Trophic plasticity in Antarctic echinoderms: an adaptive trait with implications at ecosystem wide scale?

Climate change is expected to have many adverse biological effects in Antarctica, including perturbation of feeding habits and energy fluxes. Food availability and predator/prey interactions are considered major factors dictating survival of Antarctic fauna, and foraging strategies have been shown to drive population evolution in some taxa. Whenever facing environmental changes, all organisms are expected to have some intrinsic ability to adapt. At shorter than evolutionary timescales, ecological plasticity in general, and trophic plasticity (i.e. the ability to display different feeding habits according to variation in environmental conditions) in particular, could be important adaptive mechanisms. There is increasing evidence that many key Antarctic benthos members show a high degree of trophic plasticity. It could prove to be a beneficial trait, allowing those species to shift their diet and match the new environments they will face in the future. However, diet shifts may also have detrimental aspects, such as feeding on items whose quality or nature are not optimal for the consumers. Ultimately, trophic plasticity could have important consequences at wider biological organisation levels, as it could modulate secondary production by those taxa, as well as the way they interact with other taxa through trophic relationships. Assessing trophic plasticity in Antarctic zoobenthos is therefore a promising avenue to shed light on how environmental change can shape organisms’ roles in ecosystem functioning. In this talk, we will focus on how trophic tracers (stables isotope ratios of C, N and S) can help delineating feeding plasticity in selected echinoderm (sea star and sea urchin taxa) in both Antarctic and Subantarctic coastal marine ecosystems.