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Craig R Smith - One of the best experts on this subject based on the ideXlab platform.
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an end to end dna taxonomy methodology for benthic biodiversity survey in the clarion clipperton zone central pacific abyss
Journal of Marine Science and Engineering, 2015Co-Authors: Adrian G Glover, Thomas G Dahlgren, Helena Wiklund, Inga Mohrbeck, Craig R SmithAbstract:Recent years have seen increased survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyss, driven by commercial interests from contractors in the potential extraction of polymetallic nodules in the region. Part of the International Seabed Authority (ISA) regulatory requirements are that these contractors undertake environmental research expeditions to their CCZ exploration claims following guidelines approved by the ISA Legal and Technical Commission (ISA, 2010). Section 9 (e) of these guidelines instructs contractors to “…collect data on the sea floor communities specifically relating to megafauna, Macrofauna, meiofauna, microfauna, nodule fauna and demersal scavengers”. There are a number of methodological challenges to this, including the water depth (4000–5000 m), extremely warm surface waters (~28 °C) compared to bottom water (~1.5 °C) and great distances to ports requiring a large and long seagoing expedition with only a limited number of scientists. Both scientists and regulators have recently realized that a major gap in our knowledge of the region is the fundamental taxonomy of the animals that live there; this is essential to inform our knowledge of the biogeography, natural history and ultimately our stewardship of the region. Recognising this, the ISA is currently sponsoring a series of taxonomic workshops on the CCZ fauna and to assist in this process we present here a series of methodological pipelines for DNA taxonomy (incorporating both molecular and morphological data) of the Macrofauna and megafauna from the CCZ benthic habitat in the recent ABYSSLINE cruise program to the UK-1 exploration claim. A major problem on recent CCZ cruises has been the collection of high-quality samples suitable for both morphology and DNA taxonomy, coupled with a workflow that ensures these data are made available. The DNA sequencing techniques themselves are relatively standard, once good samples have been obtained. The key to quality taxonomic work on Macrofaunal animals from the tropical abyss is careful extraction of the animals (in cold, filtered seawater), microscopic observation and preservation of live specimens, from a variety of sampling devices by experienced zoologists at sea. Essential to the long-term iterative building of taxonomic knowledge from the CCZ is an “end-to-end” methodology to the taxonomic science that takes into account careful sampling design, at-sea taxonomic identification and fixation, post-cruise laboratory work with both DNA and morphology and finally a careful sample and data management pipeline that results in specimens and data in accessible open museum collections and online repositories.
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an end to end dna taxonomy methodology for benthic biodiversity survey in the clarion clipperton zone central pacific abyss
Journal of Marine Science and Engineering, 2015Co-Authors: Adrian G Glover, Thomas G Dahlgren, Helena Wiklund, Inga Mohrbeck, Craig R SmithAbstract:Recent years have seen increased survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyss, driven by commercial interests from contractors in the potential extraction of polymetallic nodules in the region. Part of the International Seabed Authority (ISA) regulatory requirements are that these contractors undertake environmental research expeditions to their CCZ exploration claims following guidelines approved by the ISA Legal and Technical Commission (ISA, 2010). Section 9 (e) of these guidelines instructs contractors to “…collect data on the sea floor communities specifically relating to megafauna, Macrofauna, meiofauna, microfauna, nodule fauna and demersal scavengers”. There are a number of methodological challenges to this, including the water depth (4000–5000 m), extremely warm surface waters (~28 °C) compared to bottom water (~1.5 °C) and great distances to ports requiring a large and long seagoing expedition with only a limited number of scientists. Both scientists and regulators have recently realized that a major gap in our knowledge of the region is the fundamental taxonomy of the animals that live there; this is essential to inform our knowledge of the biogeography, natural history and ultimately our stewardship of the region. Recognising this, the ISA is currently sponsoring a series of taxonomic workshops on the CCZ fauna and to assist in this process we present here a series of methodological pipelines for DNA taxonomy (incorporating both molecular and morphological data) of the Macrofauna and megafauna from the CCZ benthic habitat in the recent ABYSSLINE cruise program to the UK-1 exploration claim. A major problem on recent CCZ cruises has been the collection of high-quality samples suitable for both morphology and DNA taxonomy, coupled with a workflow that ensures these data are made available. The DNA sequencing techniques themselves are relatively standard, once good samples have been obtained. The key to quality taxonomic work on Macrofaunal animals from the tropical abyss is careful extraction of the animals (in cold, filtered seawater), microscopic observation and preservation of live specimens, from a variety of sampling devices by experienced zoologists at sea. Essential to the long-term iterative building of taxonomic knowledge from the CCZ is an “end-to-end” methodology to the taxonomic science that takes into account careful sampling design, at-sea taxonomic identification and fixation, post-cruise laboratory work with both DNA and morphology and finally a careful sample and data management pipeline that results in specimens and data in accessible open museum collections and online repositories.
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comparative composition diversity and trophic ecology of sediment Macrofauna at vents seeps and organic falls
PLOS ONE, 2012Co-Authors: Angelo F Bernardino, Lisa A Levin, Andrew R Thurber, Craig R SmithAbstract:Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at Macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall Macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of Macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct Macrofaunal assemblages at broad-scales contributing to s diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities.
Lisa A Levin - One of the best experts on this subject based on the ideXlab platform.
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comparative composition diversity and trophic ecology of sediment Macrofauna at vents seeps and organic falls
PLOS ONE, 2012Co-Authors: Angelo F Bernardino, Lisa A Levin, Andrew R Thurber, Craig R SmithAbstract:Sediments associated with hydrothermal venting, methane seepage and large organic falls such as whale, wood and plant detritus create deep-sea networks of soft-sediment habitats fueled, at least in part, by the oxidation of reduced chemicals. Biological studies at deep-sea vents, seeps and organic falls have looked at Macrofaunal taxa, but there has yet to be a systematic comparison of the community-level attributes of sediment macrobenthos in various reducing ecosystems. Here we review key similarities and differences in the sediment-dwelling assemblages of each system with the goals of (1) generating a predictive framework for the exploration and study of newly identified reducing habitats, and (2) identifying taxa and communities that overlap across ecosystems. We show that deep-sea seep, vent and organic-fall sediments are highly heterogeneous. They sustain different geochemical and microbial processes that are reflected in a complex mosaic of habitats inhabited by a mixture of specialist (heterotrophic and symbiont-associated) and background fauna. Community-level comparisons reveal that vent, seep and organic-fall Macrofauna are very distinct in terms of composition at the family level, although they share many dominant taxa among these highly sulphidic habitats. Stress gradients are good predictors of Macrofaunal diversity at some sites, but habitat heterogeneity and facilitation often modify community structure. The biogeochemical differences across ecosystems and within habitats result in wide differences in organic utilization (i.e., food sources) and in the prevalence of chemosynthesis-derived nutrition. In the Pacific, vents, seeps and organic-falls exhibit distinct Macrofaunal assemblages at broad-scales contributing to s diversity. This has important implications for the conservation of reducing ecosystems, which face growing threats from human activities.
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macrobenthic assemblage structure and organismal stoichiometry control faunal processing of particulate organic carbon and nitrogen in oxygen minimum zone sediments
Biogeosciences, 2012Co-Authors: William Ross Hunter, Lisa A Levin, Hiroshi Kitazato, Ursula WitteAbstract:Abstract. The Arabian Sea oxygen minimum zone (OMZ) impinges on the western Indian continental margin between 150 and 1500 m, causing gradients in oxygen availability and sediment geochemistry at the sea floor. Oxygen availability and sediment geochemistry are important factors structuring Macrofaunal assemblages in marine sediments. However, relationships between Macrofaunal assemblage structure and sea-floor carbon and nitrogen cycling are poorly understood. We conducted in situ 13C:15N tracer experiments in the OMZ core (540 m [O2] = 0.35 μmol l–1) and lower OMZ boundary (800–1100 m, [O2] = 2.2–15.0 μmol l–1) to investigate how Macrofaunal assemblage structure, affected by different oxygen levels, and C:N coupling influence the fate of particulate organic matter. No Macrofauna were present in the OMZ core. Within the OMZ boundary, relatively high abundance and biomass resulted in the highest Macrofaunal assimilation of particulate organic carbon (POC) and nitrogen (PON) at the lower oxygen 800 m stations ([O2] = 2.2–2.36 μmol l–1). At these stations the numerically dominant cirratulid polychaetes exhibited greatest POC and PON uptake. By contrast, at the higher oxygen 1100 m station ([O2] = 15.0 μmol l–1) Macrofaunal C and N assimilation was lower, with POC assimilation dominated by one large solitary ascidian. Macrofaunal POC and PON assimilation were influenced by changes in oxygen availability, and significantly correlated to differences in Macrofaunal assemblage structure between stations. However, Macrofaunal feeding responses were ultimately characterised by preferential organic nitrogen assimilation, relative to their internal C:N budgets.
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faunal responses to oxygen gradients on the pakistan margin a comparison of foraminiferans Macrofauna and megafauna
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Andrew J Gooday, Lisa A Levin, Aranda A Da Silva, Brian J Bett, Gregory L Cowie, Delphine Dissard, John D Gage, David Hughes, Rachel M Jeffreys, Peter LamontAbstract:The Pakistan Margin is characterised by a strong mid-water oxygen minimum zone (OMZ) that intercepts the seabed at bathyal depths (150–1300 m). We investigated whether faunal abundance and diversity trends were similar among protists (foraminiferans and gromiids), metazoan Macrofauna and megafauna along a transect (140–1850 m water depth) across the OMZ during the 2003 intermonsoon (March–May) and late/post-monsoon (August–October) seasons. All groups exhibited some drop in abundance in the OMZ core (250–500 m water depth; O2: 0.10–0.13 mL L?1=4.46–5.80 ?M) but to differing degrees. Densities of foraminiferans >63 ?m were slightly depressed at 300 m, peaked at 738 m, and were much lower at deeper stations. Foraminiferans >300 ?m were the overwhelmingly dominant Macrofaunal organisms in the OMZ core. Macrofaunal metazoans reached maximum densities at 140 m depth, with additional peaks at 850, 940 and 1850 m where foraminiferans were less abundant. The polychaete Linopherus sp. was responsible for a Macrofaunal biomass peak at 950 m. Apart from large swimming animals (fish and natant decapods), metazoan megafauna were absent between 300 and 900 m (O2 0.2 mL L?1=8.92 ?M). The progressively deeper abundance peaks for foraminiferans (>63 ?m), Linopherus sp. and ophiuroids probably represent lower OMZ boundary edge effects and suggest a link between body size and tolerance of hypoxia. Macro- and megafaunal organisms collected between 800 and 1100 m were dominated by a succession of different taxa, indicating that the lower part of the OMZ is also a region of rapid faunal change. Species diversity was depressed in all groups in the OMZ core, but this was much more pronounced for Macrofauna and megafauna than for foraminiferans. Oxygen levels strongly influenced the taxonomic composition of all faunal groups. Calcareous foraminiferans dominated the seasonally and permanently hypoxic sites (136–300 m); agglutinated foraminiferans were relatively more abundant at deeper stations where oxygen concentrations were >0.13 mL L?1(=5.80 ?M). Polychaetes were the main Macrofaunal taxon within the OMZ; calcareous Macrofauna and megafauna (molluscs and echinoderms) were rare or absent where oxygen levels were lowest. The rarity of larger animals between 300 and 700 m on the Pakistan Margin, compared with the abundant Macrofauna in the OMZ core off Oman, is the most notable contrast between the two sides of the Arabian Sea. This difference probably reflects the slightly higher oxygen levels and better food quality on the western side.
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community structure and nutrition of deep methane seep macrobenthos from the north pacific aleutian margin and the gulf of mexico florida escarpment
Marine Ecology, 2007Co-Authors: Lisa A Levin, Guillermo F MendozaAbstract:Methane seeps occur at depths extending to over 7000 m along the world's continental margins, but there is little information about the infaunal communities inhabiting sediments of seeps deeper than 3000 m. Biological sampling was carried out off Unimak Island (3200–3300 m) and Kodiak Island (4500 m) on the Aleutian margin, Pacific Ocean and along the Florida Escarpment (3300 m) in the Gulf of Mexico to investigate the community structure and nutrition of Macrofauna at these sites. We addressed whether there are characteristic infaunal communities common to the deep-water seeps or to the specific habitats (clam beds, pogonophoran fields, and microbial mats) studied here, and ask how these differ from background communities or from shallow-seep settings sampled previously. We also investigated, using stable isotopic signatures, the utilization of chemosynthetically fixed and methane-derived organic matter by Macrofauna from different regions and habitats. Within seep sites, Macrofaunal densities were the greatest in the Florida microbial mats (20,961 ± 11,618 ind·m−2), the lowest in the Florida pogonophoran fields (926 ± 132 ind·m−2), and intermediate in the Unimak and Kodiak seep habitats. Seep Macrofaunal densities differed from those in nearby non-seep sediments only in Florida mat habitats, where a single, abundant species of hesionid polychaete comprised 70% of the Macrofauna. Annelids were the dominant taxon (>60%) at all sites and habitats except in Florida background sediments (33%) and Unimak pogonophoran fields (27%). Macrofaunal diversity (H′) was lower at the Florida than the Alaska seeps, with a trend toward reduced richness in clam bed relative to pogonophoran field or non-seep sediments. Community composition differences between seep and non-seep sediments were evident in each region except for the Unimak margin, but pogonophoran and clam bed Macrofaunal communities did not differ from one another in Alaska. Seep δ13C and δ15N signatures were lighter for seep than non-seep Macrofauna in all regions, indicating use of chemosynthetically derived carbon. The lightest δ13C values (average of species’ means) were observed at the Florida escarpment (−42.8‰). We estimated that on average animal tissues had up to 55% methane-derived carbon in Florida mats, 31–44% in Florida clam beds and Kodiak clam beds and pogonophoran fields, and 9–23% in Unimak seep habitats. However, some taxa such as hesionid and capitellid polychaetes exhibited tremendous intraspecific δ13C variation (>30‰) between patch types. Overall we found few characteristic communities or features common to the three deep-water seeps (>3000 m), but common properties across habitats (mat, clam bed, pogonophorans), independent of location or water depth. In general, Macrofaunal densities were lower (except at Florida microbial mats), community structure was similar, and reliance on chemosynthesis was greater than observed in shallower seeps off California and Oregon.
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isotopic evidence for chemosynthesis based nutrition of macrobenthos the lightness of being at pacific methane seeps
Limnology and Oceanography, 2002Co-Authors: Lisa A Levin, Robert H MichenerAbstract:The importance of chemosynthetic nutritional pathways was examined for Macrofaunal invertebrates (.300 mm) from methane seeps in the Gulf of Alaska (4,413‐4,443 m), on the Oregon margin (590 m), and on the northern California slope [Eel River margin] (520 m) by use of natural abundance stable isotopic data. Seep Macrofauna exhibited lighter d 13 C and d 15 N values than those in nonseep sediments, but isotopic signatures varied among seep sites. Macrofaunal isotopic signatures indicated chemosynthetically fixed carbon sources with a significant contribution from methane-derived carbon (MDC) in Macrofauna from sediments of pogonophoran fields (averaged 13
Ursula Witte - One of the best experts on this subject based on the ideXlab platform.
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macrobenthic assemblage structure and organismal stoichiometry control faunal processing of particulate organic carbon and nitrogen in oxygen minimum zone sediments
Biogeosciences, 2012Co-Authors: William Ross Hunter, Lisa A Levin, Hiroshi Kitazato, Ursula WitteAbstract:Abstract. The Arabian Sea oxygen minimum zone (OMZ) impinges on the western Indian continental margin between 150 and 1500 m, causing gradients in oxygen availability and sediment geochemistry at the sea floor. Oxygen availability and sediment geochemistry are important factors structuring Macrofaunal assemblages in marine sediments. However, relationships between Macrofaunal assemblage structure and sea-floor carbon and nitrogen cycling are poorly understood. We conducted in situ 13C:15N tracer experiments in the OMZ core (540 m [O2] = 0.35 μmol l–1) and lower OMZ boundary (800–1100 m, [O2] = 2.2–15.0 μmol l–1) to investigate how Macrofaunal assemblage structure, affected by different oxygen levels, and C:N coupling influence the fate of particulate organic matter. No Macrofauna were present in the OMZ core. Within the OMZ boundary, relatively high abundance and biomass resulted in the highest Macrofaunal assimilation of particulate organic carbon (POC) and nitrogen (PON) at the lower oxygen 800 m stations ([O2] = 2.2–2.36 μmol l–1). At these stations the numerically dominant cirratulid polychaetes exhibited greatest POC and PON uptake. By contrast, at the higher oxygen 1100 m station ([O2] = 15.0 μmol l–1) Macrofaunal C and N assimilation was lower, with POC assimilation dominated by one large solitary ascidian. Macrofaunal POC and PON assimilation were influenced by changes in oxygen availability, and significantly correlated to differences in Macrofaunal assemblage structure between stations. However, Macrofaunal feeding responses were ultimately characterised by preferential organic nitrogen assimilation, relative to their internal C:N budgets.
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Macrofaunal response to phytodetritus in a bathyal norwegian fjord
Deep Sea Research Part I: Oceanographic Research Papers, 2008Co-Authors: Andrew K. Sweetman, Ursula WitteAbstract:Abstract The continental margin (rise and shelf) constitutes approximately 1/10th of the surface area of the oceans, but 80–90% of all sedimentary organic matter (OM) is remineralised here. Recent evidence has suggested that Macrofauna may play an important role in organic matter remineralisation in deep-sea continental margin sediments, and the deep fjords of western Norway provide a relatively easily accessible opportunity for detailed studies of continental margin Macrofaunal communities and their role in C-cycling. We examined the Macrofaunal community and assessed its response to a simulated OM pulse in a fjord environment using pulse-chase tracer experiments. In each experiment, 1 g Corg m−2 of 13C-labelled Skeletonema costatum was deposited onto intact sediment cores collected from 688 m water depth and incubated ex situ for 2, 7 and 14 d. Macrofaunal abundance and biomass were comparable to those of other deep-sea continental margin sediments of similar depths, but in contrast to previous fjord studies, the Macrofaunal community was numerically dominated by ostracods. Tracer experiments revealed highest uptake of tracer after 7 and 14 d compared to 2 d. Of the seven deposit feeding polychaete families, only the Paraonidae and Cirratulidae—together with the largely carnivorous Lumbrineridae—showed a significant response to our labelled C-source. The lack of response by the majority of deposit feeders and the unexpected feeding mode of the Lumbrineridae may be attributable to species—rather than family specific feeding—ecologies or ontogenetic changes in diet/feeding mode. Total Macrofaunal C-turnover was much lower than recorded in the deep Sognefjord in a 3 d feeding experiment, and is possibly a result of (1) distinct differences in Macrofaunal community composition between sites, with a predominantly sub-surface-feeding Macrofaunal assemblage being found in this study as opposed to a surface-feeding community in the Sognefjord, or (2) variations in OM supply and demand. Overall, this investigation highlights the importance of ecological information at the species level for a detailed understanding of Macrofaunal C-cycling and early diagenesis in marine sediments.
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processing of 13c labelled phytoplankton in a fine grained sandy shelf sediment north sea relative importance of different Macrofauna species
Marine Ecology Progress Series, 2005Co-Authors: Anja Kamp, Ursula WitteAbstract:On-board and in situ experiments with 13 C-labelled diatoms were carried out to investigate the processing of algal carbon by the Macrofauna community of a fine sandy-shelf site in the southern German Bight (North Sea). The time series (12, 30, 32 and 132 h incubations) was supplemented by additional laboratory experiments on the role of the dominant Macrofauna organism, the bivalve Fabulina fabula (Bivalvia: Tellinidae), for particulate organic matter subduction to deeper sediment layers. The specific uptake of algal 13 C by Macrofauna organisms was visible after 12 h and constantly increased during the incubation periods. F. fabula, a facultative (surface) deposit- and suspension-feeder, Lanice conchilega (Polychaeta: Terebellidae), a suspension-feeder and the (surface) deposit-feeder Echinocardium cordatum (Echinodermata: Spatangidae) were responsible for the majority of Macrofaunal carbon processing. Predatory Macrofauna organisms like Nephtys spp. (Polychaeta: Nephtyidae) also quickly became labelled. The rapid subduction of fresh organic matter by F. fabula down to ca. 4 to 7 cm sediment depth could be demonstrated, and it is suggested that entrainment by Macrofauna in this fine-grained sand is much more efficient than advective transport.
Luiz Felipe Cestari Dumont - One of the best experts on this subject based on the ideXlab platform.
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response of soft bottom macrobenthic assemblages to artisanal trawling fisheries in a subtropical estuary
Estuarine Coastal and Shelf Science, 2018Co-Authors: Ileana Ortega, Leonir Andre Colling, Luiz Felipe Cestari DumontAbstract:Abstract Bottom trawling is one of the most harmful and widespread activities affecting benthic habitats and fauna. In this study, we analyzed the impact of shrimp trawling fisheries on the densities, assemblage structure and vertical stratification of the benthic Macrofauna in shallow mudflats of the Patos Lagoon Estuary (Brazil). Experimental trawls of different intensities were performed during three shrimp fishing seasons (2015–2017), comparing Macrofauna among before and after trawling, and a control zone. The changes in Macrofaunal assemblages were more consistently related to natural variability than to trawling impact, being mostly influenced by sediment structure and salinity variation. The trawling impact was mainly detected in the area with higher percentages of fine sediments, with different Macrofaunal responses in each month and stratum. Some non-significant decreases on total densities after trawling were observed, mainly on the superficial stratum, and signs of burial activities. The response to trawling disturbance of each species was different and it highly depended on their natural variability. Only five species showed significant variation to the trawling treatment ( Erodona mactroides , Heleobia australis, H. charruana, Heteromastus similis and Laeonereis acuta ), with temporally different responses. Decreasing densities were more related to the high impact treatment. In some seasons, decreases on the abundance of Monokalliapseudes schubarti after high impact trawls were up to 60% of the seasonal mean densities. Trawling fisheries may reduce macrobenthic densities but not their vertical stratification. The impact of trawling on key species may compromise the ecosystem function, as benthic Macrofauna provide food sources for many aquatic resources. This study highlights trawling impacts in an estuarine nursery area, which should be fully considered since they may be reflected in the trophic webs.
Uchman Alfred - One of the best experts on this subject based on the ideXlab platform.
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Cold-seep fossil Macrofaunal assemblages from Vestnesa Ridge, eastern Fram Strait, during the past 45 000 years
'Norwegian Polar Institute', 2019Co-Authors: Thomsen Elsebeth, Rasmussen, Tine Lander, Sztybor Kamila, Hanken Nils-martin, Tendal, Ole Secher, Uchman AlfredAbstract:Four cores from 1200 m water depth from Vestnesa Ridge on the western Svalbard margin in the eastern Fram Strait were studied for their content of fossil Macrofaunas. Three of the cores were collected from a pockmark with active methane seepage, and one core (control core) was taken just outside the seepage area for comparison. Together the cores cover the last 45 000 years (mid-late Weichselian glacial, the deglaciation and the Holocene). The records show a range of influence of methane from no seepage (control core) and, although variable through time, from moderate seepage, to strong and very strong seepage. All cores have been analysed for the macrofossils >1 mm, trace fossils, planktic foraminifera, stable isotopes, geochemistry and sedimentology. The main purpose of the study is to improve our knowledge of the fossil Macrofauna and past environmental changes related to the impact of methane emissions in the area. The core recovered outside the pockmark contained no fossil Macrofaunas, while cores from inside the pockmark contained chemosymbiotic bivalves, and in some cases a rich Macrofauna. The faunal relationships with the sedimentary environments confirm a close connection between the Macrofauna and the variability in influence of cold seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic bivalve Rhacothyas kolgae, polychaetes and an associated rich fauna of small epifaunal gastropods, showing that Arctic seeps were oases for Macrofaunas in the past as they are today
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Cold-seep Macrofaunal assemblages in cores from Vestnesa Ridge, eastern Fram Strait, during the past 45000 years
'Norwegian Polar Institute', 2019Co-Authors: Thomsen Elsebeth, Rasmussen, Tine Lander, Sztybor Kamila, Hanken Nils-martin, Tendal, Ole Secher, Uchman AlfredAbstract:Source at https://doi.org/10.33265/polar.v38.3310. Four cores from 1200 m water depth from Vestnesa Ridge on the western Svalbard margin in the eastern Fram Strait were studied for their content of fossil macro-faunas. Three of the cores were collected from a pockmark with active methane seepage, and one core (control core) was taken just outside the seepage area for comparison. Together the cores cover the last 45 000 years (mid-late Weichselian glacial, the deglaciation and the Holocene). The records show a range of influence of methane from no seepage (control core) and, although variable through time, from moderate seepage, to strong and very strong seepage. All cores have been analysed for the macrofossils >1 mm, trace fossils, planktic foraminifera, stableisotopes, geochemistry and sedimentology. The main purpose of the study is to improve our knowledge of the fossil Macrofauna and past environmental changes related to the impact of methane emissions in the area. The core recovered outside the pockmark contained no fossil Macrofaunas, while cores from inside the pock-mark contained chemosymbiotic bivalves, and in some cases a rich Macrofauna. The faunal relationships with the sedimentary environments confirm a close con-nection between the Macrofauna and the variability in influence of cold seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic bivalve Rhacothyas kolgae, polychaetes. A barren zone in the core that was taken from the deepest part of the pockmark may indicate that a blow-out took place in the late glacial and the deglaciation into the early Holocene at c. 21,000–9000 years
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Cold-seep Macrofaunal assemblages in cores from Vestnesa Ridge, eastern Fram Strait, during the past 45000 years
'Norwegian Polar Institute', 2019Co-Authors: Thomsen Elsebeth, Rasmussen, Tine Lander, Sztybor Kamila, Hanken Nils-martin, Tendal, Ole Secher, Uchman AlfredAbstract:Four cores from 1200 m water depth from Vestnesa Ridge on the western Svalbard margin in the eastern Fram Strait were studied for their content of fossil macro-faunas. Three of the cores were collected from a pockmark with active methane seepage, and one core (control core) was taken just outside the seepage area for comparison. Together the cores cover the last 45 000 years (mid-late Weichselian glacial, the deglaciation and the Holocene). The records show a range of influence of methane from no seepage (control core) and, although variable through time, from moderate seepage, to strong and very strong seepage. All cores have been analysed for the macrofossils >1 mm, trace fossils, planktic foraminifera, stableisotopes, geochemistry and sedimentology. The main purpose of the study is to improve our knowledge of the fossil Macrofauna and past environmental changes related to the impact of methane emissions in the area. The core recovered outside the pockmark contained no fossil Macrofaunas, while cores from inside the pock-mark contained chemosymbiotic bivalves, and in some cases a rich Macrofauna. The faunal relationships with the sedimentary environments confirm a close con-nection between the Macrofauna and the variability in influence of cold seepage, particularly seen in the occurrence of chemosymbiotic bivalves Archivesica arctica, Isorropodon nyeggaensis, potentially chemosymbiotic bivalve Rhacothyas kolgae, polychaetes. A barren zone in the core that was taken from the deepest part of the pockmark may indicate that a blow-out took place in the late glacial and the deglaciation into the early Holocene at c. 21,000–9000 years
