How well do we know the Antarctic marine fauna? A preliminary study of macroecological and biogeographical patterns in Southern Ocean gastropod and bivalve molluscs

Abstract

The aim of this study was to use data for gastropod and bivalve molluscs to determine whether the fauna of the Southern Ocean is sufficiently well known to establish robust biogeographical and macroecological patterns. We chose molluscs for this work because they have been collected by almost every biological expedition to Antarctica, and are relatively well known taxonomically. Sampling of the continental shelf fauna is reasonably full and extensive, although new species are still being described and there are significant gaps in sampling off Wilkes Land and in the Bellingshausen and Amundsen Seas. Species richness was highest in those areas that have been subject to the most intense research activity and this pattern remained even after correction for sampling intensity. The low species richness of the Southern Ocean molluscan fauna compared with many tropical sites is confirmed, and is related principally to the absence of the large number of rare taxa that characterize some tropical assemblages. There is as yet no convincing evidence for a latitudinal cline in molluscan diversity within the Southern Ocean. Multivariate analyses defined biogeographical provinces very similar to those established previously, though they also identified a number of finer‐scale sub‐provinces including a small area of high diversity off Enderby Land. Most Southern Ocean gastropods and bivalves are rare, with limited distributions; relatively few taxa have circumpolar distributions.

The Antarctic holothurian genus Echinopsolus Gutt, 1990 (Dendrochirotida, Cucumariidae): brood pouches, spermatozoa, spermatozeugmata and taxonomic implications

“…Clarke & Johnston 2003;Clarke et al 2007). This is also true for all "potential" Echinopsolus species, which are not included in the current investigation (see Tab.…”

Macroecology of the European soft sediment benthos: insights from the MacroBen database

“…Note that singletons can differ in density due to differences in the area sampled at different sampling stations cies occupancies displayed the strong right-skew typical of regional studies in a broad range of taxa in both terrestrial and aquatic systems using various measures of geographic distribution (e.g. Gaston 2003, Macpherson 2003, Clarke et al 2007. Most species in the MacroBen database were narrowly distributed (or at least, have been recorded in only a few locations), whereas some were much more widely distributed.…”

“…An important caveat to the inferred generality of such patterns, however, is that macroecology has developed as an overwhelmingly terrestrial discipline (Raffaelli et al 2005, Clarke et al 2007, whereas the sea is home to most of life's higher-taxon diversity (May 1994). Only a minority of studies making explicit reference to 'macroecology' have had a primarily marine focus (Raffaelli et al 2005), and just 18 of the 279 abundance-occupancy relationships reviewed by Blackburn et al (2006) derived from marine or intertidal systems.…”

Ectosymbiosis is a critical factor in the local benthic biodiversity of the Antarctic deep sea

“…Samples were taken between 26 January and 30 March 2005 during the expedition ANDEEP III of the RV 'Polarstern' (ANT XXII/3) in the Southern Ocean (Linse et al 2007). Of the 15 deep-sea benthic stations sampled in the Weddell Sea area, 10 were selected for analysis in the present study.…”

“…Extensive investigations of Southern Ocean benthic biodiversity have taken place only within the last few decades, thanks to the ever more numerous explorations, mostly consisting of photographic surveys at all depths including the deep sea , Gutt & Starmans 1998, Starmans et al 1999, Brandt et al 2007). The forces shaping benthic biodiversity in the Antarctic are not yet fully understood, but communities seem to be structured by bathymetry (Gutt 2000) as well as by the geography of the shelf (Clarke et al 2007). Communities are dominated by sessile organisms, but biomass and diversity distributions are discontinuous, with patches of high abundance and diversity surrounded by quasi-deserts (Arntz et al 1994, Gutt & Starmans 1998, Starmans et al 1999, Gutt 2000.…”