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See detailTerrestrial vs. Marine: Discrimination of Hg Sources in Arctic True Seals by a Multi-Isotopic Approach
Pinzone, Marianna ULiege; Michel, Loïc ULiege; Bérail, Sylvain et al

Conference (2021, November 17)

Intrinsic biogeochemical markers, such as stable isotope ratios of carbon (C), nitrogen (N), sulphur (S) and mercury (Hg) are increasingly used to trace the effects of trophic ecology on Hg accumulation ... [more ▼]

Intrinsic biogeochemical markers, such as stable isotope ratios of carbon (C), nitrogen (N), sulphur (S) and mercury (Hg) are increasingly used to trace the effects of trophic ecology on Hg accumulation in marine top predators. However, they are often used separately. This leaves the interpretation of the data at times incomplete. Using a multivariate approach could contend with the complexity of the natural world and reveal patterns that would not be detectable by univariate methods. Our main objective was to assess which factor influences the most Hg sourcing in Arctic marine top predators and evaluate the consequences relative to the rates of exposure. We measured THg levels, C, N, S and Hg stable isotopes in three true seal species living in the Greenland Sea: the hooded seal Cystophora cristata, the harp seal Pagophilus groenlandicus and the ringed seal Pusa hispida. They present distinct habitat use, diet and geographical distribution. We integrated all the measured parameters into a multivariate analysis and quantify species multi-isotopic niches (SEAs) with SIBER. The multi-isotopic niches of the three species resulted highly separated. Hooded seals presented the largest multivariate SEA (Mode, 95% CI: 0.93, 0.60 – 1.41), a result of its highly distributed oceanic behaviour. Harp seals presented the second largest SEA (Mode, 95% CI: 0.31, 0.14 – 0.68), while ringed seals presented the smallest niche (Mode, 95% CI: 0.22, 0.14 – 0.37) as a result of its strong territoriality within the Scoresby Sound. Ringed seals presented the highest THg levels (1190±488 ng.g-1 dw), followed by hooded (881±942 ng.g-1 dw) and harp seals (407±289 ng.g-1 dw). Our study showed how habitat use (offshore / bentho-pelagic for Cc vs. offshore / pelagic for Pg vs. coastal / sympagic for Ph) is the most important factor influencing Hg accumulation in Arctic true seals. A species like the ringed seal; which lives in the fjords, on land-fast ice, is more influenced by the enhanced MeHg production typical of these zones and accumulate higher levels of Hg compared to offshore hooded and harp seals. [less ▲]

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See detailStable isotope ratios of C, N and S in Southern Ocean sea stars (1985-2017)
Moreau, Camille; Le Bourg, Baptiste; Balazy, Piotr et al

Textual, factual or bibliographical database (2021)

This dataset is a compilation of stable isotope ratios of C, N and S in tissues of 2456 sea stars sampled from 1985 to 2017 in the Southern Ocean (Antarctica and Subantarctic Islands). Stable isotope ... [more ▼]

This dataset is a compilation of stable isotope ratios of C, N and S in tissues of 2456 sea stars sampled from 1985 to 2017 in the Southern Ocean (Antarctica and Subantarctic Islands). Stable isotope values were measured in the framework of Baptiste Le Bourg's PhD thesis at University of Liège, entitled “Trophic ecology of Southern Ocean sea stars: Influence of environmental drivers on trophic diversity”. Samples were provided by the University of Liège (Belgium), the Université Libre de Bruxelles (Belgium), the National Museum of Natural History (Paris, France) and the Institute of Oceanology of the Polish Academy of Sciences (Sopot, Poland). There could be duplicate records from collections of these institutes published on GBIF and OBIS. This work was supported by BELSPO through the vERSO and RECTO projects (contracts no. BR/132/A1/vERSO and BR/154/A1/RECTO). This dataset is published by SCAR-AntOBIS under the license CC-BY 4.0. Please follow the guidelines from the SCAR and IPY Data Policies (https://www.scar.org/excom-meetings/xxxi-scar-delegates-2010-buenos-aires-argentina/4563-scar-xxxi-ip04b-scar-data-policy/file/) when using the data. If you have any questions regarding this dataset, don't hesitate to contact us via the contact information provided in the metadata or via data-biodiversity-aq@naturalsciences.be. Issues with dataset can be reported at https://github.com/biodiversity-aq/data-publication/ [less ▲]

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See detailFactors that influence trace element levels in blood and feathers of Pygoscelis penguins from South Shetland Islands, Antarctica
Padilha, J. A.; Carvalho, G. O.; Espejo, W. et al

in Environmental Pollution (2021), 284

Contaminant levels are lower in Antarctica than elsewhere in the world because of its low anthropogenic activities. However, the northern region of the Antarctic Peninsula, is close to South America and ... [more ▼]

Contaminant levels are lower in Antarctica than elsewhere in the world because of its low anthropogenic activities. However, the northern region of the Antarctic Peninsula, is close to South America and experiences the greatest anthropogenic pressure in Antarctica. Here, we investigated, in two Antarctic Peninsula islands, intra and interspecific factors that influence the concentrations of 17 trace elements (TEs) in blood and feathers of three penguin species breeding sympatrically in relation to their trophic ecology assessed via a stable isotopic approach (C, N and S). Geographical location, foraging zone (δ13C and δ34S) and diet influences the interspecific difference, and sex and maturity stage diet influence the intraspecific difference of Pygoscelis penguins. Penguins from Livingston showed higher values (mean, ng. g−1, dry weight - dw) of Zn (103), Mn (0.3), and Fe (95) than those from King George Island (Zn: 80, Mn: 1.9, and Fe: 11). Gender-related differences were observed, as males showed significantly higher values (mean, ng. g−1, dw) of Rb (3.4) and δ15N in blood of gentoo, and Ca (1344) in Adélie feathers. Chicks of gentoo and Adélie presented higher Zn, Mg, Ca, and Sr and lower 13C values in blood than adults. The highest concentrations (mean, ng. g−1, dw) of Cd (0.2) and Cu (26), and the lowest δ15N values were found in chinstrap. Geographical, intraspecific (i.e., ontogenetic and gender-related) and interspecific differences in feeding seemed to have influenced TE and stable isotope values in these animals. The TE bioaccumulation by penguins may have also been influenced by natural enrichment in environmental levels of these elements, which seems to be the case for Fe, Zn, and Mn. However, the high level of some of the TEs (Mn, Cd, and Cr) may reflect the increase of local and global human activities. [less ▲]

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See detailVariability of amphidromous organism isotopic niches in three Guadeloupe rivers affected by damming and water catchment
Frotté, Lou; Michel, Loïc ULiege; Lepoint, Gilles ULiege et al

in Belgian Journal of Zoology (2021), 151(1),

Native fauna of the tropical volcanic part of Guadeloupe is amphidromous: juveniles born in rivers but that grow in the sea need to migrate upstream to colonise their adult habitat in rivers. This ... [more ▼]

Native fauna of the tropical volcanic part of Guadeloupe is amphidromous: juveniles born in rivers but that grow in the sea need to migrate upstream to colonise their adult habitat in rivers. This migration is affected by any human-made obstacles placed in their way. Moreover, on volcanic tropical islands, streams are the main source of water catchment for the human population. This deeply affects river hydrology and characteristics. Both damming and water catchment potentially affect community diversity and species demography, but they may also alter the trophic ecology of the river fauna. Using stable isotopes and the stable isotope Bayesian ellipses approach in R (SIBER), this study aimed to assess the isotopic niche variability of riverine fauna of three persistent small rivers of Basse-Terre Island (Guadeloupe) affected by damming and water catchment. Using electrofishing, decapods and fishes (gobies) of three rivers were sampled upstream and downstream of dams. Our results demonstrated that the variability of the isotopic niches was extremely high between rivers but varied less between stations of the same river. Our results revealed complex and river-specific effects and a pattern merged with natural variability. Our two hypotheses (i.e., increase of resources upstream of dams and differential responses of trophic guilds to damming and water catchment) were only weakly supported and never in an unambiguous manner. Our study showed that it is necessary to consider the ‘noise’ generated by natural variability to observe and understand changes in the trophic ecology of associated fauna in relation to damming and water catchment. [less ▲]

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See detailFood web structure in a rapidly changing coastal environment: the West Antarctic Peninsula
Voisin, Anthony; Lepoint, Gilles ULiege; Danis, Bruno et al

Conference (2021, May 19)

The West Antarctic Peninsula (WAP) is one of the most rapidly changing regions in the world, in great part due to anthropogenic climate change. Steep environmental gradients in water temperature, sea ice ... [more ▼]

The West Antarctic Peninsula (WAP) is one of the most rapidly changing regions in the world, in great part due to anthropogenic climate change. Steep environmental gradients in water temperature, sea ice cover and glacier melting influence are observed, but much is left to document about significance of those shifts for biological communities and ecosystem processes. Here, we aimed to study how environmental changes impact trophic interactions and ecological habits of benthic communities along the WAP. During the Belgica 121 expedition, dominant benthic mega- and macrofauna, as well as primary producers, were sampled in multiple stations featuring contrasted environmental conditions around the Gerlache Strait. Stable isotope ratios of δ 13C, δ15N and δ34S were measured and combined in an isotope niche analysis (SIBER). Our results suggest that changes in environmental features, notably ice disturbance, could cause alteration of food sources availability and fluxes to benthic organisms. Isotopic compositions of abundant species were more variable in stations with stronger ice disturbance. Besides baseline variability, this could be linked with use of alternative resources (niche expansion) in stations influenced by glacier melting. Those results provide a first step towards understanding links between environmental change and ecological responses of benthic consumers along the WAP. [less ▲]

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See detailTrophic ecology of macrofauna inhabiting seagrass litter accumulations is related to the pulses of dead leaves
Remy, François ULiege; Michel, Loïc ULiege; Mascart, Thibaud ULiege et al

in Estuarine, Coastal and Shelf Science (2021), 252

Accumulation of exported macrophytodetritus (AEM) represent unique habitats formed by the dead material originating from macrophyte ecosystems (e.g., seagrass, kelp, other seaweeds). AEM can be found ... [more ▼]

Accumulation of exported macrophytodetritus (AEM) represent unique habitats formed by the dead material originating from macrophyte ecosystems (e.g., seagrass, kelp, other seaweeds). AEM can be found everywhere, from the littoral zone to the deepest canyons, and from high to low latitudes. Seagrass AEMs are among the most common detrital accumulations found in marine environments, and sometimes include macroalgae wrack that has been ripped from the substrate. In the Mediterranean Sea, Posidonia oceanica (L.) Delile litter accumulations undergo pulses of new necromass all year, particularly in autumn, when dead leaves are shed. Here, macrofauna inhabiting AEM of Calvi Bay (Corsica, France) was sampled troughout an annual cycle (four seasons). By combining gut content examination and stable isotope analysis, we aimed to assess the effect of seasonal litter pulses on the trophic ecology of the dominant macrofauna species. Litter composition showed drastic variations throughout the sampling period, with the highest leaf litter quantity and contribution to AEMs in November. Dominant detritivores, herbivores, and omnivores responded positively to this increase by ingesting more seagrass material. A Bayesian stable isotope mixing model showed that the assimilation of carbon originating from seagrasses also increased. Additionally, isotopic niche modelling showed that consumer niches shifted towards seagrass isotopic composition in November. Predators did not shift their diet, but their isotopic composition was affected by the isotopic shift of their prey, demonstrating the transfer of seagrass carbon to higher trophic levels and the shift towards dead leaf material in the entire community. This response was, therefore, a rapid (days to weeks) parallel to that of the slow (months to years) decomposition of detrital material via physical alteration and microbial decomposition. This seemingly underestimated transfer route should be better characterised to understand the role of these seagrass beds in carbon sequestration in the marine environment. [less ▲]

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See detailStable isotope ratios of C and N in diadromous fauna from Guadeloupe, French West Indies in 2017. Marine Data Archive.
Frotté, Lou; Michel, Loïc ULiege; Lepoint, Gilles ULiege et al

Textual, factual or bibliographical database (2021)

Measurements of trophic markers performed in diadromous fauna from Guadeloupe. more This dataset contains measurements of stable isotope ratios of carbon and nitrogen made in 580 samples of diadromous ... [more ▼]

Measurements of trophic markers performed in diadromous fauna from Guadeloupe. more This dataset contains measurements of stable isotope ratios of carbon and nitrogen made in 580 samples of diadromous fauna (459 individual specimens belonging to 14 taxa) and their food items (121 samples of drifting particulate organic matter, leaf litter or biofilm). Samples were taken in 3 rivers of Guadeloupe (French West Indies) between February and May 2017. In each river, 3 stations were sampled: one upstream from a water extraction dam, one downstream from each dam, and one at the mouth of the river. Analytical measurements were performed at University of Liège (Belgium)’s stable isotope facility (Laboratory of Oceanology, Stable Isotope in Environmental Sciences and Trophic Ecology workgroup, https://www.oceanobio.uliege.be/). More info about the studies and sample preparation can be found in the publication referenced below. The dataset consists of two files: one containing the data itself, and one describing all used terms (measurements or metadata, derived from Darwin Core standards, https://dwc.tdwg.org/terms/). [less ▲]

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See detailStable isotope ratios of C, N and S in Southern Ocean sea stars (1985-2017). v1.2. Antarctic Biodiversity Information Facility (ANTABIF). Dataset/Occurrence.
Le Bourg, Baptiste; Moreau, Camille; Danis, Bruno et al

Textual, factual or bibliographical database (2021)

This dataset is a compilation of stable isotope ratios of C, N and S in tissues of 2456 sea stars sampled from 1985 to 2017 in the Southern Ocean (Antarctica and Subantarctic Islands). Stable isotope ... [more ▼]

This dataset is a compilation of stable isotope ratios of C, N and S in tissues of 2456 sea stars sampled from 1985 to 2017 in the Southern Ocean (Antarctica and Subantarctic Islands). Stable isotope values were measured in the framework of Baptiste Le Bourg's PhD thesis at University of Liège, entitled “Trophic ecology of Southern Ocean sea stars: Influence of environmental drivers on trophic diversity”. Samples were provided by the University of Liège (Belgium), the Université Libre de Bruxelles (Belgium), the National Museum of Natural History (Paris, France) and the Institute of Oceanology of the Polish Academy of Sciences (Sopot, Poland). This work was supported by BELSPO through the vERSO and RECTO projects (contracts no. BR/132/A1/vERSO and BR/154/A1/RECTO). [less ▲]

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See detailStable isotope ratios of C and N in benthic macrofauna from Mediterranean seagrass litter accumulations from Calvi Bay in 2011-2012
Michel, Loïc ULiege; Remy, François ULiege; Mascart, Thibaud ULiege et al

Textual, factual or bibliographical database (2021)

Measurements of trophic markers performed in benthic macrofauna sampled in seagrass litter accumulations from Calvi Bay (Corsica, France) in 2011-2012. more This dataset contains measurements of stable ... [more ▼]

Measurements of trophic markers performed in benthic macrofauna sampled in seagrass litter accumulations from Calvi Bay (Corsica, France) in 2011-2012. more This dataset contains measurements of stable isotope ratios of carbon and nitrogen made in 568 individual specimens of 19 different taxa of benthic macrofauna (Nemertea, Mollusca, Polychaeta, Crustacea, Actinopterygii). Samples were taken in submerged seagrass litter accumulations, seasonally in 2011-2012, and at two sites of Calvi Bay (Corsica, France). Analytical measurements were performed at University of Liège (Belgium)’s stable isotope facility (Laboratory of Oceanology, Stable Isotope in Environmental Sciences and Trophic Ecology workgroup, https://www.oceanobio.uliege.be/). More info about the studies and sample preparation can be found in the publications referenced below. The dataset consists of two files: one containing the data itself, and one describing all used terms (measurements or metadata, derived from Darwin Core standards, https://dwc.tdwg.org/terms/). Publications based on this data set: Remy, F. (2016). Characterization, dynamics and trophic ecology of macrofauna associated to seagrass macrophytodetritus accumulations (Calvi Bay, Mediterranean Sea). PhD Thesis. University of Liège: Liège. xi, 285 pp. + Remy, F. et al. (2018). Seagrass organic matter transfer in Posidonia oceanica macrophytodetritus accumulations. Est., Coast. and Shelf Sci. 212: 73-79. https://hdl.handle.net/10.1016/j.ecss.2018.07.001 + Remy et al. 2021 Trophic ecology of macrofauna inhabiting seagrass litter accumulations is related to the pulses of dead leaves. ECSS in press [less ▲]

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See detailInteractive effects of body size and environmental gradient on the trophic ecology of sea stars in an Antarctic fjord
Le Bourg, B.; Kuklinski, P.; Balazy, P. et al

in Marine Ecology. Progress Series (2021), 674

ABSTRACT: Antarctic sea stars can occupy different trophic niches and display different trophic levels, but, while the impacts of their body size and environmental features on their trophic niches are ... [more ▼]

ABSTRACT: Antarctic sea stars can occupy different trophic niches and display different trophic levels, but, while the impacts of their body size and environmental features on their trophic niches are potentially important, they are presently understudied. Here we assessed the trophic ecology in relation to the size and habitat of sea stars in a fjord on King George Island (South Shetland Islands) using stable isotope values of carbon (δ<sup>13</sup>C), nitrogen (δ<sup>15</sup>N), and sulphur (δ<sup>34</sup>S). The disc radius influenced δ<sup>13</sup>C and δ<sup>15</sup>N values, whereas more limited changes in δ<sup>13</sup>C or δ<sup>34</sup>S values were related to arm length. Specifically, δ<sup>13</sup>C and δ<sup>15</sup>N values were linked to disc radius in generalist species (<i>Diplasterias brandti</i> and <i>Odontaster validus</i>), which could indicate ontogenetic diet shifts, while this relationship occurred less frequently in more specialised species (<i>Bathybiaster loripes</i>, <i>Notasterias bongraini</i>, and <i>Perknaster sladeni</i>). <i>O. validus</i> had a smaller isotopic niche size in the inner than the outer fjord. The niche overlap between <i>D. brandti</i> and <i>O. validus</i> was low in the inner fjord. Low resource availability within the fjord, linked to higher turbidity, could induce trophic niche constriction and interspecific resource segregation. This could represent a mechanism for competition avoidance in a resource-limited system. Conversely, higher resource availability could allow <i>O. validus</i> to expand and share its isotopic niche with <i>D. brandti</i> in the outer fjord with a limited risk of competition. This trophic plasticity will likely influence how <i>O. validus</i> copes with the present and future modification of environmental conditions induced by climate change. [less ▲]

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See detailReliance of deep-sea benthic macrofauna on ice-derived organic matter highlighted by multiple trophic markers during spring in Baffin Bay, Canadian Arctic
Yunda-Guarin, Gustavo; Brown, Thomas A.; Michel, Loïc ULiege et al

in Elementa: Science of the Anthropocene (2020), 8(1), 047

Benthic organisms depend primarily on seasonal pulses of organic matter from primary producers. In the Arctic, declines in sea ice due to warming climate could lead to changes in this food supply with as ... [more ▼]

Benthic organisms depend primarily on seasonal pulses of organic matter from primary producers. In the Arctic, declines in sea ice due to warming climate could lead to changes in this food supply with as yet unknown effects on benthic trophic dynamics. Benthic consumer diets and food web structure were studied in a seasonally ice-covered region of Baffin Bay during spring 2016 at stations ranging in depth from 199 to 2,111 m. We used a novel combination of highly branched isoprenoid (HBI) lipid biomarkers and stable isotope ratios (δ13C, δ15N) to better understand the relationship between the availability of carbon sources in spring on the seafloor and their assimilation and transfer within the benthic food web. Organic carbon from sea ice (sympagic carbon [SC]) was an important food source for benthic consumers. The lipid biomarker analyses revealed a high relative contribution of SC in sediments (mean SC% ± standard deviation [SD] = 86% ± 16.0, n = 17) and in benthic consumer tissues (mean SC% ± SD = 78% ± 19.7, n = 159). We also detected an effect of sea-ice concentration on the relative contribution of SC in sediment and in benthic consumers. Cluster analysis separated the study region into three different zones according to the relative proportions of SC assimilated by benthic macrofauna. We observed variation of the benthic food web between zones, with increases in the width of the ecological niche in zones with less sea-ice concentration, indicating greater diversity of carbon sources assimilated by consumers. In zones with greater sea-ice concentration, the higher availability of SC increased the ecological role that primary consumers play in driving a stronger transfer of nutrients to higher trophic levels. Based on our results, SC is an important energy source for Arctic deep-sea benthos in Baffin Bay, such that changes in spring sea-ice phenology could alter benthic food-web structure. [less ▲]

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See detailCan mandible morphology help predict feeding habits in Antarctic amphipods?
Michel, Loïc ULiege; Nyssen, Fabienne ULiege; Dauby, Patrick ULiege et al

in Antarctic Science (2020), 32(6), 496-507

In Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod ... [more ▼]

In Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do so, we compared mandible morphology in nine species spanning seven families and five functional groups (grazers, suspension feeders, generalist predators, specialist predators and scavengers). Mandible morphology adequately depicted some aspects of amphipod trophic ecology, such as the trophic level at which animals feed or their degree of dietary specialization. On the other hand, links between mandible morphology and amphipod diet were seldom unambiguous or straightforward. Similar adaptations were found in distinct functional groups. Conversely, mandible morphology could vary within a single functional group, and phylogenetic effects sometimes complicated the interpretation of form-function relationships. Overall, mandible morphology on its own was generally not sufficient to precisely predict amphipod feeding strategies. However, when combined with other methods (e.g. gut contents, trophic markers), it constitutes a valuable source of information for integrative studies of amphipod ecological diversity in the Southern Ocean. [less ▲]

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See detailState of art and best practices for fatty acid analysis in aquatic sciences
Couturier, Lydie I. E.; Michel, Loïc ULiege; Amaro, Teresa et al

in ICES Journal of Marine Science (2020), 77(7-8), 2375-2395

Determining the lipid content and fatty acid (FA) composition of aquatic organisms has been of major interest in trophic ecology, aquaculture, and nutrition for over half a century. Although protocols for ... [more ▼]

Determining the lipid content and fatty acid (FA) composition of aquatic organisms has been of major interest in trophic ecology, aquaculture, and nutrition for over half a century. Although protocols for lipid analysis are well-described, their application to aquatic sciences often requires modifications to adapt to field conditions and to sample type. Here, we present the current state of knowledge of methods dedicated to both marine and freshwater lipid analyses, from sampling to data treatment. We review: (i) sample preservation, storage and transport protocols, and their effects on lipids, (ii) lipid extraction, separation of polar and neutral lipids, derivatization, and detection methods, and (iii) available tools for the statistical analysis of FA data. We provide recommendations for best practices in field situations and advocate for protocol standardization and interlaboratory calibration. [less ▲]

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See detailHigh environmental stress and productivity increase functional diversity along a deep‐sea hydrothermal vent gradient
Alfaro-Lucas, Joan M.; Pradillon, Florence; Zeppilli, Daniela et al

in Ecology (2020), 101(11), 03144

Productivity and environmental stress are major drivers of multiple biodiversity facets and faunal community structure. Little is known on their interacting effects on early community assembly processes ... [more ▼]

Productivity and environmental stress are major drivers of multiple biodiversity facets and faunal community structure. Little is known on their interacting effects on early community assembly processes in the deep sea (>200 m), the largest environment on Earth. However, at hydrothermal vents productivity correlates, at least partially, with environmental stress. Here, we studied the colonization of rock substrata deployed along a deep‐sea hydrothermal vent gradient at four sites with and without direct influence of vent fluids at 1,700‐m depth in the Lucky Strike vent field (Mid‐Atlantic Ridge [MAR]). We examined in detail the composition of faunal communities (>20 μm) established after 2 yr and evaluated species and functional patterns. We expected the stressful hydrothermal activity to (1) limit functional diversity and (2) filter for traits clustering functionally similar species. However, our observations did not support our hypotheses. On the contrary, our results show that hydrothermal activity enhanced functional diversity. Moreover, despite high species diversity, environmental conditions at surrounding sites appear to filter for specific traits, thereby reducing functional richness. In fact, diversity in ecological functions may relax the effect of competition, allowing several species to coexist in high densities in the reduced space of the highly productive vent habitats under direct fluid emissions. We suggest that the high productivity at fluid‐influenced sites supports higher functional diversity and traits that are more energetically expensive. The presence of exclusive species and functional entities led to a high turnover between surrounding sites. As a result, some of these sites contributed more than expected to the total species and functional β diversities. The observed faunal overlap and energy links (exported productivity) suggest that rather than operating as separate entities, habitats with and without influence of hydrothermal fluids may be considered as interconnected entities. Low functional richness and environmental filtering suggest that surrounding areas, with their very heterogeneous species and functional assemblages, may be especially vulnerable to environmental changes related to natural and anthropogenic impacts, including deep‐sea mining. [less ▲]

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See detailDeepIso - a global open database of stable isotope ratios and elemental contents for deep-sea ecosystems.
Michel, Loïc ULiege; Bell, James; Dubois, Stanislas et al

Textual, factual or bibliographical database (2020)

The use of stable isotopes as ecological tracers in deep-sea ecosystems has a long history, dating back to the late 1970’s. Stable isotopes have been instrumental to many key-findings about ecosystem ... [more ▼]

The use of stable isotopes as ecological tracers in deep-sea ecosystems has a long history, dating back to the late 1970’s. Stable isotopes have been instrumental to many key-findings about ecosystem functioning, particularly in chemosynthesis-based habitats (hydrothermal vents, cold seeps). However, constraining sampling logistics commonly limit the scope, extent, and therefore insights drawn from isotope-based deep-sea studies. Overall, much is left to discover about factors globally influencing food web structure in deep-sea ecosystems. In this context, deep-sea ecologists have to ensure that no sample is left unexploited, and that all generated data are easily discoverable, available and reusable. DeepIso is a collaborative effort to produce a global compilation of stable isotope ratios and elemental contents in organisms from deep-sea ecosystems. In doing so, it aims to provide the deep-sea community with an open data analysis tool that can be used in the context of future ecological research, and to help deep-sea researchers to use stable isotope markers at their full efficiency. More info about the project can be found at https://loicnmichel.com/deepiso/ As of v1 (2020/10/22), the database contains 15 distinct datasets, for a total of 18677 fully documented measurements. Archived parameters currently include δ13C (n = 4587), δ15N (n = 4388), δ34S (n = 951), %C (n = 2740), %N (n = 2741), %S (n = 752) and C/N ratio (n = 2518). Those measurements pertain to 4378 distinct samples belonging to 493 taxa, plus sediments, suspended particulate organic matter, plankton and detritus. Samples were taken between 1989 and 2018 in multiple environments (hydrothermal vents, cold seeps, cold water coral reefs, and other benthic or pelagic environments) and at depths ranging up to 5209 meters. The database consists of three files: one containing the data itself, one describing all used terms (measurements or metadata, derived from Darwin Core standards, https://dwc.tdwg.org/terms/), and a changelog detailing changes made between successive versions. [less ▲]

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See detailIntegrative taxonomy revisits the ontogeny and trophic niches of Rimicaris vent shrimps.
Methou, Pierre; Michel, Loïc ULiege; Segonzac, Michel et al

Conference (2020, August)

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See detailClassical and 3D anatomy and tissue-specific microbial associations in chemosymbiotic Alviniconcha gastropods from the Southwest Pacific
Laming, Sven; Hourdez, Stéphane; Michel, Loïc ULiege et al

Conference (2020, August)

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See detailHigh environmental stress and productivity increase functional diversity along a deep-sea hydrothermal vent gradient.
Alfaro-Lucas, J. M.; Pradillon, F.; Zeppilli, D. et al

Conference (2020, August)

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See detailIntegrative taxonomy revisits the ontogeny and trophic niches of Rimicaris vent shrimps
Methou, Pierre; Michel, Loïc ULiege; Segonzac, Michel et al

in Royal Society Open Science (2020), 7(7), 200837

Among hydrothermal vent species, Rimicaris exoculata is one of the most emblematic, hosting abundant and diverse ectosymbioses that provide most of its nutrition. Rimicaris exoculata co-occurs in dense ... [more ▼]

Among hydrothermal vent species, Rimicaris exoculata is one of the most emblematic, hosting abundant and diverse ectosymbioses that provide most of its nutrition. Rimicaris exoculata co-occurs in dense aggregates with the much less abundant Rimicaris chacei in many Mid-Atlantic Ridge vent fields. This second shrimp also houses ectosymbiotic microorganisms but has a mixotrophic diet. Recent observations have suggested potential misidentifications between these species at their juvenile stages, which could have led to misinterpretations of their early-life ecology. Here, we confirm erroneous identification of the earliest stages and propose a new set of morphological characters unambiguously identifying juveniles of each species. On the basis of this reassessment, combined use of C, N and S stable isotope ratios reveals distinct ontogenic trophic niche shifts in both species, from photosynthesis-based nutrition before settlement, towards a chemosynthetic diet afterwards. Furthermore, isotopic compositions in the earliest juvenile stages suggest differences in larval histories. Each species thus exhibits specific early-life strategies that would, without our re-examination, have been interpreted as ontogenetic variations. Overall, our results provide a good illustration of the identification issues persisting in deep-sea ecosystems and the importance of integrative taxonomy in providing an accurate view of fundamental aspects of the biology and ecology of species inhabiting these environments. [less ▲]

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See detailEffects of preservation methodology on stable isotope compositions of sea stars
Le Bourg, Baptiste ULiege; Lepoint, Gilles ULiege; Michel, Loïc ULiege

in Rapid Communications in Mass Spectrometry (2020), 34(2), 8589

Rationale:Stable isotope analysis is used to investigate the trophic ecology of organisms and, in order to use samples from archived collections, and it is important to know whether preservation methods ... [more ▼]

Rationale:Stable isotope analysis is used to investigate the trophic ecology of organisms and, in order to use samples from archived collections, and it is important to know whether preservation methods alter the results. This study investigates the long-term effects of four preservation methods on sea stars isotopic composition and isotopic niche parameters.Methods:We assessed effects of preservation method (freezing, drying, formaldehyde, ethanol) and duration (0, 1, 3, 6, 9, 12 and 24 months) on the stable isotope ratios of carbon, nitrogen and sulfur of sea star tissues. Isotopic ratios were measured using CF-EA-IRMS. We also monitored the evolution ofcommonly used ecological metrics (isotopic niche parameters) throughout the experiment. Results:Clear changes of δ13C values were observed for samples stored in formaldehyde and ethanol. None of the preservation methods had significant or consistent effects on δ15Nvalues. Formaldehydeinduced a decrease of δ34S values. All these changes could be mitigated using correction factors.Isotopic niches parameters slightly changed over time when computed with δ13C and δ15N values, but inconsistent variations occurred when computed with δ13C and δ34S values.Conclusions: Overall, these results show that preservation may affect the stable isotope ratios of sea stars. Correction factors can be used to mitigate the effects of the preservation method on stable isotope ratios. Isotopic niches parameters are overall unchanged. Consequently, in most cases, museum samples are suitable to calculate isotopic niche parameters. [less ▲]

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