Abundance and biomass estimates of the benthic fauna in Admiralty Bay, King George Island, South Shetland Islands

Distribution patterns in the biomass of macrozoobenthic communities in Admiralty Bay (King George Island, South Shetlands, Antarctic)

“…Until now, information about the biomass of the macrozoobenthos in Admiralty Bay had been presented only for a depth range of 15-250 m, on three a priori selected transects (Jazdzewski et al 1986) and was not studied over the entire depth range or in areas characterized by the different levels of glacial influence. The average biomass value recorded in Admiralty Bay in this study (66 g/ 0.1 m 2 ) was similar to the value recorded by Jazdzewski et al (1986) and to those at other Antarctic locations when compared with data compiled in that paper.…”

“…Biomass analyses have also been performed for the South Shetland Islands (Saiz-Salinas et al 1997, 1998Arnaud et al 1998;Saiz-Salinas and Ramos 1999;Piepenburg et al 2002). The biomass of benthic macrofaunal communities in Admiralty Bay was studied by Jazdzewski et al (1986) but the analysis was based only on three transects within 15-250 m depth range.…”

The megazoobenthos of the Scotia Arc islands

“…Dense suspension-feeder communities are absent in the Magellan channels , as well as in other extensive areas of the Scotia Arc archipelagos, such as the vast southern shelf of the South Orkneys (Ramos and Sobrino, 1991), west of Elephant Island, the shallow bays of the South Shetlands (Gallardo, 1992;Jazdzewski et al, 1986;Sáiz-Salinas et al, 1997;Arnaud et al, 1998) and in Bransfield Strait (Mühlenhardt-Siegel, 1988Ramil and Ramos, 1997). This could be due, among other factors, to their location, close to glacial fronts or in the frequent passage of large icebergs.…”

“…As they seem to grow faster than other invertebrates, particularly during some years (Kühne, 1997, cited by Arntz, 1997), they are probably more opportunistic, and could take over the ecological niche of other, much more demanding suspension feeders. This hypothesis could explain the ascidian dominance in zones with strong glacial influence, such as some bays of the South Shetlands, on bottoms less than 100 m depth (Jazdzewski et al, 1986;Kowalke, 1989;Sáiz-Salinas et al, 1997;Arnaud et al, 1998), or those subject to active volcanic conditions, such as the South Sandwich archipelago or inner and outer Deception Island (Retamal et al, 1982;Sáiz-Salinas et al, 1997;Arnaud et al, 1998;Ramos, unpubl. data).…”

“…Studies on the South Orkneys and South Shetlands are somewhat more numerous, mostly focusing on Signy Island (Hardy, 1972;Barnes, 1995a, b) and some of the South Shetlands shallow bays (Gallardo, 1992), especifically those of Greenwich (Gallardo and Castillo, 1969;Gallardo et al, 1977) and Deception islands (Retamal et al, 1982). During the last decade, this information has been expanded by the work of Jazdzewski et al (1986), Sáiz-Salinas et al (1997) and Arnaud et al (1998) in the South Shetland area, as well as that of Mühlenhardt-Siegel (1988 in the South Orkneys, South Shetlands, Elephant Island, and the Antarctic Peninsula. Since the methodology used in all those projects was aimed at studying the infauna, they offer little information on the characteristic components of the megabenthos, particularly regarding the distribution of the rich three-dimensional communities of suspension feeders that are so characteristic of the Antarctic epifauna (Arntz, 1997;.…”