Antarctic shallow-water mega-epibenthos: shaped by circumpolar dispersion or local conditions?

The mega-epibenthos of two different geographic areas, the Antarctic Peninsula and the high Antarctic (eastern Weddell Sea), were investigated using underwater video. The distribution of the marine fauna at shallow depths between 55 and 160 m in these two areas was investigated to determine whether there are any zoogeographic differences at the community level. A total of 237 taxa represented by 85,538 individuals was identified. Multivariate analyses revealed significant faunal differences between northern Marguerite Bay (western Antarctic Peninsula) and the stations from the Weddell Sea, Atka Bay and Four-Seasons Bank. Echinoderms, especially ophiuroids, dominated Marguerite Bay, bryozoans and ascidians were abundant at Atka Bay, and hydroids and gorgonians were well represented at Four-Seasons Bank. These clear differences can mainly be explained by the influence of local environmental conditions that are probably the primary feature responsible in shaping the Antarctic shallow-water epifauna and not an intensive exchange with larger depths or a limited dispersion due to scarce and isolated shallow areas. In addition, modes of reproduction and characteristics of the early life history (e.g. brooding, viviparity or budding) of key taxa may also shape patterns of species distribution in shallow benthic Antarctic communities.

Details