Invertebrate diversity in the deep Great Australian Bight (200–5000 m)

Background The Great Australian Bight (GAB) comprises the majority of Australia’s southern coastline, but to date its deep water fauna has remained almost unknown. Recent issuing of oil and gas leases in the region has highlighted this lack of baseline biological data and established a pressing need to characterise benthic abyssal fauna. Methods From 2013 to 2017, six large-scale systematic surveys of the GAB were conducted from 200 to 5000 m depth, constituting the deepest systematic biological sampling in Australia. Sampling was conducted on soft sediment and hard substrates, both at pre-determined depth intervals along north-south transect lines and at sites of interest identified by multibeam sonar. Results A total of 66,721 invertebrate specimens were collected, comprising 1267 species, with 401 species (32%) new to science. In addition to the novelty of the fauna, there was a high degree of rarity, with 31% of species known only from single specimens. Conclusions In this paper, we provide an annotated checklist of the benthic invertebrate fauna of the deep GAB, supplemented with colour photos of live specimens and commentary on taxonomy, diversity and distributions. This work represents an important addition to knowledge of Australia’s deep sea fauna, and will provide the foundation for further ecological, biogeographical and systematic research.