References of "Michel, Loïc"
     in
Bookmark and Share    
Full Text
See detailFrom seascape level to functional ecology: A case study over P. oceanica seagrass meadows in Calvi, Corsica
Lapeyra Martin, Jon ULg; Abadie, Arnaud; Richir, Jonathan ULg et al

in Actes du colloque Carhamb'ar 2017 (in press)

see long abstract

Detailed reference viewed: 51 (14 ULg)
Full Text
See detailIncreased sea ice cover disrupts food web structure in Antarctic coastal benthic ecosystem
Michel, Loïc ULg; Danis, Bruno; Dubois, Philippe et al

Conference (2017, July 10)

Antarctica currently undergoes strong and contrasted impacts linked to climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice ... [more ▼]

Antarctica currently undergoes strong and contrasted impacts linked to climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase. Here, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using time-tested integrative trophic markers (stable isotope ratios of carbon, nitrogen and sulfur) and state-of-the-art data analysis tools (Bayesian ecological models), we studied the structure of the food web associated to benthic macroinvertebrates communities. In total, 28 taxa spanning most present animal groups (sponges, sea anemones, nemerteans, nematods, sipunculids, sessile and mobile polychaetes, gastropods, bivalves, pycnogonids, crustaceans, sea stars, sea urchins, brittle stars and sea cucumbers) and functional guilds (grazers, deposit feeders, filter feeders, predators, scavengers) were investigated. Our results indicate that the absence of seasonal sea ice breakup deeply influences coastal benthic food webs. We recorded marked differences from literature data, both in terms of horizontal (i.e. primary producers and resources supporting animal populations) and vertical (i.e. trophic level of the studied consumers) structure of the food web. Overall, sympagic algae dominated the diet of many key consumers, and the trophic levels of invertebrates were low, suggesting omnivore consumers relied less on predation and/or scavenging than in normal environmental conditions. Surprisingly, few animals seemed to feed on the extremely abundant benthic biofilm, whose exceptional development was also presumably linked with the peculiar sea ice conditions. Comparison of data obtained in the austral summers of 2013-2014 (first year without seasonal breakup) and 2014-2015 (second year without seasonal breakup) clearly showed that the observed trends were linked to actual temporal changes in invertebrate feeding habits rather than with other potential ecological drivers. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden changes in environmental conditions and trophic resource availability. They also show that local and/or global trends of sea ice increase in Antarctica have the potential to cause drastic changes in food web structure and therefore impact benthic communities. This research was funded by the Belgian Federal Science Policy Office (BELSPO) in the framework of the vERSO project (http://www.versoproject.be). [less ▲]

Detailed reference viewed: 66 (7 ULg)
Full Text
See detailStable isotopes reveal effects of environmental changes on ecological niches of Iphimediidae amphipods
Michel, Loïc ULg; d'Udekem d'Acoz, Cédric; Frederich, Bruno ULg et al

Poster (2017, July)

When faced with environmental changes, organisms are expected to have some intrinsic ability to adapt through ecological plasticity. However, this process is still poorly understood in many Antarctic ... [more ▼]

When faced with environmental changes, organisms are expected to have some intrinsic ability to adapt through ecological plasticity. However, this process is still poorly understood in many Antarctic invertebrates. Here, we focused on Iphimediidae amphipods, as this widely distributed family shows important ecological diversity. In total, 248 amphipods (19 species) from two widely different zones (the West Antarctic Peninsula, or WAP, and Adélie Land, AL) were studied to elucidate how environment can influence ecological niche parameters. Ecological niches were explored using stable isotope ratios of carbon and nitrogen and the SIBER approach (Jackson et al., 2011). The isotopic niche of the whole amphipod assemblage was wider in WAP than in AL. This was true for both total (proxy of the whole range of resources exploited by animals) and the core (proxy of the most commonly used resources) isotopic niches. The ratio between total and core isotopic niches was smaller in WAP than in AL (4.13 vs. 5.74), suggesting that in WAP, animals commonly use a greater relative percentage of the resources to which they have access. Niche modelling at the specific level revealed that this trend was not found in all taxa. For example, niches of Gnathiphimedia sexdentata and Iphimediella microdentata were bigger in WAP than in AL, following the general pattern. On the other hand, niches of Echiniphimedia echinata and E. hodgsoni had the same width in both areas. Moreover, relative niche overlap between these two species was much higher in WAP (42%) than in AL (20%). Our results indicate that the widely different environmental conditions encountered by the animals in these two zones clearly influence their ecology. Overall, Iphimediidae amphipods tend to exploit more resources in WAP, i.e. in the zone where impacts of global change (temperature increase, sea ice cover decrease) are the strongest. Niche overlap between some closely related (i.e. congeneric) species was also more important in WAP. Ultimately, environmental changes in this region might reinforce these trends, which might lead to competition and perturb amphipod community structure. This research was funded by the Belgian Federal Science Policy Office (BELSPO) in the framework of the vERSO and RECTO projects. [less ▲]

Detailed reference viewed: 53 (7 ULg)
Full Text
Peer Reviewed
See detailComparative Feeding Ecology of Cardinalfishes (Apogonidae) at Toliara Reef, Madagascar
Frederich, Bruno ULg; Michel, Loïc ULg; Zaeytydt, Esther et al

in Zoological Studies (2017), 56(10), 1-14

Despite their importance in coral reef ecosystem function and trophodynamics, the trophic ecology of nocturnal fishes (e.g. Apogonidae, Holocentridae, Pempheridae) is by far less studied than diurnal ones ... [more ▼]

Despite their importance in coral reef ecosystem function and trophodynamics, the trophic ecology of nocturnal fishes (e.g. Apogonidae, Holocentridae, Pempheridae) is by far less studied than diurnal ones. The Apogonidae (cardinalfishes) include mostly carnivorous species and evidence of trophic niche partitioning among sympatric cardinalfishes is still limited. The present study combines stomach contents and stable isotope analyses to investigate the feeding ecology of an assemblage of eight cardinalfishes from the Great Reef of Toliara (SW Madagascar). δ13C and δ15N of fishes ranged between -17.49‰ and -10.03‰ and between 6.28‰ and 10.74‰, respectively. Both stomach contents and stable isotopes showed that they feed on planktonic and benthic animal prey in various proportions. Previous studies were able to group apogonids in different trophic categories but such a discrimination is not obvious here. Large intra-specific variation in the stomach contents and temporal variation in the relative contribution of prey to diet support that all apogonids should be considered as generalist, carnivorous fishes. However the exploration of the isotopic space revealed a clear segregation of isotopic niches among species, suggesting a high level of resource partitioning within the assemblage. According to low inter-specific variation in stomach content compositions, we argue that the differences in isotopic niches could be driven by variation in foraging locations (i.e. microhabitat segregation) and physiology among species. Our temporal datasets demonstrate that the trophic niche partitioning among cardinalfishes and the breadth of their isotopic niches are dynamic and change across time. Factors driving this temporal variation need to be investigated in further studies. [less ▲]

Detailed reference viewed: 70 (4 ULg)
Full Text
See detailUnusually high sea ice cover influences resource use by benthic invertebrates in coastal Antarctica
Michel, Loïc ULg; Dubois, Philippe; Eleaume, Marc et al

Conference (2017, May 04)

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice ... [more ▼]

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Changes in sea ice cover are likely to influence benthic food web structure through modifications of benthic-pelagic coupling, disruption of benthic production and/or modifications of benthic community structure (i.e. resource availability for benthic consumers). Here, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using stable isotope ratios of C and N and the SIAR mixing model, we examined importance of 4 organic matter sources (benthic macroalgae, benthic biofilm, sympagic algae, suspended particulate organic matter) for nutrition of dominant primary consumers and omnivores. 14 invertebrate taxa including sessile and mobile polychaetes, gastropods, bivalves, sea stars, sea urchins and sea cucumbers were studied. Our results indicate that most benthic invertebrates predominantly relied on sympagic algae. Despite its very high abundance, trophic role of benthic biofilm seemed limited. However, interpretation of data was complicated by the peculiar ecophysiological features of Antarctic invertebrates, whose very low metabolic rates could be associated to low isotopic turnover and long time to reach isotopic equilibrium with their food items. Resource use by consumers from Adélie Land markedly differed from literature data about invertebrate diet in coastal Antarctica, suggesting 1) important influence of increased sea ice cover on benthic food web structure and 2) high spatial and/or temporal variation in the feeding habits of studied organisms, likely linked with a high degree of trophic plasticity. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden man-driven changes in environmental conditions and trophic resource availability. [less ▲]

Detailed reference viewed: 95 (12 ULg)
Full Text
Peer Reviewed
See detailIsotopic half-life and enrichment factor in two species of European freshwater fish larvae: an experimental approach
Latli, Adrien; Sturaro, Nicolas ULg; Dujardin, Nelson et al

in Rapid Communications in Mass Spectrometry (2017), 31(8), 685-692

RATIONALE: Stable isotope ratios of carbon and nitrogen are valuable tools for field ecologists to use to analyse animal diets. However, the application of these tools requires knowledge of the tissue ... [more ▼]

RATIONALE: Stable isotope ratios of carbon and nitrogen are valuable tools for field ecologists to use to analyse animal diets. However, the application of these tools requires knowledge of the tissue enrichment factor (TEF) and half-life (HL). We experimentally compared TEF and HL in two freshwater fish larvae. We hypothesised that chub had a better growth/tissue replacement ratio than roach, due to the use of a food closer to their natural diet. METHODS: We determined the isotopic HL, the TEF and the contribution of growth or metabolic tissue replacement to dynamic isotopic incorporation. After yolk sac resorption, larvae were fed for 5 weeks with prey similar to their natural diet (Artemia nauplii) up to the isotopic equilibrium followed by Chironomid larvae. Stable isotope measurements were carried out using a continuous flow isotope ratio mass spectrometer coupled to an elemental analyser. RESULTS: Changes in isotopic composition strongly followed the predictions of exponential growth and time-dependent models. The isotopic HL varied between 8.2 and 12.6 days and the TEF of nitrogen and carbon ranged from 1.7 to 2.1‰ and from –0.9 to 1.2 ‰, respectively. The incorporation of dietary 13C was due more to the production of new tissue (between 56 and 79%) than to the metabolic process. Chub allocated more energy to growth than roach and the Chironomidae diet contributed more to the consumers’ growth than the Artemia diet. CONCLUSIONS: Metabolic rates seemed lower for chub than for roach, especially when they were fed with Chironomidae. A Chironomidae-based diet would be more profitable to chub, and the high associated growth rate could increase the development of the fish larvae. The HL and TEF were in the range of those reported in the literature. These results will be helpful for field-based studies, because they can help to increase the accuracy of models. [less ▲]

Detailed reference viewed: 43 (8 ULg)
Full Text
See detailIncreased sea ice cover disrupts food web structure in coastal Antarctica
Michel, Loïc ULg; Dubois, Philippe; Eleaume, Marc et al

Conference (2017, March 03)

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice ... [more ▼]

Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Sea ice is a major environmental driver in Antarctica, and changes in sea ice cover are likely to influence benthic food web structure through several processes (modifications of benthic-pelagic coupling, disruption of benthic production and/or modifications of benthic community structure and therefore resource availability for benthic consumers). To date, regions where sea ice cover is decreasing have received more attention than regions where it is increasing. Here, on the other hand, we studied shallow (0-20 m) benthic food web structure on the coasts of Petrels Island (Adélie Land, East Antarctica) during an event of unusually high spatial and temporal (two successive austral summers without seasonal break-up) sea ice cover. Using time-tested integrative trophic markers (stable isotope ratios of carbon, nitrogen and sulfur) and state-of-the-art data analysis tools (bayesian ecological models), we studied the structure of the food web associated to benthic macroinvertebrates communities. In total, 28 macroinvertebrate taxa spanning most present animal groups (sponges, sea anemones, nemerteans, nematods, sipunculids, sessile and mobile polychaetes, gastropods, bivalves, pycnogonids, crustaceans, sea stars, sea urchins, brittle stars and sea cucumbers) and functional guilds (grazers, deposit feeders, filter feeders, predators, scavengers) were investigated. Our results indicate that the absence of seasonal sea ice breakup deeply influences coastal benthic food webs in Antarctica. We recorded marked differences from literature data, both in terms of horizontal (i.e. primary producers and resources supporting animal populations) and vertical (i.e. trophic level of the studied consumers) structure of the food web. Overall, sympagic (sea-ice associated) algae dominated the diet of many important consumers, and the trophic levels of invertebrates were low, suggesting omnivore consumers relied less on predation and/or scavenging than in normal environmental conditions. Surprisingly, few animals seemed to feed on the extremely abundant benthic biofilm, whose exceptional development was also presumably linked with the peculiar sea ice conditions. Interpretation of data was complicated by the peculiar ecophysiological features of Antarctic invertebrates, whose very low metabolic rates could be associated to low tissue turnover. However, comparison of data obtained in the austral summers of 2013-2014 (first year without seasonal breakup) and 2014-2015 (second year without seasonal breakup) clearly showed that the observed trends were linked with actual temporal changes in invertebrate feeding habits rather than with other potential ecological drivers. Our results provide insights about how Antarctic benthic consumers, which have evolved in an extremely stable environment, might adapt their feeding habits in response to sudden man-driven changes in environmental conditions and trophic resource availability. They also show that local and/or global trends of sea ice increase in Antarctica could cause strong changes in food web structure and therefore impact zoobenthic communities. This reinforces the view that, no matter their overall direction (i.e. increase or decrease), fluctuations in sea ice cover are likely to influence Antarctic benthic ecosystems' structure and functioning. [less ▲]

Detailed reference viewed: 133 (12 ULg)
Full Text
Peer Reviewed
See detailCarbon, Nitrogen and Sulphur isotopic fractionation in captive juvenile hooded seal (Cystophora cristata): application for diet analysis
Pinzone, Marianna ULg; Acquarone, Mario; Huyghebaert, Loreen ULg et al

in Rapid Communications in Mass Spectrometry (2017)

Rationale: Intrinsic biogeochemical markers, such as stable isotope ratios of carbon, nitrogen and sulphur are increasingly used to trace the trophic ecology of marine top predators. However, insufficient ... [more ▼]

Rationale: Intrinsic biogeochemical markers, such as stable isotope ratios of carbon, nitrogen and sulphur are increasingly used to trace the trophic ecology of marine top predators. However, insufficient knowledge of fractionation processes in tissues continues to hamper the use of these markers.Methods: We performed a controlled feeding experiment with eight juvenile hooded seals (Cystophora cristata) that were held on a herring-based diet (Clupea harengus) for two years. Stable isotope ratios were measured via isotope ratio mass spectrometry in three of their tissues and related to values of these markers in their diet. Results: Diet-tissue isotope enrichment (trophic enrichment factor, TEF) values between dietary herring and seal tissues for carbon (Δ13C) were + 0.7 ‰ for red blood cells, + 1.9 ‰ for hair and + 1.1 ‰ for muscle. The TEFs for nitrogen trophic (Δ15N) were + 3.3 ‰ for red blood cells, + 3.6 ‰ for hair and + 4.3 ‰ for muscle. For sulphur, the Δ34S values were +1.1 ‰ for red blood cells, + 1.0 ‰ for hair and + 0.9 ‰ for muscle.Conclusions: These enrichment values were greater than those previously measured in adult seals. This increase may be related to the higher rate of protein synthesis and catabolism in growing animals. This study is the first report on sulphur isotope enrichment values for a marine mammal species. [less ▲]

Detailed reference viewed: 24 (1 ULg)
Full Text
Peer Reviewed
See detailIsotopic niches of Fin Whales from the Mediterranean Sea and the Celtic sea (North Atlantic)
Das, Krishna ULg; Holleville, Ophélie; Ryan, Conor et al

in Marine Environmental Research (2017), 127

The fin whale (Balaenoptera physalus) is the most abundant and widespread mysticete species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the ... [more ▼]

The fin whale (Balaenoptera physalus) is the most abundant and widespread mysticete species in the Mediterranean Sea, found mostly over deep, offshore waters of the western and central portion of the region. In the Mediterranean, this species is known to feed mainly on krill, in contrast to its Atlantic counterpart, which displays a more diversified diet. The International Whaling Commission recognizes several managements units in the Atlantic and the Mediterranean Sea and the connectivity between these populations is still being debated. Questions remain about inter-individual feeding strategies and trophic ecology. The goal of this study was to compare isotopic niches of fin whales from the Mediterranean Sea and the Celtic Sea (North Atlantic). δ13C and δ15N values were analysed in 136 skin biopsies from free-ranging Mediterranean fin whales sampled in 2010 and 2011 during campaigns at sea. δ13C and δ15N values ranged from -20.4 to -17.1 ‰ and from 5.9 to 8.9 ‰, respectively. These values are in good agreement with those estimated previously from baleen plates from Mediterranean and North Atlantic fin whales. The narrow isotopic niche width of the Mediterranean fin whale (Standard Ellipses area SEAc) compared to the North Atlantic fin whale raises many concerns in the context of global changes and long-term consequences. One could indeed expect that species displaying narrow niches would be more susceptible to ecosystem fragmentation and other anthropogenic impacts. [less ▲]

Detailed reference viewed: 50 (14 ULg)
Full Text
See detailTrophic ecology of Southern Ocean sea stars inferred from stable isotopes ratios of C and N
Le Bourg, Baptiste ULg; Blanchard, Alice; Danis, Bruno et al

Conference (2016, December 17)

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely ... [more ▼]

The Southern Ocean undergoes strong and contrasted impacts of climate change. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely impact food web structure and function. Sea stars (Echinoderms: Asteroidea) are an important group of the Southern Ocean benthos. They typically have highly variable feeding habits and are potentially more resistant than other organisms to temperature changes. Consequently, they will likely be impacted by modifications of the food web rather than by direct warming. Investigating their trophic ecology is therefore necessary to infer how climate change will impact them. In this context, the aim of this study was to use stable isotopes ratios of C, N and S to infer sea stars trophic ecology. During austral summers 2006 and 2009, sea stars were sampled in Subantarctic and Antarctic locations, with most of the samples coming from South Shetland Islands and South Georgia. The isotopic niche (proxy of the trophic niche) associated to each sea star population was explored through SIBER (Stable Isotope Bayesian Ellipses in R) metrics. Stable isotope ratios of sea stars were clearly different between South Shetland Islands and South Georgia. Sea stars of South Shetland Islands had smaller isotopic niches than sea stars of South Georgia. The overlap between the isotopic niches of sea star species was also important in South Shetland Islands, while isotopic niches of South Georgia were well separated. Difference of niche width and overlap between the two regions may be the result of different environmental conditions. In South Shetland Islands, sea star species may exploit a common benthic community relying on organic matter released during sea ice summer melting. In contrast, South Georgia is an oligotrophic environment with no sea ice. As resources are more limited, a higher trophic segregation between sea stars may appear to limit competition. Ultimately, this project highlighted the importance of sea ice in the trophic ecology of Antarctic sea stars. Our results suggest that future reduction of sea ice extent in Western Antarctica may have deleterious effect on sea star populations. [less ▲]

Detailed reference viewed: 76 (5 ULg)
Full Text
See detailWho would want to live in there? A history of Posidonia oceanica detritus accumulations, the associated invertebrate community, and its food web…
Remy, François ULg; Michel, Loïc ULg; Darchambeau, François ULg et al

Conference (2016, December 16)

Most seagrasses are rarely consumed directly by herbivore organisms. The "detrital pathway" thus represents a potentially important way of transfer of the seagrasses production to the coastal food webs ... [more ▼]

Most seagrasses are rarely consumed directly by herbivore organisms. The "detrital pathway" thus represents a potentially important way of transfer of the seagrasses production to the coastal food webs. The case of Posidonia oceanica is particularly interesting since up to 90% of its foliar primary production may constitute extensive and highly dynamic exported litter accumulations. Preliminary studies concerning these detritus accumulations suggest that an abundant community of vagile macro invertebrates (size > 500μm) lives inside them. We characterized for the first time this community in an exhaustive way (multi-site, seasonal and multi-year study), we linked the observed density and diversity variations to environmental parameters, but also described the trophic web these invertebrates compose. We sampled an abundant (up to 5000 organisms/m²) community composed of 115 species. We showed that crustaceans were massively dominant, followed by annelids and mollusks, and that one single amphipod species Gammarella fucicola represented from 20 to 85% of the whole sampled community. Observed variations appeared to be mostly linked to litter oxygen water concentration in a very species specific way. Most species were linked to no measured environmental parameter at all, but several dominant species were demonstrated (observation and in situ experimentation) to be linked positively or negatively to litter oxygen concentration. The described food web was composed of more than 3 trophic levels, indicating the presence of a trophic web composed of primary consumers/detritivore species, of omnivore species, but also of first and second order predators, each level occupying a distinct isotopic niche. From a specific point of view, we highlighted several different feeding preferences, with SIAR mixing model runs indicating that some species feed mostly on detrital material, other species feed on a mixture of detrital and algal material, other species feed on both animal and vegetal material and finally predator species feed exclusively on animal material. The fact that P. oceanica detritus constituted a non-negligible food source for some dominant species confirmed the importance of this macrofauna community as a key transfer link of seagrass organic matter from P. oceanica to the coastal food webs. [less ▲]

Detailed reference viewed: 57 (9 ULg)
Full Text
See detailExploitation of coastal fish communities by harbour porpoises Phocoena phocoena during nursing periods in German Baltic waters.
Pinzone, Marianna ULg; Michel, Loïc ULg; Gallus, Anja et al

Conference (2016, December 11)

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for ... [more ▼]

Baltic sub-populations of harbour porpoises Phocoena phocoena meet in in Southwestern waters in Spring when females reach the coastal areas for calving and nursing. In Autumn they separate again for reproduction : the Belt sea populations westwards in the Kattegat/Skarregat region, the Baltic proper population northwards in the central basin. The increased number of juvenile and newborn strandings along the German Baltic coasts give evidence for a possible existence of local calving grounds in this area. Calving and nursing habitats are the most important areas for management purposes. This project aimed to describe inhabitancy and diet of females and calves along the German Baltic coast, in order to achieve effective conservation measures. Nitrogen, carbon and, for the first time, sulphur stable isotopes (δ13C, δ15N and δ34S) were analysed in coastal species of fish and invertebrates in spring, autumn and winter 2015/2016 and in four different areas, to assess for seasonal and geographical variation of porpoises habitat use. The structure of ecological niches was inferred within and between communities using the SIBER model, and was compared to results from stomach content analysis. N, C and S values of fish and invertebrates strongly varied, seasonally and geographically, as a consequence of environmental factors characteristic of each sampling area. Additionally, each species presented large isotopic variability, suggesting possible intraspecific dietary specialisations. Females δ13C and δ34S signatures integrated both open-waters and coastal feeding, while juveniles presented a more coastal distribution. The absence of difference in δ15N values between age classes confirmed persistence of milk assimilation from the mothers. Niches structures and overlaps and stomach content analysis suggested gobies (Potamoschistus spp and Neogobius spp in particular), crabs and small coastal fish (ex. three-spined stickleback) as the main preys of juveniles. The integration of all three stable isotopes together permitted to well delineate even the highly dynamic food web of the Baltic German waters, confirming the use of sulphur isotopes in marine ecological studies. [less ▲]

Detailed reference viewed: 66 (21 ULg)
Full Text
See detailAssessing edge-effects in Posidonia oceanica seagrass meadows: A multidisciplinary approach
Lapeyra, Jon; Abadie, Arnaud; Lejeune, Pierre et al

Conference (2016, December)

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is ... [more ▼]

Structural boundaries in ecosystems play an important role both in the context of seascape architecture, ecological processes and biodiversity. The Mediterranean Seagrass Posidonia oceanica (L.) Delile is considered an ecosystem engineer species, forming habitats of great ecological value and providing many ecosystem services. This study aims to (1) determine whether there are differences between seagrass-sand corridors edges and the adjacent continuous meadow, and (2) investigate whether anthropogenic pressures can cause disturbances in the measured parameters along the edges and the meadow. We have developed a multidisciplinary approach combining plant physiology, faunal canopy community studies and seagrass structural parameters characterization. We performed in situ chlorophyll fluorescence measurements using a Pulse Amplitude Modulated (Diving-PAM) fluorometry in order to assess the photosynthetic rate of the shoots. Vagile macrofauna of the leaf stratum was sampled by a hand-towed net, and the major taxonomic groups were sorted, counted, and identified. Meadow’s biometric measurements and the epiphytic biomass were also determined. Regarding edge-meadow matrix, results have shown highest differences on matrix structural parameters such as shoot density and shoot type proportions. Shoot density was found to decrease in edges considerably. We found c.a to 60 % plagiotropic shoots on edges while in continuous meadow orthotropics were predominant (up to 90 %). Howerver vagile-fauna population densities and diversity did not differ significantly among stations studied, neither by sites. Photosynthetic rate and leaf surface values also did not show changes between edges and continuous meadow. However, results did show that plagiotropic shoots had higher photosynthetic rate than orthotropics, and also that epiphyte abundance sorted out to be much higher (up to 54 %) on edges. [less ▲]

Detailed reference viewed: 97 (23 ULg)
Full Text
Peer Reviewed
See detailSediment carbon sink in low-density temperate eelgrass meadows (Baltic Sea)
Jankowska, Emilia; Michel, Loïc ULg; Zaborska, Agata et al

in Journal of Geophysical Research. Biogeosciences (2016), 121(12), 2918-2934

Seagrass meadows are highly productive habitats that can act as “blue carbon sinks” in coastal ecosystems by facilitating sedimentation and trapping particles. However, the magnitude and occurrence of ... [more ▼]

Seagrass meadows are highly productive habitats that can act as “blue carbon sinks” in coastal ecosystems by facilitating sedimentation and trapping particles. However, the magnitude and occurrence of these effects may be species and density dependent. The present study is the first estimation of seagrass sediment carbon sink in the temperate Zostera marina beds in the Baltic Sea. Several descriptors of organic matter characteristics, along with possible organic matter sources in the sediment were compared at vegetated and unvegetated bottoms. The 210Pb dating of the sediment has been used for accumulation rate assessment. The photopigments and POC concentrations in sediments were higher in vegetated bottoms. The SIAR (Stable Isotopes in R) mixing model based on nitrogen and carbon stable isotope values, indicated that higher percentages of organic matter originated from seagrass production in vegetated sediments (40–45%) compared to unvegetated ones (5–21%). The carbon stock in the upper 10 cm of the vegetated sediments ranged from 50.2 ± 2.2 to 228.0 ± 11.6 (g m−2), whereas the annual C accumulation amount from 0.84 ± 0.2 to 3.85 ± 1.2 (g m−2 yr−1). Our study shows that even the relatively weakly developed vegetation of the small temperate seagrass species enhance organic carbon concentration in the sediments. Estimated carbon stock was much lower than those reported for most of the seagrass meadows elsewhere, and the carbon burial rate was the lowest ever reported. Evidently, the global calculations of sediment carbon stock should be reconsidered by taking into account density and species-related variability. [less ▲]

Detailed reference viewed: 37 (3 ULg)
Full Text
Peer Reviewed
See detailDiversity, dynamics and trophic ecology of animal communities associated to Posidonia oceanica (L.) Delile macrophytodetrital accumulation: synthesis of a ten year study
Lepoint, Gilles ULg; Borges, Alberto ULg; Champenois, Willy ULg et al

Poster (2016, October 17)

In the Mediterranean, Neptune grass Posidonia oceanica, produces a huge quantity of detrital biomass. These macrophytodetritus may accumulate in shallow waters, forming litter accumulations colonised by ... [more ▼]

In the Mediterranean, Neptune grass Posidonia oceanica, produces a huge quantity of detrital biomass. These macrophytodetritus may accumulate in shallow waters, forming litter accumulations colonised by abundant, yet understudied, animal communities. These accumulations are especially foraged by juvenile and adult fishes. Here, we aim to synthesize results obtained over the last ten years regarding diversity, dynamics and trophic ecology of associated meio- and macrofauna. Accumulations are found throughout the year but important seasonal and short-term variability in composition, quantity and physico-chemical parameters inside the accumulation is observed. Accumulations are dominated by respiration (litter degradation), however, primary production occurs at exposed surfaces (epiphytic production). Meio- and macrofauna have distinct traits in comparison to adjacent habitats (seagrass meadows or epilithic algae communities). A physico-chemical gradient occurs inside accumulations which partially defines assemblage composition and distribution. Meiofauna, in particular harpacticoid copepods, is diverse, abundant and composed of species from seagrass meadows, water column and sediment. In contrast, macrofaunal assemblages are simplified compared to the ones occurring in the seagrass meadows and are dominated by amphipods. Litter accumulations display a lower macrofaunal diversity than do seagrass meadows, but a higher abundance and animal biomass. Meio- and macrofauna show a high trophic diversity, dominated by ingestion and assimilation of epiphytes (macroalgae and, probably, detrivorous microbiota). Moreover, direct or indirect assimilation of carbon originating from seagrass detritus is demonstrated for many species. Although diverse trophic niches were observed, the assemblage showed a simplified trophic web structure compared to the seagrass meadows. Detritivorous organisms dominate this assemblage and are more abundant in the litter than in the living meadows. Consequently, according to its abundance and the fact it consumes directly and indirectly seagrass material, fauna associated to litter accumulation may play a significant role in the degradation and transfer to higher trophic level of detrital seagrass carbon. [less ▲]

Detailed reference viewed: 111 (3 ULg)
Full Text
Peer Reviewed
See detailAxIOM: Amphipod crustaceans from insular Posidonia oceanica seagrass meadows
Michel, Loïc ULg; Sturaro, Nicolas ULg; Heughebaert, André et al

in Biodiversity Data Journal (2016), 4

Background The Neptune grass, Posidonia oceanica (L.) Delile, 1813, is the most widespread seagrass of the Mediterranean Sea. This foundation species forms large meadows that, through habitat and trophic ... [more ▼]

Background The Neptune grass, Posidonia oceanica (L.) Delile, 1813, is the most widespread seagrass of the Mediterranean Sea. This foundation species forms large meadows that, through habitat and trophic services, act as biodiversity hotspots. In Neptune grass meadows, amphipod crustaceans are one of the dominant groups of vagile invertebrates, forming an abundant and diverse taxocenosis. They are key ecological components of the complex, pivotal, yet critically endangered Neptune grass ecosystems. Nevertheless, comprehensive qualitative and quantitative data about amphipod fauna found in Mediterranean Neptune grass meadows remain scarce, especially in insular locations. New information Here, we provide in-depth metadata about AxIOM, a sample-based dataset published on the GBIF portal. AxIOM is based on an extensive and spatially hierarchized sampling design with multiple years, seasons, day periods, and methods. Samples were taken along the coasts of Calvi Bay (Corsica, France) and of the Tavolara-Punta Coda Cavallo Marine Protected Area (Sardinia, Italy). In total, AxIOM contains 187 samples documenting occurrence (1775 records) and abundance (10720 specimens) of amphipod crustaceans belonging to 72 species spanning 29 families. The dataset is available at http://ipt.biodiversity.be/resource?r=axiom. [less ▲]

Detailed reference viewed: 26 (3 ULg)
Full Text
See detailFeeding ecology of Southern Ocean seastars inferred from stable isotopes ratios
Le Bourg, Baptiste ULg; Blanchard, Alice; Danis, Bruno et al

Poster (2016, September 05)

The Southern Ocean is currently subjected to strong and contrasted impacts of climate change. The Western Antarctic Peninsula is one of the most rapidly warming regions of the world, resulting in sea ice ... [more ▼]

The Southern Ocean is currently subjected to strong and contrasted impacts of climate change. The Western Antarctic Peninsula is one of the most rapidly warming regions of the world, resulting in sea ice cover decreases. Increasing seawater temperature and sea ice cover reduction in Western Antarctic Peninsula and associated regions will likely impact food web functioning through temperature-related changes in consumer physiology, modifications of benthic community structure (e.g. expansion of exogenous species such as predatory crabs), modifications of benthic-pelagic coupling intensity or disruption of benthic production. Asteroids (Echinoderms) are an important group of southern benthos. This group also has a great trophic variability and is potentially more resistant than other organisms to temperature changes (Peck et al. 2008). Consequently, they will be likely impacted by modifications in food webs functioning rather by direct warming and investigating their trophic ecology is necessary to infer how climate change will impact them. In this context, the aim of this study is to use stable isotopes ratios of C, N and S to infer sea stars trophic ecology. 16 species of sea stars spanning 10 different families sampled in multiple and contrasted habitats across Subantarctic (South Georgia, South Sandwich Islands, Falkland Islands) and Antarctic (South Shetland Islands, South Orkney Islands, Western Antarctic Peninsula) locations. In total, tegument samples from 213 specimens was analysed. Diversity and plasticity of asteroid diet along Southern Ocean coasts were explored through isotopic niche parametrisation (e.g. niche width and overlap between species and/or populations; Jackson et al. 2011). The data will also be used in a larger scale research project on the trophic ecology of Antarctic sea stars. This project will notably compare trophic resources supporting asteroid communities in Western Antarctic Peninsula, where sea ice cover is decreasing, and in Terre Adélie, where sea ice cover is increasing (Parkinson & Cavalieri 2012). Ultimately, this project will help understanding which ecological processes determine how an animal group copes with environmental modifications linked to climate change. [less ▲]

Detailed reference viewed: 87 (7 ULg)