The Arctic and Antarctic oceans are undergoing drastic changes in the extent of their sea-ice and ice-shelves. This has effects on biodiversity, structure and function of polar communities and will change these ecosystems, including major implications on the biogeochemical cycles. In the Arctic, sea ice loss has led to a northward shift in phytoplankton distributions and shifts have been observed also in the vertical and horizontal distributions of zooplankton communities, while impacts and responses on benthic communities are less studied. In the Antarctic, ice shelves have had large calving events and, in some cases, entire ice shelves have collapsed enabling sunlight and currents to reach the underlying benthic communities and providing new spaces for pelagic ecosystems. This session invites contributions that provide up-to-date information on species richness and biogeographic responses in marine biodiversity adapted to ice-covered environments as well as on their phylogeographic relationships and how they affect biogeochemical cycles. We seek interdisciplinary data and synthesis products that elucidate the status of the effects of ice loss on marine biogeochemistry and biodiversity on regional and global scales, how feedbacks and controls could change these systems and ultimately, what new conditions might be present in these regions on decadal and longer time scales.