Benthic community heterogeneity on the Eastern Antarctic continental shelf

Antarctica, one of the most rapidly changing places on the planet due to global climate change, hosts an impressive diversity of marine fauna. Previous efforts have recognized 23 ecoregions around the Antarctic. However, most of our understanding of the Southern Ocean’s benthic communities is based on more accessible regions (e.g. Antarctic Peninsula) or near established research stations. Thus, our overall understanding of habitat variability and biodiversity around the Antarctic continent is limited and boundaries of these ecoregions need further verification. To this end, in early 2023, researchers aboard the RVIB Nathanial B. Palmer collected photo-transect surveys from remote regions of the Eastern Antarctic continental shelf. Organismal abundances in benthic communities along the Eastern Antarctic shelf were generally equivalent to those on the Western Antarctic Shelf. Asteroids, crinoids, and echinoids were more abundant in Western Antarctic than in Eastern Antarctic regions. Sea cucumbers, on the other hand, appeared more abundant on the continental shelf of Wilkes Land in Eastern Antarctica, comprising over half of the communities within this ecoregion. Benthic environments in Eastern Antarctica seem to have less hard substrate cover than Western Antarctica based on our characterization of the seafloor through these photos, presumably due to ice scour. Our observations across a 3200 km transect of the Eastern Antarctic continental shelf support the presence of multiple ecoregions in this area. Observations of continental shelf communities in this remote part of the world will help researchers better estimate current patterns of diversity in Southern Ocean ecosystems, providing a baseline for how they will change over time in response to climate variations.