Using CPR surveys to map distributions of trophically important subantarctic prey species

The Southern Ocean Continuous Plankton Recorder (SO-CPR) program represents a 30+ years long dataset that can be used to map the distribution of Southern Ocean zooplankton. For the needs of this project, namely the ecoregionalisation of ‘High Seas’ regions of the subantarctic to complement protected regions under national jurisdictions (MPAs), we have focussed on links between zooplankton prey and marine predators. The prey species that feature strongly in the diets of one or two predators, and those which are commonly found in many predator diets are an important focus for the mapping component of this project. Understanding the preyfields of marine predators will enhance our decision-making about which areas to prioritise for protection and management. Here we have mapped some examples of zooplankton that are commonly found in subantarctic waters, and which have been reported as prey items in the literature. These prey species share attributes of being energy dense, as a function of their lipid stores, large (> 5 mm) and in some cases the formation of swarms in surface waters. From here we will (1) combine the SO-CPR data with Australian CPR data to increase the latitudinal extent of distributions to 30oS, (2) combine CPR data with results from net tows to increase longitudinal range (though only as presence/absence) and (3) apply Ecological Niche Models to describe the habitat requirements of key prey species.