Increased sea ice cover disrupts food web structure in coastal Antarctica

• Main Authors: Michel, Loïc, Dubois, Philippe, Eleaume, Marc, Fournier, Jérôme, Gallut, Cyril, Jane, Philip, Lepoint, Gilles
• Other Authors: MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège, FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège
• Format: Conference Object
• Language: English
• Published: 2017
• Subjects: antarctica; food web; stable isotopes; benthos; invertebrates; sea ice; Life sciences; Zoology; Aquatic sciences & oceanology; Environmental sciences & ecology; Sciences du vivant; Zoologie; Sciences aquatiques & océanologie; Sciences de l’environnement & écologie; Antarc*; Antarctic; Antarctic Peninsula; Antarctica; East Antarctica; Sea ice
• Online Access: https://orbi.uliege.be/handle/2268/207557; https://orbi.uliege.be/bitstream/2268/207557/1/Michel_VLIZ.pdf

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 ...