Benthic hydroids off Scott Island and the shelf and slope of the Ross Sea (Antarctica) collected during the IPY-CAML TAN0802 voyage by R/V Tangaroa

Abstract

During the IPY-CAML TAN0802 survey with RV Tangaroa, marine communities on the shelf and slope of the Ross Sea, as well as around the remote Scott Island and seamounts east of the Balleny Islands, were sampled using various sampling gears (epibenthic sled, rough-bottom fish trawl, beam trawl and multicorer). Amongst the numerous benthic samples obtained, an important collection of hydroids was present. Thirty-five species, including Sertularella pseudovervoorti sp. nov., have been recorded. Anthoathecata are represented only by Bouillonia denhartogi. The collection is essentially dominated by Leptothecata, with 34 species, belonging to the families Lafoeidae, Haleciidae, Kirchenpaueriidae, Schizotrichidae, Sertularellidae, Staurothecidae, Symplectoscyphidae, Tiarannidae and Zygophylacidae. Symplectoscyphidae is by far the most diversified family with 12 species (34%), followed by Kirchenpaueriidae and Staurothecidae with 5 each (14%) and Haleciidae with 4 species (11%). At the generic level, Symplectoscyphus with seven species, Antarctoscyphus, Oswaldella and Staurotheca with five species and Halecium with four are the most speciose genera. Symplectoscyphus frondosus is clearly the species with the highest occurrence. The depth range of 15 species is increased, considerably in most cases. Several species so far considered to be inhabitants of the Antarctic shelf clearly extend their distribution to the slope. Twenty species were found on the shelf and slope of the Ross Sea, with Stegopoma plicatile representing the new single record for the area, raising the number of known species to 78. Ten species (including the new species) come from the virtually unknown area of Scott Island, 8 constituting new records, raising the number of species known in this isolated area to 11. Sixty-eight percent of the species are Antarctic endemic and 94% are restricted to Antarctic or Antarctic/sub-Antarctic waters.