Benthic Deposit Feeders Research Articles

Environmental Characteristic of Phyllophorus sp. (Echinodermata, Holothuroidea, Phyllophoridae) Habitat in the Madura Strait, Indonesia

Information on the environmental characteristics of many sea cucumber habitat is limited, despite these species exhibiting rapid exploitation and may lead to depletion. The present study combined a survey on many seawaters and sediment characteristics of habitat valuable aspidochirote holothurian, Sea Ball Cucumber, Phyllophorus sp. to compare with location with no sea cucumber in Madura Strait, Indonesia. Data from detailed surveys were used to compare both locations with measures of physical and chemical seawater parameters including temperature, salinity, dissolved oxygen, pH, phosphate, nitrate, ammonia, chlorophyll-a, total suspended solids, light transparency, and depth of water. The comparison was also carried out on physical and chemical parameters of surface sediment, i.e. phosphate, nitrate, ammonia, chlorophyll-a, grain size, total organic matter, and carbon-organic content. The data then were analyzed using Mann-Whitney U-Non Parametric Test with SPSS v. 16. The result revealed that there were significant differences between sediment characteristics of Sea Ball Cucumber habitat and no Sea Ball cucumber location, but not for seawater. Seawater parameter value in Madura Strait showed in the range required for its life. This analyzes proved the importance of sediment characteristics for Phyllophorus sp. As benthic deposit feeders, they did not only utilize substrate underneath the body for its habitat but also primarily to supply their natural food.

Long-term effects of sediment-associated silver nanoparticles and silver nitrate on the deposit-feeding polychaete Capitella teleta.

Aquatic sediments are predicted to be an important sink for released silver nanoparticles (AgNPs). Knowing the long-term effects of AgNPs on benthic deposit-feeders is therefore an important step towards assessing their potential environmental risks. The aim of this study was to examine the effects on survival, growth and reproduction of the deposit-feeding polychaete Capitella teleta exposed for ten weeks to sediment-associated un-coated AgNPs or silver nitrate (AgNO3). C. teleta exhibited tolerance towards exposure to both AgNPs and AgNO3. Significant effects were observed for percentage of pairs that reproduced as well as worm growth after eight weeks, but the effects did not show a clear concentration- or Ag type-dependent pattern. Further investigations of long-term effects of un-coated AgNPs in additional sediment-dwelling organisms are needed and should involve comparisons to coated AgNPs.

Biological Effects of Activated Carbon on Benthic Macroinvertebrates are Determined by Particle Size and Ingestibility of Activated Carbon.

The application of activated carbon (AC) to the surface of contaminated sediments is a promising technology for sediment remediation in situ. Amendment with AC has proved to be effective in reducing bioavailability and sediment-to-water release of hydrophobic organic contaminants. However, AC may cause positive or negative biological responses in benthic organisms. The causes of these effects, which include changes in growth, reproduction, and mortality, are unclear but are thought to be related to the size of AC particles. The present study investigated biological response to AC ranging from ingestible powdered AC to noningestible granular AC in two benthic deposit feeders: the polychaete Marenzelleria spp. and the clam Limecola balthica (syn. Macoma balthica). In the polychaete, exposure to powdered AC (ingestible) reduced both dry weight and carbon assimilation, whereas exposure to granular AC (noningestible) increased both dry weight and carbon assimilation. Responses in the clam were similar but less pronounced, indicating that response levels are species-specific and may vary within a benthic community. In addition, worms exposed to the finest ingestible AC particles had reduced gut microvilli length and reduced gut lumen, indicating starvation. These results strongly suggest that biological responses to AC depend on particle ingestibility, whereby exposure to ingestible particles may cause starvation through reduced bioavailability of food coingested with AC or due to rejection of AC-treated sediment as a food source. Environ Toxicol Chem 2021;40:3465-3477. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Tracing pollution in estuarine benthic organisms and its impacts on food webs of the Vitoria Bay estuary

Estuaries in South America commonly receive untreated effluents from nearby metropolitan areas demanding ecosystem-based management solutions to access pollutant impacts. In this study we investigated how organic enrichment in Vitória Bay changes benthic macrofaunal isotopic signatures (δ13C and δ15N) and if highly contaminated areas would exhibit lower food web diversity. Geochemical markers of sewage input (coprostanol) revealed low to high levels of pollution in the bay area. The δ15N isotope signatures of benthic deposit-feeders and omnivores were lower in contaminated sites indicating preferential intake of raw sewage and that the effect size of sewage input changes among benthic feeding modes. Sites with high sediment coprostanol concentrations (>0.5 μg g−1) were associated with a lower abundance of basal resources and niche shrinking of the benthic food web, suggesting that eutrophication leads to a funtional loss in the sediment-water interface in this estuary. Our study revealed that pollution in the Vitória Bay estuary has functional impacts to the estuarine food webs and support previous ascertions that stable isotopes may be a useful and low-cost method to indicate ecosystem health monitoring in estuarine ecosystems.

Temporal Variation in the Trophic Levels of Secondary Consumers in a Mediterranean Coastal Lagoon (Cabras Lagoon, Italy)

Trophic levels (TLs) of fish were estimated on three sampling dates (March, May, and August 2006) for different fish sizes in the Cabras Lagoon (Sardinia, Italy). A temporal TL variation for Atherina boyeri, Gobius niger, and Engraulis encrasicolus was observed. In March and May, the TL ranged from 3.3 to 3.4, characterizing these species as secondary consumers, while in August, this range moved to between 3.7 and 3.8, indicating a TL shift towards tertiary consumers. For Liza ramada, TL was consistently lower in small individuals (mean TL 2.5) than in larger individuals (mean TL 3.0). Increased TL of the fish species A. boyeri, G. niger, and E. encrasicolus in August was consistent with the seasonal changes in the macrobenthic assemblage in this system, with a dominance of primary consumers (benthic deposit feeders) in winter–spring and a dominance of secondary consumers (the nereidids Alitta succinea and Hediste diversicolor) in summer. These fish species took advantage of the high availability of nereidids leading to a rise in their TL values. Furthermore, the increase of TL with size of L. ramada, the most economically valuable fish species in the Cabras Lagoon, indicated an ontogenetic diet shift, the juveniles being omnivorous, while the adults being secondary consumers. We conclude that variability in the trophic levels of fish due to species traits, ontogenetic diet shifts, and variation in prey availability should be taken into account to further understand the food web structure of coastal lagoons.

Feeding dynamics of Terebralia palustris (Gastropoda: Potamididae) from a subtropical mangrove ecosystem

ABSTRACTMangrove gastropods are largely recognised for their roles as benthic deposit feeders that consume macrophyte-derived detritus. However, microalgae may also make a significant contribution towards the diet of these snails. Here we provide the first report on the rates at which microphytobenthos (MPB) is consumed by Terebralia palustris, an Indo-Pacific mangrove gastropod. Although juvenile T. palustris are generally detritivorous, there is increasing evidence that their occurrence on the seaward edge of the mangrove habitat allows them to incorporate a more nutritious food source to their diets in the form of microalgae. Using an experimental approach that incorporated fluorometric techniques, we found that the feeding activity of T. palustris on MPB was not clearly related to diel and tidal cycles at the subtropical location of Kosi Bay, South Africa during two sampling occasions in February and July 2015. However, a faster ingestion rate and higher consumption/digestion efficiency were recorded during experiments carried out in July. On this sampling occasion a higher percentage consumption of the available MPB was recorded, which corresponded to a lower per-capita availability in this resource. As T. palustris is able to consume MPB at variable rates, the impact of this species on benthic primary productivity within Indo-Pacific mangroves should not be overlooked when considering its integral ecological role within these threatened habitats.

Projecting the effects of climate-driven changes in organic matter supply on benthic food webs in the northern Bering Sea

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 548:11-30 (2016) - DOI: https://doi.org/10.3354/meps11651 Projecting the effects of climate-driven changes in organic matter supply on benthic food webs in the northern Bering Sea James R. Lovvorn1,*, Christopher A. North2,5, Jason M. Kolts2,6, Jacqueline M. Grebmeier3, Lee W. Cooper3, Xuehua Cui4 1Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois 62901, USA 2Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071, USA 3Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, Maryland 20688, USA 4Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996, USA 5Present address: Department of Botany, University of Wyoming, Laramie, Wyoming 82071, USA 6Present address: Department of Biology, Metropolitan State University of Denver, Denver, Colorado 80217, USA *Corresponding author: lovvorn@siu.edu ABSTRACT: Climate-driven changes in seasonal sea ice are expected to affect the timing, magnitude, and fate of phytoplankton production. Production may be increased by longer ice-free periods, or decreased by reduced stratification of the water column without freshwater input from melting ice. Benthic deposit-feeders may experience changes in organic matter (OM) supply owing to altered phytoplankton production, increased zooplankton grazing, or redistribution of settling phytodetritus. Where most benthic taxa subsist on a longer-term pool of sediment OM and bacteria, communities may be partially buffered against varied inputs of phytodetritus. We used network models of benthic food webs in 3 sectors of the northern Bering Sea to simulate effects of changes in OM supply. In the models, sediment OM content, which integrates longer-term inputs of microalgae, was gradually reduced or increased over 10 yr to the lowest or highest levels observed among sampling stations. In both samples and model predictions, decreased sediment OM was linked to quite variable declines among trophic groups, with effective loss of some taxa. Increased sediment OM was coupled with moderate to dramatic increases of different taxa, sometimes with lagged peaks and declines of prey and predators. In the models, meiofauna, protists, and bacteria responded quickly, while macrofauna exhibited 2 yr delays, suggesting short-term but limited buffering by the sediment OM pool. Our results indicate that climate-related changes in phytodetrital inputs can lead to important shifts in benthic biomass, community structure, and functional diversity, with loss of various common taxa. KEY WORDS: Benthic communities · Deposit-feeders · Food web limitation · Food web models · Network models · Phytodetritus · Sediment organic matter Full text in pdf format PreviousNextCite this article as: Lovvorn JR, North CA, Kolts JM, Grebmeier JM, Cooper LW, Cui X (2016) Projecting the effects of climate-driven changes in organic matter supply on benthic food webs in the northern Bering Sea. Mar Ecol Prog Ser 548:11-30. https://doi.org/10.3354/meps11651 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 548. Online publication date: April 21, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Spatial distribution of microphytobenthos, meiofauna and macrofauna in the north-western Adriatic Sea: a synoptic study

<p>In view of the general paucity of integrated information on offshore benthic communities in the Adriatic Sea and given the vulnerability of this particular coastal system, microphytobenthos, meiofauna and macrofauna were synoptically investigated in front of the Emilia-Romagna coast (northern Adriatic Sea) in September 2010 and March 2011. As required by the Marine Strategy Framework Directive, which extends its action beyond the territorial waters (within 12 nmi) of the Member States, our findings could help to fill the gap of knowledge on the environmental status in offshore areas since the study was carried out also at >12 nmi from the coastline. In fact, sediment samples for the analysis of the benthic communities were collected from a 10-point-station grid that covered an area of about 400 km<sup>2</sup> with water depths ranging from 13 to 50 m. The variability of the sediment grain size and other chemical variables in the sediment suggests the presence of two distinct environmental contexts that enhance the proliferation of different benthic communities. At the inshore stations (depth <20 m) the higher sand percentages and the maxima of dissolved inorganic nitrogen concentrations indicate the presence of hydrodynamic perturbations and the influence of nutrient loads of terrestrial origin. Inshore, both meio- and macrofaunal communities were poorly structured and dominated by relatively more opportunistic taxa, such as nematodes and the bivalve <em>Corbula gibba</em>. Offshore stations (depth >20 m) had muddier sediments, which likely exerted a greater retention of sediment-bound organic matter. These conditions seemed to favour benthic deposit feeders like meio- and macrofaunal annelids. Surprisingly, a conspicuous microphytobenthic community, mainly represented by the diatom <em>Paralia sulcata, </em>has been observed even at remarkable depths (~50 m) opening new questions regarding the role of these organisms in dim-light conditions. Although the investigated benthic communities were, to some extent, moderately influenced by multiple stressors, the co-existence of sensitive taxa (such as meiofaunal copepods and the amphipod <em>Ampelisca </em>spp.) with opportunistic ones (<em>i.e</em>., <em>C. gibba</em>) suggests that the benthic domain in the investigated area is not severely impacted.</p>

Benthic and Pelagic Pathways of Methylmercury Bioaccumulation in Estuarine Food Webs of the Northeast United States

Methylmercury (MeHg) is a contaminant of global concern that bioaccumulates and bioamagnifies in marine food webs. Lower trophic level fauna are important conduits of MeHg from sediment and water to estuarine and coastal fish harvested for human consumption. However, the sources and pathways of MeHg to these coastal fisheries are poorly known particularly the potential for transfer of MeHg from the sediment to biotic compartments. Across a broad gradient of human land impacts, we analyzed MeHg concentrations in food webs at ten estuarine sites in the Northeast US (from the Hackensack Meadowlands, NJ to the Gulf of Maine). MeHg concentrations in water column particulate material, but not in sediments, were predictive of MeHg concentrations in fish (killifish and Atlantic silversides). Moreover, MeHg concentrations were higher in pelagic fauna than in benthic-feeding fauna suggesting that MeHg delivery to the water column from methylation sites from within or outside of the estuary may be an important driver of MeHg bioaccumulation in estuarine pelagic food webs. In contrast, bulk sediment MeHg concentrations were only predictive of concentrations of MeHg in the infaunal worms. Our results across a broad gradient of sites demonstrate that the pathways of MeHg to lower trophic level estuarine organisms are distinctly different between benthic deposit feeders and forage fish. Thus, even in systems with contaminated sediments, transfer of MeHg into estuarine food webs maybe driven more by the efficiency of processes that determine MeHg input and bioavailability in the water column.

Organochlorine Pollutants in Western Antarctic Peninsula Sediments and Benthic Deposit Feeders

Sediments and benthic deposit feeding holothurians were collected near the Palmer Long Term Ecological Research grid during the austral winter of 2008. Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were measured in Western Antarctic Peninsula continental shelf sediments, porewater, and benthic biota. Concentrations and fluxes in sediments decreased sharply away from the tip of the peninsula toward its interior. Sedimentary PCB fluxes were an order of magnitude lower than reported elsewhere, supporting the notion of a pristiner Antarctic environment. Hexa-chlorinated biphenyls dominated (40-100%) the PCB profiles in the sediments, while trichlorinated biphenyl 28 was the most abundant PCB congener in the porewater. PCB and OCP concentrations in holothurians were comparable to concentrations in other low trophic level biota in the Antarctic food web (i.e., krill). The partitioning of PCBs and OCPs between the sediments and porewater can be explained by a dual-mode model, which included both organic carbon and black carbon as partitioning media. Alternatively, a simpler one-parameter prediction assuming coal tar-like organic carbon performed equally well in explaining porewater concentrations The majorities of PCBs (63-94%) in the Western Antarctic Peninsula sediments were bound to black carbon or recalcitrant tar-like organic carbon, thereby lowering porewater concentrations. PCBs and OCPs in the holothurians were in equilibrium with those in the porewater.

Elucidating trophic pathways in benthic deep-sea assemblages of the Mid-Atlantic Ridge north and south of the Charlie-Gibbs Fracture Zone

The Mid-Atlantic Ridge (MAR) is a topographically complex feature in the North Atlantic Ocean with little exploration of benthic fauna except in association with hydrothermal venting, resulting in the biodiversity and ecosystem functioning of the MAR benthos away from these sites remaining largely unknown. Stable isotope analysis of carbon, nitrogen and sulphur were undertaken on fauna collected north and south of the Charlie-Gibbs Fracture Zone, in areas believed to be devoid of hydrothermal venting, to investigate the trophodynamics of the benthic assemblage. δ13C and δ34S values of the benthic and bentho-pelagic fauna indicated a dependence on photosynthetic primary production, with no influence from an unknown chemosynthetic source. A large trophic discrimination in δ13C between consumers and potential food sources (particulate organic matter and surficial sediments) suggested reworking of organic carbon before assimilation by benthic fauna. Interpretation of sediment δ15N values was difficult as these ranged between −0.74 and 23.14‰, suggesting further work is required to understand nitrogen utilisation by benthic deposit feeders. Differences in trophic guilds (predators, predator–scavenger, surface deposit feeders, subsurface deposit feeders and suspension feeders) were evident for δ13C and δ15N, with the main difference between the mobile predators–scavengers and the benthic deposit feeders. Dividing the assemblage based on trophic guilds into food chains dependent on phytodetritus (deposit and suspension feeders) and predation–scavenging (fishes and crustaceans) resulted in strong positive correlations between δ15N and δ13C at both stations. These reflected the 2 dominant trophic pathways organic matter passed through deposit feeders and predatory and scavenging deep-sea fishes and crustaceans.

Can UV radiation affect benthic deposit-feeders through biochemical alteration of food resources? An experimental study with juveniles of the benthic polychaete Eupolymnia nebulosa

The growth, tentacle development and feeding activity of the benthic polychaete Eupolymnia nebulosa were examined to determine whether UV might affect marine deposit-feeders indirectly through the modification of the nutritional quality of their resources. Since marine invertebrates have higher nutritional requirements during the period following settlement, we tested the effect of UV-altered phytodetritus on freshly settled juveniles of E. nebulosa. Phytodetritus was prepared from cultures of the diatom Skeletonema costatum either grown under or sheltered from UVB radiation. Sterol content of phytodetritus was unmodified by UV radiation. Conversely, phytodetritus was noticeably depleted in polyunsaturated fatty acids. Growth and tentacle development of juveniles fed on altered phytodetritus were reduced by 35% and 15% respectively, suggesting potential deficiencies in essential nutrients. In response to the lower quality of the phytodetritus, juveniles explored a wider area as they search for food, a strategy that could compensate for low food quality.

Dietary contribution of the microphytobenthos to infaunal deposit feeders in an estuarine mudflat in Japan

The food sources of benthic deposit feeders were investigated at three stations in an estuarine mudflat (Idoura Lagoon, Sendai Bay, Japan) during July and August 2005, using δ13C and δ15N ratios. Sediment at the stations was characterized by low chlorophyll (chl) a content (0–1 cm depth, <4 μg cm−2) and the dominance of riverine–terrestrial materials (RTM) in the sediment organic matter (SOM) pool. Surface-deposit feeders (Macoma contabulata, Macrophthalmus japonicus, and Cyathura muromiensis) exhibited much higher δ13C values (−18.4 to −12.4‰) than did the SOM pool (<−25‰). A δ13C-based isotopic mixing model estimated that benthic diatoms comprised 45–100% (on average) of their assimilated diet, whereas RTM comprised a lesser fraction (29% maximum). The major diet of the deep-deposit feeding polychaetes Notomastus sp. and Heteromastus sp. was benthic diatoms and/or marine particulate organic matter (POM), with little RTM assimilated (39% maximum). The consumers appeared to lack specific digestive enzymes and to use detritus-derived carbon only after its transfer to the microbial biomass. The isotopic mixing model also showed that the dietary contribution of RTM increased slightly (15% maximum) in the vicinity of freshwater input, suggesting that spatial changes in RTM supply affect the dietary composition of deposit feeders. These results clearly demonstrate that deposit feeders selectively ingest and/or assimilate the more nutritious microalgal fractions in the SOM pool. Such adaptations may allow enhanced energy gain in estuarine mudflats that are rich in vascular plant detritus with low nutritive value.

Transfer of brevetoxins to a tellinid bivalve by suspension- and deposit-feeding and its implications for clay mitigation of Karenia brevis blooms

Blooms of the brevetoxin-producing Karenia brevis in the Gulf of Mexico cause massive fish kills, food poisoning and adverse respiratory effects in humans. Sedimentation of toxic cells following inert clay application could reduce toxin incorporation by commercially important suspension-feeding bivalves and thus prevent direct public health impacts, but could potentially lead to brevetoxin (PbTx) accumulation by benthic deposit-feeders. The goal of this study was therefore to compare suspension- and deposit-feeding as pathways for brevetoxins. We investigated: (1) the effect of toxic K. brevis on both feeding modes using a facultative deposit-suspension feeding tellinid bivalve, the clam Macoma balthica, as a model species and (2) the relative effectiveness of brevetoxin transfer via suspension- and deposit-feeding over 24-h exposure. Sedimentation of K. brevis was achieved by treatment with 0.25 g phosphatic clay l−1 and brevetoxin concentrations were measured by ELISA. Karenia brevis reduced both suspension- and deposit-feeding activity. This study demonstrates that brevetoxins can be rapidly accumulated by a surface deposit-feeding bivalve from sedimented K. brevis cells and that comparable toxin levels can be attained by both suspension- and deposit-feeding modes [1.2–1.6 μg PbTx (g tissue wet weight)−1]. Deposit-feeding clams generally do not pose a direct threat to humans but may provide a pathway for brevetoxin food web transfer.

Uptake of sedimentary organic matter by the deposit-feeding Baltic amphipods Monoporeia affinis and Pontoporeia femorata

Some benthic deposit-feeders mainly eat freshly deposited phytodetritus, while others feed more on older material that has been mixed with the sediment and modified by diagenetic processes before being ingested. We studied the uptake of sedimentary foods of different ages by the Baltic amphipods Monoporeia affinis (Lindstrom) and Pontoporeia femorata Kroyer in laboratory experiments using 3 isotopic tracers. The amphipods were offered fresh 14 C-labelled diatoms spread on top of a thin unlabelled sediment layer, underlain by 1 yr old sediment to which 13 C- and 15 N-labelled diatoms had been added. Thus, 14 C uptake represented surface feeding on fresh organic material, and 13 C: 15 N uptake subsurface feeding on aged phytodetritus. Experiments using a single species only or mixed species were conducted in spring with 1 yr old adults and in summer with 3 mo old juveniles. Adult M. affinis (initial dry mass 1.6 mg) took up ∼5 times more 14 C than P. femorata (initial dry mass 1.7 mg), indicating that M. affinis depended more on fresh phytodetritus, while P. femorata had significantly higher 13 C: 15 N uptake, showing a greater reliance of this species on aged organic matter from the deep sediment. In experiments, adult P. femorata consistently fed at depth in the sediment, whereas adult M. affinis modified feeding depth depending on food quality. Juveniles (0.1 mg initial dry mass) of both species had similar tracer uptake and fed both on surface and subsurface sediment, suggesting greater potential for interspecific food competition in juveniles than in adults. Juveniles of both species had higher mass-specific 14 C uptake than adults. Single species treatments had higher 14 C uptake than mixed treatments in both adults and juveniles, indicating food competition at the higher density of the mixed treatments.

Do biogenic sulphur compounds in phytodetritus act as cues for deposit-feeder activity? Field experiments and observations on the echiuran worm Maxmuelleria lankesteri

In temperate coastal seas, phytodetritus settling from the spring phytoplankton bloom is a potential food source for benthic deposit-feeders. The ability to exploit this seasonally variable resource could be enhanced by sensitivity to chemical cues signalling its arrival at the seabed. The biogenic sulphur compound dimethylsulphide (DMS), a breakdown product of dimethylsulphonioproprionate (DMSP) produced by some phytoplankton species, is a potential candidate for this role. We investigated the behavioural response of a sedentary surface deposit-feeder, the echiuran worm Maxmuelleria lankesteri, to DMS by observations and manipulative experimentation under natural conditions in a Scottish sea loch. Experimental addition of sediment enriched with DMSP-producing phytoplankton caused no significant increase in either the frequency of feeding by M. lankesteri or the rate of sediment ejection from observed burrows. Naturally occurring (DMSP+DMS) content of surface sediment was low during the winter, then peaked in April before declining in May. There was no consistent relationship between this parameter and rate of sediment ejection from M. lankesteri burrows. The results therefore provide no evidence that M. lankesteri uses DMSP or DMS as a stimulus to increased activity. An observed imbalance between the frequency of surface deposit-feeding and sediment ejection from individual burrows remains unexplained.

Food web structure in the high Arctic Canada Basin: evidence from ?13C and ?15N analysis

The food-web structure of the Arctic deep Canada Basin was investigated in summer 2002 using carbon and nitrogen stable isotope tracers. Overall food-web length of the range of organisms sampled occupied four trophic levels, based on 3.8‰ trophic level enrichment (δ15N range: 5.3–17.7‰). It was, thus, 0.5–1 trophic levels longer than food webs in both Arctic shelf and temperate deep-sea systems. The food sources, pelagic particulate organic matter (POM) (δ13C=−25.8‰, δ15N=5.3‰) and ice POM (δ13C=−26.9‰, δ15N=4.1‰), were not significantly different. Organisms of all habitats, ice-associated, pelagic and benthic, covered a large range of δ15N values. In general, ice-associated crustaceans (δ15N range 4.6–12.4‰, mean 6.9‰) and pelagic species (δ15N range 5.9–16.5, mean 11.5‰) were depleted relative to benthic invertebrates (δ15N range 4.6–17.7‰, mean 13.2‰). The predominantly herbivorous and predatory sympagic and pelagic species constitute a shorter food chain that is based on fresh material produced in the water column. Many benthic invertebrates were deposit feeders, relying on largely refractory material. However, sufficient fresh phytodetritus appeared to arrive at the seafloor to support some benthic suspension and surface deposit feeders on a low trophic level (e.g., crinoids, cumaceans). The enriched signatures of benthic deposit feeders and predators may be a consequence of low primary production in the high Arctic and the subsequent high degree of reworking of organic material.

Feeding behaviour and functional response of Abra ovata and A. nitida compared by image analysis

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 267:195-208 (2004) - doi:10.3354/meps267195 Feeding behaviour and functional response of Abra ovata and A. nitida compared by image analysis A. Grémare1,*, J. C. Duchêne1, R. Rosenberg2, E. David1, M. Desmalades1 1Laboratoire d¹Océanographie Biologique de Banyuls, UMR7621, CNRS et Université Pierre et Marie Curie, BP44, 66651 Banyuls-sur-Mer Cedex, France 2Department of Marine Ecology, Göteborg University, Kristineberg Marine Research Station, 450 34 Fiskebäckskil, Sweden *Email: gremare@obs-banyuls.fr ABSTRACT: An automated image analysis system was used to monitor sediment surface feeding activity of 2 bivalves (Abra ovata and A. nitida) inhabiting contrasting environments. A larger variety of feeding behaviours was recorded in A. nitida, whereas A. ovata mostly fed at the sediment surface. There were also clear differences in the behaviour of the 2 species during surface deposit feeding (i.e. a wider extension of the inhalant siphon in A. ovata, and the exhalant siphon being located below the sediment-water interface in A. ovata and above this interface in A. nitida). In A. nitida, increase in feeding activity resulted mostly from an increase in feeding intensity, and not from an increase in the amount of time devoted to feeding. In A. ovata, the most active bivalves tended to increase their activity mostly by increasing the amount of time devoted to feeding. This suggests that feeding intensity was limited in A. ovata but not in A. nitida. Food dilution and food addition experiments were carried out to assess the functional response in the 2 species. The results of the food dilution experiments were statistically insignificant due to high inter-individual variability. Food addition significantly affected feeding activity in A. ovata and A. nitida, although in different ways. In A. ovata, feeding activity was highest at intermediate food concentrations, and inhibited at the highest ones. In A. nitida, increased feeding activity was induced at higher concentrations than in A. ovata, and feeding activity was greatest at the highest food concentration. Such discrepancies in feeding behaviour and functional response in closely related species characterise the difficulty in delineating functional groups in benthic deposit-feeders. KEY WORDS: Deposit feeding · Behaviour · Image analysis · Bivalves Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 267. Online publication date: February 19, 2004 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2004 Inter-Research.

Impact of grazing and bioturbation of marine benthic deposit feeders on dinoflagellate cysts

The impact of benthic deposit feeders on marine dinoflagellate cysts was studied by adding a concentrated natural Swedish cyst assemblage to sediment with different deposit feeders in replicate 4-l aquaria. The deposit feeders used were the bivalve Abra nitida, the echinoderm Amphiura filiformis, and the polychaetes Melinna cristata and Nereis diversicolor. These species occur naturally near the Swedish west coast and were selected to represent different ways of feeding. The results showed a significant relative decrease of unfossilizable cyst species; whereas, the common fossilizable species Lingulodinium polyedrum significantly increased in the cyst assemblage after grazing. This work suggests that differences in dinoflagellate cyst compositions can in part be caused by different animal grazing behaviors.

Comparing rate and depth of feeding in benthic deposit-feeders: a test on two amphipods, Monoporeia affinis (Lindström) and Pontoporeia femorata Kröyer

Feeding depth is a critical aspect of habitat use by deposit-feeders. There is evidence of two partly separated food webs in infaunal benthos, where one relies directly on newly sedimented fresh phytodetritus, available mostly at the sediment surface, while the other primarily uses older organic matter in the sediment. We have developed a procedure for objective experimental identification of these two feeding types without relying on assumptions based on morphology. The rate and depth of feeding in the two deposit-feeding amphipods Monoporeia affinis and Pontoporeia femorata were studied in two laboratory experiments using 14C-labelled diatoms ( Skeletonema costatum) as food. Experiments were performed in spring and summer, with diatoms added on top and mixed down into the sediment in the spring experiment, and either on top or mixed into the sediment in the summer experiment. Treatments included the two species both in sympatry and allopatry, and at field-relevant densities between 1000 and 2600 individuals m −2. An overall greater 14C-assimilation was found for M. affinis, confirming that M. affinis has a higher ingestion rate and metabolism than P. femorata. In the spring experiment, M. affinis had similar 14C-assimilation both in treatments with labelled algae in the sediment and with labelled algae on the sediment surface, while P. femorata had ∼4× greater assimilation when the algae were mixed into the sediment. The summer experiment showed the same pattern for P. femorata, but M. affinis had ∼3× greater assimilation from algae spread on the sediment surface. No significant differences were found between densities or between sympatric and allopatric treatments indicating that competition between the two species had little effect under the conditions of the experiments. We conclude that the two species differ in feeding depth, with M. affinis more of a surface deposit-feeder and P. femorata almost exclusively a subsurface deposit-feeder, suggesting that they use partly different food resources. Depending on their local abundance, the two amphipods will affect mineralisation and bioturbation rates differently.