental changes. The bottom of the section was dated between lowest Burdigalian to middle Langhian (20.393-17.721 Ma) based on calcareous nannofossils bioevents: LO Helicosphaera ampliaperta, HCO Sphenolithus belemnos and LCO Sphenolithus heteromorphus. The benthic foraminifera fauna identified in the studied samples is composed for the majority of calcareous hyaline tests and is dominated by infaunal taxas. Species belonging to the genera Uvigerina and Lenticulina are commonly occurring in the studied section together with other species typical of outer-shelf upper-bathyal environment. Cibicidoides spp., abundant in the lower part of the section, abruptly decreases in abundance in the upper part. Species belonging to the opportunistic genera Bulimina and Bolivina are more abundant in the upper part of the section. Variability in the abundance of opportunistic species can be associated with tectonic disturbance on the Sinu-San Jacinto fold belt (NW of Colombia) as a result of collision of the Caribbean plate against NW of South America. The tectonics could lead a perturbation on deep ocean sedimentation and circulation.

Benthic nitrogen loss in the Arabian Sea off Pakistan

Directory of Open Access Journals (Sweden)

Sarah eSokoll

2012-11-01

Full Text Available A pronounced deficit of nitrogen (N in the oxygen minimum zone (OMZ of theArabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagicprocesses. However, the OMZ water is in direct contact with sediments on three sides of thebasin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largelyunassessed. In October 2007, we sampled the water column and surface sediments along atransect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering arange of station depths from 360 to 1430 m. Benthic denitrification and anammox rates weredetermined by using 15N-stable isotope pairing experiments. Intact core incubations showeddeclining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m-2 d-1.While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmolN m-2 d-1 with water depth, anammox rates increased from 0.21 to 0.89 mmol N m-2 d-1.Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to40% at 1430 m. This trend is further supported by the quantification of nirS, the biomarkerfunctional gene encoding for cytochrome cd1-nitrite reductases of microorganisms involved inboth N-loss processes. Anammox-like nirS genes within the sediments increased in proportionto total nirS gene copies with water depth. Moreover, phylogenetic analyses of nirS revealeddifferent communities of both denitrifying and anammox bacteria between shallow and deepstations. Together, rate measurement and nirS analyses showed that anammox, determined forthe first time in the Arabian Sea sediments, is an important benthic N-loss process at thecontinental margin off Pakistan, especially in the sediments at deeper water depths.Extrapolation from the measured benthic N-loss to all shelf sediments within the basinsuggests that benthic N-loss may be responsible for about half of the overall N-loss in theArabian Sea.

Tracing the incorporation of carbon into benthic foraminiferal calcite following the Deepwater Horizon event.

Science.gov (United States)

Schwing, Patrick T; Chanton, Jeffrey P; Romero, Isabel C; Hollander, David J; Goddard, Ethan A; Brooks, Gregg R; Larson, Rebekka A

2018-06-01

Following the Deepwater Horizon (DWH) event in 2010, hydrocarbons were deposited on the continental slope in the northeastern Gulf of Mexico through marine oil snow sedimentation and flocculent accumulation (MOSSFA). The objective of this study was to test the hypothesis that benthic foraminiferal δ 13 C would record this depositional event. From December 2010 to August 2014, a time-series of sediment cores was collected at two impacted sites and one control site in the northeastern Gulf of Mexico. Short-lived radioisotopes ( 210 Pb and 234 Th) were employed to establish the pre-DWH, DWH, and post-DWH intervals. Benthic foraminifera (Cibicidoides spp. and Uvigerina spp.) were isolated from these intervals for δ 13 C measurement. A modest (0.2-0.4‰), but persistent δ 13 C depletion in the DWH intervals of impacted sites was observed over a two-year period. This difference was significantly beyond the pre-DWH (background) variability and demonstrated that benthic foraminiferal calcite recorded the depositional event. The longevity of the depletion in the δ 13 C record suggested that benthic foraminifera may have recorded the change in organic matter caused by MOSSFA from 2010 to 2012. These findings have implications for assessing the subsurface spatial distribution of the DWH MOSSFA event. Copyright © 2018 Elsevier Ltd. All rights reserved.

Sensitivity of Coastal Environments and Wildlife to Spilled Oil: South Florida: BENTHIC (Benthic Polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains benthic habitats, including coral reef and hardbottom, seagrass, algae, and others in [for] South Florida. Vector polygons in the data set...

Spatio-Temporal Patterns in the Coral Reef Communities of the Spermonde Archipelago, 2012–2014, II: Fish Assemblages Display Structured Variation Related to Benthic Condition

Directory of Open Access Journals (Sweden)

Jeremiah G. Plass-Johnson

2018-02-01

Full Text Available The Spermonde Archipelago is a complex of ~70 mostly populated islands off Southwest Sulawesi, Indonesia, in the center of the Coral Triangle. The reefs in this area are exposed to a high level of anthropogenic disturbances. Previous studies have shown that variation in the benthos is strongly linked to water quality and distance from the mainland. However, little is known about the fish assemblages of the region and if their community structure also follows a relationship with benthic structure and distance from shore. In this study, we used eight islands of the archipelago, varying in distance from 1 to 55 km relative to the mainland, and 3 years of surveys, to describe benthic and fish assemblages and to examine the spatial and temporal influence of benthic composition on the structure of the fish assemblages. Cluster analysis indicated that distinct groups of fish were associated with distance, while few species were present across the entire range of sites. Relating fish communities to benthic composition using a multivariate generalized linear model confirmed that fish groups relate to structural complexity (rugosity or differing benthic groups; either algae, reef builders (coral and crustose coralline algae or invertebrates and rubble. From these relationships we can identify sets of fish species that may be lost given continued degradation of the Spermonde reefs. Lastly, the incorporation of water quality, benthic and fish indices indicates that local coral reefs responded positively after an acute disturbance in 2013 with increases in reef builders and fish diversity over relatively short (1 year time frames. This study contributes an important, missing component (fish community structure to the growing literature on the Spermonde Archipelago, a system that features environmental pressures common in the greater Southeast Asian region.

Benthic nutrient cycling and diagenetic pathways in the North-western Black Sea

NARCIS (Netherlands)

Friedrich, J.; Dinkel, C.; Friedl, G.; Pimenov, N.; Wijsman, J.W.M.; Gomoiu, M-T.; Cociasu, A.; Popa, L.; Wehrli, B.

2002-01-01

Benthic fluxes of nutrients and metals were measured in the coastal zone of the north-western Black Sea, which is influenced by the Danube and Dniestr rivers. The results from the benthic flux chambers deployed during two EROS 21 cruises in summer 1995 and in spring 1997 yield information on benthic

Analytical characterization of selective benthic flux components in estuarine and coastal waters

Science.gov (United States)

King, Jeffrey N.

2011-01-01

Benthic flux is the rate of flow across the bed of a water body, per unit area of bed. It is forced by component mechanisms, which interact. For example, pressure gradients across the bed, forced by tide, surface gravity waves, density gradients, bed–current interaction, turbulence, and terrestrial hydraulic gradients, drive an advective benthic flux of water and constituents between estuarine and coastal waters, and surficial aquifers. Other mechanisms also force benthic flux, such as chemical gradients, bioturbation, and dispersion. A suite of component mechanisms force a total benthic flux at any given location, where each member of the suite contributes a component benthic flux. Currently, the types and characteristics of component interactions are not fully understood. For example, components may interact linearly or nonlinearly, and the interaction may be constructive or destructive. Benthic flux is a surface water–groundwater interaction process. Its discharge component to a marine water body is referred to, in some literature, as submarine groundwater discharge. Benthic flux is important in characterizing water and constituent budgets of estuarine and coastal systems. Analytical models to characterize selective benthic flux components are reviewed. Specifically, these mechanisms are for the component associated with the groundwater tidal prism, and forced by surface gravity wave setup, surface gravity waves on a plane bed, and the terrestrial hydraulic gradient. Analytical models are applied to the Indian River Lagoon, Florida; Great South Bay, New York; and the South Atlantic Bight in South Carolina and portions of North Carolina.

National Coral Reef Monitoring Program: Benthic Images Collected from Climate Stations across American Samoa in 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across American Samoa in...

Benthic Light Availability Improves Predictions of Riverine Primary Production

Science.gov (United States)

Kirk, L.; Cohen, M. J.

2017-12-01

Light is a fundamental control on photosynthesis, and often the only control strongly correlated with gross primary production (GPP) in streams and rivers; yet it has received far less attention than nutrients. Because benthic light is difficult to measure in situ, surrogates such as open sky irradiance are often used. Several studies have now refined methods to quantify canopy and water column attenuation of open sky light in order to estimate the amount of light that actually reaches the benthos. Given the additional effort that measuring benthic light requires, we should ask if benthic light always improves our predictions of GPP compared to just open sky irradiance. We use long-term, high-resolution dissolved oxygen, turbidity, dissolved organic matter (fDOM), and irradiance data from streams and rivers in north-central Florida, US across gradients of size and color to build statistical models of benthic light that predict GPP. Preliminary results on a large, clear river show only modest model improvements over open sky irradiance, even in heavily canopied reaches with pulses of tannic water. However, in another spring-fed river with greater connectivity to adjacent wetlands - and hence larger, more frequent pulses of tannic water - the model improved dramatically with the inclusion of fDOM (model R2 improved from 0.28 to 0.68). River shade modeling efforts also suggest that knowing benthic light will greatly enhance our ability to predict GPP in narrower, forested streams flowing in particular directions. Our objective is to outline conditions where an assessment of benthic light conditions would be necessary for riverine metabolism studies or management strategies.

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

Energy Technology Data Exchange (ETDEWEB)

Martinez-Llado, Xavier [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain); Gibert, Oriol [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain); Marti, Vicens [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain)]. E-mail: vicens.marti@upc.edu; Diez, Sergi [Environmental Chemistry Department, IIQAB-CSIC, c/Jordi Girona 18-26, 08034 Barcelona (Spain); Environmental Geology Department, ICTJA-CSIC, Lluis Sole i Sabaris, s/n, 08028 Barcelona (Spain); Romo, Javier [Environmental Service of Barcelona Harbour Authority, Carretera de la Circumval.lacio, s/n, Tram VI, Sector 6, Barcelona (Spain); Bayona, Josep Maria [Environmental Chemistry Department, IIQAB-CSIC, c/Jordi Girona 18-26, 08034 Barcelona (Spain); Pablo, Joan de [Environmental Technology Area, CTM-UPC, Avda. Bases de Manresa 1, 08240 Manresa (Spain)

2007-09-15

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

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

International Nuclear Information System (INIS)

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

2007-01-01

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

Ocean acidification induces biochemical and morphological changes in the calcification process of large benthic foraminifera.

Science.gov (United States)

Prazeres, Martina; Uthicke, Sven; Pandolfi, John M

2015-03-22

Large benthic foraminifera are significant contributors to sediment formation on coral reefs, yet they are vulnerable to ocean acidification. Here, we assessed the biochemical and morphological impacts of acidification on the calcification of Amphistegina lessonii and Marginopora vertebralis exposed to different pH conditions. We measured growth rates (surface area and buoyant weight) and Ca-ATPase and Mg-ATPase activities and calculated shell density using micro-computer tomography images. In A. lessonii, we detected a significant decrease in buoyant weight, a reduction in the density of inner skeletal chambers, and an increase of Ca-ATPase and Mg-ATPase activities at pH 7.6 when compared with ambient conditions of pH 8.1. By contrast, M. vertebralis showed an inhibition in Mg-ATPase activity under lowered pH, with growth rate and skeletal density remaining constant. While M. vertebralis is considered to be more sensitive than A. lessonii owing to its high-Mg-calcite skeleton, it appears to be less affected by changes in pH, based on the parameters assessed in this study. We suggest difference in biochemical pathways of calcification as the main factor influencing response to changes in pH levels, and that A. lessonii and M. vertebralis have the ability to regulate biochemical functions to cope with short-term increases in acidity. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Modelling temporal and spatial dynamics of benthic fauna in North-West-European shelf seas

Science.gov (United States)

Lessin, Gennadi; Bruggeman, Jorn; Artioli, Yuri; Butenschön, Momme; Blackford, Jerry

2017-04-01

Benthic zones of shallow shelf seas receive high amounts of organic material. Physical processes such as resuspension, as well as complex transformations mediated by diverse faunal and microbial communities, define fate of this material, which can be returned to the water column, reworked within sediments or ultimately buried. In recent years, numerical models of various complexity and serving different goals have been developed and applied in order to better understand and predict dynamics of benthic processes. ERSEM includes explicit parameterisations of several groups of benthic biota, which makes it particularly applicable for studies of benthic biodiversity, biological interactions within sediments and benthic-pelagic coupling. To assess model skill in reproducing temporal (inter-annual and seasonal) dynamics of major benthic macrofaunal groups, 1D model simulation results were compared with data from the Western Channel Observatory (WCO) benthic survey. The benthic model was forced with organic matter deposition rates inferred from observed phytoplankton abundance and model parameters were subsequently recalibrated. Based on model results and WCO data comparison, deposit-feeders exert clear seasonal variability, while for suspension-feeders inter-annual variability is more pronounced. Spatial distribution of benthic fauna was investigated using results of a full-scale NEMO-ERSEM hindcast simulation of the North-West European Shelf Seas area, covering the period of 1981-2014. Results suggest close relationship between spatial distribution of biomass of benthic faunal functional groups in relation to bathymetry, hydrodynamic conditions and organic matter supply. Our work highlights that it is feasible to construct, implement and validate models that explicitly include functional groups of benthic macrofauna. Moreover, the modelling approach delivers detailed information on benthic biogeochemistry and food-web at spatial and temporal scales that are unavailable

National Benthic Infaunal Database (NBID)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The NBID is a quantitative database on abundances of individual benthic species by sample and study region, along with other synoptically measured environmental...

NEPR Benthic Habitat Map 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

Comparative efficacy of benthic biotic indices in assessing the Ecological Quality Status (EcoQS) of the stressed Ulhas estuary, India.

Science.gov (United States)

Mulik, Jyoti; Sukumaran, Soniya; Srinivas, Tatiparthi; Vijapure, Tejal

2017-07-15

Ecostatus of Ulhas estuary, one of the most polluted estuaries along the industrialized and urbanized northwest coast of India, was evaluated by six widely accepted benthic indices viz. H'(log 2 ), AMBI, M-AMBI, BENTIX, BOPA and BO2A to test their efficiency in a tropical setting. The mesohaline zone, which presented eutrophic conditions, was classified as 'bad' by all indices due to the azoic status. Despite significant correlations obtained between indices, there were discrepancies in the accurate level of EcoQS assigned to each station. AMBI was observed to be most efficient in indicating a clear spatial variability from a 'poor' to 'bad' ecological quality status in the middle and upstream zones to an improved status in the downstream region. Limitations of all indices are discussed in light of their suitability for assessing the estuarine environmental condition. The present results could provide a fillip to environmental improvement initiatives currently being undertaken in the estuary. Copyright © 2017 Elsevier Ltd. All rights reserved.

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, and Marine Debris Sightings of the Pacific Remote Island Areas since 2014

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National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Large-scale assessment of benthic communities across multiple marine protected areas using an autonomous underwater vehicle.

Science.gov (United States)

Ferrari, Renata; Marzinelli, Ezequiel M; Ayroza, Camila Rezende; Jordan, Alan; Figueira, Will F; Byrne, Maria; Malcolm, Hamish A; Williams, Stefan B; Steinberg, Peter D

2018-01-01

Marine protected areas (MPAs) are designed to reduce threats to biodiversity and ecosystem functioning from anthropogenic activities. Assessment of MPAs effectiveness requires synchronous sampling of protected and non-protected areas at multiple spatial and temporal scales. We used an autonomous underwater vehicle to map benthic communities in replicate 'no-take' and 'general-use' (fishing allowed) zones within three MPAs along 7o of latitude. We recorded 92 taxa and 38 morpho-groups across three large MPAs. We found that important habitat-forming biota (e.g. massive sponges) were more prevalent and abundant in no-take zones, while short ephemeral algae were more abundant in general-use zones, suggesting potential short-term effects of zoning (5-10 years). Yet, short-term effects of zoning were not detected at the community level (community structure or composition), while community structure varied significantly among MPAs. We conclude that by allowing rapid, simultaneous assessments at multiple spatial scales, autonomous underwater vehicles are useful to document changes in marine communities and identify adequate scales to manage them. This study advanced knowledge of marine benthic communities and their conservation in three ways. First, we quantified benthic biodiversity and abundance, generating the first baseline of these benthic communities against which the effectiveness of three large MPAs can be assessed. Second, we identified the taxonomic resolution necessary to assess both short and long-term effects of MPAs, concluding that coarse taxonomic resolution is sufficient given that analyses of community structure at different taxonomic levels were generally consistent. Yet, observed differences were taxa-specific and may have not been evident using our broader taxonomic classifications, a classification of mid to high taxonomic resolution may be necessary to determine zoning effects on key taxa. Third, we provide an example of statistical analyses and

Analytical approaches used in stream benthic macroinvertebrate biomonitoring programs of State agencies in the United States

Science.gov (United States)

Carter, James L.; Resh, Vincent H.

2013-01-01

Biomonitoring programs based on benthic macroinvertebrates are well-established worldwide. Their value, however, depends on the appropriateness of the analytical techniques used. All United States State, benthic macroinvertebrate biomonitoring programs were surveyed regarding the purposes of their programs, quality-assurance and quality-control procedures used, habitat and water-chemistry data collected, treatment of macroinvertebrate data prior to analysis, statistical methods used, and data-storage considerations. State regulatory mandates (59 percent of programs), biotic index development (17 percent), and Federal requirements (15 percent) were the most frequently reported purposes of State programs, with the specific tasks of satisfying the requirements for 305b/303d reports (89 percent), establishment and monitoring of total maximum daily loads, and developing biocriteria being the purposes most often mentioned. Most states establish reference sites (81 percent), but classify them using State-specific methods. The most often used technique for determining the appropriateness of a reference site was Best Professional Judgment (86 percent of these states). Macroinvertebrate samples are almost always collected by using a D-frame net, and duplicate samples are collected from approximately 10 percent of sites for quality assurance and quality control purposes. Most programs have macroinvertebrate samples processed by contractors (53 percent) and have identifications confirmed by a second taxonomist (85 percent). All States collect habitat data, with most using the Rapid Bioassessment Protocol visual-assessment approach, which requires ~1 h/site. Dissolved oxygen, pH, and conductivity are measured in more than 90 percent of programs. Wide variation exists in which taxa are excluded from analyses and the level of taxonomic resolution used. Species traits, such as functional feeding groups, are commonly used (96 percent), as are tolerance values for organic pollution

National Coral Reef Monitoring Program: Benthic Images Collected from Climate Stations across the Hawaiian Archipelago since 2013

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across the Hawaiian...

National Coral Reef Monitoring Program: Benthic Images Collected from Climate Stations across the Mariana Archipelago in 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across the Mariana...

Bacterial Liasons: Bacteria Associated With Marine Benthic Meiofauna in the Gulf of Mexico

Science.gov (United States)

Diaz, K. S.; Sevigny, J.; Leasi, F.; Thomas, W. K.

2017-12-01

All macroorganisms are colonized by and harbor microbial associates that form their microbiome. Some microbial associates establish predictable symbioses across a host species. Other microbial assemblages, such as the human gut microbiome, exhibit semi-predictable patterns dependent on various factors such as host habitat and diet. Host species typically share core microbiota that remain temporally and spatially stable, but turnover of accessory microbiota due to to environmental change often confers adaptive advantage to the host would not receive from its own genome or core microbiome. Benthic meiofauna, microscopic eukaryotes that live in marine sediments, harbor bacterial associates that may confer functional advantages in the face of environmental perturbation that allow the host to persist and adapt during an environmental disturbance such as an oil spill. However, benthic meiofauna and their microbiota represent relatively unknown components of marine environments. In 2010, the Deepwater Horizon oil spill poured over 0.5 million metric tons of crude oil into the Gulf of Mexico. Now, much of the oil has dispersed, but some still lingers in environments such as marine sediments. Benthic meiofauna remain affected by these lingering hydrocarbons. Their inability to simply leave their habitat makes them ideal sentinels of environmental change that can factor into understanding oil spill impacts and inform response and mitigation of similar future events. Binning bacterial sequences from host whole shotgun genomes allows for analysis of microbiome gene coding and functional potentials that may assist the host through environmental disturbances, such as genes involved in hydrocarbon degradation pathways. 16S rRNA gene surveys reveal of microbiome composition of diverse meiofaunal taxa collected throughout the Gulf of Mexico. This work will examine structure and distribution of benthic meiofauna microbiomes in the Gulf of Mexico. Thus far, 16S surveys display

Benthic oxygen consumption on continental shelves off eastern Canada

Science.gov (United States)

Grant, Jonathan; Emerson, Craig W.; Hargrave, Barry T.; Shortle, Jeannette L.

1991-08-01

The consumption of phytoplankton production by the benthos is an important component of organic carbon budgets for continental shelves. Sediment texture is a major factor regulating benthic processes because fine sediment areas are sites of enhanced deposition from the water column, resulting in increased organic content, bacterial biomass and community metabolism. Although continental shelves at mid- to high latitudes consist primarily of coarse relict sediments ( PIPER, Continental Shelf Research, 11, 1013-1035), shelf regions of boreal and subarctic eastern Canada contain large areas of silt and clay sediments ( FADER, Continental Shelf Research, 11, 1123-1153). We collated estimates of benthic oxygen consumption in coarse (<20% silt-clay, <0.5% organic matter) and fine sediments (20% silt-clay, 0.5% organic matter) for northwest Atlantic continental shelves including new data for Georges Bank, the Scotian Shelf, the Grand Banks of Newfoundland and Labrador Shelf. Estimates were applied to the areal distribution of sediment type on these shelves to obtain a general relationship between sediment texture and benthic carbon consumption. Mean benthic oxygen demand was 2.7 times greater in fine sediment than in coarse sediment, when normalized to mean annual temperature. In terms of carbon equivalents, shelf regions with minimal fine sediment (Georges Bank, the Grand Banks of Newfoundland-northeast Newfoundland) consumed only 5-8% of annual primary production. Benthos of the Gulf of Maine (100% fine sediment) and the Scotian Shelf (35% fine sediment) utilized 16-19% of primary production. Although 32% of the Labrador Shelf area contained fine sediments, benthic consumption of pelagic production (8%) was apparently limited by low mean annual temperature (2°C). These results indicate that incorporation of sediment-specific oxygen uptake into shelf carbon budgets may increase estimates of benthic consumption by 50%. Furthermore, respiration and production by large

Assessing the impact of chemical pollution on benthic invertebrates from three different European rivers using a weight-of-evidence approach

Czech Academy of Sciences Publication Activity Database

Wolfram, G.; Höss, S.; Orendt, C.; Schmitt, C.; Adámek, Zdeněk; Bandow, N.; Grossschartner, M.; Kukkonen, J. V. K.; Leloup, V.; López Doval, J. C.; Munoz, I.; Traunspurger, W.; Tuikka, A.; Van Liefferinge, C.; von der Ohe, P. C.; de Deckere, E.

2012-01-01

Roč. 438, X (2012), s. 498-509 ISSN 0048-9697 Institutional support: RVO:68081766 Keywords : Benthic macroinvertebrates * Nematodes * Chemical pollution * Bioassays * Sediment-quality triad (SQT) * Weight of evidence (WoE) Subject RIV: EH - Ecology, Behaviour Impact factor: 3.258, year: 2012

Explosive diversification following a benthic to pelagic shift in freshwater fishes.

Science.gov (United States)

Hollingsworth, Phillip R; Simons, Andrew M; Fordyce, James A; Hulsey, C Darrin

2013-12-17

Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America's most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition in this group and generated fossil-calibrated estimates of when this shift occurred. This transition could have represented evolution into a novel adaptive zone, and therefore, we tested for a period of accelerated lineage accumulation after this historical habitat shift. Ancestral state reconstructions inferred a similar and concordant region of our mtDNA and nDNA based gene trees as representing the shift from benthic to pelagic habitats in the OPM clade. Two independent tests conducted on each gene tree suggested an increased diversification rate after this inferred habitat transition. Furthermore, lineage through time analyses indicated rapid early cladogenesis in the clade arising after the benthic to pelagic shift. A burst of diversification followed the earliest benthic to pelagic transition during the radiation of OPM cyprinids in eastern North America. As such, the benthic/pelagic habitat axis has likely influenced the generation of biodiversity across disparate freshwater ecosystems.

Variation in sensitivity of large benthic Foraminifera to the combined effects of ocean warming and local impacts.

Science.gov (United States)

Prazeres, Martina; Roberts, T Edward; Pandolfi, John M

2017-03-23

Large benthic foraminifera (LBF) are crucial marine calcifiers in coral reefs, and sensitive to environmental changes. Yet, many species successfully colonise a wide range of habitats including highly fluctuating environments. We tested the combined effects of ocean warming, local impacts and different light levels on populations of the common LBF Amphistegina lobifera collected along a cross-shelf gradient of temperature and nutrients fluctuations. We analysed survivorship, bleaching frequency, chlorophyll a content and fecundity. Elevated temperature and nitrate significantly reduced survivorship and fecundity of A. lobifera across populations studied. This pattern was exacerbated when combined with below optimum light levels. Inshore populations showed a consistent resistance to increased temperature and nitrate levels, but all populations studied were significantly affected by light reduction. These findings demonstrated the capacity of some populations of LBF to acclimate to local conditions; nonetheless improvements in local water quality can ultimately ameliorate effects of climate change in local LBF populations.

Complex Effects of Ecosystem Engineer Loss on Benthic Ecosystem Response to Detrital Macroalgae.

Directory of Open Access Journals (Sweden)

Francesca Rossi

Full Text Available Ecosystem engineers change abiotic conditions, community assembly and ecosystem functioning. Consequently, their loss may modify thresholds of ecosystem response to disturbance and undermine ecosystem stability. This study investigates how loss of the bioturbating lugworm Arenicola marina modifies the response to macroalgal detrital enrichment of sediment biogeochemical properties, microphytobenthos and macrofauna assemblages. A field manipulative experiment was done on an intertidal sandflat (Oosterschelde estuary, The Netherlands. Lugworms were deliberately excluded from 1× m sediment plots and different amounts of detrital Ulva (0, 200 or 600 g Wet Weight were added twice. Sediment biogeochemistry changes were evaluated through benthic respiration, sediment organic carbon content and porewater inorganic carbon as well as detrital macroalgae remaining in the sediment one month after enrichment. Microalgal biomass and macrofauna composition were measured at the same time. Macroalgal carbon mineralization and transfer to the benthic consumers were also investigated during decomposition at low enrichment level (200 g WW. The interaction between lugworm exclusion and detrital enrichment did not modify sediment organic carbon or benthic respiration. Weak but significant changes were instead found for porewater inorganic carbon and microalgal biomass. Lugworm exclusion caused an increase of porewater carbon and a decrease of microalgal biomass, while detrital enrichment drove these values back to values typical of lugworm-dominated sediments. Lugworm exclusion also decreased the amount of macroalgae remaining into the sediment and accelerated detrital carbon mineralization and CO2 release to the water column. Eventually, the interaction between lugworm exclusion and detrital enrichment affected macrofauna abundance and diversity, which collapsed at high level of enrichment only when the lugworms were present. This study reveals that in nature the

Complex Effects of Ecosystem Engineer Loss on Benthic Ecosystem Response to Detrital Macroalgae.

Science.gov (United States)

Rossi, Francesca; Gribsholt, Britta; Gazeau, Frederic; Di Santo, Valentina; Middelburg, Jack J

2013-01-01

Ecosystem engineers change abiotic conditions, community assembly and ecosystem functioning. Consequently, their loss may modify thresholds of ecosystem response to disturbance and undermine ecosystem stability. This study investigates how loss of the bioturbating lugworm Arenicola marina modifies the response to macroalgal detrital enrichment of sediment biogeochemical properties, microphytobenthos and macrofauna assemblages. A field manipulative experiment was done on an intertidal sandflat (Oosterschelde estuary, The Netherlands). Lugworms were deliberately excluded from 1× m sediment plots and different amounts of detrital Ulva (0, 200 or 600 g Wet Weight) were added twice. Sediment biogeochemistry changes were evaluated through benthic respiration, sediment organic carbon content and porewater inorganic carbon as well as detrital macroalgae remaining in the sediment one month after enrichment. Microalgal biomass and macrofauna composition were measured at the same time. Macroalgal carbon mineralization and transfer to the benthic consumers were also investigated during decomposition at low enrichment level (200 g WW). The interaction between lugworm exclusion and detrital enrichment did not modify sediment organic carbon or benthic respiration. Weak but significant changes were instead found for porewater inorganic carbon and microalgal biomass. Lugworm exclusion caused an increase of porewater carbon and a decrease of microalgal biomass, while detrital enrichment drove these values back to values typical of lugworm-dominated sediments. Lugworm exclusion also decreased the amount of macroalgae remaining into the sediment and accelerated detrital carbon mineralization and CO2 release to the water column. Eventually, the interaction between lugworm exclusion and detrital enrichment affected macrofauna abundance and diversity, which collapsed at high level of enrichment only when the lugworms were present. This study reveals that in nature the role of this

Effect of hypoxia on benthic nutrient fluxes in the northwestern Black Sea

Science.gov (United States)

Friedrich, J.

2012-04-01

The western Black Sea shelf has been affected by eutrophication from the 1960s to the mid 1990s. A combination of increased nutrient loads from the major inflowing rivers Danube, Dniester and Dnepr and favourable climate conditions led to high productivity regimes. As a consequence, increased oxygen consumption due to decomposition of organic matter caused recurrent seasonal bottom water hypoxia for more than 20 years. In addition, recycling of nutrients from organic matter settling to the seafloor along with tight benthic-pelagic coupling represents an important internal source for productivity, hence internally supporting eutrophication. From the 1970s to 1990s, the benthic and pelagic systems deteriorated and ecosystem structure and functioning changed. Following the collapse of the centrally planned economies in the eastern European countries during the 1990s, the riverine nutrient input decreased, and the ecosystem, now slowly responding, shows signs of recovery; e.g. by a decrease in hypoxic events. In this study, benthic nutrient flux data from in-situ and ex-situ experiments during the 1990s on the Danube-influenced north-western Black Sea shelf and data from the 2000s, including the EU-FP7 HYPOX experiments, are analysed to reveal the effect of hypoxia on benthic nutrient fluxes. Mann-Whitney statistical tests have been applied to demonstrate the significance of differences in fluxes due to varying oxygen conditions in the water. During the 1990s experiments, bottom water hypoxia was encountered in all locations, while during the 2000s hypoxia has been met only during summer in the Danube Prodelta area and near the Dniester mouth. Indeed, bottom water oxygen in the 1990s has been statistically significantly lower than in the 2000s while benthic oxygen consumption was higher during eutrophication-induced hypoxia. The benthic nutrient fluxes in the 1990s and the 2000s however do not differ significantly. During hypoxia, despite ceasing eutrophication

Predictive models of benthic invertebrate methylmercury in Ontario and Quebec lakes

Energy Technology Data Exchange (ETDEWEB)

Rennie, M.D.; Collins, N.C.; Purchase, C.F. [Toronto Univ., ON (Canada). Dept. of Biology; Tremblay, A. [Hydro-Quebec, Montreal, PQ (Canada)

2005-12-01

In both North America and Europe, high levels of mercury have been reported in lakes that do not receive obvious point-source mercury inputs. Concern over high contaminant levels in waterfowl and fish have prompted several government-issued advisories on safe levels of fish and wildlife intake for humans. Although the primary source of mercury in pristine lakes is directly through atmospheric deposition or indirectly via terrestrial runoff, there can be large variations in mercury concentrations in organisms in neighbouring lakes. Therefore, factors other than atmospheric deposition must influence bioavailability and accumulation of mercury in aquatic organisms. For that reason, multivariate analyses on benthic invertebrate methylmercury concentrations and water chemistry from 12 Quebec water bodies were used to construct simple, predictive models of benthic invertebrate methylmercury in 23 lakes in Ontario and Quebec. The study showed that the primary means of mercury accumulation for organisms in higher trophic positions is dietary through the assimilation of organic forms of mercury, principally methylmercury. The data from 12 Quebec water bodies, revealed that benthic invertebrates in reservoirs have higher methylmercury than those in natural lakes, and methylmercury is generally higher in predatory invertebrates. Reservoir age was found to correlate with fish, benthic invertebrate methylmercury, and also with lake chemistry parameters such as pH and dissolved organic carbon (DOC). The objective of the study was to determine the appropriate level of taxonomic or functional resolution for generating benthic invertebrate methylmercury models, and to identify which environmental variables correlate most with benthic invertebrate methylmercury. Empirical models using these correlations were constructed and their predicted efficiency was tested by cross-validation. In addition, the effect of exposure to fish digestive enzymes on invertebrate methylmercury was

Air Quality and Climate Change

International Nuclear Information System (INIS)

Colette, A.; Rouil, L.; Bessagnet, B.; Schucht, S.; Szopa, S.; Vautard, R.; Menut, L.

2013-01-01

Climate change and air quality are closely related: through the policy measures implemented to mitigate these major environmental threats but also through the geophysical processes that drive them. We designed, developed and implemented a comprehensive regional air quality and climate modeling System to investigate future air quality in Europe taking into account the combined pressure of future climate change and long range transport. Using the prospective scenarios of the last generation of pathways for both climate change (emissions of well mixed greenhouse gases) and air pollutants, we can provide a quantitative view into the possible future air quality in Europe. We find that ozone pollution will decrease substantially under the most stringent scenario but the efforts of the air quality legislation will be adversely compensated by the penalty of global warming and long range transport for the business as usual scenario. For particulate matter, the projected reduction of emissions efficiently reduces exposure levels. (authors)

Benthic fauna of mangrove environment

Digital Repository Service at National Institute of Oceanography (India)

Parulekar, A.H.

distribution of benthic communities in mangrove environment is governEd. by tidal amplitude, light penetration, nature of substratum and distance from the sea. The littoral zone, neritic zone, Barnacle-oyster zone, Uca zone, Polychaeta zone have been delineated...

Benthic algal vegetation in Isfjorden, Svalbard

Directory of Open Access Journals (Sweden)

Stein Fredriksen

2015-08-01

Full Text Available Benthic algal vegetation was investigated at 10 sites in Isfjorden, Svalbard. Five sites were visited during summer 2010 and five during summer 2012. Both the littoral and sublittoral vegetation were sampled, the littoral by hand-picking and use of a throwable rake and the sublittoral using a triangular dredge. A total of 88 different taxa were registered, comprising 17 Chlorophyta, 40 Ochrophyta, 30 Rhodophyta and the Xantophyceae Vaucheria sp. The green algae Ulvaria splendens (Ruprecht Vinogradova was recorded in Svalbard for the first time. Most of the sites consisted of hard bottom substrate, but one site, Kapp Wijk, consisted of loose-lying calcareous red algae (rhodoliths and had species not recorded elsewhere. The sublittoral at the other sites was dominated by kelp. Molecular analysis confirmed the presence of the red alga Ceramium virgatum and a dwarf form of the brown alga Fucus vesiculosus. This study provides a baseline for future studies investigating changes in the vegetation due to environmental changes.

Benthic Macroinvertebrate Assemblages in the Near Coastal Zone of Lake Erie

Science.gov (United States)

Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

Benthic cover derived from analysis of benthic images collected at coral reef sites in Batangas, Philippines from 2015-05-23 to 2015-06-03 (NCEI Accession 0162828)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The benthic cover data described here result from benthic photo-quadrat surveys conducted by the NOAA Coral Reef Ecosystem Program (CREP) in 2015 along transects at...

Persistent natural acidification drives major distribution shifts in marine benthic ecosystems

Science.gov (United States)

Linares, C.; Vidal, M.; Canals, M.; Kersting, D. K.; Amblas, D.; Aspillaga, E.; Cebrián, E.; Delgado-Huertas, A.; Díaz, D.; Garrabou, J.; Hereu, B.; Navarro, L.; Teixidó, N.; Ballesteros, E.

2015-01-01

Ocean acidification is receiving increasing attention because of its potential to affect marine ecosystems. Rare CO2 vents offer a unique opportunity to investigate the response of benthic ecosystems to acidification. However, the benthic habitats investigated so far are mainly found at very shallow water (less than or equal to 5 m depth) and therefore are not representative of the broad range of continental shelf habitats. Here, we show that a decrease from pH 8.1 to 7.9 observed in a CO2 vent system at 40 m depth leads to a dramatic shift in highly diverse and structurally complex habitats. Forests of the kelp Laminaria rodriguezii usually found at larger depths (greater than 65 m) replace the otherwise dominant habitats (i.e. coralligenous outcrops and rhodolith beds), which are mainly characterized by calcifying organisms. Only the aragonite-calcifying algae are able to survive in acidified waters, while high-magnesium-calcite organisms are almost completely absent. Although a long-term survey of the venting area would be necessary to fully understand the effects of the variability of pH and other carbonate parameters over the structure and functioning of the investigated mesophotic habitats, our results suggest that in addition of significant changes at species level, moderate ocean acidification may entail major shifts in the distribution and dominance of key benthic ecosystems at regional scale, which could have broad ecological and socio-economic implications. PMID:26511045

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch

DEFF Research Database (Denmark)

Glud, Ronnie N.; Berg, Peter; Stahl, Henrik

2016-01-01

Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a ~65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated by the b......Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a ~65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated....... The average benthic O2 exchange as derived by chamber incubations and the eddy covariance approach were similar (14.9 ± 2.5 and 13.1 ± 9.0 mmol m−2 day−1) providing confidence in the two measuring approaches. Moreover, the non-invasive eddy approach revealed a flow-dependent benthic O2 flux that was partly...... ascribed to enhanced ventilation of infauna burrows during periods of elevated flow rates. The ratio in exchange rates of ΣCO2 and O2 was close to unity, confirming that the O2 uptake was a good proxy for the benthic carbon mineralization in this setting. The infauna activity resulted in highly dynamic...

Classification of threespine stickleback along the benthic-limnetic axis

OpenAIRE

Willacker, James J.; von Hippel, Frank A.; Wilton, Peter R.; Walton, Kelly M.

2010-01-01

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have b...

Benthic algae compensate for phytoplankton losses in large aquatic ecosystems.

Science.gov (United States)

Brothers, Soren; Vadeboncoeur, Yvonne; Sibley, Paul

2016-12-01

Anthropogenic activities can induce major trophic shifts in aquatic systems, yet we have an incomplete understanding of the implication of such shifts on ecosystem function and on primary production (PP) in particular. In recent decades, phytoplankton biomass and production in the Laurentian Great Lakes have declined in response to reduced nutrient concentrations and invasive mussels. However, the increases in water clarity associated with declines in phytoplankton may have positive effects on benthic PP at the ecosystem scale. Have these lakes experienced oligotrophication (a reduction of algal production), or simply a shift in autotrophic structure with no net decline in PP? Benthic contributions to ecosystem PP are rarely measured in large aquatic systems, but our calculations based on productivity rates from the Great Lakes indicate that a significant proportion (up to one half, in Lake Huron) of their whole-lake production may be benthic. The large declines (5-45%) in phytoplankton production in the Great Lakes from the 1970s to 2000s may be substantially compensated by benthic PP, which increased by up to 190%. Thus, the autotrophic productive capacity of large aquatic ecosystems may be relatively resilient to shifts in trophic status, due to a redirection of production to the near-shore benthic zone, and large lakes may exhibit shifts in autotrophic structure analogous to the regime shifts seen in shallow lakes. © 2016 John Wiley & Sons Ltd.

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

DEFF Research Database (Denmark)

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

2018-01-01

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

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.

The Power of Computer-aided Tomography to Investigate Marine Benthic Communities

Science.gov (United States)

Utilization of Computer-aided-Tomography (CT) technology is a powerful tool to investigate benthic communities in aquatic systems. In this presentation, we will attempt to summarize our 15 years of experience in developing specific CT methods and applications to marine benthic co...

Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

DEFF Research Database (Denmark)

Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

2011-01-01

of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

Living Behaviors and Molecular Characterization of Benthic Foraminifera in the Arabian Gulf

Science.gov (United States)

Arslan, Muhammad; Kaminski, Michael; Khalil, Amjad; Holzmann, Maria

2016-04-01

The benthic foraminifera are among the major carbonate producers in modern Arabian Gulf waters and are found living in all marine habitats. They have been recognized as proxies to assess paleoenvironmental changes, however, their biological behaviors in modern environments needs to be further studied. The current study attempts to explain the biology of benthic foraminifera in terms of their living behaviors and molecular characterization, from different regions of the western side of the Arabian Gulf. Accordingly, two major groups of benthic foraminifera, namely rotaliids and miliolids, are examined under laboratory conditions. Results illustrate that the rotaliids are more resistant to environmental changes than miliolids, as their granular reticulopodial network is stronger than among the miliolids, with high cytoplasmic streaming. The pseudopodia extend out from both primary and secondary apertures, and aid the organism in locomotion by attaching to the wall of hard substrate. As a result they drag their whole bodies toward the direction of motion. In rotaliids, the movement rate is high and is attributed to the extension of pseudopodia through all apertures, compared with miliolids in which pseudopodia extend out from the primary aperture only. The innate behavior of both groups was observed as a function of external stimulus, i.e., light, nutrients, and availability of substrate. The observation on average life span reflected that the rotaliids was able to survive longer than miliolids. Molecular analysis reveals the presence of four groups, i.e., Ammonia, Murrayinella, Glabratellina, and Elphidium which support the morphological taxonomy at the genus level. However, BLAST analysis contradicts the species level taxonomy, which challenges the classification based upon hard-shell morphology. Nevertheless, monophyletic clustering is observed among all major groups. The study concludes that the morphological taxonomy needs to be augmented by molecular analysis

RESEARCH ON THE ENVIRONMENTAL QUALITY IN BRATIA RIVER

Directory of Open Access Journals (Sweden)

Alina - Mihaela Truţă

2017-12-01

Full Text Available The main purpose of the study was to determine the quality of Bratia River. The present paper was based on the bibliographic material as well as the field research carried out during 2016-2017. The research objectives were the following: identification of qualitative and quantitative structure of phytobenthic biocenoses in the established monitoring points; determination of the phytoplankton algae families in the monitoring stations; identification of the structure of benthic biocenoses in the monitoring points; establishing saprobity indices for each species identified and incorporation of the monitoring sections into the appropriate saprobity class; determining the quality of Bratia River according to the Water Framework Directive 2000/60/EU. We have identified 54 species in the phytobenthonic samples, grouped in three phyla: Cyanobacteria, Bacillariophyta and Chlorophyta. We have also identified 47 species in the structure of benthic zoocenosis belonging to 25 families from 8 genera. The main benthic invertebrate groups in the Bratia River were: Ephemeroptera, Plecoptera, Chironomidae, Trichoptera, and Gammaridae. Oboarele Mari and Gămăceşti recorded a high quality ecological status, while Berevoiesti station had a good ecological status.

Tolerance of benthic macroinvertebrates to organic enrichment in highland streams of northeastern Rio Grande do Sul, Brazil

Directory of Open Access Journals (Sweden)

Aline Correa Mazzoni

2014-06-01

Full Text Available AIM: the aim of this study was to determine the ecological valence of benthic macroinvertebrates at different pollution levels in highland rivers and streams of Rio Grande do Sul; METHODS: the dataset proceeds from samplings performed between 2002-2011 in 35 lotic ecosystems. The Chemical Index was used to determine pollution levels. Indices of richness and Shannon diversity were applied to characterize the structure of benthic communities. The descriptors used to determine taxa's ecological valence were selected according to Coefficient of Variation and regression analyses. Groups of tolerance were identified using Interquartile range and cluster analysis; RESULTS: Conductivity and Chemical Index were the descriptors best related with diversity of benthic macroinvertebrate community. These metrics were used to determine the tolerance range of 38 taxa. Interquartile range and cluster analysis revealed three groups of taxa, according to their occurrence in different levels of pollution: taxa with narrow amplitudes, present at sites with very low or very high load of organic enrichment; taxa with moderate amplitude, found until moderately polluted sites; and taxa with occurrence in widespread environmental conditions. The results, when compared to other studies in Brazil, showed differences in some taxa's tolerance. This observation indicates the need to assess the bioindication potential of these taxa in genus and species level; CONCLUSION: the present study contributes to increase knowledge about the bioindicator potential of benthic macroinvertebrates. Therefore, the study supports an advanced biomonitoring of ecological quality in mountain streams of southern Brazil.

Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California: 2014

Science.gov (United States)

Cain, Daniel J.; Thompson, Janet K.; Crauder, Jeff; Parcheso, Francis; Stewart, Robin; Kleckner, Amy E.; Dyke, Jessica; Hornberger, Michelle I.; Luoma, Samuel N.

2015-01-01

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer (km) south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2014 to December 2014. These append to long-term datasets extending back to 1974, and serve as the basis for the City of Palo Alto’s Near-Field Receiving Water Monitoring Program, initiated in 1994. 

Human exploitation and benthic community structure on a tropical intertidal mudflat

NARCIS (Netherlands)

Boer, de W.F.; Prins, H.H.T.

2002-01-01

Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic

Latest paleocene benthic extinction event on the southern tethyan shelf (Egypt): Foraminiferal stable isotopic (delta C-13,delta O-18) records

OpenAIRE

Schmitz, B; Speijer, Robert; Aubry, MP

1996-01-01

The dramatic global extinction of 35%-50% of benthic foraminifera species in the deep sea in the latest Paleocene and associated negative excursions in delta(13)C and delta(18)O may be related to spreading of warm, saline bottom water from subtropical Tethyan shallow regions over the sea floor worldwide, Our study of neritic sections in Egypt shows that in the southern shallow Tethys, a prominent long-term change in bottom-water chemistry, sedimentation, and benthic foraminifera fauna was ini...

Pacific Reef Assessment and Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, including Marine Debris Sightings, of the U.S. Pacific Reefs from 2000 to 2012

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Contrasting responses to long-term climate change of carbon flows to benthic consumers in two different sized lakes in the Baltic area.

Science.gov (United States)

Belle, Simon; Freiberg, Rene; Poska, Anneli; Agasild, Helen; Alliksaar, Tiiu; Tõnno, Ilmar

2018-05-01

The study of lake sediments and archived biological remains is a promising approach to better understand the impacts of climate change on aquatic ecosystems. Small lakes have been shown to be strongly sensitive to past climate change, but similar information is lacking for large lakes. By identifying responses to climate change of carbon flows through benthic food web in two different sized lakes, we aimed to understand how lake morphometry can mediate the effects of climate change. We reconstructed the dynamics of phytoplankton community composition and carbon resources sustaining chironomid biomass during the Holocene from the combined analysis of sedimentary pigment quantification and carbon stable isotopic composition of subfossil chironomid head capsules (δ13CHC) in a large lake in the Baltic area (Estonia). Our results showed that chironomid biomass in the large lake was mainly sustained by phytoplankton, with no significant relationship between δ13CHC values and temperature fluctuations. We suggest that lake morphometry (including distance of the sampling zone to the shoreline, and lake volume for primary producers) mediates the effects of climate change, making large lakes less sensitive to climate change. Complementary studies are needed to better understand differences in organic matter dynamics in different sized lakes and to characterize the response of the aquatic carbon cycle to past climate change.

THE WATER QUALITY DEGRADATION OF UPPER AWASH RIVER ...

African Journals Online (AJOL)

Osondu

2013-01-11

Jan 11, 2013 ... Benthic macroinvertebrate based assessment of water quality in the ... of the upper Awash River had low water quality status which is likely to be ..... Frydenborg, R., McCarron, E., White, J.S. and ... A framework for biological.

Aspects of the biology of three benthic-feeding teleosts from King's ...

African Journals Online (AJOL)

Aspects of the biology of three benthic-feeding teleosts from King's Beach, Algoa Bay. Theresa A. Lasiak. Department of Zoology, University of Port Elizabeth, Port Elizabeth. The lengths, abundance pattems and feeding habits of three species of benthic·feeding teleosts, Lithognathus mormyrus,. Lithognathus lithognathus ...

Response of benthic foraminifera to 4.2 ka cooling event in the Nakdong River delta, southeast Korea

Science.gov (United States)

Takata, H.; Khim, B. K.; Cheong, D.; Shin, S.

2016-02-01

Here we report the change of benthic foraminifera in response to 4.2 ka cooling event in the Nakdong River delta (southeastern Korea). It has been known that this cooling event caused climatic deteriorations in the world, which is closely related to the decline/development of the civilizations (e.g., Kawahata et al., 2009). This event was also correlated to one of Bond Events in the North Atlantic. Because coastal sediment depositions have been influenced by both oceanographic and terrestrial climatic changes, the study may provide us clue to understand the possible teleconnection of the cooling event between the North Atlantic and the East Asian margin. We investigated fossil benthic foraminiferal faunas and planktonic/total foraminiferal ratio (P/T ratio) at two borehole cores, ND-01 and ND-02 (landward and seaward sites, respectively). Common constituents are taxa from bay to shelf environments in the East Asian margin. Biotic response of benthic foraminifera partly changed after 4.2 ka showing that Haynesina sp. A (opportunistic species?) decreased significantly at core ND-01. In addition, P/T ratio at both core sites showed temporal decline at 4.2 ka. This suggests the decreasing influence of the seawater relative to the coastal water. Holocene fluctuations of the Tsushima Warm Current, a branch of Kuroshio, flowing off the Nakdong River delta, have been documented. The decline pattern of P/T ratio in this area is similar to that of total sulfur content in Lake Tougou-ike, southwestern Japan at 4 ka which was interpreted as the influence of the small sea-level falling (Kato et al., 2003). According to the similar stratigraphic variation patterns between our and their studies, our finding suggests that this event was not regional but related to the fluctuations of the Tsushima Warm Current. Thus, biotic response of benthic foraminifera in the Nakdong River delta recorded 4.2 ka cooling event related to temporal weakening of the Tsushima Warm Current.

Development of a benthic multimetric index for biomonitoring of a neotropical watershed

Directory of Open Access Journals (Sweden)

WR. Ferreira

Full Text Available Biotic indices are important tools for evaluating water quality in Biomonitoring Programmes of river basins. The objective of this study was to develop a Benthic Multimetric Index (BMI to evaluate the water quality in a neotropical catchment in southeastern Brazil. Thirty metrics were evaluated and six were selected to calculate the BMI: family richness, % Oligochaeta, % Chironomidae + Oligochaeta (% CHOL, % EPT (Ephemeroptera, Plecoptera and Trichoptera, % Collector-gatherers, and BMWP-CETEC biotic index. Sampling was carried in triplicate at 21 sampling sites (8 in the river channel and 13 in the tributaries during 4 annual collecting trips from June 2004 to November 2007, making a total of 945 samples. Scores (5, 3 or 1 were attributed to each chosen metric and were added up to establish the water quality criteria (a score of 6-12 - poor; 13-18 - intermediate; 19-24 - good; and 25-30 - very good water quality. Our results indicated that 48% of the sampling sites analysed in the catchment basin presented very good water quality, 14% good quality, 19% regular, and 19% poor water quality. This methodology proved to be an efficient tool for evaluating water quality in the Biomonitoring Programme of the Velhas River basin, and that it may serve to evaluate water quality in other river basins in South America.

Functional diversity of benthic ciliate communities in response to environmental gradients in a wetland of Yangtze Estuary, China.

Science.gov (United States)

Xu, Yuan; Fan, Xinpeng; Warren, Alan; Zhang, Liquan; Xu, Henglong

2018-02-01

Researches on the functional diversity of benthic ecosystems have mainly focused on macrofauna, and studies on functional structure of ciliate communities have been based only on trophic- or size-groups. Current research was carried out on the changing patterns of classical and functional diversity of benthic ciliates in response to environmental gradients at three sites in a wetland in Yangtze Estuary. The results showed that changes of environmental factors (e.g. salinity, sediment grain size and hydrodynamic conditions) in the Yangtze Estuary induce variability in species composition and functional trait distribution. Furthermore, increased species richness and diversity did not lead to significant changes in functional diversity due to functional redundancy. However, salt water intrusion of Yangtze Estuary during the dry season could cause reduced functional diversity of ciliate communities. Current study provides the first insight into the functional diversity of ciliate communities in response to environmental gradients. Copyright © 2018 Elsevier Ltd. All rights reserved.

Production by intertidal benthic animals and limits to their predation by shorebirds : a heuristic model

NARCIS (Netherlands)

Piersma, Theunis

1987-01-01

This review examines the question whether the cumulative amount of benthic biomass removed by feeding shorebirds on a certain intertidal area is limited by the renewal rate of benthic food stocks. Limitations of current methods to estimate both predatory impact by shorebirds and harvestable benthic

Benthic studies in south Gujarat estuaries

Digital Repository Service at National Institute of Oceanography (India)

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

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

Sources of beta diversity in estuarine benthic macro-invertebrate communities in the Baltic Sea - North Sea transition

DEFF Research Database (Denmark)

Josefson, Alf B.; Göke, Cordula

Identification of sources of beta diversity, the change of diversity, is important to understand regulation of overall diversity. Additive partitioning of diversity (species richness and expH) compared to random, was performed on a quantitative benthic macro-invertebrate collection of > 400 speci...

A Servicewide Benthic Mapping Program for National Parks

Science.gov (United States)

Moses, Christopher S.; Nayegandhi, Amar; Beavers, Rebecca; Brock, John

2010-01-01

In 2007, the National Park Service (NPS) Inventory and Monitoring Program directed the initiation of a benthic habitat mapping program in ocean and coastal parks in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. With 74 ocean and Great Lakes parks stretching over more than 5,000 miles of coastline across 26 States and territories, this Servicewide Benthic Mapping Program (SBMP) is essential. This program will deliver benthic habitat maps and their associated inventory reports to NPS managers in a consistent, servicewide format to support informed management and protection of 3 million acres of submerged National Park System natural and cultural resources. The NPS and the U.S. Geological Survey (USGS) convened a workshop June 3-5, 2008, in Lakewood, Colo., to discuss the goals and develop the design of the NPS SBMP with an assembly of experts (Moses and others, 2010) who identified park needs and suggested best practices for inventory and mapping of bathymetry, benthic cover, geology, geomorphology, and some water-column properties. The recommended SBMP protocols include servicewide standards (such as gap analysis, minimum accuracy, final products) as well as standards that can be adapted to fit network and park unit needs (for example, minimum mapping unit, mapping priorities). SBMP Mapping Process. The SBMP calls for a multi-step mapping process for each park, beginning with a gap assessment and data mining to determine data resources and needs. An interagency announcement of intent to acquire new data will provide opportunities to leverage partnerships. Prior to new data acquisition, all involved parties should be included in a scoping meeting held at network scale. Data collection will be followed by processing and interpretation, and finally expert review and publication. After publication, all digital materials will be archived in a common format. SBMP Classification Scheme. The SBMP will map using the Coastal and Marine Ecological

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

Science.gov (United States)

Barnes, David K A

2017-07-01

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

BENTHIC MACROFAUNAL ALIENS IN WILLAPA BAY

Science.gov (United States)

Benthic macrofaunal samples were collected at random stations in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Z...

Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Upper Coast of Texas: BENTHIC (Benthic habitat polygons)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains known locations of patchy and continuous seagrass and oyster reef habitat for the Upper Coast of Texas benthic habitat data. This data set...

Inland-coastal water interaction: Remote sensing application for shallow-water quality and algal blooms modeling

Science.gov (United States)

Melesse, Assefa; Hajigholizadeh, Mohammad; Blakey, Tara

2017-04-01

In this study, Landsat 8 and Sea-Viewing Wide Field-of-View Sensor (SeaWIFS) sensors were used to model the spatiotemporal changes of four water quality parameters: Landsat 8 (turbidity, chlorophyll-a (chl-a), total phosphate, and total nitrogen) and Sea-Viewing Wide Field-of-View Sensor (SeaWIFS) (algal blooms). The study was conducted in Florda bay, south Florida and model outputs were compared with in-situ observed data. The Landsat 8 based study found that, the predictive models to estimate chl-a and turbidity concentrations, developed through the use of stepwise multiple linear regression (MLR), gave high coefficients of determination in dry season (wet season) (R2 = 0.86(0.66) for chl-a and R2 = 0.84(0.63) for turbidity). Total phosphate and TN were estimated using best-fit multiple linear regression models as a function of Landsat TM and OLI,127 and ground data and showed a high coefficient of determination in dry season (wet season) (R2 = 0.74(0.69) for total phosphate and R2 = 0.82(0.82) for TN). Similarly, the ability of SeaWIFS for chl-a retrieval from optically shallow coastal waters by applying algorithms specific to the pixels' benthic class was evaluated. Benthic class was determined through satellite image-based classification methods. It was found that benthic class based chl-a modeling algorithm was better than the existing regionally-tuned approach. Evaluation of the residuals indicated the potential for further improvement to chl-a estimation through finer characterization of benthic environments. Key words: Landsat, SeaWIFS, water quality, Florida bay, Chl-a, turbidity

National Coral Reef Monitoring Program: Benthic Images Collected from Climate Stations across the Mariana Archipelago in 2014 (NCEI Accession 0157759)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across the Mariana...

Benthic carbonate factories of the Phanerozoic

NARCIS (Netherlands)

Schlager, W.

2003-01-01

Marine carbonate precipitation occurs in three basic modes: abiotic (or quasi-abiotic), biotically induced, and biotically controlled. On a geologic scale, these precipitation modes combine to form three carbonate production systems, or "factories" in the benthic environment: (1) tropical

Food web flows through a sub-arctic deep-sea benthic community

Science.gov (United States)

Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

2011-11-01

The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

Benthic plastic debris in marine and fresh water environments.

Science.gov (United States)

Corcoran, Patricia L

2015-08-01

This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

Variability in benthic exchange rate, depth, and residence time beneath a shallow coastal estuary

Science.gov (United States)

Russoniello, C. J.; Michael, H. A.; Heiss, J.

2017-12-01

Hydrodynamically-driven exchange of water between the water column and shallow seabed aquifer, benthic exchange, is a significant and dynamic component of coastal and estuarine fluid budgets, but wave-induced benthic exchange has not been measured in the field. Mixing between surface water and groundwater solutes promotes ecologically important chemical reactions, so quantifying benthic exchange rates, depths, and residence times, constrains estimates of coastal chemical cycling. In this study, we present the first field-based direct measurements of wave-induced exchange and compare it to exchange induced by the other primary drivers of exchange - tides, and currents. We deployed instruments in a shallow estuary to measure benthic exchange and temporal variability over an 11-day period. Differential pressure sensors recorded pressure gradients across the seabed, and up-and down-looking ADCPs recorded currents and pressures from which wave parameters, surface-water currents, and water depth were determined. Wave-induced exchange was calculated directly from 1) differential pressure measurements, and indirectly with an analytical solution based on wave parameters from 2) ADCP and 3) weather station data. Groundwater flow models were used to assess the effects of aquifer properties on benthic exchange depth and residence time. Benthic exchange driven by tidal pumping or current-bedform interaction was calculated from tidal stage variation and from ADCP-measured currents at the bed, respectively. Waves were the primary benthic exchange driver (average = 20.0 cm/d, maximum = 92.3 cm/d) during the measurement period. Benthic exchange due to tides (average = 3.7 cm/d) and current-bedform interaction (average = 6.5x10-2 cm/d) was much lower. Wave-induced exchange calculated from pressure measurements and ADCP-measured wave parameters matched well, but wind-based rates underestimated wave energy and exchange. Groundwater models showed that residence time and depth increased

Global assessment of benthic nepheloid layers and linkage with upper ocean dynamics

Science.gov (United States)

Gardner, Wilford D.; Richardson, Mary Jo; Mishonov, Alexey V.

2018-01-01

Global maps of the maximum bottom concentration, thickness, and integrated particle mass in benthic nepheloid layers are published here to support collaborations to understand deep ocean sediment dynamics, linkage with upper ocean dynamics, and assessing the potential for scavenging of adsorption-prone elements near the deep ocean seafloor. Mapping the intensity of benthic particle concentrations from natural oceanic processes also provides a baseline that will aid in quantifying the industrial impact of current and future deep-sea mining. Benthic nepheloid layers have been mapped using 6,392 full-depth profiles made during 64 cruises using our transmissometers mounted on CTDs in multiple national/international programs including WOCE, SAVE, JGOFS, CLIVAR-Repeat Hydrography, and GO-SHIP during the last four decades. Intense benthic nepheloid layers are found in areas where eddy kinetic energy in overlying waters, mean kinetic energy 50 m above bottom (mab), and energy dissipation in the bottom boundary layer are near the highest values in the ocean. Areas of intense benthic nepheloid layers include the Western North Atlantic, Argentine Basin in the South Atlantic, parts of the Southern Ocean and areas around South Africa. Benthic nepheloid layers are weak or absent in most of the Pacific, Indian, and Atlantic basins away from continental margins. High surface eddy kinetic energy is associated with the Kuroshio Current east of Japan. Data south of the Kuroshio show weak nepheloid layers, but no transmissometer data exist beneath the Kuroshio, a deficiency that should be remedied to increase understanding of eddy dynamics in un-sampled and under-sampled oceanic areas.

Antarctic sea ice losses drive gains in benthic carbon drawdown.

Science.gov (United States)

Barnes, D K A

2015-09-21

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

Benthic ecological mapping of the Ayeyarwady delta shelf off Myanmar, using foraminiferal assemblages

Digital Repository Service at National Institute of Oceanography (India)

Panchang, R.; Nigam, R.

Information on benthic ecologies is a prerequisite to evaluate marine resources, their management and monitoring the impact arising from their exploitation. In the present study, benthic foraminiferal distributions from 124 surface sediment samples...

Soundscape of a management and exploitation area of benthic resources in central Chile

Directory of Open Access Journals (Sweden)

Alfredo Borie

2015-11-01

Full Text Available Acoustic ecology is an emerging and poorly known field of research. Soundscape has been used to infer the behavior of several species in different environments and can serve as a reliable indicator of the habitat type and quality; also, it is believed that it is an important factor for larvae orientation in settlement areas. We used the passive acoustic method to evaluate the soundscape of a management and exploitation area of benthic resources, a rocky reef area in central Chile. It was possible to hear a continuous cracking sound during recording and underwater observations. We detected two distinct frequency bands with similar parameters during the night and day, a band between 90 and 300 Hz, which corresponded to the effects of sea waves (geophony, and a frequency band with a range of 1,500 to 2,700 Hz (biophony, with a fundamental frequency of 2,070 Hz. Both bands had similar energy (~88.0 dB re: 1V/µPa. These results show the relevant acoustic activity in the area, which may have important ecological implications for the recruitment of commercially important benthic resources.

Modeling food web interactions in benthic deep-sea ecosystems. A practical guide

NARCIS (Netherlands)

Soetaert, K.E.R.; Van Oevelen, D.J.

2009-01-01

Deep-sea benthic systems are notoriously difficult to sample. Even more than for other benthic systems, many flows among biological groups cannot be directly measured, and data sets remain incomplete and uncertain. In such cases, mathematical models are often used to quantify unmeasured biological

Biodiversity assessment of benthic macroinvertebrates along a reservoir cascade in the lower São Francisco river (northeastern Brazil

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M. Callisto

Full Text Available In order to verify the cascade-system effect in benthic macroinvertebrate communities, and the implications for policy making and proposals for conservation and sustainable use of the lower portion of São Francisco river basin (Bahia State, Brazil, a three-reservoir cascade system including two stretches downstream were studied during dry (June, 1997 and rainy (March, 1998 periods. The dominant groups found were Mollusca (Melanoides tuberculata, Oligochaeta, and Chironomidae larvae. Low Shannon-Wiener and Pielou index values were found, but with no significant difference between the sampling periods. However, density and taxonomic richness were significantly different (t(0.05; 31 = -2.1945; p < 0.05; e t(0.05; 31 = -3.0600; p < 0.01 between the sampling periods, with a reduction in the number of taxaand macroinvertebrate abundance during the rainy period. An increasing gradient in benthic macroinvertebrate community structures was noted along the reservoir cascade from the first reservoir (Apolônio Sales, followed by a decrease downstream from the third reservoir of the system (Xingó. Despite the negative consequences of rapid proliferation of dams, which have caused widespread loss of freshwater habitats, the reservoir cascade system promoted an increase in benthic macroinvertebrate diversity, due to water-quality improvement along the system.

Contribution of benthic microalgae to the temporal variation in phytoplankton assemblages in a macrotidal system.

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Hernández Fariñas, Tania; Ribeiro, Lourenço; Soudant, Dominique; Belin, Catherine; Bacher, Cédric; Lampert, Luis; Barillé, Laurent

2017-10-01

Suspended marine benthic microalgae in the water column reflect the close relationship between the benthic and pelagic components of coastal ecosystems. In this study, a 12-year phytoplankton time-series was used to investigate the contribution of benthic microalgae to the pelagic system at a site along the French-Atlantic coast. Furthermore, all taxa identified were allocated into different growth forms in order to study their seasonal patterns. The highest contribution of benthic microalgae was observed during the winter period, reaching up to 60% of the carbon biomass in the water column. The haptobenthic growth form showed the highest contribution in terms of biomass, dominant in the fall-winter period when the turbidity and the river flow were high. The epipelic growth form did not follow any seasonal pattern. The epiphytic diatom Licmophora was most commonly found during summer. As benthic microalgae were found in the water column throughout the year, the temporal variation detected in the structure of pelagic assemblages in a macrotidal ecosystem was partly derived from the differentiated contribution of several benthic growth forms. © 2017 Phycological Society of America.

Native freshwater species get out of the way: Prussian carp (Carassius gibelio) impacts both fish and benthic invertebrate communities in North America.

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Ruppert, Jonathan L W; Docherty, Cassandra; Neufeld, Kenton; Hamilton, Kyle; MacPherson, Laura; Poesch, Mark S

2017-10-01

Prussian carp ( Carassius gibelio ) are one of the most noxious non-native species in Eurasia. Recently, Prussian carp, a non-native freshwater fish species, were genetically confirmed in Alberta, Canada and have been rapidly expanding their range in North America since establishment. Given their rapid range expansion, there is an increasing need to determine how Prussian carp may impact native species. We assessed the severity of the Prussian carp invasion by (i) determining their impact on fish communities, (ii) assessing their impact on benthic invertebrate communities, (iii) evaluating if Prussian carp alter abiotic conditions, and (iv) identifying where we find higher abundances of Prussian carp. When Prussian carp were established, we found significant changes to the fish community. Correspondingly, the degree of impact to benthic invertebrate communities was related to the stage of invasion (none, early or recent), where changes in fish communities were significantly concordant with changes in benthic invertebrate communities. Finally, we found that higher abundances of Prussian carp were significantly associated with lower abundances of a majority of native fish species. Altogether, using three lines of evidence, we determine that Prussian carp can have wide-ranging impacts on freshwater ecosystems in North America, pressing the need for management intervention.

Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

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This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

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Andreas F Haas

Full Text Available Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata--Ochrophyta; Amansia rhodantha--Rhodophyta; Halimeda opuntia--Chlorophyta, a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii and a dominant hermatypic coral (Porites lobata. Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h⁻¹ dm⁻², stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h⁻¹ and concomitant oxygen drawdown (0.16±0.05 µmol L⁻¹ h⁻¹ dm⁻². Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence

Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

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Leticia M. Mesa

2013-12-01

Full Text Available The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

Atlantic Deep-Water Canyons (Benthic Landers) 2013

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National Oceanic and Atmospheric Administration, Department of Commerce — Each benthic lander contains a programmable sediment trap which can take 12 monthly samples, plus instruments to record temperature, salinity, dissolved oxygen,...

Use of tolerance values to diagnose water-quality stressors to aquatic biota in New England streams

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Meador, M.R.; Carlisle, D.M.; Coles, J.F.

2008-01-01

Identification of stressors related to biological impairment is critical to biological assessments. We applied nationally derived tolerance indicator values for four water-quality variables to fish and benthic macroinvertebrate assemblages at 29 sites along an urban gradient in New England. Tolerance indicator values (TIVs), as biologically based predictors of water-quality variables, were determined for dissolved oxygen, nitrite plus nitrate (nitrate), total phosphorus, and water temperature for each site based on observed biological assemblages (TIVO), and for expected assemblages (TIVE). The quotient method, based on a ratio of the TIVs for observed and expected assemblages (tolerance units), was used to diagnose potential water-quality stressors. In addition, the ratio of measured water-quality values to water-quality criteria (water-quality units) was calculated for each water-quality variable to assess measured water-quality stressors. Results from a RIVPACS predictive model for benthic macroinvertebrates and Bray-Curtis dissimilarity for fish were used to classify sites into categories of good or impaired ecological condition. Significant differences were detected between good and impaired sites for all biological tolerance units (fish and benthic macroinvertebrate assemblages averaged) except for nitrate (P = 0.480), and for all water-quality units except for nitrate (P = 0.183). Diagnosis of water-quality stressors at selected sites was, in general, consistent with State-reported causes of impairment. Tolerance units for benthic macroinvertebrate and fish assemblages were significantly correlated for water temperature (P = 0.001, r = 0.63), dissolved oxygen (P = 0.001, r = 0.61), and total phosphorus (P = 0.001, r = 0.61), but not for nitrate (P = 0.059, r = -0.35). Differences between the two assemblages in site-specific diagnosis of water-quality stressors may be the result of differences in nitrate tolerance.

Immediate response of meio and macrobenthos to disturbance caused by a benthic disturber

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Ingole, B.S.; Ansari, Z.A.; Matondkar, S.G.P.; Rodrigues, N.

The probable impact of nodule mining on benthic biota was studied by creating a benthic disturbance. During the predisturbance study in the Central Indian Basin, box core samples were analyzed for the distribution, composition and abundance...

Latest Paleocene benthic extinction event on the southern Tethyan shelf (Egypt): Foraminiferal stable isotopic (δ13C, δ18O) records

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Schmitz, B.; Speijer, R. P.; Aubry, M.-P.

1996-04-01

The dramatic global extinction of 35% 50% of benthic foraminifera species in the deep sea in the latest Paleocene and associated negative excursions in δ13C and δ18O may be related to spreading of warm, saline bottom water from subtropical Tethyan shallow regions over the sea floor worldwide. Our study of neritic sections in Egypt shows that in the southern shallow Tethys, a prominent long-term change in bottom-water chemistry, sedimentation, and benthic foraminifera fauna was initiated at the time when the deep-sea benthic extinction event (BEE) took place. Bottom-water δ13C values on the Tethyan shelf show a sudden 3.0‰ negative shift at this event; however, contrary to the deep sea, in which the δ13C excursion was of short duration, Tethyan δ13C values did not fully return to preboundary values, but remained depressed by ˜1.5‰ for at least 1 m.y. The δ13C values at the Egyptian shelf during the BEE are much lower than would be expected if this was a source region for global deep water. The δ18O values indicate no significant change in bottom-water salinity or temperature at the BEE. The long-lasting environmental changes that began on the Egyptian shelf at the BEE may be related to, for example, gateway reorganization along the Tethyan seaway. Paleogeographic changes possibly also triggered a change in the loci of global deep-water formation; however, these loci must be sought in another part of the Tethys.

Quantifying benthic nitrogen fluxes in Puget Sound, Washington: a review of available data

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Sheibley, Richard W.; Paulson, Anthony J.

2014-01-01

Understanding benthic fluxes is important for understanding the fate of materials that settle to the Puget Sound, Washington, seafloor, as well as the impact these fluxes have on the chemical composition and biogeochemical cycles of marine waters. Existing approaches used to measure benthic nitrogen flux in Puget Sound and elsewhere were reviewed and summarized, and factors for considering each approach were evaluated. Factors for selecting an appropriate approach for gathering information about benthic flux include: availability of resources, objectives of projects, and determination of which processes each approach measures. An extensive search of literature was undertaken to summarize known benthic nitrogen fluxes in Puget Sound. A total of 138 individual flux chamber measurements and 38 sets of diffusive fluxes were compiled for this study. Of the diffusive fluxes, 35 new datasets were located, and new flux calculations are presented in this report. About 65 new diffusive flux calculations are provided across all nitrogen species (nitrate, NO3-; nitrite, NO2-; ammonium, NH4+). Data analysis of this newly compiled benthic flux dataset showed that fluxes beneath deep (greater than 50 meters) water tended to be lower than those beneath shallow (less than 50 meters) water. Additionally, variability in flux at the shallow depths was greater, possibly indicating a more dynamic interaction between the benthic and pelagic environments. The overall range of bottom temperatures from studies in the Puget Sound area were small (5–16 degrees Celsius), and only NH4+ flux showed any pattern with temperature. For NH4+, flux values and variability increased at greater than about 12 degrees Celsius. Collection of additional study site metadata about environmental factors (bottom temperature, depth, sediment porosity, sediment type, and sediment organic matter) will help with development of a broader regional understanding benthic nitrogen flux in the Puget Sound.

Benthic algal production across lake size gradients: interactions among morphometry, nutrients, and light.

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Vadeboncoeur, Yvonne; Peterson, Garry; Vander Zanden, M Jake; Kalff, Jacob

2008-09-01

Attached algae play a minor role in conceptual and empirical models of lake ecosystem function but paradoxically form the energetic base of food webs that support a wide variety of fishes. To explore the apparent mismatch between perceived limits on contributions of periphyton to whole-lake primary production and its importance to consumers, we modeled the contribution of periphyton to whole-ecosystem primary production across lake size, shape, and nutrient gradients. The distribution of available benthic habitat for periphyton is influenced by the ratio of mean depth to maximum depth (DR = z/ z(max)). We modeled total phytoplankton production from water-column nutrient availability, z, and light. Periphyton production was a function of light-saturated photosynthesis (BPmax) and light availability at depth. The model demonstrated that depth ratio (DR) and light attenuation strongly determined the maximum possible contribution of benthic algae to lake production, and the benthic proportion of whole-lake primary production (BPf) declined with increasing nutrients. Shallow lakes (z benthic or pelagic primary productivity depending on trophic status. Moderately deep oligotrophic lakes had substantial contributions by benthic primary productivity at low depth ratios and when maximum benthic photosynthesis was moderate or high. Extremely large, deep lakes always had low fractional contributions of benthic primary production. An analysis of the world's largest lakes showed that the shapes of natural lakes shift increasingly toward lower depth ratios with increasing depth, maximizing the potential importance of littoral primary production in large-lake food webs. The repeatedly demonstrated importance of periphyton to lake food webs may reflect the combination of low depth ratios and high light penetration characteristic of large, oligotrophic lakes that in turn lead to substantial contributions of periphyton to autochthonous production.

Herbivorous snails can increase water clarity by stimulating growth of benthic algae.

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Zhang, Xiufeng; Taylor, William D; Rudstam, Lars G

2017-11-01

Eutrophication in shallow lakes is characterized by a switch from benthic to pelagic dominance of primary productivity that leads to turbid water, while benthification is characterized by a shift in primary production from the pelagic zone to the benthos associated with clear water. A 12-week mesocosm experiment tested the hypothesis that the herbivorous snail Bellamya aeruginosa stimulates the growth of pelagic algae through grazing on benthic algae and through accelerating nutrient release from sediment. A tube-microcosm experiment using 32 P-PO 4 as a tracer tested the effects of the snails on the release of sediment phosphorus (P). The mesocosm experiment recorded greater total nitrogen (TN) concentrations and a higher ratio of TN:TP in the overlying water, and a higher light intensity and biomass of benthic algae as measured by chlorophyll a (Chl a) in the snail treatment than in the control. Concentrations of total phosphorus (TP), total suspended solids (TSSs), and inorganic suspended solids (ISSs) in the overlying water were lower in the snail treatment than in the control, though no significant difference in Chl a of pelagic algae between the snail treatment and control was observed. In the microcosm experiment, 32 P activity in the overlying water was higher in the snail treatment than in the control, indicating that snails accelerated P release from the sediment. Our interpretation of these results is that snails enhanced growth of benthic algae and thereby improved water clarity despite grazing on the benthic algae and enhancing P release from the sediment. The rehabilitation of native snail populations may therefore enhance the recovery of eutrophic shallow lakes to a clear water state by stimulating growth of benthic algae.

Application of TSL Underwater Robots (AUV) for Investigation of Benthic Ecosystems and Quantification of Benthic Invertebrate Reserves

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Golikov, S. Yu; Dulepov, V. I.; Maiorov, I. S.

2017-11-01

The issues on the application of autonomous underwater vehicles for assessing the abundance, biomass, distribution and reserves of invertebrates in the marine benthic ecosystems and on the environmental monitoring are discussed. An example of the application of methodology to assess some of the quantitative characteristics of macrobenthos is provided based upon using the information obtained from the TSL AUV in the Peter the Great Gulf (the Sea of Japan) in the Bay of Paris and the Eastern Bosphorus Strait within the area of the bridge leading to the Russian island. For the quantitative determination of the benthic invertebrate reserves, the values of biomass density of specific species are determined. Based on the data of direct measurements and weightings, the equations of weight dependencies on the size of animals are estimated according to the studied species that are well described by the power law dependence.

Shallow-water Benthic Habitats in Jobos Bay

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National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of Jobos Bay, Puerto Rico were mapped and characterized using visual interpretation...

Benthic fauna of 41 acid sensitive headwater lakes in north central Ontario. [Chironomidae salinarius; Chironomidae anthracinus; Tanytarsini

Energy Technology Data Exchange (ETDEWEB)

Dermott, R.; Kelso, J.R.M.; Douglas, A.

1986-01-01

The benthic fauna of 41 nonhumic, soft water lakes situated north of lakes Superior and Huron were sampled during 1980. The pH range of the lakes sampled was 4.6 to 7.7. The benthic infauna displayed regional differences in abundance and composition, with large variation with each district. Total abundance, biomass, and number of taxa were not correlated with lake pH or alkalinity. The Chironomidae displayed a slight change in percent composition of the major species with lower pH. The Tanytarsini and Chironomus Salinarius group decreased, while C. anthracinus group increased in relative abundance in those lakes with lower pH. Other factors appear to control the distribution of the various invertebrate orders, with depth and sediment nature being important variables.

Blooms of a benthic ciliate, Maristentor dinoferus (Heterotrichea: Maristentoridae, on coral reefs of Guam, Mariana Islands. (Note

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Schefter, M.

2012-05-01

Full Text Available Maristentor dinoferus is visible in situ with the naked eye; it forms aggregations at several scales: individuals form dynamic clusters within colonies that are normally widely scattered, but in recurrent blooms during the dry seasons of 2005 through 2007, colonies often formed close together in patches (metapopulations. Patches were extremely abundant in Guam, both in Apra Harbor and on the outer coast. This is the first time that long-term changes in a benthic ciliate population have been documented in situ and that multi-scale patchiness has been reported for a benthic ciliate. Colonies were mapped and monitored; some patches over 1 m diameter were recorded. Since 2008, the distribution has again consisted of scattered colonies, as it did from 1999–2004.

Benthic macrofauna variations and community structure in Cenomanian cyclic chalk-marl from Southerham Grey Pit, SE England

DEFF Research Database (Denmark)

Lauridsen, Bodil Wesenberg; Gale, A. S.; Surlyk, Finn

2009-01-01

Cenomanian chalk-marl couplets from England represent the 20 ka Milankovitch precession cycle. Fossil communities from both chalk and marl are identified to test if the orbital fluctuations and the associated changes in substrate lithology and climate exerted any control on the benthic macrofauna...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, including Marine Debris Sightings, of American Samoa from 2015-02-15 to 2015-03-23 (NCEI Accession 0157566)

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National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Recent benthic foraminifera and sedimentary facies distribution of the Abu Dhabi (United Arab Emirates) coastline

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Fiorini, Flavia; Lokier, Stephen W.

2014-05-01

The distribution of benthic foraminifera and sedimentary facies from Recent coastline environments adjacent to the coastline of Abu Dhabi (UAE) was studied in detail with the aim to: 1) provide reliable analogs for understanding and interpreting the depositional environment of ancient shallow-marine sediments from the UAE; 2) assess any modifications in the distribution of benthic environments and sedimentary facies in an area affected by significant anthropogenic activities - particular construction and land reclamation. A total of 100 sea-floor sediment samples were collected in different shallow-marine sedimentary environments (nearshore shelf, beach-front, channels, ooid shoals, lagoon and mangals) close to the coastline of Abu Dhabi Island. Where possible, we revisited the sampling sites used in several studies conducted in the middle of last century (prior to any significant anthropogenic activities) to assess temporal changes in Recent benthic foraminifera and sedimentary facies distribution during the last 50 years. Five foraminiferal assemblages were recognized in the studied area. Species with a porcellaneous test mainly belonging to the genera Quinqueloculina, Triloculina, Spiroloculina, Sigmoilinita are common in all studied areas. Larger benthic foraminifera Peneroplis and Spirolina are particularly abundant in samples collected on seaweed. Hyaline foraminifera mostly belonging to the genera Elphidium, Ammonia, Bolivina and Rosalina are also common together with Miliolidae in the nearshore shelf and beach front. Agglutinated foraminifera (Clavulina, Textularia, Ammobaculites and Reophax) are present in low percentages. The species belonging to the genera Ammobaculites and Reophax are present only in the finest grain samples particularly in lagoons and mangal environments and have not been reported previously in the studied area. The majority of the ooid shoal sediments, the coarser sediments of the beach-front and samples collected in dredged channels

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

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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

Relation of periphyton and benthic invertebrate communities to environmental factors and land use at selected sites in part of the upper Mississippi River basin, 1996-98

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ZumBerge, Jeremy Ryan; Lee, Kathy E.; Goldstein, Robert M.

2003-01-01

The Upper Mississippi River Basin is one of the hydrologic systems selected for study by the National Water-Quality Assessment (NAWQA) Program of the U.S. Geological Survey. NAWQA utilizes a multi-disciplinary approach to explain factors that affect water quality. Part of the NAWQA design addresses the relation of land use and environmental factors to periphyton and benthic invertebrate communities in streams.

USVI Land-Based Threat to Benthic Habitats

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National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's study,...

Carbon cycling in the deep eastern North Pacific benthic food web: Investigating the effect of organic carbon input

NARCIS (Netherlands)

Dunlop, K.M.; Van Oevelen, D.; Ruhl, H.A.; Huffard, C.L.; Kuhnz, L.A.; Smith, K.L.

2016-01-01

The deep ocean benthic environment plays a role in long-term carbon sequestration. Understanding carbon cycling in the deep ocean floor is critical to evaluate the impact of changing climate on the oceanic systems. Linear inverse modeling was used to quantify carbon transfer between compartments in

Relationship between bifenthrin sediment toxic units and benthic community metrics in urban California streams.

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Hall, Lenwood W; Anderson, Ronald D

2013-08-01

The objective of this study was to use ecologically relevant field measurements for determining the relationship between bifenthrin sediment toxic units (TUs) (environmental concentrations/Hyalella acute LC50 value) and 15 benthic metrics in four urban California streams sampled from 2006 to 2011. Data from the following four California streams were used in the analysis: Kirker Creek (2006, 2007), Pleasant Grove Creek (2006, 2007, and 2008), Arcade Creek (2009, 2010, and 2011), and Salinas streams (2009, 2010, and 2011). The results from univariate analysis of benthic metrics versus bifenthrin TU calculations for the four California streams with multiple-year datasets combined by stream showed that there were either nonsignificant relationships or lack of metric data for 93 % of cases. For 7 % of the data (4 cases) where significant relationships were reported between benthic metrics and bifenthrin TUs, these relationships were ecologically meaningful. Three of these significant direct relationships were an expression of tolerant benthic taxa (either % tolerant taxa or tolerance values, which are similar metrics), which would be expected to increase in a stressed environment. These direct significant tolerance relationships were reported for Kirker Creek, Pleasant Grove Creek, and Arcade Creek. The fourth significant relationship was an inverse relationship between taxa richness and bifenthrin TUs for the 3-year Pleasant Grove Creek dataset. In summary, only a small percent of the benthic metric × bifenthrin TU relationships were significant for the four California streams. Therefore, the general summary conclusion from this analysis is that there is no strong case for showing consistent meaningful relationships between various benthic metrics used to characterize the status of benthic communities and bifenthrin TUs for these four California streams.

Benthic Dinitrogen Fixation Traversing the Oxygen Minimum Zone Off Mauritania (NW Africa

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Jessica Gier

2017-12-01

Full Text Available Despite its potential to provide new nitrogen (N to the environment, knowledge on benthic dinitrogen (N2 fixation remains relatively sparse, and its contribution to the marine N budget is regarded as minor. Benthic N2 fixation is often observed in organic-rich sediments coupled to heterotrophic metabolisms, such as sulfate reduction. In the present study, benthic N2 fixation together with sulfate reduction and other heterotrophic metabolisms were investigated at six station between 47 and 1,108 m water depth along the 18°N transect traversing the highly productive upwelling region known as Mauritanian oxygen minimum zone (OMZ. Bottom water oxygen concentrations ranged between 30 and 138 μM. Benthic N2 fixation determined by the acetylene reduction assay was detected at all stations with highest rates (0.15 mmol m−2 d−1 on the shelf (47 and 90 m water depth and lowest rates (0.08 mmol m−2 d−1 below 412 m water depth. The biogeochemical data suggest that part of the N2 fixation could be linked to sulfate- and iron-reducing bacteria. Molecular analysis of the key functional marker gene for N2 fixation, nifH, confirmed the presence of sulfate- and iron-reducing diazotrophs. High N2 fixation further coincided with bioirrigation activity caused by burrowing macrofauna, both of which showed high rates at the shelf sites and low rates in deeper waters. However, statistical analyses proved that none of these processes and environmental variables were significantly correlated with benthic diazotrophy, which lead to the conclusion that either the key parameter controlling benthic N2 fixation in Mauritanian sediments remains unidentified or that a more complex interaction of control mechanisms exists. N2 fixation rates in Mauritanian sediments were 2.7 times lower than those from the anoxic Peruvian OMZ.

Benthic response to the sedimentation of particulate organic matter at the BIOTRANS station, 47°N, 20°W

Science.gov (United States)

Pfannkuche, O.

The benthic response to the sedimentation of particulate organic matter (POM) was investigated during 1985-1990 at 47°N, 20°W (BIOTRANS station). The first noticeable annual sedimentation of phytodetritus, as indicated by chlorophyll a concentrations in the sediment, occurred as early as late April-early May. Maximum amounts were found in June-July. Two different sedimentation pulses to the sea bed are described that demonstrate interannual variation: the occurrence of salp faecal pellets early in the year 1988 and the massive fall out of a plankton bloom in summer 1986, which deposited approximately 15 mmol C m -2. The benthic reaction to POM pulses was quite diverse. The mega-, macro- and meiobenthos showed no change in biomass, whereas bacterial biomass doubled between March and July. This corresponds to a seasonal maximum of total adenylate biomass. The relative abundance of Foraminifera among the meiobenthos increased during the summer. Benthic activity (ATP, ratio ATP/ETSA), as well as in situ sediment community oxygen consumption rates (SCOC), showed distinct seasonal maxima in July-August of 0.75 mmol C m -2 day -1. Based on SCOC and the carbon demand for growth, a benthic carbon consumption of 0.94 mmol C m -2 day -1 was estimated. This represents about 1.1% of spring bloom primary production and 9.6% of the export flux beneath the 150 m layer, measured during the North Atlantic Bloom Experiment. Bacteria and protozoans colonizing the epibenthic phytodetrital layer were responsible for 60-80% of the seasonal increase in SCOC. The strong reaction of the smaller benthic size groups (bacteria, protozoans) to POM pulses stresses their particular importance for sediment-water interface flux rates.

Benthic carbon mineralization in hadal trenches

DEFF Research Database (Denmark)

Wenzhofer, F.; Oguri, K.; Middelboe, M.

2016-01-01

Hadal trenches are considered to act as depo-centers for organic material at the trench axis and host unique and elevated biomasses of living organisms as compared to adjacent abyssal plains. To explore the diagenetic activity in hadal trench environments we quantified in situ benthic O-2 consump...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, including Marine Debris Sightings, of the Hawaiian Archipelago from 2016-07-13 to 2016-09-26 (NCEI Accession 0157565)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitats, Key Benthic Species, and Marine Debris Sightings of the Mariana Archipelago from 2017-05-04 to 2017-06-20 (NCEI Accession 0166629)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Spatial analyses of benthic habitats to define coral reef ecosystem regions and potential biogeographic boundaries along a latitudinal gradient.

Directory of Open Access Journals (Sweden)

Brian K Walker

Full Text Available Marine organism diversity typically attenuates latitudinally from tropical to colder climate regimes. Since the distribution of many marine species relates to certain habitats and depth regimes, mapping data provide valuable information in the absence of detailed ecological data that can be used to identify and spatially quantify smaller scale (10 s km coral reef ecosystem regions and potential physical biogeographic barriers. This study focused on the southeast Florida coast due to a recognized, but understudied, tropical to subtropical biogeographic gradient. GIS spatial analyses were conducted on recent, accurate, shallow-water (0-30 m benthic habitat maps to identify and quantify specific regions along the coast that were statistically distinct in the number and amount of major benthic habitat types. Habitat type and width were measured for 209 evenly-spaced cross-shelf transects. Evaluation of groupings from a cluster analysis at 75% similarity yielded five distinct regions. The number of benthic habitats and their area, width, distance from shore, distance from each other, and LIDAR depths were calculated in GIS and examined to determine regional statistical differences. The number of benthic habitats decreased with increasing latitude from 9 in the south to 4 in the north and many of the habitat metrics statistically differed between regions. Three potential biogeographic barriers were found at the Boca, Hillsboro, and Biscayne boundaries, where specific shallow-water habitats were absent further north; Middle Reef, Inner Reef, and oceanic seagrass beds respectively. The Bahamas Fault Zone boundary was also noted where changes in coastal morphologies occurred that could relate to subtle ecological changes. The analyses defined regions on a smaller scale more appropriate to regional management decisions, hence strengthening marine conservation planning with an objective, scientific foundation for decision making. They provide a framework

Benthic macroinvertebrates in Italian rice fields

Directory of Open Access Journals (Sweden)

Daniela Lupi

2013-02-01

Full Text Available Rice fields can be considered man-managed temporary wetlands. Five rice fields handled with different management strategies, their adjacent channels, and a spring were analysed by their benthic macroinvertebrate community to i evaluate the role of rice agroe- cosystem in biodiversity conservation; ii find indicator species which can be used to compare the ecological status of natural wetlands with rice agroecosystems; and iii find the influence of environmental variables on biodiversity. Different methods of data analysis with increasing degree of complexity – from diversity index up to sophisticated multivariate analysis – were used. The investigation provided a picture of benthic macroinvertebrates inhabiting rice agroecosystems where 173 taxa were identified, 89 of which detected in rice paddies. Among them, 4 phyla (Mollusca, Annelida, Nematomorpha, and Arthropoda, 8 classes (Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Gordioida, Insecta, Branchiopoda, and Malacostraca, 24 orders, 68 families, 127 genera and 159 species have been found. Ten threatened and 3 invasive species were detected in the habitats examined. The information obtained by the different methods of data analysis allowed a more comprehensive view on the value of the components of rice agroecosystems. Data analyses highlighted significant differences between habitats (feeding channel and rice field, with higher diversity observed in channels, and emphasised the role of the water chemical-physical parameters. The period of water permanence in rice fields resulted to be only one of the factors influencing the community of benthic macroinvertebrates. The presence of rare/endangered species allowed characterising some stations, but it was less informative about management strategies in rice paddies because most of these species were absent in rice fields.

Cyanobacteria-derived nitrogen uptake by benthic invertebrates in Lake Taihu: a mesocosm study using 15N labeling

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Yu J.

2014-01-01

Full Text Available Eutrophication of lakes can lead to dominance by cyanobacteria, which are hardly used by zooplankton due to their low nutrition value. However, sedimented cyanobacterial detritus may be a useful source for benthic invertebrates. We studied the Microcystis-derived nitrogen incorporation in benthic invertebrates in Lake Taihu using stable isotopic nitrogen (15N as a tracer. The δ15N of all organisms increased significantly with time after addition of the labeled Microcystis detritus. δ15N values of POM and periphyton peaked earlier than for benthic invertebrates, and the maximum levels were also higher than bivalves, snails and worms (Limnodrilus spp.. Among benthic invertebrates, Radix swinhoei peaked later than other invertebrates, but the maximum level and the excess 15N of the last sampling day were higher. At the end of the experiment, approximately 70% of the added 15N was retained in the benthic food web, while only a small fraction (less than 1% of the added detritus 15N occurred in the pelagic food web. Our results suggest that nitrogen from cyanobacteria can be incorporated more in benthic than pelagic food webs and cyanobacterial blooms may contribute to the development of benthic animals.

Benthic boundary layer modelling studies

International Nuclear Information System (INIS)

Richards, K.J.

1984-01-01

A numerical model has been developed to study the factors which control the height of the benthic boundary layer in the deep ocean and the dispersion of a tracer within and directly above the layer. This report covers tracer clouds of horizontal scales of 10 to 100 km. The dispersion of a tracer has been studied in two ways. Firstly, a number of particles have been introduced into the flow. The trajectories of these particles provide information on dispersion rates. For flow conditions similar to those observed in the abyssal N.E. Atlantic the diffusivity of a tracer was found to be 5 x 10 6 cm 2 s -1 for a tracer within the boundary layer and 8 x 10 6 cm 2 s -1 for a tracer above the boundary layer. The results are in accord with estimates made from current meter measurements. The second method of studying dispersion was to calculate the evolution of individual tracer clouds. Clouds within and above the benthic boundary layer often show quite different behaviour from each other although the general structure of the clouds in the two regions were found to have no significant differences. (author)

Longitudinal patterns and response lengths of algae in riverine ecosystems: A model analysis emphasising benthic-pelagic interactions.

Science.gov (United States)

Jäger, Christoph G; Borchardt, Dietrich

2018-04-07

In riverine ecosystems primary production is principally possible in two habitats: in the benthic layer by sessile algae and in the surface water by planktonic algae being transported downstream. The relevance of these two habitats generally changes along the rivers' continuum. However, analyses of the interaction of algae in these two habitats and their controlling factors in riverine ecosystems are, so far, very rare. We use a simplified advection-diffusion model system combined with ecological process kinetics to analyse the interaction of benthic and planktonic algae and nutrients along idealised streams and rivers at regional to large scales. Because many of the underlying processes affecting algal dynamics are influenced by depth, we focus particularly on the impact of river depth on this interaction. At constant environmental conditions all state variables approach stable spatial equilibria along the river, independent of the boundary conditions at the upstream end. Because our model is very robust against changes of turbulent diffusion and stream velocity, these spatial equilibria can be analysed by a simplified ordinary differential equation (ode) version of our model. This model variant reveals that at shallower river depths, phytoplankton can exist only when it is subsidised by detaching benthic algae, and in turn, at deeper river depths, benthic algae can exist only in low biomasses which are subsidised by sinking planktonic algae. We generalise the spatial dynamics of the model system using different conditions at the upstream end of the model, which mimic various natural or anthropogenic factors (pristine source, dam, inflow of a waste water treatment plant, and dilution from e.g. a tributary) and analyse how these scenarios influence different aspects of the longitudinal spatial dynamics of the full spatial model: the relation of spatial equilibrium to spatial maximum, the distance to the spatial maximum, and the response length. Generally, our

Similar effects of bottom trawling and natural disturbance on composition and function of benthic communities across habitats

NARCIS (Netherlands)

Denderen, van Daniel; Bolam, Stefan G.; Hiddink, Jan Geert; Jennings, Simon; Kenny, Andrew; Rijnsdorp, Adriaan D.; Kooten, Van Tobias

2015-01-01

Bottom trawl fishing has widespread impacts on benthic habitats and communities. The benthic response to trawling seems to be smaller or absent in areas exposed to high natural disturbance, leading to the hypothesis that natural and trawl disturbance affect benthic communities in a similar way.

Ways that Social Change Predicts Personal Quality of Life

Science.gov (United States)

Cheung, Chau-Kiu; Leung, Kwok

2010-01-01

A notable way that social change affects personal quality of life would rely on the person's experience with social change. This experience may influence societal quality of life and quality of work life, which may in turn affect personal quality of life. Additionally, the experience of social change is possibly less detrimental to personal…

Benthic foraminiferal census data from Mobile Bay, Alabama--counts of surface samples and box cores

Science.gov (United States)

Richwine, Kathryn A.; Osterman, Lisa E.

2012-01-01

A study was undertaken in order to understand recent environmental change in Mobile Bay, Alabama. For this study a series of surface sediment and box core samples was collected. The surface benthic foraminiferal data provide the modern baseline conditions of the bay and can be used as a reference for changing paleoenvironmental parameters recorded in the box cores. The 14 sampling locations were chosen in the bay to cover the wide diversity of fluvial and marine-influenced environments on both sides of the shipping channel.

Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study.

Science.gov (United States)

Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh D; Liu, Zhengwen

2015-03-01

Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems.

Benthic community structure on coral reefs exposed to intensive recreational snorkeling.

Directory of Open Access Journals (Sweden)

Bobbie Renfro

Full Text Available Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1-3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1 in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling.

Ecological diversification associated with the benthic-to-pelagic transition by North American minnows.

Science.gov (United States)

Burress, E D; Holcomb, J M; Tan, M; Armbruster, J W

2017-03-01

Ecological opportunity is often regarded as a key factor that explains why diversity is unevenly distributed across life. Colonization of novel environments or adaptive zones may promote diversification. North American minnows exhibit an ancestral benthic-to-pelagic habitat shift that coincided with a burst in diversification. Here, we evaluate the phenotypic and ecological implications of this habitat shift by assessing craniofacial and dietary traits among 34 species and testing for morphology-diet covariation, convergence and adaptive optima. There were several instances of morphology-diet covariation such as correlations between mouth angle and the consumption of terrestrial insects and between relative gut length and the consumption of algae. After accounting for size and phylogenetic nonindependence, benthic species had longer heads, longer snouts, eyes positioned higher on their head, smaller mouth angles and longer digestive tracts than pelagic minnows. Benthic minnows also consumed more algae but less terrestrial insects, by volume, than pelagic minnows. Lastly, there were three distinct evolutionary regimes and more convergence in morphology and dietary characteristics than expected under a Brownian motion model of evolution. These findings indicate that colonization of the pelagic zone by minnows involved myriad phenotypic and dietary changes associated with exploitation of terrestrial subsidies. Thus, minnows exhibit phenotype-dietary covariation, an expansion of ecological roles and a burst in diversification rates in response to the ecological opportunity afforded by the colonization of a novel habitat. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Explosive diversification following a benthic to pelagic shift in freshwater fishes

OpenAIRE

Hollingsworth, Phillip R; Simons, Andrew M; Fordyce, James A; Hulsey, C Darrin

2013-01-01

Background Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America’s most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition ...

Eocene to Oligocene benthic foraminiferal isotopic record in the Bay of Biscay

International Nuclear Information System (INIS)

Miller, K.G.; Curry, W.B.

1982-01-01

Oxygen and carbon isotopic records of Eocene to Oligocene benthic foraminifera from two Bay of Biscay Deep Sea Drilling Project sites are presented. The delta 18 O figures for benthic foraminifera are significantly higher than those previously reported from deeper North Atlantic sites, the differences arising it is believed from diagenetic alteration of the sediments in the deeper-buried sites. (U.K.)

Unified Geomorphological Analysis Workflows with Benthic Terrain Modeler

Directory of Open Access Journals (Sweden)

Shaun Walbridge

2018-03-01

Full Text Available High resolution remotely sensed bathymetric data is rapidly increasing in volume, but analyzing this data requires a mastery of a complex toolchain of disparate software, including computing derived measurements of the environment. Bathymetric gradients play a fundamental role in energy transport through the seascape. Benthic Terrain Modeler (BTM uses bathymetric data to enable simple characterization of benthic biotic communities and geologic types, and produces a collection of key geomorphological variables known to affect marine ecosystems and processes. BTM has received continual improvements since its 2008 release; here we describe the tools and morphometrics BTM can produce, the research context which this enables, and we conclude with an example application using data from a protected reef in St. Croix, US Virgin Islands.

Inorganic carbon availability in benthic diatom communities: photosynthesis and migration.

Science.gov (United States)

Marques da Silva, Jorge; Cruz, Sónia; Cartaxana, Paulo

2017-09-05

Diatom-dominated microphytobenthos (MPB) is the main primary producer of many intertidal and shallow subtidal environments, being therefore of critical importance to estuarine and coastal food webs. Owing to tidal cycles, intertidal MPB diatoms are subjected to environmental conditions far more variable than the ones experienced by pelagic diatoms (e.g. light, temperature, salinity, desiccation and nutrient availability). Nevertheless, benthic diatoms evolved adaptation mechanisms to these harsh conditions, including the capacity to move within steep physical and chemical gradients, allowing them to perform photosynthesis efficiently. In this contribution, we will review present knowledge on the effects of dissolved inorganic carbon (DIC) availability on photosynthesis and productivity of diatom-dominated MPB. We present evidence of carbon limitation of photosynthesis in benthic diatom mats and highly productive MPB natural communities. Furthermore, we hypothesize that active vertical migration of epipelic motile diatoms could overcome local depletion of DIC in the photic layer, providing the cells alternately with light and inorganic carbon supply. The few available longer-term experiments on the effects of inorganic carbon enrichment on the productivity of diatom-dominated MPB have yielded inconsistent results. Therefore, further studies are needed to properly assess the response of MPB communities to increased CO 2 and ocean acidification related to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'. © 2017 The Author(s).

Biogeographical distribution of the benthic thecate hydroids collected during the Spanish Antartida 8611 expedition and comparison between Antarctic and Magellan benthic hydroid faunas

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A. L. Peña Cantero

1999-12-01

Full Text Available The biogeographical distribution of the benthic hydroid species collected during the Spanish Antarctic expedition Antártida 8611 has been studied. An inventory of the Antarctic and Magellan benthic thecate hydroid faunas, along with a comparison between the two, have been also carried out. 104 and 126 species of thecate hydroids have been considered in the Antarctic and Magellan areas, respectively. 72 species (69% of the Antarctic species and 49 (39% of the Magellan species are endemic. 23 species are present both in the Antarctic Region and in the Magellan area, representing 22% and 18% respectively, and indicating an important relationship between both faunas.

The truth is out there: measured, calculated and modelled benthic fluxes.

Science.gov (United States)

Pakhomova, Svetlana; Protsenko, Elizaveta

2016-04-01

In a modern Earth science there is a great importance of understanding the processes, forming the benthic fluxes as one of element sources or sinks to or from the water body, which affects the elements balance in the water system. There are several ways to assess benthic fluxes and here we try to compare the results obtained by chamber experiments, calculated from porewater distributions and simulated with model. Benthic fluxes of dissolved elements (oxygen, nitrogen species, phosphate, silicate, alkalinity, iron and manganese species) were studied in the Baltic and Black Seas from 2000 to 2005. Fluxes were measured in situ using chamber incubations (Jch) and at the same time sediment cores were collected to assess the porewater distribution at different depths to calculate diffusive fluxes (Jpw). Model study was carried out with benthic-pelagic biogeochemical model BROM (O-N-P-Si-C-S-Mn-Fe redox model). It was applied to simulate biogeochemical structure of the water column and upper sediment and to assess the vertical fluxes (Jmd). By the behaviour at the water-sediment interface all studied elements can be divided into three groups: (1) elements which benthic fluxes are determined by the concentrations gradient only (Si, Mn), (2) elements which fluxes depend on redox conditions in the bottom water (Fe, PO4, NH4), and (3) elements which fluxes are strongly connected with organic matter fate (O2, Alk, NH4). For the first group it was found that measured fluxes are always higher than calculated diffusive fluxes (1.5disadvantages and the main facing us question is - which value should be taken for calculation the balance? This research is funded by VISTA - a basic research program and collaborative partnership between the Norwegian Academy of Science and Letters and Statoil.

NEFSC Benthic Habitat Survey (AL0304, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This survey will collect benthic samples using acoustics, nets, and grab samplers. The survey will monitor and map the geological, physical, and biological habitats...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitat, Key Benthic Species, including Marine Debris Sightings, of the Pacific Remote Island Areas from 2015-01-26 to 2015-04-26 (NCEI Accession 0157564)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

National Coral Reef Monitoring Program: Towed-diver Surveys of Benthic Habitats, Key Benthic Species, and Marine Debris Sightings of the Pacific Remote Island Areas from 2017-04-02 to 2017-04-20 (NCEI Accession 0164023)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Mapping ecosystem services provided by benthic habitats in the European North Atlantic Ocean

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Ibon eGalparsoro

2014-07-01

Full Text Available Mapping and assessing the ecosystem services provided by benthic habitats are a highly valuable source of information for understanding their current and potential benefits to society. The main objective of this investigation is to assess and map the ecosystem services provided by benthic habitats of the European North Atlantic Ocean, in the context of Mapping and Assessment of Ecosystems and their Services (MAES programme, the European Biodiversity Strategy and the implementation of the Marine Strategy Framework Directive. In total, 62 habitats have been analysed in relation to 12 ecosystem services over 1.7 million km2. Results indicated that more than 90% of the mapped area provides biodiversity maintenance and food provision services; meanwhile grounds providing reproduction and nursery services are limited to half of the mapped area. Benthic habitats generally provide more services closer to shore than offshore and in shallower waters. This gradient is likely to be explained by difficult access (i.e. distance and depth and lack of scientific knowledge for most of the services provided by distant benthic habitats. This research has provided a first assessment of the benthic ecosystem services at Atlantic European scale, with the provision of ecosystem services maps and their general spatial distribution patterns. Related to the objectives of this research, the conclusions are: (i benthic habitats provide a diverse set of ecosystem services, being the food provision and biodiversity maintenance services the ones that are more extensively represented. In addition, other regulating and cultural services are provided in a more limited area; and (ii the ecosystem services assessment categories are significantly related to the distance to the coast and with depth (higher near the coast and in shallow waters.

Sensitivity of heterogeneous marine benthic habitats to subtle stressors.

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Iván F Rodil

Full Text Available It is important to understand the consequences of low level disturbances on the functioning of ecological communities because of the pervasiveness and frequency of this type of environmental change. In this study we investigated the response of a heterogeneous, subtidal, soft-sediment habitat to small experimental additions of organic matter and calcium carbonate to examine the sensitivity of benthic ecosystem functioning to changes in sediment characteristics that relate to the environmental threats of coastal eutrophication and ocean acidification. Our results documented significant changes between key biogeochemical and sedimentary variables such as gross primary production, ammonium uptake and dissolved reactive phosphorus flux following treatment additions. Moreover, the application of treatments affected relationships between macrofauna communities, sediment characteristics (e.g., chlorophyll a content and biogeochemical processes (oxygen and nutrient fluxes. In this experiment organic matter and calcium carbonate showed persistent opposing effects on sedimentary processes, and we demonstrated that highly heterogeneous sediment habitats can be surprisingly sensitive to subtle perturbations. Our results have important biological implications in a world with relentless anthropogenic inputs of atmospheric CO2 and nutrients in coastal waters.

Dynamics of dissolved organic matter in riverine sediments affected by weir impoundments: Production, benthic flux, and environmental implications.

Science.gov (United States)

Chen, Meilian; Kim, Sung-Han; Jung, Heon-Jae; Hyun, Jung-Ho; Choi, Jung Hyun; Lee, Hyo-Jin; Huh, In-Ae; Hur, Jin

2017-09-15

In order to understand the characteristics and dynamics of dissolved organic matter (DOM) in the sediment of rivers affected by impoundments, we examined the vertical profiles and the benthic fluxes of DOM in four different core sediments located at upstream sites of weirs in major rivers of South Korea. In three out of four sites, exponential accumulation of dissolved organic carbon (DOC) with depth was observed with the signature of seasonal variability. Except for the site displaying a below-detection limit of Fe(II), the general accumulation trends of DOC with depth was concurrent with the increases of Fe(II) and NH 4 + and the decrease of PO 4 3- , signifying a close linkage of the DOM dynamics with anaerobic respiration via iron reduction, an important early diagenesis pathway. The estimated benthic fluxes from the cores revealed that the sediments likely serve as DOC, chromophoric DOM (CDOM), and fluorescent DOM (FDOM) sources to the overlying water. The benthic effluxes based on DOC were comparable to the ranges previously reported in lake and coastal areas, and those of CDOM and FDOM showed even higher levels. These findings imply that impoundment-affected river systems would change the DOM composition of the overlying water, ultimately influencing the subsequent water treatment processes such as disinfection byproducts production and membrane fouling. A simple mass balance model indicated that the impoundment-affected river sediments may operate as a net carbon sink in the environments due to a greater extent of sedimentation compared to the estimated benthic efflux and sediment biological respiration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Trophic Ecology of Benthic Marine Invertebrates with Bi-Phasic Life Cycles: What Are We Still Missing?

Science.gov (United States)

Calado, Ricardo; Leal, Miguel Costa

2015-01-01

The study of trophic ecology of benthic marine invertebrates with bi-phasic life cycles is critical to understand the mechanisms shaping population dynamics. Moreover, global climate change is impacting the marine environment at an unprecedented level, which promotes trophic mismatches that affect the phenology of these species and, ultimately, act as drivers of ecological and evolutionary change. Assessing the trophic ecology of marine invertebrates is critical to understanding maternal investment, larval survival to metamorphosis, post-metamorphic performance, resource partitioning and trophic cascades. Tools already available to assess the trophic ecology of marine invertebrates, including visual observation, gut content analysis, food concentration, trophic markers, stable isotopes and molecular genetics, are reviewed and their main advantages and disadvantages for qualitative and quantitative approaches are discussed. The challenges to perform the partitioning of ingestion, digestion and assimilation are discussed together with different approaches to address each of these processes for short- and long-term fingerprinting. Future directions for research on the trophic ecology of benthic marine invertebrates with bi-phasic life cycles are discussed with emphasis on five guidelines that will allow for systematic study and comparative meta-analysis to address important unresolved questions. © 2015 Elsevier Ltd. All rights reserved.

Autofluorescence imaging system to discriminate and quantify the distribution of benthic cyanobacteria and diatoms

NARCIS (Netherlands)

Carreira, C.; Staal, M.; Middelboe, M.; Brussaard, C.P.D.

2015-01-01

Observation of benthic photoautotrophs on sediment surfaces shows a single algal layer without distinction between photosynthetic groups. Until now it has not been possible to distinguish between benthic photosynthetic microorganisms, i.e. cyanobacteria and diatoms, at μm to mm scales using a single

Deposition and benthic mineralization of organic carbon

DEFF Research Database (Denmark)

Nordi, Gunnvor A.; Glud, Ronnie N.; Simonsen, Knud

2018-01-01

Seasonal variations in sedimentation and benthic mineralization of organic carbon (OC) were investigated in a Faroese fjord. Deposited particulate organic carbon (POC) was mainly of marine origin, with terrestrial material only accounting for b1%. On an annual basis the POC export fromthe euphotic...

Benthic freshwater nematode community dynamics under conditions ...

African Journals Online (AJOL)

Studies of the influence of fish aquaculture on benthic freshwater nematode assemblages are scarce, but could provide a way of gauging environmental effects. The abundance and diversity of nematode assemblages in response to Oreochromis niloticus aquaculture were investigated in Kafr El-Sheikh Governorate, Egypt, ...

Accumulation of phosphorus in coastal marine sediments: relationship to benthic and diffusive fluxes

Directory of Open Access Journals (Sweden)

Rocio Ponce

2010-11-01

Full Text Available Sedimentary phosphorus was characterized in sediment cores from 3 coastal ecosystems of the Gulf of Cadiz. High spatial variability was observed in total phosphorus (from 445 to 20291 μg g.sed-1 and in the other phosphorus phases studied. This variability correlates with the proximity of the 10 sampling stations to sources of urban and/or industrial effluent in the zone. The benthic and diffusive fluxes were measured concurrently with sediment collection at these stations. The measured values of benthic fluxes range between –14 and 6 mmol m-2 d-1. Generally, stations that showed increased interstitial phosphate concentrations with increasing depth were characterized by positive values in phosphate benthic fluxes and by high percentages of reactive forms of sedimentary phosphorus. Negative benthic fluxes were associated with stations receiving more anthropogenic matter, which showed progressively decreasing phosphate concentrations in the interstitial water with depth. In these anthropogenic areas, the non-reactive forms of phosphorus (those associated with ferric oxyhydroxide and authigenic carbonate fluorapatite are abundant, and reach values exceeding 75% of total phosphorus in sediment.

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

Deep-sea benthic community and environmental impact assessment at the Atlantic Frontier

Science.gov (United States)

Gage, John D.

2001-05-01

The seabed community provides a sensitive litmus for environmental change. North Sea analysis of benthic populations provides an effective means for monitoring impacts from man's interventions, such as offshore oil exploitation and fishing, against baseline knowledge of the environment. Comparable knowledge of the benthic biology in the deep waters of the Atlantic Frontier beyond the N.E. Atlantic shelf edge is poorly developed. But uncertainties should not encourage assumptions and extrapolations from the better-known conditions on the continental shelf. While sampling at present still provides the best means to assess the health of the deepwater benthic habitat, protocols developed for deep-sea fauna should be applied. These are necessary because of (a) lower faunal densities, (b) higher species richness, (c) smaller body size, and (d) to ensure comparability with other deep-sea data. As in the North Sea, species richness and relative abundance can be analysed from quantitative samples in order to detect impacts. But analysis based on taxonomic sufficiency above species level is premature, even if arguably possible for coastal communities. Measures also need to ensure identifications are not forced to more familiar coastal species without proper study. Species-level analysis may be applied to seabed photographs of megafauna in relation to data on bottom environment, such as currents and the sediment, to monitor the health of the deep-water community. Although the composition of higher taxa in the benthic community is broadly similar to soft sediments on the shelf, concordance in sensitivities is speculative. Moreover, new organisms occur, such as giant protozoan xenophyophores, unknown on the continental shelf, whose sensitivities remain conjectural. Past knowledge of the benthic biology of the deep-water areas off Scotland is based on scattered stations and some more focussed, multidisciplinary studies, and should be significantly augmented by the results from

Natural disturbance shapes benthic intertidal macroinvertebrate communities of high latitude river deltas

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Churchwell, Roy T.; Kendall, Steve J.; Blanchard, Amy L.; Dunton, Kenneth H.; Powell, Abby N.

2016-01-01

Unlike lower latitude coastlines, the estuarine nearshore zones of the Alaskan Beaufort Sea are icebound and frozen up to 9 months annually. This annual freezing event represents a dramatic physical disturbance to fauna living within intertidal sediments. The main objectives of this study were to describe the benthic communities of Beaufort Sea deltas, including temporal changes and trophic structure. Understanding benthic invertebrate communities provided a baseline for concurrent research on shorebird foraging ecology at these sites. We found that despite continuous year-to-year episodes of annual freezing, these estuarine deltas are populated by a range of invertebrates that represent both marine and freshwater assemblages. Freshwater organisms like Diptera and Oligochaeta not only survive this extreme event, but a marine invasion of infaunal organisms such as Amphipoda and Polychaeta rapidly recolonizes the delta mudflats following ice ablation. These delta sediments of sand, silt, and clay are fine in structure compared to sediments of other Beaufort Sea coastal intertidal habitats. The relatively depauperate invertebrate community that ultimately develops is composed of marine and freshwater benthic invertebrates. The composition of the infauna also reflects two strategies that make life on Beaufort Sea deltas possible: a migration of marine organisms from deeper lagoons to the intertidal and freshwater biota that survive the 9-month ice-covered period in frozen sediments. Stable isotopic analyses reveal that both infaunal assemblages assimilate marine and terrestrial sources of organic carbon. These results provide some of the first quantitative information on the infaunal food resources of shallow arctic estuarine systems and the long-term persistence of these invertebrate assemblages. Our data help explain the presence of large numbers of shorebirds in these habitats during the brief summer open-water period and their trophic importance to migrating

Environmental and Spatial Influences on Biogeography and Community Structure of Benthic Diatoms

Science.gov (United States)

Plante, C.; Hill-Spanik, K.; Lowry, J.

2016-02-01

Several theoretical and practical reasons suggest that benthic microalgae could be useful bioindicators. For instance, an ideal indicator species or community would be associated with a given habitat due to local physical conditions or biotic interactions (i.e., `environmental filtering'), not due to dispersal limitation. Due to their small size, immense abundances, and reliance on passive dispersal, the popular notion about micro-organisms is that `Everything is everywhere, but, the environment selects' (Baas-Becking 1934). Although much recent research concerning planktonic bacteria and dispersal limitation has been conducted, very little in this regard is known about microeukaryotes, especially benthic microbes. The purpose of our study was to identify and compare spatial and environmental influences on benthic diatom community structure and biogeography. In summer 2015, sediment was sampled at various spatial scales from four barrier island beaches in South Carolina, USA, and high-throughput (Ion Torrent) DNA sequencing was used to characterize diatom assemblages. ANOSIM and principal coordinates analysis revealed that communities were statistically distinct on the four islands. Community dissimilarity was compared to both spatial distance and environmental differences to determine potential influences of these variables on community structure. We found that geographic distance had the strongest correlation with community similarity, with and without one anomalous location, while differences in temperature (air, water, and sediment), nutrients, organic matter, and turbidity also had significant but weaker relationships with community structure. Surprisingly, air temperature, which changes on very short time scales, appeared to be the environmental factor most strongly related to diatom species composition, potentially implicating some unmeasured variable (e.g., cloud cover). However, we also found that temperature and geographic distance were strongly

Shallow-Water Benthic Habitats of Southwest Puerto Rico

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

Puerto Rico Land-Based Threat to Benthic Habitats

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's study,...

Benthic foraminifera as proxy for oxygen-depleted conditions off the central west coast of India

Digital Repository Service at National Institute of Oceanography (India)

Nigam, R.; Mazumder, A.; Henriques, P.J.; Saraswat, R.

In order to study the response of benthic foraminifera, especially the rectilinear bi- and tri-serial benthic foraminifera (RBF) to oxygen-depleted conditions from the Arabian Sea off central west coast of India, 103 surface sediment samples...

Possible impacts of Hg and PAH contamination on benthic foraminiferal assemblages: An example from the Sicilian coast, central Mediterranean

Energy Technology Data Exchange (ETDEWEB)

Di Leonardo, Rossella [Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse e ai Rischi Naturali (CFTA), Universita di Palermo, Via Archirafi 36, 90123 Palermo (Italy); Bellanca, Adriana [Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse e ai Rischi Naturali (CFTA), Universita di Palermo, Via Archirafi 36, 90123 Palermo (Italy)], E-mail: bellanca@unipa.it; Capotondi, Lucilla [ISMAR-CNR, Marine Geology Section, Via Gobetti 101, 40129 Bologna (Italy); Cundy, Andrew [School of the Environment, University of Brighton, Moulsecoomb, Brighton, BN2 4GJ (United Kingdom); Neri, Rodolfo [Dipartimento di Chimica e Fisica della Terra ed Applicazioni alle Georisorse e ai Rischi Naturali (CFTA), Universita di Palermo, Via Archirafi 36, 90123 Palermo (Italy)

2007-12-15

The Palermo and Augusta urban/industrial areas (Sicily) are examples of contaminated coastal environments with a relatively high influx of unregulated industrial and domestic effluents. Three sediment box-cores were collected offshore of these urban/industrial areas in water depths of 60-150 m during two cruises (summers 2003/2004), dated by {sup 210}Pb and {sup 137}Cs, and analysed for total mercury concentration and total polycyclic aromatic hydrocarbon (PAH) concentration. Benthic foraminiferal assemblages were also examined (in terms of their distribution and morphology) to assess the potential use of benthic foraminifera as bioindicators of pollutant input and environmental change in these Mediterranean shelf environments. The Hg and PAHs vs depth profiles show a clear increase in concentration with decreasing depth. Most of the sediments are highly enriched in mercury and show concentrations more than 20 times the background mercury value estimated for sediments from the Sicily Strait. The Hg and PAH concentrations appear to be potentially hazardous, grossly exceeding national and international regulatory guidelines. A reduction in abundance of benthic foraminifera, increasing percentages of tests with various morphological deformities, and the dominance of opportunistic species in more recent sediments can be correlated to anthropogenic impact.

Possible impacts of Hg and PAH contamination on benthic foraminiferal assemblages: An example from the Sicilian coast, central Mediterranean

International Nuclear Information System (INIS)

Di Leonardo, Rossella; Bellanca, Adriana; Capotondi, Lucilla; Cundy, Andrew; Neri, Rodolfo

2007-01-01

The Palermo and Augusta urban/industrial areas (Sicily) are examples of contaminated coastal environments with a relatively high influx of unregulated industrial and domestic effluents. Three sediment box-cores were collected offshore of these urban/industrial areas in water depths of 60-150 m during two cruises (summers 2003/2004), dated by 210 Pb and 137 Cs, and analysed for total mercury concentration and total polycyclic aromatic hydrocarbon (PAH) concentration. Benthic foraminiferal assemblages were also examined (in terms of their distribution and morphology) to assess the potential use of benthic foraminifera as bioindicators of pollutant input and environmental change in these Mediterranean shelf environments. The Hg and PAHs vs depth profiles show a clear increase in concentration with decreasing depth. Most of the sediments are highly enriched in mercury and show concentrations more than 20 times the background mercury value estimated for sediments from the Sicily Strait. The Hg and PAH concentrations appear to be potentially hazardous, grossly exceeding national and international regulatory guidelines. A reduction in abundance of benthic foraminifera, increasing percentages of tests with various morphological deformities, and the dominance of opportunistic species in more recent sediments can be correlated to anthropogenic impact

Microplastic effect thresholds for freshwater benthic macroinvertebrates

NARCIS (Netherlands)

Redondo Hasselerharm, P.E.; Dede Falahudin, Dede; Peeters, E.T.H.M.; Koelmans, A.A.

2018-01-01

Now that microplastics have been detected in lakes, rivers and estuaries all over the globe, evaluating their effects on biota has become an urgent research priority. This is the first study that aims at determining the effect thresholds for a battery of six freshwater benthic macroinvertebrates

Benthic deversity in the Rhine-Meuse estuary

NARCIS (Netherlands)

Wolff, W.J.

1974-01-01

The benthic diversity of the Rhine-Meuse estuary has been investigated by means of three diversity indices: the Shannon-Weaver information function, an index obtained by SANDERS' rarefaction method and the number of the species per sample. Succession proved to be a very important factor in the

Colonization by benthic macroinvertebrates in two artificial substrate types of a Riparian Forest

Directory of Open Access Journals (Sweden)

Lívia Borges dos Santos

Full Text Available Abstract: Aim To analyze the efficiency of organic and inorganic substrates in samples of benthic macroinvertebrates of riparian forests from the Cerrado. Specific objectives (i characterize the ecological succession and taxonomic richness of benthic macroinvertebrates in stream affluent of a riparian forest; (ii analyze the influence of seasonality on the colonization of macroinvertebrates; and (iii determine the effect of the types of artificial substrates on the richness, composition and abundance of the benthic community. Methods Sampling was carried out in the rainy and dry seasons, and we installed in the watercourse two types of substrates: organic (leaf packs and inorganic (bricks, organized in pairs. Six samples per season were done to verify colonization, succession, richness and abundance of benthic community. The substrates were carefully sorted and the organisms were identified to the lowest possible taxonomic level. Results The ecological succession was clearly observed, with the initial occurrence of Chironomidae and Baetidae (considered early colonizers, and a late occurrence of organisms such as Helotrephidae and Trichoptera (considered late colonizers. No significant difference was found in the richness and abundance among the studied seasons (rainy and dry, but the organic substrate was significantly higher than the inorganic substrate for these parameters. Conclusion Organic artificial substrates are more efficient in characterizing the community of benthic macroinvertebrates in the study area, because they are more similar to the conditions of the substrate found naturally in the environment.

Benthic harpacticoid copepods of Jiaozhou Bay, Qingdao

Science.gov (United States)

Ma, Lin; Li, Xinzheng

2017-09-01

The species richness of benthic harpacticoid copepod fauna in Jiaozhou Bay, Qingdao, on the southern coast of Shandong Peninsula, has not been comprehensively studied. We present a preliminary inventory of species for this region based on material found in nine sediment samples collected from 2011 to 2012. Our list includes 15 species belonging to 15 genera in 9 families, the most speciose family was the Miraciidae Dana, 1846 (seven species); all other families were represented by single species only. Sediment characteristics and depth are determined to be important environmental determinants of harpacticoid distribution in this region. We briefly detail the known distributions of species and provide a key to facilitate their identification. Both harpacticoid species richness and the species/genus ratio in Jiaozhou Bay are lower than in Bohai Gulf and Gwangyang Bay. The poor knowledge of the distribution of benthic harpacticoids, in addition to low sampling effort in Jiaozhou Bay, likely contribute to low species richness.

27 years of benthic and coral community dynamics on turbid, highly urbanised reefs off Singapore.

Science.gov (United States)

Guest, J R; Tun, K; Low, J; Vergés, A; Marzinelli, E M; Campbell, A H; Bauman, A G; Feary, D A; Chou, L M; Steinberg, P D

2016-11-08

Coral cover on reefs is declining globally due to coastal development, overfishing and climate change. Reefs isolated from direct human influence can recover from natural acute disturbances, but little is known about long term recovery of reefs experiencing chronic human disturbances. Here we investigate responses to acute bleaching disturbances on turbid reefs off Singapore, at two depths over a period of 27 years. Coral cover declined and there were marked changes in coral and benthic community structure during the first decade of monitoring at both depths. At shallower reef crest sites (3-4 m), benthic community structure recovered towards pre-disturbance states within a decade. In contrast, there was a net decline in coral cover and continuing shifts in community structure at deeper reef slope sites (6-7 m). There was no evidence of phase shifts to macroalgal dominance but coral habitats at deeper sites were replaced by unstable substrata such as fine sediments and rubble. The persistence of coral dominance at chronically disturbed shallow sites is likely due to an abundance of coral taxa which are tolerant to environmental stress. In addition, high turbidity may interact antagonistically with other disturbances to reduce the impact of thermal stress and limit macroalgal growth rates.

Spatial and temporal distribution patterns of benthic foraminifera in the Northeast Water Polynya, Greenland

Science.gov (United States)

Ahrens, Michael J.; Graf, Gerhard; Altenbach, Alexander V.

1997-01-01

Abundance, biofacies and ATP content of benthic foraminifera (>63 μm) were studied in the Northeast Water (NEW) Polynya (77-81°N, 5-17°W) over the ice-free summer, 1993, to investigate how a polynya system might influence the underlying benthic community. In the living assemblage, distinguished by Rose Bengal staining, over 60 taxa could be identified. The biofacies identified was similar to that of other Arctic shelf habitats. Foraminifera were counted in 3 size fractions (63-125 μm, 125-250 μm and >250 μm), with 65% of the foraminifera occurring in the smallest size fraction (63-125 μm). Total abundances (>63 μm) in the uppermost 1 cm averaged approximately 200 ind/10 cm 3 and declined down-core, as did the number of species. Abundances and species composition correlated positively with sediment chlorophyll and ATP content, with maxima occurring in the shallower northern regions of the polynya, suggesting a general dependence on food. Foraminera biomass was estimated to be 0.1-0.3 g C org/m 2. Abundances, biomass and ATP content were comparable to ice-free, deep-sea regions in the Norwegian Sea. Temporal changes observed over a 2 month period at one location were difficult to distinguish from spatial and analytical variability. Contrary to expectations, growth was unpronounced at the community and at a species level, implying either a delayed response of the benthic foraminiferal community to food inputs from the overlying water column or the presence of biological limitations other than food, such as predation.

Pacific Reef Assessment and Monitoring Program: Towed-diver Surveys of Benthic Habitats, Key Benthic Species, and Marine Debris Sightings of the U.S. Pacific Reefs from 2000-09-09 to 2012-05-19 (NCEI Accession 0163745)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The towed-diver method is used to conduct benthic surveys, assessing large-scale disturbances (e.g., bleaching) and quantifying benthic components such as habitat...

Depth distribution of benthic dinoflagellates in the Caribbean Sea

Science.gov (United States)

Boisnoir, Aurélie; Pascal, Pierre-Yves; Cordonnier, Sébastien; Lemée, Rodolophe

2018-05-01

Monitoring of benthic dinoflagellates is usually conducted between sub-surface and 5 m depth, where these organisms are supposed to be in highest abundances. However, only few studies have focused on the small-scale depth distribution of benthic dinoflagellates. In the present study, abundances of dinoflagellates were evaluated on an invasive macrophyte Halophila stipulacea in two coastal sites in Guadeloupe (Caribbean Sea) along a depth gradient from sub-surface to 3 m at Gosier and until 20 m at Rivière Sens during the tropical wet and dry seasons. Species of genus Ostreopsis and Prorocentrum were the most abundant. Depth did not influence total dinoflagellate abundance but several genera showed particular depth-distribution preferences. The highest abundances of Ostreopsis and Gambierdiscus species were estimated preferentially in surface waters, whereas Coolia spp. were found in the same proportions but in deeper waters. Halophila stipulacea biomass was positively correlated with Ostreopsis spp. abundance. Our study suggests that sampling of benthic dinoflagellates should be conducted at different water depths taking into account the presence of the macroalgal substrate as well. In the Caribbean area, special attention should be addressed to the presence of H. stipulacea which tends to homogenize the marine landscape and represents a substrate for hosting dinoflagellate growth.

Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: Are benthic systems at risk?

International Nuclear Information System (INIS)

Li, Shibin; Wallis, Lindsay K.; Ma, Hongbo; Diamond, Stephen A.

2014-01-01

This study investigated phototoxicity of TiO 2 nanoparticles (nano-TiO 2 ) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (> 77%) in LSW was observed after 0.5 h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m 2 . Phototoxicity of nano-TiO 2 under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5–23.3) Wh/m 2 when exposed to 20 mg/L nano-TiO 2 . Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO 2 to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. - Graphical abstract: Display Omitted - Highlights: •Large aggregation of TiO 2 nanoparticles in Lake Superior water was observed. •Phototoxicity was dependent on the dose of both solar radiation and nanoparticle. •A solar radiation favored surface attachment of nanoparticles was observed. •Hyalella azteca exhibited negative phototaxis in the presence of shelters. •Factors influencing phototoxicity in the real environment were

Temporal variability of live (stained benthic foraminiferal faunas in a river-dominated shelf – Faunal response to rapid changes of the river influence (Rhône prodelta, NW Mediterranean

Directory of Open Access Journals (Sweden)

E. Legrand

2012-04-01

Full Text Available In the context of the French research project CHACCRA (Climate and Human-induced Alterations in Carbon Cycling at the River-seA connection, living (rose Bengal-stained benthic foraminifera were investigated at two stations (24 and 67 m depth in the Rhône prodelta (NW Mediterranean, Gulf of Lions. The aim of this study was to precise the response of benthic foraminiferal faunas to temporal changes of the Rhône River inputs (e.g. organic and terrigeneous material. Each site was sampled in April 2007, September 2007, May 2008 and December 2008, permitting to observe foraminiferal faunas of the 63–150 and >150 μm size fractions under a wide range of environmental conditions. Obvious variations in foraminiferal faunal composition were observed during the four investigated periods at the shallowest Station A located in the close vicinity of the Rhône River mouth. After major Rhône River flood events, different colonisation stages were observed with foraminiferal faunas responding with an opportunistic strategy few days to weeks after the creation of a peculiar sedimentary environment (Leptohalysis scottii, May 2008 or high organic matter supplies (Ammonia tepida, December 2008. Under more stable conditions, relatively diverse and equilibrated faunas grew in the sediments. Species benefited from noticeable input of riverine phytodetritus to the sediment during spring bloom conditions (April 2007; e.g. Bolivina dilatata, Nonionella stella, Stainforthia fusiformis, or high amounts of still bio-available organic matter under more oligotrophic conditions (September 2007; e.g. Ammonia tepida, Psammosphaera fusca. The reduced influence of the Rhône River input at the farther Station N led to less contrasted environmental conditions during the four sampling periods, and so to less obvious variations in foraminiferal faunal composition. During reduced riverine influence (i.e. low Rhône discharge, species able to feed on fresh phytodetritus (e

Effects of acid mine drainage on water, sediment and associated benthic macroinvertebrate communities

International Nuclear Information System (INIS)

Rutherford, L.G.; Cherry, D.S.; Dobbs, M.G.; Cairns, J. Jr.; Zipper, C.E.

1995-01-01

The toxic constituents of abandoned mined land (AML) discharges (acidic pH, heavy metals, total suspended solids) are extremely toxic to aquatic life . Studies were undertaken to ascertain environmental impacts to the upper Powell River, Lee and Wise Counties, Va. These impacts included disruptions in physical water quality, sediment quality, altered benthic macroinvertebrate assemblages, and toxicity of the water column and sediments from short-term impairment bioassays, and the potential to bioaccumulate selected metals (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) by periphyton and resident bivalves. Water chemistry and macroinvertebrate assemblages were collected at upstream control, just below acid mine drainage and other downstream sites. Selected trace metal concentrations (Al, Fe, Mn, P, Zn, Cu, Mg, S, Ni, Cd) were determined for water, sediment and resident bivalves using ICP-AES. Acidic pH ranged from 2.15--3.3 at three AML-influenced seeps and varied from 6.4--8.0 at reference stations. At one AML-influenced creek, acidic pH conditions worsened from summer to fall and eradicated aquatic life throughout a 1.5 km stretch of that creek as it flowed into another creek. An additional dilution of 3.4 km in the second creek was needed to nearly neutralize the acidic pH problem. Conductivity (umhos/cm) ranged from 32--278 at reference sites and from 245--4,180 at AML-impact sites. Benthic macroinvertebrate abundance and taxon richness were essentially eliminated in the seeps or reached numbers of 1 -3 taxa totaling < 10 organisms relative to reference areas where richness values were 12--17 and comprised 300--977 organisms. Concentrations of Fe, Al, Mg and Cu and Zn were highest in the environmentally stressed stations of low pH and high conductivity relative to the reference stations. Iron was, by far, the element in highest concentration followed by Al and Mg

Benthic fluxes in a tropical estuary and their role in the ecosystem

Digital Repository Service at National Institute of Oceanography (India)

Pratihary, A.K.; Naqvi, S.W.A.; Naik, H.; Thorat, B.R.; Narvenkar, G.; Manjunatha, B.R.; Rao, V.P.

in the Estuary. Based on these observations we hypothesize that it is mainly benthic NH 4 + efflux that sustains high estuarine productivity in the NO 3 - depleted dry season. Keywords: Nutrients; Primary production; Denitrification; Bioturbation; Benthic..., nearshore and continental shelves occupy just about 10 % of the global oceanic area, between 30-50 % of the marine primary production occurs in these regions (Romankevich, 1984; Walsh, 1991) which also sustains about 90 % of the fisheries resource. Coastal...

The changing role of the quality professional

International Nuclear Information System (INIS)

Thompson, R.G.

1989-01-01

This paper discusses the historic role of the quality professionals in a Department of Energy Idaho Operations Office (DOE-ID) contractor's organization. The quality professional's changing role is presented

Interlinking backscatter, grain size and benthic community structure

Science.gov (United States)

McGonigle, Chris; Collier, Jenny S.

2014-06-01

The relationship between acoustic backscatter, sediment grain size and benthic community structure is examined using three different quantitative methods, covering image- and angular response-based approaches. Multibeam time-series backscatter (300 kHz) data acquired in 2008 off the coast of East Anglia (UK) are compared with grain size properties, macrofaunal abundance and biomass from 130 Hamon and 16 Clamshell grab samples. Three predictive methods are used: 1) image-based (mean backscatter intensity); 2) angular response-based (predicted mean grain size), and 3) image-based (1st principal component and classification) from Quester Tangent Corporation Multiview software. Relationships between grain size and backscatter are explored using linear regression. Differences in grain size and benthic community structure between acoustically defined groups are examined using ANOVA and PERMANOVA+. Results for the Hamon grab stations indicate significant correlations between measured mean grain size and mean backscatter intensity, angular response predicted mean grain size, and 1st principal component of QTC analysis (all p PERMANOVA for the Hamon abundance shows benthic community structure was significantly different between acoustic groups for all methods (p ≤ 0.001). Overall these results show considerable promise in that more than 60% of the variance in the mean grain size of the Clamshell grab samples can be explained by mean backscatter or acoustically-predicted grain size. These results show that there is significant predictive capacity for sediment characteristics from multibeam backscatter and that these acoustic classifications can have ecological validity.

Benthic foraminifera in the plankton following storms: what does this mean for (palaeo)-ecological interpretations?

Science.gov (United States)

Hart, Malcolm; Molina, Giulia; Smart, Christopher; Widdicombe, Claire

2017-04-01

subsequent interpretations of ecology less accurate, but in the fossil record such changes could go completely undetected and lead to considerable inaccuracy in the interpretation of palaeoecology. Murray, J.W. 1965. Significance of benthic foraminiferids in plankton samples. Journal of Paleontology, 39, 156-157. Smyth, T., Atkinson, A., Widdicombe, S., Frost, M., Allen, I., Fishwick, J., Queiros, A., Sims, D. & Barange, M. 2015. The Western Channel Observatory. Progress in Oceanography, 137, 335-341.

Benthic Habitat Maps for Rose Atoll Marine National Monument in American Samoa from 2004 to 2010

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps for Rose Atoll, American Samoa were derived from high resolution, multispectral satellite imagery for 2004, 2006, and 2010. The benthic habitat...

Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

Energy Technology Data Exchange (ETDEWEB)

Bond, M.J.; Rowan, D.; Silke, R.; Carr, J., E-mail: bondm@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

2013-12-15

The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

Eukaryotic Life Inhabits Rhodolith-forming Coralline Algae (Hapalidiales, Rhodophyta), Remarkable Marine Benthic Microhabitats

Science.gov (United States)

Krayesky-Self, Sherry; Schmidt, William E.; Phung, Delena; Henry, Caroline; Sauvage, Thomas; Camacho, Olga; Felgenhauer, Bruce E.; Fredericq, Suzanne

2017-04-01

Rhodoliths are benthic calcium carbonate nodules accreted by crustose coralline red algae which recently have been identified as useful indicators of biomineral changes resulting from global climate change and ocean acidification. This study highlights the discovery that the interior of rhodoliths are marine biodiversity hotspots that function as seedbanks and temporary reservoirs of previously unknown stages in the life history of ecologically important dinoflagellate and haptophyte microalgae. Whereas the studied rhodoliths originated from offshore deep bank pinnacles in the northwestern Gulf of Mexico, the present study opens the door to assess the universality of endolithic stages among bloom-forming microalgae spanning different phyla, some of public health concerns (Prorocentrum) in marine ecosystems worldwide.

Benthic prey fish assessment, Lake Ontario 2013

Science.gov (United States)

Weidel, Brian C.; Walsh, Maureen; Connerton, Michael J.

2014-01-01

The 2013 benthic fish assessment was delayed and shortened as a result of the U.S. Government shutdown, however the assessment collected 51 of the 62 planned bottom trawls. Over the past 34 years, Slimy Sculpin abundance in Lake Ontario has fluctuated, but ultimately decreased by two orders of magnitude, with a substantial decline occurring in the past 10 years. The 2013 Slimy Sculpin mean bottom trawl catch density (0.001 ind.·m-2, s.d.= 0.0017, n = 52) and mean biomass density (0.015 g·m-2 , s.d.= 0.038, n = 52) were the lowest recorded in the 27 years of sampling using the original bottom trawl design. From 2011-2013, the Slimy Sculpin density and biomass density has decreased by approximately 50% each year. Spring bottom trawl catches illustrate Slimy Sculpin and Round Goby Neogobius melanostoma winter habitat overlaps for as much as 7 months out of a year, providing opportunities for competition and predation. Invasive species, salmonid piscivory, and declines in native benthic invertebrates are likely all important drivers of Slimy Sculpin population dynamics in Lake Ontario. Deepwater Sculpin Myoxocephalus thompsonii, considered rare or absent from Lake Ontario for 30 years, have generally increased over the past eight years. For the first time since they were caught in this assessment, Deepwater Sculpin density and biomass density estimates declined from the previous year. The 2013 abundance and density estimates for trawls covering the standard depths from 60m to 150m was 0.0001 fish per square meter and 0.0028 grams per square meter. In 2013, very few small (recruitment. Nonnative Round Gobies were first detected in the USGS/NYSDEC Lake Ontario spring Alewife assessment in 2002. Since that assessment, observations indicate their population has expanded and they are now found along the entire south shore of Lake Ontario, with the highest densities in U.S. waters just east of the Niagara River confluence. In the 2013 spring-based assessment, both the

Estimation of sediment properties during benthic impact experiments

Digital Repository Service at National Institute of Oceanography (India)

Yamazaki, T.; Sharma, R

Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans...

Global warming and mass mortalities of benthic invertebrates in the Mediterranean Sea.

Directory of Open Access Journals (Sweden)

Irene Rivetti

Full Text Available Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945-2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a non-homogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas.

Global Warming and Mass Mortalities of Benthic Invertebrates in the Mediterranean Sea

Science.gov (United States)

Rivetti, Irene; Fraschetti, Simonetta; Lionello, Piero; Zambianchi, Enrico; Boero, Ferdinando

2014-01-01

Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface) of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945–2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a non-homogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas. PMID:25535973

Variation in composition of macro-benthic invertebrates as an ...

African Journals Online (AJOL)

Mo

1 Makerere University Institute of Environment & Natural Resources, P.O. Box 7062 Kampala-Uganda ... benthic macro-invertebrates communities were evaluated using GIS techniques along an ...... Kendall Hunt Publishing Company, Iowa.

14 CFR 21.147 - Changes in quality control system.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Changes in quality control system. 21.147 Section 21.147 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... quality control system. After the issue of a production certificate, each change to the quality control...

Benthic Ammonia Oxidizers Differ in Community Structure and Biogeochemical Potential Across a Riverine Delta

Directory of Open Access Journals (Sweden)

Julian eDamashek

2015-01-01

Full Text Available Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California’s Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the massive discharge of ammonium into the Sacramento River has altered this ecosystem by increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (encoding the α-subunit of ammonia monooxygenase. There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB outnumbering ammonia-oxidizing archaea (AOA only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The community structure and biogeochemical function of benthic ammonia oxidizers appears related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways is a critical step toward understanding how such ecosystems respond to the changing environmental conditions wrought by human development and climate change.

Global modelling of river water quality under climate change

Science.gov (United States)

van Vliet, Michelle T. H.; Franssen, Wietse H. P.; Yearsley, John R.

2017-04-01

Climate change will pose challenges on the quality of freshwater resources for human use and ecosystems for instance by changing the dilution capacity and by affecting the rate of chemical processes in rivers. Here we assess the impacts of climate change and induced streamflow changes on a selection of water quality parameters for river basins globally. We used the Variable Infiltration Capacity (VIC) model and a newly developed global water quality module for salinity, temperature, dissolved oxygen and biochemical oxygen demand. The modelling framework was validated using observed records of streamflow, water temperature, chloride, electrical conductivity, dissolved oxygen and biochemical oxygen demand for 1981-2010. VIC and the water quality module were then forced with an ensemble of bias-corrected General Circulation Model (GCM) output for the representative concentration pathways RCP2.6 and RCP8.5 to study water quality trends and identify critical regions (hotspots) of water quality deterioration for the 21st century.

Studies on the benthic fauna of Cochin backwater

Digital Repository Service at National Institute of Oceanography (India)

Desai, B.N.; Kutty, M.K.

Studies on the macrofauna from the five selected stations spread over a distance of about 25 km in the Cochin backwaters showed that the benthic biomass was greater in the region which were near the sea The abundance of organisms decreased...

The Impact of Global Warming and Anoxia on Marine Benthic Community Dynamics: an Example from the Toarcian (Early Jurassic)

Science.gov (United States)

Danise, Silvia; Twitchett, Richard J.; Little, Crispin T. S.; Clémence, Marie-Emilie

2013-01-01

The Pliensbachian-Toarcian (Early Jurassic) fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK), and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed). Two main faunal turnover events occurred: (i) at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0) and (ii) in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II). The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of “dead zones” in modern oceans. PMID:23457537

National Coral Reef Monitoring Program: Benthic Images Collected from Climate Stations across Wake Island from 2014-03-16 to 2014-03-19 (NCEI Accession 0159139)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across the Pacific Remote...

Climate Change and Global Wine Quality

Energy Technology Data Exchange (ETDEWEB)

Jones, G.V. [Department of Geography, Southern Oregon University, 1250 Siskiyou Blvd, Ashland, Oregon, 97520 (United States); White, M.A. [Department of Aquatic, Watershed, and Earth Resources, Utah State University, Logan, Utah, 84322 (United States); Cooper, O.R. [Cooperative Institute for Research in Environmental Sciences CIRES, University of Colorado/NOAA Aeronomy Laboratory, Boulder, Colorado, 80305 (United States); Storchmann, K. [Department of Economics, Yale University, New Haven, Connecticut, 06520 (United States)

2005-12-01

From 1950 to 1999 the majority of the world's highest quality wine-producing regions experienced growing season warming trends. Vintage quality ratings during this same time period increased significantly while year-to-year variation declined. While improved winemaking knowledge and husbandry practices contributed to the better vintages it was shown that climate had, and will likely always have, a significant role in quality variations. This study revealed that the impacts of climate change are not likely to be uniform across all varieties and regions. Currently, many European regions appear to be at or near their optimum growing season temperatures, while the relationships are less defined in the New World viticulture regions. For future climates, model output for global wine producing regions predicts an average warming of 2C in the next 50 yr. For regions producing high-quality grapes at the margins of their climatic limits, these results suggest that future climate change will exceed a climatic threshold such that the ripening of balanced fruit required for existing varieties and wine styles will become progressively more difficult. In other regions, historical and predicted climate changes could push some regions into more optimal climatic regimes for the production of current varietals. In addition, the warmer conditions could lead to more poleward locations potentially becoming more conducive to grape growing and wine production.

Live autochthonous benthic diatoms on the lower depths of Arctic continental shelf. Preliminary results

Directory of Open Access Journals (Sweden)

Elena Druzhkova

2018-01-01

Full Text Available An autochthonous community of benthic diatoms was discovered in June 2015 in the upper sediment layer at depths of 170, 205, and 245 m in the central Barents Sea. At least three benthic microalgae species (Gyrosigma fasciola, Pleurosigma angulatum, and Pleurosigma sp. 1 were detected in the sediment but not the upper water column. Analyses revealed that these benthic microalgae represent a depleted fragment of Arctic littoral microphytobenthos. Compared with the littoral flora, the deep-water assemblage is less diverse and displays low abundance. The data reported here challenge the generally accepted belief that the presence of certain microalgae at significant depths results from vertical or horizontal transfer.

Benthic Percent Cover Derived from Analysis of Benthic Images Collected during Towed-diver Surveys of the U.S. Pacific Reefs Since 2003

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data products described herein are part of the NOAA Coral Reef Conservation Program (CRCP) funded projects aimed at documenting the status and trends for benthic...

Transfer of seston lipids during a flagellate bloom from the surface to the benthic community in the Weddell Sea

Directory of Open Access Journals (Sweden)

Sergio Rossi

2013-09-01

Full Text Available Total lipid and fatty acid concentrations were studied in a late spring-early summer flagellate-dominated bloom in the Weddell Sea. These indicators were considered a good tool for assessing the quality of organic matter settling from surface to deep-water layers (epibenthic water layers. The results showed different patterns between the early (11-15 December 2003 and the late sampling period (18-27 December 2003 at all studied depths (5 m, 50 m and near-bottom water layers. Low phytoplankton biomass (mainly flagellates in the first half of the study corresponded to low total lipid and fatty acid concentrations. In the second sampling period a spring bloom (mainly flagellates and diatoms was detected, increasing the total lipid and fatty acid concentrations in the water column. The amount of settling organic matter from surface waters to the near-bottom water layers was high, especially in the late sampling period. Trophic markers showed evidence of a sink of available organic matter rich in quality and quantity, especially in terms of polyunsaturated fatty acids, for benthic organisms from surface layers to bottom layers in only a few days. The importance of studying short-time cycles in order to detect organic matter availability for benthic biota in view of the pulse-like dynamics of primary production in Antarctic waters is discussed.

Benthic fauna around Mauritius island, southwest Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

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

Distribution of benthic fauna in the Exclusive Economic Zone of Mauritius was studied during September-October 1987. Mean faunal density (macro+meio) and dry weight biomass was 10848 no.m/2 and 228.8 mg.m/2, respectively. The macrofauna was dominat...

Anticipated water quality changes in response to climate change and potential consequences for inland fishes

Science.gov (United States)

Chen, Yushun; Todd, Andrew S.; Murphy, Margaret H.; Lomnicky, Gregg

2016-01-01

Healthy freshwater ecosystems are a critical component of the world's economy, with a critical role in maintaining public health, inland biological diversity, and overall quality of life. Globally, our climate is changing, with air temperature and precipitation regimes deviating significantly from historical patterns. Healthy freshwater ecosystems are a critical component of the world's economy, with a critical role in maintaining public health, inland biological diversity, and overall quality of life. Globally, our climate is changing, with air temperature and precipitation regimes deviating significantly from historical patterns. Changes anticipated with climate change in the future are likely to have a profound effect on inland aquatic ecosystems through diverse pathways, including changes in water quality. In this brief article, we present an initial discussion of several of the water quality responses that can be anticipated to occur within inland water bodies with climate change and how those changes are likely to impact fishes.

Developing Benthic Class Specific, Chlorophyll-a Retrieving Algorithms for Optically-Shallow Water Using SeaWiFS

Directory of Open Access Journals (Sweden)

Tara Blakey

2016-10-01

Full Text Available This study evaluated the ability to improve Sea-Viewing Wide Field-of-View Sensor (SeaWiFS chl-a retrieval from optically shallow coastal waters by applying algorithms specific to the pixels’ benthic class. The form of the Ocean Color (OC algorithm was assumed for this study. The operational atmospheric correction producing Level 2 SeaWiFS data was retained since the focus of this study was on establishing the benefit from the alternative specification of the bio-optical algorithm. Benthic class was determined through satellite image-based classification methods. Accuracy of the chl-a algorithms evaluated was determined through comparison with coincident in situ measurements of chl-a. The regionally-tuned models that were allowed to vary by benthic class produced more accurate estimates of chl-a than the single, unified regionally-tuned model. Mean absolute percent difference was approximately 70% for the regionally-tuned, benthic class-specific algorithms. Evaluation of the residuals indicated the potential for further improvement to chl-a estimation through finer characterization of benthic environments. Atmospheric correction procedures specialized to coastal environments were recognized as areas for future improvement as these procedures would improve both classification and algorithm tuning.

Do lake littoral benthic invertebrates respond differently to eutrophication, hydromorphological alteration, land use and fish stocking?

Directory of Open Access Journals (Sweden)

Šiling Rebeka

2016-01-01

Full Text Available In order to provide adequate guidelines in freshwater management, managers need reliable bioindicators that can respond differently to varied stressors. Managers also have to consider hierarchical structure of environmental factors. Thus, our research aims to test the independence of taxa responses along environmental gradients and to examine in what order natural and anthropogenic factors constrain the structure of littoral benthic assemblages. The rank of explained variance of littoral benthic assemblage's variable group hierarchy was: land use > landscape characteristics > eutrophication > fish stocking > hydromorphological alteration. We determined nine gradients (two natural and seven stressor gradients, separated into five groups based on statistically significant differences in responsiveness of taxa. Apart from responsiveness to natural factors, littoral benthic invertebrates could be used as bioindicators for stressors reflecting urbanization, eutrophication, hydromorphological alteration and fish stocking. The taxonomical composition of littoral benthic invertebrates, especially when taxa with preference for certain relatively narrow environmental conditions along gradients are present, can be used to identify effects of key stressors. Our findings have profound implications for ecological assessment and management of lakes, as they indicate that benthic invertebrates can be used when the effects of multiple stressors need to be disentangled.

NEFSC 2015 Benthic Habitat Survey (HB1507, EK60)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This survey collects benthic samples using acoustics, nets, and grab samplers. The survey monitors and maps the geological, physical, and biological habitats of the...

Dinoflagellate cysts and benthic foraminifera in surface sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

Science.gov (United States)

Ferraro, L.; Rubino, F.; Frontalini, F.; Belmonte, M.; Di Leo, A.; Giandomenico, S.; Greco, M.; Lirer, F.; Spada, L.; Vallefuoco, M.

2012-12-01

Coastal areas have traditionally been places of human settlement, with the increasing development of cities, industries and other human-related activities possibly having an impact on the aquatic ecosystem. These impacts may take the form of pollution from industrial, domestic, agricultural or mining activities. For this reason, attention to marine environmental problems has recently increased and the search for new methodologies and techniques for the monitoring of coastal-marine areas become more and more active and accurate. In this context biological indicators result a useful tool to provide indication of environmental conditions including the presence or absence of contaminants; in fact biological monitoring is more directly related to the ecological health of an ecosystem than are chemical data. The increasing importance of bioindicators is also encouraged within the European Union's Water Framework Directive (WFD), which aims to achieve a good ecological status in all European water bodies (i.e., rivers, lakes and coastal waters). Among the wide range of bioindicators, 5 biological elements are listed within the WFD: phytoplankton, macroalgae, angiosperms, benthic invertebrates and fishes. Benthic invertebrates as foraminifera represent a group of protozoa widely distributed in all brackish and marine environments which are used in studies assessing the environmental quality of areas subject to intense human activity. Moreover in coastal marine environments benthic and pelagic domain present several relationships, one of these is represented by the life cycles of phytoplankton species, as Dinoflagellates, which include the production of benthic stages (cysts). These dormant stages, which accumulate in confined marine muddy areas, such as ports, lagoons or estuaries, can reach high densities, similar to the seed banks of terrestrial plants. The cysts have a high preservation potential and can rest in/on the sediments for decades. Due to this peculiar

National Coral Reef Monitoring Program: benthic images collected from climate stations across the Hawaiian Archipelago from 2016-07-16 to 2016-09-21 (NCEI Accession 0164296)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Photoquadrat benthic images were collected at NCRMP climate stations and permanent sites identified by the Ocean and Climate Change team across the Hawaiian...

Benthic phosphorus cycling in the Peruvian oxygen minimum zone

Science.gov (United States)

Lomnitz, Ulrike; Sommer, Stefan; Dale, Andrew W.; Löscher, Carolin R.; Noffke, Anna; Wallmann, Klaus; Hensen, Christian

2016-03-01

Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P at six stations, including the analysis of particles from the water column, surface sediments, and pore fluids, as well as in situ benthic flux measurements. A major fraction of solid-phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m-2 d-1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC / TPP burial ratio. Benthic dissolved P fluxes were always higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating ongoing phosphorite formation. This is further supported by decreasing porewater phosphate concentrations with sediment depth, whereas solid-phase P concentrations were comparatively

Complexity and simplification in understanding recruitment in benthic populations

KAUST Repository

Pineda, Jesús

2008-11-13

Research of complex systems and problems, entities with many dependencies, is often reductionist. The reductionist approach splits systems or problems into different components, and then addresses these components one by one. This approach has been used in the study of recruitment and population dynamics of marine benthic (bottom-dwelling) species. Another approach examines benthic population dynamics by looking at a small set of processes. This approach is statistical or model-oriented. Simplified approaches identify "macroecological" patterns or attempt to identify and model the essential, "first-order" elements of the system. The complexity of the recruitment and population dynamics problems stems from the number of processes that can potentially influence benthic populations, including (1) larval pool dynamics, (2) larval transport, (3) settlement, and (4) post-settlement biotic and abiotic processes, and larval production. Moreover, these processes are non-linear, some interact, and they may operate on disparate scales. This contribution discusses reductionist and simplified approaches to study benthic recruitment and population dynamics of bottom-dwelling marine invertebrates. We first address complexity in two processes known to influence recruitment, larval transport, and post-settlement survival to reproduction, and discuss the difficulty in understanding recruitment by looking at relevant processes individually and in isolation. We then address the simplified approach, which reduces the number of processes and makes the problem manageable. We discuss how simplifications and "broad-brush first-order approaches" may muddle our understanding of recruitment. Lack of empirical determination of the fundamental processes often results in mistaken inferences, and processes and parameters used in some models can bias our view of processes influencing recruitment. We conclude with a discussion on how to reconcile complex and simplified approaches. Although it

Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments

Science.gov (United States)

Fisher, Rebecca; Stark, Clair; Ridd, Peter; Jones, Ross

2015-01-01

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (~20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging

Spatial Patterns in Water Quality Changes during Dredging in Tropical Environments.

Science.gov (United States)

Fisher, Rebecca; Stark, Clair; Ridd, Peter; Jones, Ross

2015-01-01

Dredging poses a potential risk to tropical ecosystems, especially in turbidity-sensitive environments such as coral reefs, filter feeding communities and seagrasses. There is little detailed observational time-series data on the spatial effects of dredging on turbidity and light and defining likely footprints is a fundamental task for impact prediction, the EIA process, and for designing monitoring projects when dredging is underway. It is also important for public perception of risks associated with dredging. Using an extensive collection of in situ water quality data (73 sites) from three recent large scale capital dredging programs in Australia, and which included extensive pre-dredging baseline data, we describe relationships with distance from dredging for a range of water quality metrics. Using a criterion to define a zone of potential impact of where the water quality value exceeds the 80th percentile of the baseline value for turbidity-based metrics or the 20th percentile for the light based metrics, effects were observed predominantly up to three km from dredging, but in one instance up to nearly 20 km. This upper (~20 km) limit was unusual and caused by a local oceanographic feature of consistent unidirectional flow during the project. Water quality loggers were located along the principal axis of this flow (from 200 m to 30 km) and provided the opportunity to develop a matrix of exposure based on running means calculated across multiple time periods (from hours to one month) and distance from the dredging, and summarized across a broad range of percentile values. This information can be used to more formally develop water quality thresholds for benthic organisms, such as corals, filter-feeders (e.g. sponges) and seagrasses in future laboratory- and field-based studies using environmentally realistic and relevant exposure scenarios, that may be used to further refine distance based analyses of impact, potentially further reducing the size of the dredging

BENTHIC FORAMINIFERAL BIOSTRATIGRAPHY OF MALATYA OLIGO-MIOCENE SUCCESSION (EASTERN TAURIDS, EASTERN TURKEY

Directory of Open Access Journals (Sweden)

Fatma GEDİK

2015-10-01

Full Text Available The benthic foraminiferal biostratigraphy of Oligo-Miocene aged Muratlı and Petekkaya formations which crop out over wide regions around Akçadağ town, west of Malatya pro- vince in Eastern Taurids were revealed in this study. Systematical sampling was carried out in measured stratigraphical sections in four locations in order to perform stratigraphical and paleontological investigations. Benthic foraminifera taken from 182 hard rock samples were defined and three biozones were determined as; SBZ 21-22, belonging to Oligocene (Rupe- lian - Early Chattian, SBZ 23 (Late Chattian and SBZ 25 belonging to Lower Miocene in shallow marine deposits in the region. It was stated that the assemblage of planktic forami- nifer and nannoplankton which stratigraphically detected within Chattian - Burdigalian units in the succession most probably indicated Aquitanian age. Besides; Oligo-Miocene transition in the region was approved with this study based on biostratigraphical locations of benthic foraminiferal taxa.

Internal tides affect benthic community structure in an energetic submarine canyon off SW Taiwan

Science.gov (United States)

Liao, Jian-Xiang; Chen, Guan-Ming; Chiou, Ming-Da; Jan, Sen; Wei, Chih-Lin

2017-07-01

other hand, rebounded more rapidly due to their fast growth rate and short generation time and thus did not display bathymetric pattern in the canyon. To our knowledge, this is the first benthic ecological study in a submarine canyon connected to a high-sediment-yield SMR. The biological responses to extreme physical conditions in the GPSC could have broad implications on understanding the anthropogenic and climate change impacts in the deep-sea ecosystems.

Assessing the suitability of benthic foraminiferal morpho-groups to ...

Indian Academy of Sciences (India)

Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal .... procedure was followed for the processing of sedi- ...... Microhabitat selection of benthic foraminifera in sedi- ments off ...

Ecology of intertidal benthic algae of Northern Karnataka coast

Digital Repository Service at National Institute of Oceanography (India)

Untawale, A.G.; Reddy, C.R.K.; Deshmukhe, G.V.

The intertidal benthic marine algal flora has been studied for distribution, phenology, biomass and zonation along with the environmental conditions. About 65 species belonging to 42 genera of Chlorophyta, Phaeophyta have been recorded. Rhodophyta...

National Coral Reef Monitoring Program: Benthic Percent Cover Derived from Analysis of Benthic Images Collected for Climate Stations across American Samoa in 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at climate stations and permanent sites identified by the Ocean and...

The Economic Value of Changes in Water Quality

DEFF Research Database (Denmark)

Jensen, Anne Kejser

Water quality is from both a European and Danish perspective challenged by private use of the resource. The public good characteristics of the resource require that regulation should internalize the non-market values of water quality, in order to reach an optimal level from a welfare economic...... perspective. Valuation using stated preference techniques to value changes in ecosystem services has been widely used to estimate values of water quality. However, heterogeneity in values exists across different groups in the population. The objective of this PhD-thesis is to explore two different kinds...... of preference heterogeneity, when valuing changes in water quality. The PhD thesis consists of four papers all related to heterogeneity in the public preferences for water quality improvements. Papers referred to as 1, 2 and 3 are based on a discrete choice experiment (DCE) on water quality improvements...

Replacement of benthic communities in two Neoproterozoic-Cambrian subtropical-to-temperate rift basins, High Atlas and Anti-Atlas, Morocco

Science.gov (United States)

Clausen, Sébastien; Álvaro, J. Javier; Zamora, Samuel

2014-10-01

The ‘Cambrian explosion’ is often introduced as a major shift in benthic marine communities with a coeval decline of microbial consortia related to the diversification of metazoans and development of bioturbation (‘Agronomic Revolution’). Successive community replacements have been reported along with ecosystem diversification and increase in guild complexity from Neoproterozoic to Cambrian times. This process is recorded worldwide but with regional diachroneities, some of them directly controlled by the geodynamic conditions of sedimentary basins. The southern High Atlas and Anti-Atlas of Morocco record development of two rifts, Tonian (?) - early Cryogenian and latest Ediacarian-Cambrian in age, separated by the onset of the Pan-African Orogeny. This tectonically controlled, regional geodynamic change played a primary control on pattern and timing of benthic ecosystem replacements. Benthic communities include microbial consortia, archaeocyathan-thromboid reefal complexes, chancelloriid-echinoderm-sponge meadows, and deeper offshore echinoderm-dominated communities. Microbial consortia appeared in deeper parts of the Tonian (?) - early Cryogenian fluvio-deltaic progradational rift sequences, lacustrine environments of the Ediacaran Volcanic Atlasic Chain (Ouarzazate Supergroup) and the Ediacaran-Cambrian boundary interval, characterized by the peritidal-dominated Tifnout Member (Adoudou Formation). They persisted and were largely significant until Cambrian Age 3, as previous restricted marine conditions precluded the immigration of shelly metazoans in the relatively shallow epeiric parts of the Cambrian Atlas Rift. Successive Cambrian benthic communities were replaced as a result of distinct hydrodynamic and substrate conditions, which allow identification of biotic (e.g., antagonistic relationships between microbial consortia and echinoderms, and taphonomic feedback patterns in chancelloriid-echinoderm-sponge meadows) and abiotic (e.g., rifting

Ecological Assessment of Lake Hora, Ethiopia, Using Benthic and ...

African Journals Online (AJOL)

Bheema

Lake Hora needs protection management strategies to maintain its sustainable use. Key words: Benthic Fauna, Ethiopia, Lake Hora, Specimens, Weed-bed. 1. ..... Loam soils often contain a good amount of organic matter. 3.3. Ecological ...

Effects of Karenia brevis on clearance rates and bioaccumulation of brevetoxins in benthic suspension feeding invertebrates.

Science.gov (United States)

Echevarria, Michael; Naar, Jerome P; Tomas, Carmelo; Pawlik, Joseph R

2012-01-15

Blooms of the toxic alga Karenia brevis occur along coastlines where sessile suspension feeding invertebrates are common components of benthic communities. We studied the effects of K. brevis on four benthic suspension feeding invertebrates common to the coast of the SE United States: the sponge Haliclona tubifera, the bryozoan Bugula neritina, the bivalve Mercenaria mercenaria, and the tunicate Styela plicata. In controlled laboratory experiments, we determined the rate at which K. brevis was cleared from the seawater by these invertebrates, the effect of K. brevis on clearance rates of a non-toxic phytoplankton species, Rhodomonas sp., and the extent to which brevetoxins bioaccumulated in tissues of invertebrates using an enzyme-linked immunosorbent assay (ELISA). All four invertebrate species cleared significant quantities of K. brevis from seawater, with mean clearance rates ranging from 2.27 to 6.71 L g h⁻¹ for H. tubifera and S. plicata, respectively. In the presence of K. brevis, clearance rates of Rhodomonas sp. by B. neritina and S. plicata were depressed by 75% and 69%, respectively, while clearance rates by H. tubifera and M. mercenaria were unaffected. Negative effects of K. brevis were impermanent; after a recovery period of 13 h, B. neritina and S. plicata regained normal clearance rates. All four invertebrates accumulated high concentrations of brevetoxin after a 4h exposure to K. brevis, but when animals were transferred to filtered seawater for 15 h after exposure, brevetoxin concentrations in the tissues of H. tubifera and B. neritina decreased by ∼80%, while there was no change in toxin concentration in the tissues of S. plicata and M. mercenaria. High cell concentrations of K. brevis may cause a suppression of clearance rates in benthic suspension feeding invertebrates, resulting in a positive feedback for bloom formation. Also, high concentrations of toxin may accumulate in the tissues of benthic suspension feeding invertebrates that may

Bottom trawling and oxygen minimum zone influences on continental slope benthic community structure off Vancouver Island (NE Pacific)

Science.gov (United States)

De Leo, Fabio C.; Gauthier, Maéva; Nephin, Jessica; Mihály, Steven; Juniper, S. Kim

2017-03-01

Understanding responses of benthic ecosystems to cumulative impacts of natural stressors, long-term ocean change and increasing resource exploitation is an emerging area of interest for marine ecologists and environmental managers. Few, if any, studies have quantitatively addressed cumulative effects in the deep sea. We report here on a study from the continental slope off Vancouver Island (Canada) in the northeast Pacific Ocean, where the Oxygen Minimum Zone impinges on seabed habitats that are subjected to widespread bottom trawling, primarily by the fishery for thornyhead (Sebastolobus ssp.). We examined how the benthic megafauna in this area was influenced by varying levels of dissolved oxygen and trawling activity, along a depth gradient that was also likely to shape community composition. Continuous video and sonar records from two ROV surveys (50 linear km total; depth range 300-1400 m) respectively provided data on faunal attributes (composition, abundance and diversity) and the frequency of trawl door marks on the seabed. Faunal and trawl data were compiled in a geo-referenced database along with corresponding dissolved oxygen data, and pooled into 500 m segments for statistical analysis. Trawl mark occurrence peaked between 500 and 1100 m, corresponding to areas of slope subjected to hypoxia (PERMANOVA analyses, with characterizing taxa identified for all three factors. Depth, dissolved oxygen and trawl mark density accounted for 21% to 52% of the variability in benthic community structure according to multiple regression (DISTLM) models. Species richness was highest at intermediate depths and in areas subject to intermediate levels of trawling, and higher under hypoxia than under severe hypoxia. These statistically significant trends demonstrate that the structuring influences of bottom trawling on deep-sea benthic communities can be observed even where communities are being shaped by strong environmental gradients.

Flow enhances photosynthesis in marine benthic autotrophs by increasing the efflux of oxygen from the organism to the water.

Science.gov (United States)

Mass, Tali; Genin, Amatzia; Shavit, Uri; Grinstein, Mor; Tchernov, Dan

2010-02-09

Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism's photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO(2). No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs.

Long-term patterns of benthic irradiance and kelp production in the central Beaufort sea reveal implications of warming for Arctic inner shelves

Science.gov (United States)

Bonsell, Christina; Dunton, Kenneth H.

2018-03-01

This study synthesizes a multidecadal dataset of annual growth of the Arctic endemic kelp Laminaria solidungula and corresponding measurements of in situ benthic irradiance from Stefansson Sound in the central Beaufort Sea. We incorporate long-term data on sea ice concentration (National Sea Ice Data Center) and wind (National Weather Service) to assess how ice extent and summer wind dynamics affect the benthic light environment and annual kelp production. We find evidence of significant changes in sea ice extent in Stefansson Sound, with an extension of the ice-free season by approximately 17 days since 1979. Although kelp elongation at 5-7 m depths varies significantly among sites and years (3.8-49.8 cm yr-1), there is no evidence for increased production with either earlier ice break-up or a longer summer ice-free period. This is explained by very low light transmittance to the benthos during the summer season (mean daily percent surface irradiance ± SD: 1.7 ± 3.6 to 4.5 ± 6.6, depending on depth, with light attenuation values ranging from 0.5 to 0.8 m-1), resulting in minimal potential for kelp production on most days. Additionally, on month-long timescales (35 days) in the ice-free summer, benthic light levels are negatively related to wind speed. The frequent, wind-driven resuspension of sediments following ice break-up significantly reduce light to the seabed, effectively nullifying the benefits of an increased ice-free season on annual kelp growth. Instead, benthic light and primary production may depend substantially on the 1-3 week period surrounding ice break-up when intermediate sea ice concentrations reduce wind-driven sediment resuspension. These results suggest that both benthic and water column primary production along the inner shelf of Arctic marginal seas may decrease, not increase, with reductions in sea ice extent.

Benthic foraminiferal assemblages as bio-indicators of metals contamination in sediments, Qarun Lake as a case study, Egypt

Science.gov (United States)

Abd El Naby, Ahmed; Al Menoufy, Safia; Gad, Ahmed

2018-03-01

Qarun Lake, in the Fayoum Depression of the Western Desert of Egypt, lies within the deepest area in the River Nile flood plain. The drainage water in the Qarun Lake is derived from the discharge of the natural and artificial drainage systems in the Fayoum. Mixed domestic and agricultural pollutants, including heavy metals, nitrates, phosphates, sulfates and pesticides, are discharged into Qarun Lake. Forty-six samples, collected from the undisturbed layer of sediments were used for benthic foraminiferal analysis. Concentrations of some selected trace metal elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, and Zn) were also determined. Statistical analysis of the abiotic variables (Texture distribution of sediments, Physico-chemical parameters, and metals concentrations) and of the biotic variables (distribution of benthic foraminiferal species) were also performed. The Q-mode cluster analysis of benthic foraminiferal distribution has provided evidence that the Qarun Lake can be subdivided into two cluster groups (A and B), reflecting environmental changes in the lake ecosystem. Cluster B can also be subdivided into two sub-clusters (B1 and B2). The presence of only pollution tolerant taxa with higher faunal density and lower diversity and the absence of the other foraminiferal assemblages in cluster A were attributed to the high concentration of trace metal elements and the strong environmental stress at the eastern and central parts of the Qarun Lake.

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.

The role of zooplankton in the pelagic-benthic coupling of the Southern Ocean

Directory of Open Access Journals (Sweden)

Sigrid B. Schnack-Schiel

2005-12-01

Full Text Available Zooplankton contributes in different ways to pelagic-benthic coupling: Their faecal material is a major route of energy flow and the vertical migrations of many species as well as the production of pelagic larvae by benthic organisms represent different paths to link the two subsystems. Antarctic particle fluxes have been shown to be highly variable in size and composition within a given region and even at the same site from year to year. There are also differences throughout the water column, where particle fluxes close to the sea floor beyond the continental shelf break do not normally show seasonal variation within shallow environments. Commonly, at depths shallower than 500 m, the most evident feature is that more than 90% of the annual fluxes occur during a short period of the spring-summer. This event is masked near the seabed at greater depths due to resupension and lateral advection of particles. Faecal material of various origins is one of the main constituents of the biogenic matter flux. It usually reaches its maximum in February once the early phytoplankton bloom has developed. However, the presence of faecal pellets is ubiquitous during the months of the year when there is enough light to support primary production. At this stage more research is needed to elucidate the particular role of distinct taxa—including among others salps, krill, copepods and protozoans—in the transport of organic matter to the benthos, and their contribution to the biogeochemical cycles of carbon, nitrogen, phosphorus and silicon. Aggregation of particles is another important process controlling the development and dynamics of pelagic-benthic coupling due to its influence on the sinking velocity of particles and the enhancement of organic matter utilisation by members of the microbial loop in the upper layers of the water column. Also in shallow waters, aggregation favours the transfer of high-quality organic matter to the benthic realm. At greater

Bioturbation determines the response of benthic ammonia-oxidizing microorganisms to ocean acidification

Science.gov (United States)

Laverock, B.; Kitidis, V.; Tait, K.; Gilbert, J. A.; Osborn, A. M.; Widdicombe, S.

2013-01-01

Ocean acidification (OA), caused by the dissolution of increasing concentrations of atmospheric carbon dioxide (CO2) in seawater, is projected to cause significant changes to marine ecology and biogeochemistry. Potential impacts on the microbially driven cycling of nitrogen are of particular concern. Specifically, under seawater pH levels approximating future OA scenarios, rates of ammonia oxidation (the rate-limiting first step of the nitrification pathway) have been shown to dramatically decrease in seawater, but not in underlying sediments. However, no prior study has considered the interactive effects of microbial ammonia oxidation and macrofaunal bioturbation activity, which can enhance nitrogen transformation rates. Using experimental mesocosms, we investigated the responses to OA of ammonia oxidizing microorganisms inhabiting surface sediments and sediments within burrow walls of the mud shrimp Upogebia deltaura. Seawater was acidified to one of four target pH values (pHT 7.90, 7.70, 7.35 and 6.80) in comparison with a control (pHT 8.10). At pHT 8.10, ammonia oxidation rates in burrow wall sediments were, on average, fivefold greater than in surface sediments. However, at all acidified pH values (pH ≤ 7.90), ammonia oxidation rates in burrow sediments were significantly inhibited (by 79–97%; p < 0.01), whereas rates in surface sediments were unaffected. Both bacterial and archaeal abundances increased significantly as pHT declined; by contrast, relative abundances of bacterial and archaeal ammonia oxidation (amoA) genes did not vary. This research suggests that OA could cause substantial reductions in total benthic ammonia oxidation rates in coastal bioturbated sediments, leading to corresponding changes in coupled nitrogen cycling between the benthic and pelagic realms. PMID:23980243

Ecological assessment of the Tajan river using feeding groups of benthic macroinvertebrates and biotic indices

Directory of Open Access Journals (Sweden)

M Sharifinia

2012-06-01

Full Text Available One of the best practical methods to understand ecological status of a water body and determine impacts of human intervention in reducing water quality is using benthic macroinvertebrates as assessment tools for monitoring their biological integrity and health. The Tajan River is one of the rivers of Caspian Southernsub-basin that drains the Caspian Sea. Macroinvertebrate samples were taken using Surber’s sampler (40 x 40 cm and 100µ mesh size in 45 day intervals with 3 replicates in each sampling site for a period of one year (May 2010 to May 2011. The collected organisms were preserved in 4% formalin solution and transferred to the laboratory for identification and counting. Six different functional feeding groups of macroinvertebrate e.g. Collector-gathering, Collector-filtering, Predator, Collector-gathering /Scraper, Predator/Collector-gathering and Scraper were determined. Feeding groups of Collector-gathering, Collector-filtering and Collector-gathering /Scraper were relatively dominant in comparison to other groups. Groups of Collector-filtering and Collector-gathering were dominant in slightly and heavily polluted stations, respectively. In this study population structure measures including abundance, EPT percent and the EPT and EPT/CHIR indics were mearsured. Species diversity, species richness were also determined using Shannon- Weiner, Margalef and Jacardindics. The minimum and maximum values of Hilsenhoff biotic index were observedin stations 1 (4.29 and 5 (5.57, respectively. Moreover, the highest and lowest values of BMWP/ASPT were observed in station 1 (4.51 and 5 (3.25, respectively. Evaluation of indicators revealed less water quality at stations 2, 3 and 5 which located at the lowermost of fish farms and effluent of factory. This reduction might be implicated to the effluents of water damps from fish farms running into the stream as diversity and total abundance (% of sociable macroinvertebrates decreased and that of

WASP7 BENTHIC ALGAE - MODEL THEORY AND USER'S GUIDE

Science.gov (United States)

The standard WASP7 eutrophication module includes nitrogen and phosphorus cycling, dissolved oxygen-organic matter interactions, and phytoplankton kinetics. In many shallow streams and rivers, however, the attached algae (benthic algae, or periphyton, attached to submerged substr...

Integrated quality assessment of sediments from harbour areas in Santos-São Vicente Estuarine System, Southern Brazil

Science.gov (United States)

Buruaem, Lucas Moreira; de Castro, Ítalo Braga; Hortellani, Marcos Antonio; Taniguchi, Satie; Fillmann, Gilberto; Sasaki, Silvio Tarou; Varella Petti, Mônica Angélica; Sarkis, Jorge Eduardo de Souza; Bícego, Márcia Caruso; Maranho, Luciane Alves; Davanso, Marcela Bergo; Nonato, Edmundo Ferraz; Cesar, Augusto; Costa-Lotufo, Leticia Veras; Abessa, Denis Moledo de Souza

2013-09-01

Santos-São Vicente Estuarine System is a highly populated coastal zone in Brazil and where it is located the major port of Latin America. Historically, port activities, industrial and domestic effluents discharges have constituted the main sources of contaminants to estuarine system. This study aimed to assess the recent status of sediment quality from 5 zones of Port of Santos by applying a lines-of-evidence approach through integrating results of: (1) acute toxicity of whole sediment and chronic toxicity of liquid phases; (2) grain size, organic matter, organic carbon, nitrogen, phosphorus, trace metals, polycyclic aromatic hydrocarbons, linear alkylbenzenes and butyltins; (3) benthic community descriptors. Results revealed a gradient of increasing contamination for metals and organic compounds, alongside with their geochemical carriers. Sediment liquid phases were more toxic compared to whole sediment. Low number of species and individuals indicated the impoverishment of benthic community. The use of site-specific sediment quality guidelines was more appropriate to predict sediment toxicity. The integration of results through Sediment Quality Triad approach and principal component analysis allowed observing the effects of natural stressors and dredging on sediment quality and benthic distribution. Even with recent governmental efforts to control, pollution is still relevant in Port of Santos and a threat to local ecosystems.

Anthropogenic infilling of a Bermudian sinkhole and its impact on sedimentation and benthic foraminifera in the adjacent anchialine cave environment

Directory of Open Access Journals (Sweden)

Jacquelyn N. Cresswell

2017-09-01

Full Text Available In the mid-20th century, an inland brackish pond from Bermuda, known as Eve’s Pond, was filled with marine sediment from an adjacent coastal lagoon. At this time, an eyewitness reported “…sediment billowing out of the Green Bay Cave for days…”, which is a marine-dominated anchialine cave located proximal to the former location of Eve’s Pond (~200 m. The purpose of this study was to evaluate the potential impact of this infilling event on cave sedimentation and benthic meiofaunal communities, as proxied by the unicellular protists foraminifera that remain preserved in the sediment record. Eight sediment cores were collected from an underwater passage in Green Bay Cave in a transect towards the location where Eve’s Pond was surveyed in 1901 CE. The sediment cores were analyzed for visual and density changes (photography, X-radiography, textural variability, benthic foraminifera fauna and diversity, and radiocarbon dating. The recovered sediment cores mostly sampled a late Holocene carbonate mud facies that had been described during previous research in the cave, with benthic foraminiferal assemblages post-dating the onset of seawater circulating between the saline groundwater flooding the cave and the adjacent Harrington Sound ~1,900 years ago. However, two cores located further into the cave (cores 13 and 17 contain a carbonate sand layer with lagoon foraminifera that is anomalous with respect to the Holocene depositional history of the cave and is most likely related to the mid-20th century infilling of Eve’s Pond. Examination of these two cores showed that after the infilling event, the community of benthic foraminifera rapidly reverted to pre-impact assemblages with foraminiferal stygophiles (e.g., Spirophthalmidium emaciatum, Sigmoilina tenuis, which were not displaced by new colonizers introduced into the cave by the dredge spoils. We caution that the results cannot be extrapolated to the pelagic crustacean community, but the

Interactions Between Hydropeaking and Thermopeaking Waves and Their Effect on the Benthic Community in Flume Simulations

Science.gov (United States)

Bruno, M.; Carolli, M.; Maiolini, B.; Siviglia, A.; Zolezzi, G.

2013-12-01

M. C. Bruno1*, M. Carolli2, B. Maiolini1, A. Siviglia2, Zolezzi, G.2 1 Fondazione Edmund Mach, Research and Innovation Centre. S. Michele all'Adige, I-38010, Italy 2 Department of Civil, Environmental and Mechanical Engineering, University of Trento, I-38100, Trento, Italy * cristina.bruno@fmach.it In Alpine regions, hydroelectricity generation is a key power source and its ability to quickly respond to short-term changes in energy demand makes it an ideal source to meet the needs of the deregulated energy market. This economic need is reflected in the temporal patterns of dam operations with consequences for the water bodies that receive downstream releases in the form of ';hydropeaking', typically consisting of sharp water releases in river reaches below dams. The unsteadiness related to this highly intermittent phenomenon has cascading effects on both biotic and abiotic river resources. Regulation by dams may also significantly affect the thermal regime of riversespecially in mountain areas, where releases from high-elevation reservoirs are often characterized by a markedly different temperature from that of the receiving body, thus causing also sharp water temperature variations, named ';thermopeaking'. While interacting with external forcing, the hydrodynamic and thermal waves propagate downstream with different celerities and a first phase of mutual overlap is followed by a second phase in which the two waves proceed separately. The asynchronous propagation of the two waves produces two distinct but consecutive impacts on the benthic community. Because it is difficult to disentangle the multiple effects of hydropeaking and thermopeaking on benthic macroinvertebrates in experiments conducted in natural conditions, we conducted our studies in an experimental structure of five steel channels directly fed by an alpine stream, the Fersina, a tributary to the Adige River of northern Italy. We simulated two sets of cold and warm thermopeaking waves, and measured the

Response of meiofauna to immediate benthic disturbance in the Central Indian Ocean Basin

Digital Repository Service at National Institute of Oceanography (India)

Ingole, B.S.; Ansari, Z.A.; Rathod, V.; Rodrigues, N.

before (striped bars) and after (solid bars) disturbanceexperiment at selected stations. main constraint for benthic faunal abundance in the deep sea. The mobile organisms areknown to graze on the nodule surface,and the sesile ones use them as a hard... undis-turbed benthic environment,mainly because of the deployment of a large volume of equip- ment and infrastructure facilities on the sea bottom. The sediment plume caused by the mininghead while collecting the raw materials (nodules) will sharply...

Bathymetric preference of four major genera of rectilinear benthic ...

Indian Academy of Sciences (India)

(OMZ), both shallow marine (50–60 m water depth) and intermediate to deep water (150–1500 m water depth) ... depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for ..... in processing the samples.

National Coral Reef Monitoring Program: Benthic Percent Cover Derived from Analysis of Benthic Images Collected for Climate Stations across the Hawaiian Archipelago since 2013

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at climate stations and permanent sites identified by the Ocean and...

National Coral Reef Monitoring Program: Benthic Percent Cover Derived from Analysis of Benthic Images Collected for Climate Stations across the Mariana Archipelago in 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at climate stations and permanent sites identified by the Ocean and...

Assessment of Machine Learning Algorithms for Automatic Benthic Cover Monitoring and Mapping Using Towed Underwater Video Camera and High-Resolution Satellite Images

Directory of Open Access Journals (Sweden)

Hassan Mohamed

2018-05-01

Full Text Available Benthic habitat monitoring is essential for many applications involving biodiversity, marine resource management, and the estimation of variations over temporal and spatial scales. Nevertheless, both automatic and semi-automatic analytical methods for deriving ecologically significant information from towed camera images are still limited. This study proposes a methodology that enables a high-resolution towed camera with a Global Navigation Satellite System (GNSS to adaptively monitor and map benthic habitats. First, the towed camera finishes a pre-programmed initial survey to collect benthic habitat videos, which can then be converted to geo-located benthic habitat images. Second, an expert labels a number of benthic habitat images to class habitats manually. Third, attributes for categorizing these images are extracted automatically using the Bag of Features (BOF algorithm. Fourth, benthic cover categories are detected automatically using Weighted Majority Voting (WMV ensembles for Support Vector Machines (SVM, K-Nearest Neighbor (K-NN, and Bagging (BAG classifiers. Fifth, WMV-trained ensembles can be used for categorizing more benthic cover images automatically. Finally, correctly categorized geo-located images can provide ground truth samples for benthic cover mapping using high-resolution satellite imagery. The proposed methodology was tested over Shiraho, Ishigaki Island, Japan, a heterogeneous coastal area. The WMV ensemble exhibited 89% overall accuracy for categorizing corals, sediments, seagrass, and algae species. Furthermore, the same WMV ensemble produced a benthic cover map using a Quickbird satellite image with 92.7% overall accuracy.

Identification of threshold body burdens of metals for the protection of the aquatic ecological status using two benthic invertebrates

International Nuclear Information System (INIS)

Bervoets, Lieven; De Jonge, Maarten; Blust, Ronny

2016-01-01

In this study accumulated concentrations of As, Cd, Cr, Cu, Ni, Pb and Zn in two benthic invertebrate taxa, Chironomus sp. and Tubificidae are related to ecological responses expressed as changes in macro invertebrate communities. In addition critical body burdens were estimated above which ecological quality was always lower than a certain threshold. Data from existing studies on bioaccumulation of the metals in both taxa were combined with different biological water quality indices. For all metal-endpoint combinations threshold values could be calculated above which ecological quality was always low. Safe threshold body burdens could be estimated for both species for all metals although the data set was more extended for Chrionomus sp. with estimated threshold values being 65, 3.2, 10, 57, 6.5, 73 and 490 μg/g dw for As, Cd, Cr, Cu, Ni, Pb and Zn. This study demonstrated that metal accumulation in resistant species such as chironomids and tubificid worms have the potential to be used as predictors of ecological effects in aquatic ecosystems. However, the estimated threshold values have to be validated and supported by more lines of evidence before they can be used by regulators. - Highlights: • Chironomid larvae and Tubificid worms can be used to relate accumulated metals to ecological endpoints. • Ecological water quality, calculated with biotic indices, is always low at high accumulated metal concentrations. • Critical body burdens in chironomids and tubificds could be estimated for As, Cd, Cr, Cu, Ni, Pb and Zn. - Maximal body burdens of metals in two invertebrate species could be estimated above which ecological quality was always low.

Using benthic macroinvertebrate and fish communities as bioindicators of the Tanshui River basin around the greater Taipei area - multivariate analysis of spatial variation related to levels of water pollution.

Science.gov (United States)

Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

2014-07-14

After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15-35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted.

Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

Directory of Open Access Journals (Sweden)

Francesca Pasotti

Full Text Available The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands, a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii over time driving the benthic assemblages into a more compact trophic structure with

Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat.

Science.gov (United States)

Pasotti, Francesca; Saravia, Leonardo Ariel; De Troch, Marleen; Tarantelli, Maria Soledad; Sahade, Ricardo; Vanreusel, Ann

2015-01-01

The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ13C and δ15N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased

Changes of communities of phytobenthos of Drevnica River - ecological condition assessment in space and time; Zmeny spolecenstev fytobentosu reky Drevnice - hodnoceni ekologickeho stavu v prostoru a case

Energy Technology Data Exchange (ETDEWEB)

Safarova, M.; Uher, B.; Chattova, B. [Masarykova univerzita, Ustav botaniky a zoologie, 62100 Brno-Reckovice (Czech Republic)

2013-04-16

The study deals with a biological evaluation of water quality of the Drevnice River (Eastern Moravia) by a community of cyanobacteria and algae which are tied to the bottom substrate (e.g. mud, sand, stones). Phytobenthos, as this file of benthic autotrophic organisms is called, has a significant position among bioindicators of water quality for the ability to reflect environmental changes in a short time. The work consisted in monitoring changes in diversity of phytobenthos community and measurement of physicochemical parameters within one year. The aim was to find relations between the organisms and parameters and to determinate the current ecological status of the river. (authors)

Human Stressors Are Driving Coastal Benthic Long-Lived Sessile Fan Mussel Pinna nobilis Population Structure More than Environmental Stressors.

Science.gov (United States)

Deudero, Salud; Vázquez-Luis, Maite; Álvarez, Elvira

2015-01-01

Coastal degradation and habitat disruption are severely compromising sessile marine species. The fan shell Pinna nobilis is an endemic, vulnerable species and the largest bivalve in the Mediterranean basin. In spite of species legal protection, fan shell populations are declining. Models analyzed the contributions of environmental (mean depth, wave height, maximum wave height, period of waves with high energy and mean direction of wave source) versus human-derived stressors (anchoring, protection status, sewage effluents, fishing activity and diving) as explanatory variables depicting Pinna nobilis populations at a mesoscale level. Human stressors were explaining most of the variability in density spatial distribution of fan shell, significantly disturbing benthic communities. Habitat protection affected P. nobilis structure and physical aggression by anchoring reveals a high impact on densities. Environmental variables instead played a secondary role, indicating that global change processes are not so relevant in coastal benthic communities as human-derived impacts.

Northeast Puerto Rico and Culebra Island - Benthic Habitat Map 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

Limited differences in fish and benthic communities and possible cascading effects inside and outside a protected marine area in Sagres (SW Portugal).

Science.gov (United States)

Gil Fernández, C; Paulo, D; Serrão, E A; Engelen, A H

2016-03-01

Marine protected areas (MPAs) are a relatively recent fisheries management and conservation tool for conservation of marine ecosystems and serve as experimental grounds to assess trophic cascade effects in areas were fishing is restricted to some extent. A series of descriptive field studies were performed to assess fish and benthic communities between two areas within a newly established MPA in SW Portugal. We characterized benthic macroalgal composition and determined the size, density and biomass of the main benthic predatory and herbivorous fish species as well as the main benthic herbivorous invertebrates to assess indications of top-down control on the phytobenthic assemblages. Fish species were identical inside and outside the MPA, in both cases Sarpa salpa was the most abundant fish herbivore and Diplodus spp. accounted for the great majority of the benthic predators. However, size and biomass of D. spp. were higher inside than outside the MPA. The main herbivorous invertebrate was the sea urchin Paracentrotus lividus, which was smaller and predominantly showing a crevice-dwelling behaviour in the MPA. In addition, P. lividus size frequency distribution showed a unimodal pattern outside and a bimodal pattern inside the MPA. We found significant differences in the algal assemblages between inside and outside the MPA, with higher abundance of turf and foliose algae inside, and articulated calcareous and corticated macrophytes outside the MPA, but no differences in the invasive Asparagopsis spp. The obtained results show differences in predatory fish and benthic community structure, but not in species richness, inside and outside the MPA. We hypothesize these differences lead to variation in species interactions: directly through predation and indirectly via affecting sea urchins behavioural patterns, predators might drive changes in macroalgal assemblages via trophic cascade in the study area. However due to non-biological differences between the two areas it

New records of benthic marine algae and Cyanobacteria for Costa Rica, and a comparison with other Central American countries

Science.gov (United States)

Bernecker, Andrea; Wehrtmann, Ingo S.

2009-09-01

We present the results of an intensive sampling program carried out from 2000 to 2007 along both coasts of Costa Rica, Central America. The presence of 44 species of benthic marine algae is reported for the first time for Costa Rica. Most of the new records are Rhodophyta (27 spp.), followed by Chlorophyta (15 spp.), and Heterokontophyta, Phaeophycea (2 spp.). Overall, the currently known marine flora of Costa Rica is comprised of 446 benthic marine algae and 24 Cyanobacteria. This species number is an under estimation, and will increase when species of benthic marine algae from taxonomic groups where only limited information is available (e.g., microfilamentous benthic marine algae, Cyanobacteria) are included. The Caribbean coast harbors considerably more benthic marine algae (318 spp.) than the Pacific coast (190 spp.); such a trend has been observed in all neighboring countries. Compared to other Central American countries, Costa Rica has the highest number of reported benthic marine algae; however, Panama may have a similarly high diversity after unpublished results from a Rhodophyta survey (Wysor, unpublished) are included. Sixty-two species have been found along both the Pacific and Caribbean coasts of Costa Rica; we discuss this result in relation to the emergence of the Central American Isthmus.

Ventilation changes in the western North Pacific since the last glacial period

Directory of Open Access Journals (Sweden)

Y. Okazaki

2012-01-01

Full Text Available We reconstructed the ventilation record of deep water at 2100 m depth in the mid-latitude western North Pacific over the past 25 kyr from radiocarbon measurements of coexisting planktic and benthic foraminiferal shells in sediment with a high sedimentation rate. The ¹⁴C data on fragile and robust planktic foraminiferal shells were concordant with each other, ensuring high quality of the reconstructed ventilation record. The radiocarbon activity changes were consistent with the atmospheric record, suggesting that no massive mixing of old carbon from the abyssal reservoir occurred throughout the glacial to deglacial periods.

Species diversity variations in Neogene deep-sea benthic ...

Indian Academy of Sciences (India)

early Miocene Climatic Optimum (∼17.2–16.4 Ma) followed by a decrease during 16.4–13 Ma ... The benthic foraminiferal populations and diversity at Hole 730A .... counted to calculate percentages. ..... Findlater J 1971 Monthly mean airflow at low levels over ... mass stratification in the northeastern Indian Ocean;.

A mathematical model of algae growth in a pelagic-benthic coupled shallow aquatic ecosystem.

Science.gov (United States)

Zhang, Jimin; Shi, Junping; Chang, Xiaoyuan

2018-04-01

A coupled system of ordinary differential equations and partial differential equations is proposed to describe the interaction of pelagic algae, benthic algae and one essential nutrient in an oligotrophic shallow aquatic ecosystem with ample supply of light. The existence and uniqueness of non-negative steady states are completely determined for all possible parameter range, and these results characterize sharp threshold conditions for the regime shift from extinction to coexistence of pelagic and benthic algae. The influence of environmental parameters on algal biomass density is also considered, which is an important indicator of algal blooms. Our studies suggest that the nutrient recycling from loss of algal biomass may be an important factor in the algal blooms process; and the presence of benthic algae may limit the pelagic algal biomass density as they consume common resources even if the sediment nutrient level is high.

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

is devoted to obtaining more and better data describing this exchange. Efforts to quantify exchange between the water column and the sediment must continue. However, such studies will not, in themselves, lead to a quantification of pelagic-benthic coupling in the North Sea. We identify here other areas......The coupling between pelagic and benthic processes occurs through the signals sent between the water column and the seabed. Huge methodological challenges are associated with the quantification of the signals being sent between these two domains - especially in a relatively shallow and heavily...... fished region such as the North Sea where deployment of sediment traps or bottom mounted cameras or samplers is difficult. Thus, there are relatively few sites in the North Sea for which good data are available for describing pelagic-benthic (or near shore-offsbore) coupling and considerable effort...

Bioaccumulation of sediment-bound Cr-51, Ni-63 and C-14 by benthic invertebrates

International Nuclear Information System (INIS)

Kumblad, L.; Bradshaw, C.; Giled, M.

2004-01-01

Sediments in many areas of the Baltic Sea are highly contaminated with particle-reactive trace metals and/or radionuclides. These may be re-mobilised into aquatic food chains by bioaccumulation into benthic organisms. In this study, we examined and compared assimilation efficiencies and bioaccumulation kinetics (rates of uptake and elimination) of sediment-associated Cr-51, Ni-63 and organic-associated C- 14 in three common benthic invertebrates from the Baltic Sea (the bivalve Macoma balthica, the amphipod Monoporeia affinis and the priapulid worm Halicryptus spinulosus). There were differences between animals and radionuclides in both the rate of uptake and elimination and the maximum amount accumulated. Understanding how and to what degree different deposit-feeding benthic invertebrates are exposed to and bio-accumulate sediment-associated metals are important for both ecological risk assessment and management decisions in coastal ecosystems. (author)

First phase monitoring studies of simulated benthic disturbance delineating movement of fine particles in the Central Indian Basin

Digital Repository Service at National Institute of Oceanography (India)

Valsangkar, A.B.

Benthic disturbance due to future deep-sea polymetallic nodule mining would involve extensive sediment plume generation and resedimentation on the sea floor. In order to evaluate the effects of resedimentation on benthic environment, the Indian...

Tracking Biological and Ecosystem Responses to Changing Environmental Conditions in the Pacific Arctic

Science.gov (United States)

Grebmeier, J. M.; Cooper, L. W.; Frey, K. E.; Moore, S. E.

2014-12-01

Changing seasonal sea ice conditions and seawater temperatures strongly influence biological processes and marine ecosystems at high latitudes. In the Pacific Arctic, persistent regions termed "hotspots", are localized areas with high benthic macroinfaunal biomass that have been documented over four decades (see Figure). These regions are now being more formally tracked to relate physical forcing and ecosystem response as an Arctic Distributed Biological Observatory (DBO) supported by the US National Ocean Policy Implementation Plan and international partners. These hotspots are important foraging areas for upper trophic level benthic feeders, such as marine mammals and seabirds. South of St. Lawrence Island (SLI) in the northern Bering Sea, benthic feeding spectacled eiders, bearded seals and walruses are important winter consumers of infauna, such as bivalves and polychaetes. Gray whales have historically been a major summer consumer of benthic amphipods in the Chirikov Basin to the north of SLI, although summertime sightings of gray whales declined in the Chirikov from the 1980s up until at least 2002. The SE Chukchi Sea hotspot, as are the other hotspots, is maintained by export of high chlorophyll a that is produced locally as well as advected by water masses transiting northward through the system. Both walrus and gray whales are known to forage in this hotspot seasonally on high biomass levels of benthic prey. Notably the center of the highest benthic biomass regions has shifted northward in three of the DBO hotspots in recent years. This has coincided with changing sediment grain size, an indicator of current speed, and is also likely a response to changes in primary production in the region. Studies of these broad biological responses to changing physical drivers have been facilitated through development of the DBO cooperative effort by both US and international scientists. The DBO includes a series of coordinated, multi-trophic level observations that

St. John Benthic Habitat Mapping - Moderate Depth Ground Validation Sites

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitats of the moderate-depth marine environment in and around the Virgin Islands Coral Reef National Monument were mapped using a combination of...

Benthic foraminiferal Mn / Ca ratios reflect microhabitat preferences

NARCIS (Netherlands)

Koho, K.A.; de Nooijer, L.J.; Fontanier, C.; Toyofuku, T.; Oguri, K.; Kitazato, H.; Reichart, G.-J.

2017-01-01

The Mn / Ca of calcium carbonate tests of living (rose-Bengal-stained) benthic foraminifera (Elphidium batialis, Uvigerina spp., Bolivina spissa, Nonionellina labradorica and Chilostomellina fimbriata) were determined in relation to pore water manganese (Mn) concentrations for the first time along a

Cross shelf benthic biodiversity patterns in the Southern Red Sea

KAUST Repository

Ellis, Joanne; Anlauf, Holger; Kurten, Saskia; Lozano-Corté s, Diego; Alsaffar, Zahra Hassan Ali; Curdia, Joao; Jones, Burton; Carvalho, Susana

2017-01-01

The diversity of coral reef and soft sediment ecosystems in the Red Sea has to date received limited scientific attention. This study investigates changes in the community composition of both reef and macrobenthic communities along a cross shelf gradient. Coral reef assemblages differed significantly in species composition and structure with location and depth. Inner shelf reefs harbored less abundant and less diverse coral assemblages with higher percentage macroalgae cover. Nutrient availability and distance from the shoreline were significantly related to changes in coral composition and structure. This study also observed a clear inshore offshore pattern for soft sediment communities. In contrast to the coral reef patterns the highest diversity and abundance of soft sediment communities were recorded at the inshore sites, which were characterized by a higher number of opportunistic polychaete species and bivalves indicative of mild disturbance. Sediment grain size and nutrient enrichment were important variables explaining the variability. This study aims to contribute to our understanding of ecosystem processes and biodiversity in the Red Sea region in an area that also has the potential to provide insight into pressing topics, such as the capacity of reef systems and benthic macrofaunal organisms to adapt to global climate change.

Cross shelf benthic biodiversity patterns in the Southern Red Sea

KAUST Repository

Ellis, Joanne

2017-03-21

The diversity of coral reef and soft sediment ecosystems in the Red Sea has to date received limited scientific attention. This study investigates changes in the community composition of both reef and macrobenthic communities along a cross shelf gradient. Coral reef assemblages differed significantly in species composition and structure with location and depth. Inner shelf reefs harbored less abundant and less diverse coral assemblages with higher percentage macroalgae cover. Nutrient availability and distance from the shoreline were significantly related to changes in coral composition and structure. This study also observed a clear inshore offshore pattern for soft sediment communities. In contrast to the coral reef patterns the highest diversity and abundance of soft sediment communities were recorded at the inshore sites, which were characterized by a higher number of opportunistic polychaete species and bivalves indicative of mild disturbance. Sediment grain size and nutrient enrichment were important variables explaining the variability. This study aims to contribute to our understanding of ecosystem processes and biodiversity in the Red Sea region in an area that also has the potential to provide insight into pressing topics, such as the capacity of reef systems and benthic macrofaunal organisms to adapt to global climate change.

Using Benthic Macroinvertebrate and Fish Communities as Bioindicators of the Tanshui River Basin Around the Greater Taipei Area — Multivariate Analysis of Spatial Variation Related to Levels of Water Pollution

Directory of Open Access Journals (Sweden)

Shuh-Sen Young

2014-07-01

Full Text Available After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI. The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15–35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI and Biotic Index (BI from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted.

Using Benthic Macroinvertebrate and Fish Communities as Bioindicators of the Tanshui River Basin Around the Greater Taipei Area — Multivariate Analysis of Spatial Variation Related to Levels of Water Pollution

Science.gov (United States)

Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

2014-01-01

After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15–35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted. PMID:25026081

Functional group diversity is key to Southern Ocean benthic carbon pathways.

Directory of Open Access Journals (Sweden)

David K A Barnes

Full Text Available High latitude benthos are globally important in terms of accumulation and storage of ocean carbon, and the feedback this is likely to have on regional warming. Understanding this ecosystem service is important but difficult because of complex taxonomic diversity, history and geography of benthic biomass. Using South Georgia as a model location (where the history and geography of benthic biology is relatively well studied we investigated whether the composition of functional groups were critical to benthic accumulation, immobilization and burial pathway to sequestration-and also aid their study through simplification of identification. We reclassified [1], [2] morphotype and carbon mass data to 13 functional groups, for each sample of 32 sites around the South Georgia continental shelf. We investigated the influence on carbon accumulation, immobilization and sequestration estimate by multiple factors including the compositions of functional groups. Functional groups showed high diversity within and between sites, and within and between habitat types. Carbon storage was not linked to a functional group in particular but accumulation and immobilization increased with the number of functional groups present and the presence of hard substrata. Functional groups were also important to carbon burial rate, which increased with the presence of mixed (hard and soft substrata. Functional groups showed high surrogacy for taxonomic composition and were useful for examining contrasting habitat categorization. Functional groups not only aid marine carbon storage investigation by reducing time and the need for team size and speciality, but also important to benthic carbon pathways per se. There is a distinct geography to seabed carbon storage; seabed boulder-fields are hotspots of carbon accumulation and immobilization, whilst the interface between such boulder-fields and sediments are key places for burial and sequestration.

Nitrogen budget of the northwestern Black Sea shelf inferred from modeling studies and in situ benthic measurements

NARCIS (Netherlands)

Grégoire, M.; Friedrich, J.

2004-01-01

A 3D eddy-resolving coupled biogeochemical-hydrodynamical model and in situ observations are used to investigate benthic processes on the Black Sea's NW shelf. Measurements of benthic fluxes (oxygen, nutrients, redox compounds) with in situ flux chambers are analyzed in regard to sediment dynamics

Effects of logging activities on ecological water quality indicators in the Berasau River, Johor, Malaysia.

Science.gov (United States)

Nor Zaiha, A; Mohd Ismid, M S; Salmiati; Shahrul Azri, M S

2015-08-01

Influence of deforestation on biodiversity of aquatic organisms was investigated in a stream in the Ulu Sedili Forest Reserve. The stream was monitored five (5) times from December 2011 until December 2012 with 2-month intervals. Sampling of benthic communities was carried out using rectangular dip net while water quality study using a YSI ProPlus meter and the rest were done in the laboratory. Physicochemical parameters and water quality index (WQI) calculation showed no significant difference among the investigated events. WQI classified the Berasau River between Class II (good) to III (moderate) of river water quality. In total, 603 individuals representing 25 taxa that were recorded with Decapods from genus Macrobrabchium were widely distributed. Several intolerant taxa, especially Ephemeroptera and Odonata, were also observed in this river. According to Pearson's correlation analysis, the richness and diversity indices were generally influenced by water quality parameters represented by WQI (P < 0.01). In conclusion, logging activities have strong attributes for variation in benthic macroinvertebrate assemblage.

Coastal Bend Texas Benthic Habitat Mapping Reprocessed DOQQ Aerial Imagery

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to reprocess existing digital multi-spectral imagery (ADS-40) and create digital benthic...

Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Geodatabase

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Substrate

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Biotic

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Substrate

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geoform

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geodatabase

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Biotic

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

National Coral Reef Monitoring Program: Benthic Cover Derived from Analysis of Benthic Images Collected for Climate Stations across American Samoa in 2015 (NCEI Accession 0157753)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at climate stations and permanent sites identified by the Ocean and...

Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait.

Directory of Open Access Journals (Sweden)

Cecile Cathalot

Full Text Available The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents. Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m, a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1 compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1. The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger

Maestrichtian benthic foraminifers from Ocean Point, North Slope, Alaska ( USA).

Science.gov (United States)

McDougall, K.

1987-01-01

Previous studies of fauna and flora from Ocean Point, Alaska, have suggested ages ranging from Campanian to early Eocene and that these assemblages are either highly endemic or commonplace. I demonstrate that the moderately abundant benthic foraminifers constitute early Maestrichtian boreal assemblages common to Canada and northern Europe. Paleoenvironmental analysis indicates that deposition took place in outer neritic settings (50 to 150m). The Ocean Point benthic foraminiferal assemblages contain species that migrated from the US Gulf Coast, North American Interior and Europe during the Campanian, and from Europe during the Maestrichtian. These faunal affinities suggest that seaways connected the Arctic to the North American Interior and Atlantic during the Campanian and that a shallow seaway connected the Arctic to the Atlantic during the early Maestrichtian. - from Author

Contribution of sea ice microbial production to Antarctic benthic communities is driven by sea ice dynamics and composition of functional guilds.

Science.gov (United States)

Wing, Stephen R; Leichter, James J; Wing, Lucy C; Stokes, Dale; Genovese, Sal J; McMullin, Rebecca M; Shatova, Olya A

2018-04-28

Organic matter produced by the sea ice microbial community (SIMCo) is an important link between sea ice dynamics and secondary production in near-shore food webs of Antarctica. Sea ice conditions in McMurdo Sound were quantified from time series of MODIS satellite images for Sept. 1 through Feb. 28 of 2007-2015. A predictable sea ice persistence gradient along the length of the Sound and evidence for a distinct change in sea ice dynamics in 2011 were observed. We used stable isotope analysis (δ 13 C and δ 15 N) of SIMCo, suspended particulate organic matter (SPOM) and shallow water (10-20 m) macroinvertebrates to reveal patterns in trophic structure of, and incorporation of organic matter from SIMCo into, benthic communities at eight sites distributed along the sea ice persistence gradient. Mass-balance analysis revealed distinct trophic architecture among communities and large fluxes of SIMCo into the near-shore food web, with the estimates ranging from 2 to 84% of organic matter derived from SIMCo for individual species. Analysis of patterns in density, and biomass of macroinvertebrate communities among sites allowed us to model net incorporation of organic matter from SIMCo, in terms of biomass per unit area (g/m 2 ), into benthic communities. Here, organic matter derived from SIMCo supported 39 to 71 per cent of total biomass. Furthermore, for six species, we observed declines in contribution of SIMCo between years with persistent sea ice (2008-2009) and years with extensive sea ice breakout (2012-2015). Our data demonstrate the vital role of SIMCo in ecosystem function in Antarctica and strong linkages between sea ice dynamics and near-shore secondary productivity. These results have important implications for our understanding of how benthic communities will respond to changes in sea ice dynamics associated with climate change and highlight the important role of shallow water macroinvertebrate communities as sentinels of change for the Antarctic marine

Effects of sediment organic matter quality on bioaccumulation, degradation, and distribution of pyrene in two macrofaunal species and their surrounding sediment

DEFF Research Database (Denmark)

Granberg, Maria E.; Selck, Henriette

2007-01-01

Sediment dwelling macrofauna (infauna) are important vectors for the transfer of sediment-associated contaminants to higher trophic levels. Sedimenting organic matter constitutes an important food source for all benthic organisms and changes seasonally in terms of quantity and quality. Sediment...... imply that bioaccumulation and trophic transfer of sediment-associated PAH should increase following fresh organic matter input, e.g. after sedimentation of phytoplankton blooms. We stress the importance of considering behavioural characteristics of infauna and the trophic situation of the system when...

Influence of invasive Acer negundo leaf litter on benthic microbial abundance and activity in the littoral zone of a temperate river in Lithuania

Directory of Open Access Journals (Sweden)

Krevš Alina

2017-01-01

Full Text Available Riparian forests are known as important source of allochthonous organic matter entering to water ecosystems via fallen leaves. However, leaf litter, depending on their quality, may create different conditions for benthic microorganisms functioning in littoral zone of water bodies. In order to evaluate the impact of riparian invasive Acer negundo on littoral water zone of the River Neris (Lithuania, we performed physicochemical and microbiological investigations in bottom sediments of three different sites of the river. One sampling site was close by riparian A. negundo, another close by native Alnus glutinosa location and a third zone was near the shore without riparian vegetation. Content of nutrients in the littoral sediments differed between invasive and native trees leaf litter accumulation sites, while not always significantly. The highest microbial densities as well as benthic community respiratory activity (expressed as the rate of organic carbon mineralization occurred in A. negundo leaves accumulation site. In sediments of this site, the most intensive anaerobic terminal organic carbon mineralization process − sulfate reduction and the highest concentration of hydrogen sulfide were also observed. Differences in the intensity of mineralization processes between sites suggest that the replacement of the riparian native species such as dominant A. glutinosa by invasive A. negundo with higher biodegradability leaves may induce local changes in organic matter processing in the littoral zone of the river. The increase of littoral bioproductivity in the accumulation zone of A. negundo leaf litter can occur due to the inflow of available organic matter and its intensive mineralization.

Studies on benthic denitrification in the Chwaka Bay mangrove ...

African Journals Online (AJOL)

Spatial variations in denitrification rates were due to variations in concentration levels of organic matter and possibly to disproportionate competition for inorganic nitrogen between denitrifiers and benthic autotrophs among sites. There were no seasonal differences in denitrification rates. Results from the present study ...

Stable-isotope analysis of a deep-sea benthic-fish assemblage: evidence of an enriched benthic food web.

Science.gov (United States)

Boyle, M D; Ebert, D A; Cailliet, G M

2012-04-01

In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T(P) ) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T(P) from SCA yielded significant results (stomach content: P 0·05). © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Near-field receiving water monitoring of trace metals and a benthic community near the Palo Alto Regional Water Quality Control Plant in south San Francisco Bay, California: 2011

Science.gov (United States)

Dyke, Jessica; Thompson, Janet K.; Cain, Daniel J.; Kleckner, Amy E.; Parcheso, Francis; Luoma, Samuel N.; Hornberger, Michelle I.

2012-01-01

Trace-metal concentrations in sediment and in the clam Macoma petalum (formerly reported as Macoma balthica), clam reproductive activity, and benthic macroinvertebrate community structure were investigated in a mudflat 1 kilometer south of the discharge of the Palo Alto Regional Water Quality Control Plant (PARWQCP) in South San Francisco Bay, Calif. This report includes the data collected by U.S. Geological Survey (USGS) scientists for the period January 2011 to December 2011. These data serve as the basis for the City of Palo Alto's Near-Field Receiving Water Monitoring Program, initiated in 1994. Following significant reductions in the late 1980s, silver (Ag) and copper (Cu) concentrations in sediment and M. petalum appear to have stabilized. Data for other metals, including chromium, mercury, nickel, selenium, and zinc, have been collected since 1994. Over this period, concentrations of these elements have remained relatively constant, aside from seasonal variation that is common to all elements. In 2011, concentrations of Ag and Cu in M. petalum varied seasonally in response to a combination of site-specific metal exposures and annual growth and reproduction, as reported previously. Seasonal patterns for other elements, including Cr, Hg, Ni, Se, and Zn, were generally similar in timing and magnitude as those for Ag and Cu. In 2011, metal concentrations in both sediments and clam tissue were among the lowest concentrations on record. This record suggests that regional-scale factors now largely control sedimentary and bioavailable concentrations of Ag and Cu, as well as other elements of regulatory interest, at the Palo Alto site. Analyses of the benthic community structure of a mudflat in South San Francisco Bay over a 38-year period show that changes in the community have occurred concurrent with reduced concentrations of metals in the sediment and in the tissues of the biosentinel clam, M. petalum, from the same area. Analysis of the M. petalum community

Multiscale patterns in the diversity and organization of benthic intertidal fauna among French Atlantic estuaries

Science.gov (United States)

Blanchet, Hugues; Gouillieux, Benoît; Alizier, Sandrine; Amouroux, Jean-Michel; Bachelet, Guy; Barillé, Anne-Laure; Dauvin, Jean-Claude; de Montaudouin, Xavier; Derolez, Valérie; Desroy, Nicolas; Grall, Jacques; Grémare, Antoine; Hacquebart, Pascal; Jourde, Jérôme; Labrune, Céline; Lavesque, Nicolas; Meirland, Alain; Nebout, Thiebaut; Olivier, Frédéric; Pelaprat, Corine; Ruellet, Thierry; Sauriau, Pierre-Guy; Thorin, Sébastien

2014-07-01

Based on a parallel sampling conducted during autumn 2008, a comparative study of the intertidal benthic macrofauna among 10 estuarine systems located along the Channel and Atlantic coasts of France was performed in order to assess the level of fauna similarity among these sites and to identify possible environmental factors involved in the observed pattern at both large (among sites) and smaller (benthic assemblages) scales. More precisely this study focused on unraveling the observed pattern of intertidal benthic fauna composition and diversity observed at among-site scale by exploring both biotic and abiotic factors acting at the among- and within-site scales. Results showed a limited level of similarity at the among-site level in terms of intertidal benthic fauna composition and diversity. The observed pattern did not fit with existing transitional water classification methods based on fish or benthic assemblages developed in the frame of the European Water Framework Directive (WFD). More particularly, the coastal plain estuaries displayed higher among-site similarity compared to ria systems. These coastal plain estuaries were characterized by higher influence of river discharge, lower communication with the ocean and high suspended particulate matter levels. On the other hand, the ria-type systems were more dissimilar and different from the coastal plain estuaries. The level of similarity among estuaries was mainly linked to the relative extent of the intertidal "Scrobicularia plana-Cerastoderma edule" and "Tellina tenuis" or "Venus" communities as a possible consequence of salinity regime, suspended matter concentrations and fine particles supply with consequences on the trophic functioning, structure and organization of benthic fauna. Despite biogeographical patterns, the results also suggest that, in the context of the WFD, these estuaries should only be compared on the basis of the most common intertidal habitat occurring throughout all estuarine systems

PCB-induced changes of a benthic community and expected ecosystem recovery following in situ sorbent amendment

Science.gov (United States)

Janssen, Elisabeth M.-L.; Thompson, Janet K.; Luoma, Samuel N.; Luthy, Richard G.

2011-01-01

The benthic community was analyzed to evaluate pollution-induced changes for the polychlorinated biphenyl (PCB)-contaminated site at Hunters Point (HP) relative to 30 reference sites in San Francisco Bay, California, USA. An analysis based on functional traits of feeding, reproduction, and position in the sediment shows that HP is depauperate in deposit feeders, subsurface carnivores, and species with no protective barrier. Sediment chemistry analysis shows that PCBs are the major risk drivers at HP (1,570 ppb) and that the reference sites contain very low levels of PCB contamination (9 ppb). Different feeding traits support the existence of direct pathways of exposure, which can be mechanistically linked to PCB bioaccumulation by biodynamic modeling. The model shows that the deposit feeder Neanthes arenaceodentata accumulates approximately 20 times more PCBs in its lipids than the facultative deposit feeder Macoma balthica and up to 130 times more than the filter feeder Mytilus edulis. The comparison of different exposure scenarios suggests that PCB tissue concentrations at HP are two orders of magnitude higher than at the reference sites. At full scale, in situ sorbent amendment with activated carbon may reduce PCB bioaccumulation at HP by up to 85 to 90% under favorable field and treatment conditions. The modeling framework further demonstrates that such expected remedial success corresponds to exposure conditions suggested as the cleanup goal for HP. However, concentrations remain slightly higher than at the reference sites. The present study demonstrates how the remedial success of a sorbent amendment, which lowers the PCB availability, can be compared to reference conditions and traditional cleanup goals, which are commonly based on bulk sediment concentrations.

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

International Nuclear Information System (INIS)

Horikoshi, Masuoki

1975-01-01

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.)

Benthic metabolic feedbacks to carbonate chemistry on coral reefs:implications for ocean acidification

Science.gov (United States)

Price, N.; Rohwer, F. L.; Stuart, S. A.; Andersson, A.; Smith, J.

2012-12-01

The metabolic activity of resident organisms can cause spatio-temporal variability in carbonate chemistry within the benthic boundary layer, and thus potentially buffer the global impacts of ocean acidification. But, little is known about the capacity for particular species assemblages to contribute to natural daily variability in carbonate chemistry. We encapsulated replicate areas (~3m2) of reef across six Northern Line Islands in the central Pacific for 24 hrs to quantify feedbacks to carbonate chemistry within the benthic boundary layer from community metabolism. Underneath each 'tent', we quantified relative abundance and biomass of each species of corals and algae. We coupled high temporal resolution time series data on the natural diurnal variability in pH, dissolved oxygen, salinity, and temperature (using autonomous sensors) with resident organisms' net community calcification and productivity rates (using change in total dissolved carbon and total alkalinity over time) to examine feedbacks from reef metabolism to boundary layer carbonate chemistry. These reefs experienced large ranges in pH (> 0.2 amplitude) each day, similar to the magnitude of 'acidification' expected over the next century. Daily benthic pH, pCO2, and aragonite saturation state (Ωaragonite) were contrasted with seasonal threshold values estimated from open ocean climatological data extrapolated at each island to determine relative inter-island feedbacks. Diurnal amplitude in pH, pCO2, and Ωaragonite at each island was dependent upon the resident species assemblage of the benthos and was particularly reliant upon the biomass, productivity, and calcification rate of Halimeda. Net primary productivity of fleshy algae (algal turfs and Lobophora spp.) predominated on degraded, inhabited islands where net community calcification was negligible. In contrast, the chemistry over reefs on 'pristine', uninhabited islands was driven largely by net calcification of calcareous algae and stony

National Coral Reef Monitoring Program: Benthic Images Collected from Stratified Random Sites (StRS) across American Samoa in 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here are benthic habitat imagery that result from benthic photo-quadrat surveys conducted along transects at stratified random sites across...

National Coral Reef Monitoring Program: Benthic Cover Derived from Analysis of Benthic Images Collected during Stratified Random Surveys (StRS) across American Samoa in 2015

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at stratified random sites across American Samoa in 2015 as a part of...

Fringing reefs exposed to different levels of eutrophication and sedimentation can support similar benthic communities

International Nuclear Information System (INIS)

Rouzé, H.; Lecellier, G.; Langlade, M.J.; Planes, S.; Berteaux-Lecellier, V.

2015-01-01

Highlights: • We assess anthropogenic pressures on coral reef health. • We present a spatio-temporal survey of environmental parameters as bio-indicators. • Poor water quality (e.g. high turbidity and high sediments) was not correlated with lower coral cover. • Phytoplankton community size-composition and habitat stability were important predictors of coral reef health. - Abstract: Benthic communities are sensitive to anthropogenic disturbances which can result in changes in species assemblages. A spatio-temporal survey of environmental parameters was conducted over an 18-month period on four different fringing reefs of Moorea, French Polynesia, with unusual vs. frequent human pressures. This survey included assessment of biological, chemical, and physical parameters. First, the results showed a surprising lack of a seasonal trend, which was likely obscured by short-term variability in lagoons. More frequent sampling periods would likely improve the evaluation of a seasonal effect on biological and ecological processes. Second, the three reef habitats studied that were dominated by corals were highly stable, despite displaying antagonistic environmental conditions through eutrophication and sedimentation gradients, whereas the reef dominated by macroalgae was relatively unstable. Altogether, our data challenge the paradigm of labelling environmental parameters such as turbidity, sedimentation, and nutrient-richness as stress indicators

Regional monitoring of temporal changes in groundwater quality

NARCIS (Netherlands)

Broers, H.P.; Grift, B. van der

2004-01-01

Changes in agricultural practices are expected to affect groundwater quality by changing the loads of nutrients and salts in recharging groundwater, but regional monitoring networks installed to register the changes often fail to detect them and interpretation of trend analysis results is difficult.

Benthic macroinvertebrate community of a fourth order stream in ...

African Journals Online (AJOL)

cinthia

Full Length Research Paper. Benthic macroinvertebrate community of a fourth order stream in Kashmir Himalaya, India. Shazia Habib1* and A.R. Yousuf2. 1Department of Environmental Science, University of Kashmir, Srinagar, India. 2National Green Tribunal, Government of India, India. Received 31 December, 2013; ...

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

African Journals Online (AJOL)

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

Glomospirella cantabrica n. sp., and other benthic foraminifera from Lower Cretaceous Urgonian-type carbonates of Cantabria, Spain: Biostratigraphic implications

Energy Technology Data Exchange (ETDEWEB)

Schlagintweit, F.; Rosales, I.; Najarro, M.

2016-07-01

A new benthic foraminifer is described as Glomospirella cantabrica n. sp. from several sections of the upper Aptian Reocín Formation and one occurrence from the lowermost Albian Las Peñosas Formation of Cantabria (northern Spain). It represents a rather large-sized Glomospirella, with up to eight planispiral whorls, observed in lagoonal wackestones and packstones. The upper Aptian (upper Gargasian–Clansayesian) age is indicated by the co-occurrence with other benthic foraminifera, i.e. orbitolinids. Further biostratigraphic data of the Aptian-p.p. Albian shallow-water carbonates of the North Cantabrian Basin is provided. The rareness of dasycladalean green algae in these deposits is also highlighted. The resulting stratigraphic and biostratigraphic scheme is integrated in a framework of depositional sequences of the North Cantabrian Basin and compared with the sequential schemes of other areas of the Basque-Cantabrian Basin and the Iberian Chain. Similitudes suggest that these depositional sequences are related to global sea-level changes. (Author)

Human Stressors Are Driving Coastal Benthic Long-Lived Sessile Fan Mussel Pinna nobilis Population Structure More than Environmental Stressors.

Directory of Open Access Journals (Sweden)

Salud Deudero

Full Text Available Coastal degradation and habitat disruption are severely compromising sessile marine species. The fan shell Pinna nobilis is an endemic, vulnerable species and the largest bivalve in the Mediterranean basin. In spite of species legal protection, fan shell populations are declining. Models analyzed the contributions of environmental (mean depth, wave height, maximum wave height, period of waves with high energy and mean direction of wave source versus human-derived stressors (anchoring, protection status, sewage effluents, fishing activity and diving as explanatory variables depicting Pinna nobilis populations at a mesoscale level. Human stressors were explaining most of the variability in density spatial distribution of fan shell, significantly disturbing benthic communities. Habitat protection affected P. nobilis structure and physical aggression by anchoring reveals a high impact on densities. Environmental variables instead played a secondary role, indicating that global change processes are not so relevant in coastal benthic communities as human-derived impacts.

[Impacts of large hydropower station on benthic algal communities].

Science.gov (United States)

Jia, Xing-Huan; Jiang, Wan-Xiang; Li, Feng-Qing; Tang, Tao; Duan, Shu-Gui; Cai, Qing-Hua

2009-07-01

To investigate the impacts of large hydropower station in Gufu River on benthic algae, monthly samplings were conducted from September 2004 to June 2007 at the site GF04 which was impacted by the hydropower station, with the site GL03 in Gaolan River as reference. During sampling period, no significant differences were observed in the main physicochemical variables between GF04 and GL03, but the hydrodynamics differed significantly. GL03 was basically at a status of slow flow; while GF04, owing to the discharging from the reservoir, was at a riffle status during more than 60% of the sampling period. Such a difference in hydrodynamics induced significant differences in the community similarity of benthic algae and the relative abundance of unattached diatoms, erect diatoms, and stalked diatoms between GF04 and GL03, which could better reflect the impacts of irregular draw-off by large hydropower station on river eco-system.

Benthic Habitat Mapping by Combining Lyzenga’s Optical Model and Relative Water Depth Model in Lintea Island, Southeast Sulawesi

Science.gov (United States)

Hafizt, M.; Manessa, M. D. M.; Adi, N. S.; Prayudha, B.

2017-12-01

Benthic habitat mapping using satellite data is one challenging task for practitioners and academician as benthic objects are covered by light-attenuating water column obscuring object discrimination. One common method to reduce this water-column effect is by using depth-invariant index (DII) image. However, the application of the correction in shallow coastal areas is challenging as a dark object such as seagrass could have a very low pixel value, preventing its reliable identification and classification. This limitation can be solved by specifically applying a classification process to areas with different water depth levels. The water depth level can be extracted from satellite imagery using Relative Water Depth Index (RWDI). This study proposed a new approach to improve the mapping accuracy, particularly for benthic dark objects by combining the DII of Lyzenga’s water column correction method and the RWDI of Stumpt’s method. This research was conducted in Lintea Island which has a high variation of benthic cover using Sentinel-2A imagery. To assess the effectiveness of the proposed new approach for benthic habitat mapping two different classification procedures are implemented. The first procedure is the commonly applied method in benthic habitat mapping where DII image is used as input data to all coastal area for image classification process regardless of depth variation. The second procedure is the proposed new approach where its initial step begins with the separation of the study area into shallow and deep waters using the RWDI image. Shallow area was then classified using the sunglint-corrected image as input data and the deep area was classified using DII image as input data. The final classification maps of those two areas were merged as a single benthic habitat map. A confusion matrix was then applied to evaluate the mapping accuracy of the final map. The result shows that the new proposed mapping approach can be used to map all benthic objects in

Benthic hypoxia and early diagenesis in the Black Sea shelf sediments

Science.gov (United States)

Plante, Audrey; Roevros, Nathalie; Capet, Arthur; Grégoire, Marilaure; Fagel, Nathalie; Chou, Lei

2017-04-01

Marine waters of semi-enclosed seas are affected by a major environmental issue which is oxygen depletion in bottom waters. Deoxygenation is one of the most widespread man-induced consequences which can be catastrophic for living species. Between 1970 and 1990, the benthic compartment of the Black Sea underwent modifications due to the occurrence and increase of hypoxia. Indeed, these changes might cause a deterioration of the structure and functioning of the ecosystems. Nowadays, some regions, such as the north-western shelf, are still affected seasonally by this phenomenon. Within the framework of the BENTHOX project, a biogeochemical study focusing on the early diagenesis is conducted in the Black Sea. It aims (1) to obtain a better understanding of the impact of benthic hypoxia on the diagenetic pathways, (2) to contribute to a new dataset of biogeochemical measurements in the sediments including porewaters. During a cruise (Emblas II - May 2016), on board the RV Mare Nigrum, sediment cores were taken at 4 stations on the Ukrainian shelf. Porewaters were extracted on board the ship using Rhizon technique under N2 atmosphere and will be analyzed for dissolved nutrients and major ions. In addition, sediments were sliced and will be determined for major solid phases and trace element contents. A multi-proxies (biological, sedimentological, mineralogical and geochemical) approach will be used to identify the hypoxic events and to reconstruct the history of bottom hypoxia. The results obtained will be presented and discussed with emphasis on the first outcomes and the major biogeochemical processes involved in the early diagenesis.

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...

Next generation sequencing assays for benthic monitoring of the environmental impact associated with salmon farming (pilot study)

DEFF Research Database (Denmark)

Pawlowski, Jan; Esling, Philippe; Lejzerowicz, Franck

2015-01-01

This report presents the study of foraminiferal and metazoan benthic community based on next-generation sequencing (NGS) of environmental DNA and RNA (eDNA/RNA). The objective of this study was to test the application of NGS assays for benthic monitoring of salmon farms in Norway, in order to ove...

Climate warming reduces fish production and benthic habitat in Lake Tanganyika, one of the most biodiverse freshwater ecosystems

Science.gov (United States)

Cohen, Andrew S.; Gergurich, Elizabeth L.; Kraemer, Benjamin M.; McGlue, Michael M.; McIntyre, Peter B.; Russell, James M.; Simmons, Jack D.; Swarzenski, Peter W.

2016-01-01

Warming climates are rapidly transforming lake ecosystems worldwide, but the breadth of changes in tropical lakes is poorly documented. Sustainable management of freshwater fisheries and biodiversity requires accounting for historical and ongoing stressors such as climate change and harvest intensity. This is problematic in tropical Africa, where records of ecosystem change are limited and local populations rely heavily on lakes for nutrition. Here, using a ∼1,500-y paleoecological record, we show that declines in fishery species and endemic molluscs began well before commercial fishing in Lake Tanganyika, Africa’s deepest and oldest lake. Paleoclimate and instrumental records demonstrate sustained warming in this lake during the last ∼150 y, which affects biota by strengthening and shallowing stratification of the water column. Reductions in lake mixing have depressed algal production and shrunk the oxygenated benthic habitat by 38% in our study areas, yielding fish and mollusc declines. Late-20th century fish fossil abundances at two of three sites were lower than at any other time in the last millennium and fell in concert with reduced diatom abundance and warming water. A negative correlation between lake temperature and fish and mollusc fossils over the last ∼500 y indicates that climate warming and intensifying stratification have almost certainly reduced potential fishery production, helping to explain ongoing declines in fish catches. Long-term declines of both benthic and pelagic species underscore the urgency of strategic efforts to sustain Lake Tanganyika’s extraordinary biodiversity and ecosystem services.

Benthic invertebrate exposure and chronic toxicity risk analysis for cyclic volatile methylsiloxanes: Comparison of hazard quotient and probabilistic risk assessment approaches.

Science.gov (United States)

Woodburn, Kent B; Seston, Rita M; Kim, Jaeshin; Powell, David E

2018-02-01

This study utilized probabilistic risk assessment techniques to compare field sediment concentrations of the cyclic volatile methylsiloxane (cVMS) materials octamethylcyclotetrasiloxane (D4, CAS # 556-67-2), decamethylcyclopentasiloxane (D5, CAS # 541-02-6), and dodecamethylcyclohexasiloxane (D6, CAS # 540-97-6) to effect levels for these compounds determined in laboratory chronic toxicity tests with benthic organisms. The concentration data for D4/D5/D6 in sediment were individually sorted and the 95th centile concentrations determined in sediment on an organic carbon (OC) fugacity basis. These concentrations were then compared to interpolated 5th centile benthic sediment no-observed effect concentration (NOEC) fugacity levels, calculated from a distribution of chronic D4/D5/D6 toxicologic assays per OECD guidelines using a variety of standard benthic species. The benthic invertebrate fugacity biota NOEC values were then compared to field-measured invertebrate biota fugacity levels to see if risk assessment evaluations were similar on a field sediment and field biota basis. No overlap was noted for D4 and D5 95th centile sediment and biota fugacity levels and their respective 5th centile benthic organism NOEC values. For D6, there was a small level of overlap at the exposure 95th centile sediment fugacity and the 5th centile benthic organism NOEC fugacity value; the sediment fugacities indicate that a negligible risk (1%) exists for benthic species exposed to D6. In contrast, there was no indication of risk when the field invertebrate exposure 95th centile biota fugacity and the 5th centile benthic organism NOEC fugacity values were compared. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

National Coral Reef Monitoring Program: Benthic Percent Cover Derived from Analysis of Benthic Images Collected for Climate Stations across the Pacific Remote Island Areas since 2014

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The data described here result from benthic photo-quadrat surveys conducted along transects at climate stations and permanent sites identified by the Ocean and...

STUDY UPON THE MACROZOOBENTHIC COMMUNITIES FROM THE DANUBE RIVER BY BAZIAŞ-PORŢILE DE FIER SECTOR (SOUTH-WESTERN ROMANIA

Directory of Open Access Journals (Sweden)

ADINA-MIRELA PANĂ

2009-01-01

Full Text Available Different sensitivity of benthic macroinvertebrates was used in determining water quality of the eight major tributaries of the Danube, which drains two mountain ranges: Locvei and Almăjului, within the context in which the macrozoobenthic community is influenced by changes in the qualitative parameters of aquatic ecosystems. To get an overview, a series of physical- chemical parameters (water temperature, pH, oxygen, conductivity, cyanide, nitrites, nitrates, phosphates was studied in parallel with the study of benthic community. Elevated abundance of benthic groups in the case of water quality characteristic (Ephemeroptera, Trichoptera, Plecoptera, Amphipoda, along with their high frequency in all the monitored tributaries in the present study and the water quality parameters maintained within normal limits fits these lotic ecosystems in the A class of surface water quality.

Compliance of secondary production and eco-exergy as indicators of benthic macroinvertebrates assemblages' response to canopy cover conditions in Neotropical headwater streams.

Science.gov (United States)

Linares, Marden Seabra; Callisto, Marcos; Marques, João Carlos

2018-02-01

Riparian vegetation cover influences benthic assemblages structure and functioning in headwater streams, as it regulates light availability and autochthonous primary production in these ecosystems.Secondary production, diversity, and exergy-based indicators were applied in capturing how riparian cover influences the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams. Four hypotheses were tested: (1) open canopy will determine the occurrence of higher diversity in benthic macroinvertebrate assemblages; (2) streams with open canopy will exhibit more complex benthic macroinvertebrate communities (in terms of information embedded in the organisms' biomass); (3) in streams with open canopy benthic macroinvertebrate assemblages will be more efficient in using the available resources to build structure, which will be reflected by higher eco-exergy values; (4) benthic assemblages in streams with open canopy will exhibit more secondary productivity. We selected eight non-impacted headwater streams, four shaded and four with open canopy, all located in the Neotropical savannah (Cerrado) of southeastern Brazil. Open canopy streams consistently exhibited significantly higher eco-exergy and instant secondary production values, exemplifying that these streams may support more complex and productive benthic macroinvertebrate assemblages. Nevertheless, diversity indices and specific eco-exergy were not significantly different in shaded and open canopy streams. Since all the studied streams were selected for being considered as non-impacted, this suggests that the potential represented by more available food resources was not used to build a more complex dissipative structure. These results illustrate the role and importance of the canopy cover characteristics on the structure and functioning of benthic macroinvertebrate assemblages in tropical headwater streams, while autochthonous production appears to play a crucial role as food

Integrated assessment of river health based on the conditions of water quality,aquatic life and physical habitat

Institute of Scientific and Technical Information of China (English)

MENG Wei; ZHANG Nan; ZHANG Yuan; ZHENG Binghui

2009-01-01

The health conditions of Liao River were assessed using 25 sampling sites in April 2005, with water quality index, biotic index and physical habitat quality index.Based on the method of cluster analysis (CA) for water quality indices, it reveals that heavily polluted sites of Liao River are located at estuary and mainstream.The aquatic species surveyed were attached algae and benthic invertebrates.The result shows that the diversity and biomass of attached algae and benthic index of biotic integrity (B-IBI) are degrading as the chemical and physical quality of water bodies deteriorating.Physiochemical parameters, BOD5, CODCr, TN, TP, NH3-N, DO, petroleum hydrocarbon and conductivity, were statistically analyzed with principal component analysis and correlation analysis.The statistical results were incorporated into the integrated assessing water quality index, combining fecal coliform count, attached algae diversity, B-IBI and physical habitat quality score, a comprehensive integrated assessing system of river ecological health was established.Based on the systimetic assesment, the assessed sites are categorized into 9 "healthy" and "sub-healthy" sites and 8 "sub-sick" and "sick" sites.

Deep-sea benthic footprint of the deepwater horizon blowout.

Directory of Open Access Journals (Sweden)

Paul A Montagna

Full Text Available The Deepwater Horizon (DWH accident in the northern Gulf of Mexico occurred on April 20, 2010 at a water depth of 1525 meters, and a deep-sea plume was detected within one month. Oil contacted and persisted in parts of the bottom of the deep-sea in the Gulf of Mexico. As part of the response to the accident, monitoring cruises were deployed in fall 2010 to measure potential impacts on the two main soft-bottom benthic invertebrate groups: macrofauna and meiofauna. Sediment was collected using a multicorer so that samples for chemical, physical and biological analyses could be taken simultaneously and analyzed using multivariate methods. The footprint of the oil spill was identified by creating a new variable with principal components analysis where the first factor was indicative of the oil spill impacts and this new variable mapped in a geographic information system to identify the area of the oil spill footprint. The most severe relative reduction of faunal abundance and diversity extended to 3 km from the wellhead in all directions covering an area about 24 km(2. Moderate impacts were observed up to 17 km towards the southwest and 8.5 km towards the northeast of the wellhead, covering an area 148 km(2. Benthic effects were correlated to total petroleum hydrocarbon, polycyclic aromatic hydrocarbons and barium concentrations, and distance to the wellhead; but not distance to hydrocarbon seeps. Thus, benthic effects are more likely due to the oil spill, and not natural hydrocarbon seepage. Recovery rates in the deep sea are likely to be slow, on the order of decades or longer.

Baseline assessment of the benthic communities of the Flower Garden Banks

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...