Environmental drivers of sea stars feeding ecology in the Southern Ocean

• Main Authors: Le Bourg, Baptiste, Blanchard, Alice, Danis, Bruno, Jossart, Quentin, Lepoint, Gilles, Moreau, Camille, Michel, Loïc
• Format: Conference Object
• Language: English
• Published: 2019
• Subjects: sea stars; trophic ecology; stable isotopes; Southern Ocean; 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; Sea ice
• Online Access: https://orbi.uliege.be/handle/2268/235407; https://orbi.uliege.be/bitstream/2268/235407/1/polarcolloquium-BLB2019-3.pdf

The Antarctic continent and the surrounding Southern Ocean undergo strong and contrasted impacts of climate change. In the Western Antarctic Peninsula, sea ice cover and ice season duration are decreasing, presumably in relation with increased air and water temperature and northwesterly winds originating from the also warming subtropical Pacific. In contrast, despite increased air and deep water temperatures, sea ice cover and ice season duration are increasing in other Antarctic regions. This is possibly linked with ocean stratification due to freshwater inputs from the melting continental ice. These changes are likely to impact marine communities and food webs of the Southern Ocean. Sea stars (Echinoderms: Asteroidea) are an important group of the Southern Ocean benthos. Compared to other organisms, they seem to have relatively high physiological tolerance to warming. However, they could be indirectly affected by climate change, notably through quantitative and qualitative modifications of food availability. In this context, the aim of this study was to infer the trophic diversity of sea stars of the Southern Ocean to assess their potential trophic plasticity regarding food web changes. Thanks to collaborative networking and valorization of museum samples, Sea stars samples taken in summer in various regions around the Antarctic continent with different types of environment (Antarctic or Subantarctic, deep-sea or coastal, presence of sea ice or not) were obtained. Stable isotopes ratios of C (denoted δ13C) and N (denoted δ15N) were then analysed in the tegument of sea stars in order to investigate their trophic ecology. Isotopic niches metrics were also computed to assess differences of trophic diversity between regions. Variability in stable isotope ratios and isotopic niche metrics revealed strong differences in sea star feeding ecology between and within locations, possibly in relation with differences in environmental conditions, notably sea ice coverage and dynamics. For example, on the continental shelf ...