The biogeography of ectotherm species of the Southern Ocean is partly determined by temperature as it is observed on the spatial distribution of species according to the latitudinal temperature gradient. The REPCCOAI surveys aim to (1) continue the mesozooplankton sampling with the Continuous Plankton Recorder and (2) to sample on few sampling sites macrozooplankton (mainly euphausiids) and mesopelagic fish by the mean of an Isaacs Kidd Midwater Trawl, a small pelagic trawl.

These surveys will be conducted simultaneously with the oceanographic project OISO and with THEMISTO in acoustics, which will allow us to study the spatial distribution of the pelagic diversity from the subtropical to the Antarctic zone in the Indian part of the Southern Ocean. Actual models on climate change predicts that the subtropical and subantarctic zones will shift southwards and will limit the Antarctic zone south of the Antarctic polar front. It is in these transition zones that we observe strong biogeographic and abundance gradients of plankton and mesopelagic fish, preys of numerous birds and marine mammals.

One of the objectives of these surveys will be to evaluate, by experiments, the capacity of resilience of different species or populations of krill towards the increase of temperature in the marine environment. It consists in studying resistance capabilities of an organism to a thermal shock but also to understand the physiologic mechanisms associated to it. It will help to explain the actual species distribution but also to predict how the global increase of temperature may impact species where they are but also to assume how they are capable to face it.