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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 ▲]

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See detailCaractérisation des habitats et communautés benthiques en baie de Calvi (Corse) : évaluation du potentiel de l’imagerie ROV.
Sirjacobs, Damien ULg; Aguera Garcia, Antonio; Pelaprat, Corinne et al

in Bajjouk, Touria; Mahier, Marie; Piel, Steven (Eds.) et al Carhambar, 2017. Cartographie des habitats marins benthiques : de l’acquisition à la restitution. Actes de colloque. Édition Ifremer‐AFB. 161 p. (2017, March 15)

La Station de Recherches Sous-Marines et Océanographiques (STARESO) contribue à l’étude des habitats et communautés benthiques depuis de nombreuses années, notamment en baie de Calvi (Corse). Une campagne ... [more ▼]

La Station de Recherches Sous-Marines et Océanographiques (STARESO) contribue à l’étude des habitats et communautés benthiques depuis de nombreuses années, notamment en baie de Calvi (Corse). Une campagne d’acquisition d’image a été réalisée en juillet 2016 à l’aide d’un robot de type VideoRay afin d’évaluer les apports potentiels de cette approche dans certains des suivis environnementaux menés en baie de Calvi. Le robot a été équipé de caméras go-pro orientées vers le bas et vers l’avant (configurations d’acquisition en mode vidéo, vidéo stéréoscopique ou photos digitales). Le potentiel de certaines de ces approches sera évalué et illustré, notamment sur base de comparaison avec des observations produites en plongée. Ces exemples se focalisent tant sur des communautés globales et des indices paysagers (indice Lima) que sur des compartiments de ces communautés (macroalgues) ou encore sur la marge inférieure des habitats remarquables que constituent les herbiers de Posidonies. [less ▲]

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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 ▲]

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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 ▲]

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See detailSCAR-MarBIN, the Antarctic marine biodiversity information network.
Danis, Bruno; Dauby, Patrick ULg

Poster (2007, April 12)

Detailed reference viewed: 24 (2 ULg)
See detailBIANZO: biodiversity of three representative groups of the Antarctic Zoobenthos: comparative structure, distribution and fucntion
De Broyer, Claude; Vanreusel, Ann; Vanhove, Sandra et al

Report (2007)

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See detailLevels and effects of PCDD/Fs and co-PCBs in sediments, mussels, and sea stars of the intertidal zone in the southern North Sea and the English Channel.
Danis, Bruno; Debacker, Virginie ULg; Trujilo Miranda, Carmen et al

in Ecotoxicology & Environmental Safety (2006), 65(2), 188-200

There is considerable concern regarding dioxin-like compounds (DLCs) in the marine environment. These ubiquitous contaminants are highly resistant to degradation, highly accumulated by marine organisms ... [more ▼]

There is considerable concern regarding dioxin-like compounds (DLCs) in the marine environment. These ubiquitous contaminants are highly resistant to degradation, highly accumulated by marine organisms, and extremely toxic. Concentrations of DLCs, including 7 polychlorodibenzo-p-dioxins, 10 polychlorodibenzofurans, and 4 coplanar polychlorinated biphenyls, were determined in sediments, mussels (Mytilus edulis), and sea stars (Asterias rubens) from five intertidal stations distributed along the Belgian coast and the English Channel. The induction of a biomarker, cytochrome P450 immunopositive protein (CYP1A IPP), was also measured in sea star pyloric caeca. Although no significant differences were found between the considered stations, DLC levels were found to be relatively high in biota, especially when the toxicity of these compounds is considered. Particular concern arises from TEQ values determined in mussels from all locations. Sea stars were found to be more discriminant between the stations. CYP1A IPP induction was found to be significantly related to DLC levels measured in sea stars and allowed significant discrimination between the considered stations. (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

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Peer Reviewed
See detailToxards a SCAR Marine Biodiversity Information Network (SCAR MarBIN)
De Broyer, Claude; Danis, Bruno; Meerhaege, Angelo et al

Poster (2004, September)

Detailed reference viewed: 16 (0 ULg)
Peer Reviewed
See detailTowards a SCAR 'Marine Biodiversity Information Network'
De Broyer, Claude; Danis, Bruno; Meerhaeghe, A et al

Poster (2004, July)

Detailed reference viewed: 8 (0 ULg)