[en] The Southern Ocean currently undergoes major environmental modifications related to climate change. When faced with environmental changes, all organisms are expected to have some intrinsic capacity to adapt their ecological habits to their new life conditions. Currently, biological traits of many Antarctic species are still unknown and we need such information to assess their capacity to adapt to natural and anthropogenic perturbations. Notothenioidei (Perciformes), or icefishes, are endemic to the Southern Ocean and they are an important trophic component of these marine ecosystems. Here we used stable isotopes ratios of carbon (δ13C) and nitrogen (δ15N) of two well represented genera of icefishes (Trematomus and Lepidonotothen) sampled in 2002/2004 and/or in 2015/2016 to better understand their resources partitioning and the influence of environmental changes on their trophic ecology. Isotopic niches (which are a proxy of the realized ecological niches) were modeled using the SIBER (Stable Isotope Bayesian Ellipses in R) R-package. Our results revealed a great variation in isotopic compositions among icefishes, suggesting that they exploit a wide array of resources. The overlap between the isotopic niches of Trematomus and Lepidonotothen genera in 2002/2004 highlights a possible past competition for resources. Moreover, temporal evolution of niches suggests taxon-specific ecological plasticity in response to variation in environmental parameters and/or in prey availability. An increase in resources partitioning between the two genera was observed over the studied period. In the future, it would be interesting to use mixing models including isotopic composition of potential preys to identify possible changes in their trophic ecology.
Research Center/Unit :
FOCUS - Freshwater and OCeanic science Unit of reSearch - ULiège MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
