Polychaete species diversity on the West Antarctic Peninsula deep continental shelf

Abstract

We assessed macrofaunal polychaete species diversity on the West Antarctic Peninsula at mean depths of 500 to 600 m along a cross-shelf transect near Anvers Island, Antarctica. Fifteen megacore samples from 3 sites were analysed to species level, revealing 78 polychaete species of which several are new to science. Quantitative samples allowed an assessment of species abundances and the relative contribution of dominance to overall species diversity. The composition of the assemblages varied across the shelf: the 2 outermost stations on the transect were relatively similar but differed from the innermost station, which had higher diversity and major differences in species composition, possibly linked to changes in the sediment characteristics and degree of food availability. Species diversity, measured by rarefaction, evenness and species richness estimators, was similar to values reported at other bathyal settings and slightly higher than that reported from the Arctic shelf, but in general lower than that reported at temperate and tropical abyssal sites. Dominance was much higher at Antarctic deep-shelf sites in comparison to temperate bathyal and abyssal sites.

Macrofaunal Ecology of Sedimented Hydrothermal Vents in the Bransfield Strait, Antarctica

“…Therefore we accept hypothesis 2 and suggest that the proposed increase and subsequent decrease of diversity ( Figure 5) with increasing hydrothermal influence (Bernardino et al, 2012) does not capture the high background biodiversity common in the deep-sea (Rex and Etter, 2010;Chown, 2012; Figure 5). Species accumulation curves from the Bransfield Strait, elsewhere in the Southern Ocean and Pacific SHV (Grassle and Petrecca, 1994;Flach and Heip, 1996;Levin et al, 2009;Neal et al, 2011) show that species richness was higher in background/ inactive sediments than at active vents (Figure 6), which is consistent with lower diversity at active vents (Figure 6). The Bransfield Strait SHV was generally more species rich than vents from the Manus Basin and comparable to NE Pacific vents at Middle Valley (Figure 6; Levin et al, 2009).…”

“…At high temperature vents, meiofaunal taxa showed a similar pattern in species richness to that present here (Gollner et al, 2015), illustrating differences between taxa and environmental settings. Species richness was also generally lower in the Bransfield strait when compared with the West Antarctic shelf seas (Figure 6; Neal et al, 2011) although it should be noted that these samples were from sites ∼500 m shallower and measure only polychaete species richness.…”

Comparative marine biodiversity and depth zonation in the Southern Ocean: evidence from a new large polychaete dataset from Scotia and Amundsen seas

“…For example, using grab samples from Livingstone and Deception Island San Martín et al (2000) recovered 3700 specimens of polychaetes belonging to 89 species. Pabis and Sicinski (2012) collected grab samples at Admiralty Bay, South Shetlands and found 76 polychaete species in depths ranging from 200 to 500 m. Comparative analysis by Neal et al (2011) also showed Admiralty Bay to have a depressed diversity similar to that of species-poor Arctic shelves, although depending on a choice of comparative Arctic site, these results can vary (see Pabis et al 2015c). There are 162 species known polychaete species from Admiralty Bay based on summary of more than 30 years of research in this area (Sicinski et al 2010).…”

“…the relative numbers of undescribed species) and stressed that degrees of endemism varied among taxa, but did not make direct global comparisons of Antarctic biodiversity. In global comparisons, Antarctic shelf diversity (of polychaetes) has been shown to be higher than Arctic sites, similar to general bathyal sites and lower than most abyssal sites but comparative data are rare (Neal et al 2011). Gutt et al (2004) estimated that the total expected number of macrozoobenthic species for the entire Southern Ocean shelf lies between 11,000 and 17,000 suggesting Bintermediate^species richness when compared to other selected habitats.…”

Small-scale spatial variation of soft-bottom polychaete biomass in an Antarctic glacial fjord (Ezcurra Inlet, South Shetlands): comparison of sites at different levels of disturbance

“…However, almost all previous studies of the Antarctic benthic communities were focused on total polychaete biomass, and there is only scarce knowledge on biomass of particular species (Bromberg et al 2000;Barbosa et al 2010), especially when compared to the abundance data (e.g., Richardson and Hedgpeth 1977;Gambi et al 1997;San Martin et al 2000;Sicinski 2004;Neal et al 2011;Parapar et al 2011). Such data are very important for future assessments of the energy flow in the Antarctic benthic ecosystem.…”