Marine, intertidal, freshwater and terrestrial biodiversity of an isolated polar archipelago

Abstract

Aim We ask how biodiverse is a polar archipelago; how this faunal richness is spread across marine, intertidal, freshwater, terrestrial and parasitic realms; and how fast species are accumulated with increased sampling effort. Location The South Orkney Islands (SOI), Scotia Arc, Southern Ocean. Methods We sampled mega‐ and macro‐benthos at the SOI using scuba in the shallows (0–10 m), a rough bottom otter trawl at 150–250 m and an Agassiz trawl and epibenthic sledge, both at depths of 200, 500, 1000 and 1500 m. We also collated species occurrence at the SOI in each realm from a century of literature and modern databases to investigate patterns in species accumulation, endemism, faunistic affinities and bathymetric ranges in three model taxa. Results Our 11 benthic samples showed that point biodiversity at the SOI is high, yielding 19 classes and 158 species. Nearly a third were new to the area, whilst five species and one genus were new to science. The shallowest samples were richest but had fewest new records of species. Known richness at the SOI is dominated by marine species (1026), of which 821 (83.3%) were benthic. Across all realms, 1224 species (50 classes, 24 phyla) were recorded, of which 43 were intertidal, 64 freshwater, 100 terrestrial, 60 parasitic and 40 birds. Species accumulation curves for model taxa showed new sampling yields about 0.75% per sample of known benthic richness, so by Antarctic standards we know the SOI quite well. Most species are Southern Ocean endemics, but very few occur only at the SOI. Main conclusions This first estimate of faunal biodiversity of a polar locality demonstrates both high richness and high levels of knowledge at the SOI. As suspected but never quantified, the benthos dominates polar biodiversity, at least at the SOI. Marine species there constitute 20% of those recently listed for the entire Southern Ocean, whilst > 60% of terrestrial species are known from Antarctica. The SOI, being one of the better‐studied polar locations, of known age and with a discrete shelf, represent an important source of comparison for biodiversity studies. Our data clearly show that richness and our knowledge of the polar fauna differ across environments.

Biodiversity of an unknown Antarctic Sea: assessing isopod richness and abundance in the first benthic survey of the Amundsen continental shelf

“…In contrast, isopod richness in our Amundsen Sea samples was high across all taxonomic levels studied (family, genus and species), relative to similar samples collected elsewhere. Scotia Sea biodiversity is considered high for a polar sea (see Clarke and Johnston 2003;Barnes et al 2008) but isopod richness was not significantly different to that in our Amundsen Sea samples at familial level. Furthermore our results showed Scotia samples were significantly less rich than those from the Amundsen Sea at generic and species levels in desmosomatids and nannoniscids (see Fig.…”

“…Standardised values (to 1,000 m) in parentheses. PB data from Barnes et al (2008), ST data from Kaiser et al (2008) Multibeam sonar images of the Amundsen shelf have revealed complex bottom topography (unpublished BIO-PEARL 2 cruise data). There are irregular and abundant plough marks (caused by icescours), even at 500-m depth (Lowe and Anderson 2002;Dowdeswell and Bamber 2007).…”

“…The remote South Sandwich forearc, a combination of (active and non-active) volcanic islands and seamounts, are one of the youngest features within the Scotia arc (<5 Ma, Barker 2001 Kaiser et al 2008, and the South Orkney Is. (PB), see Barnes et al 2008]. During both cruises (JR 144 and JR 179) benthic samples were taken using an EBS (for a detailed description see Brenke 2005).…”

The spatial structure of Antarctic biodiversity

“…Indeed, several taxa (e.g., polychaetes and pycnogonids) are represented at higher than global average levels in Antarctica Johnston 2003, Barnes andPeck 2008). The South Orkney Islands have an overall species richness as high as temperate and some tropical archipelagos (Barnes et al 2009a). However, while the extremely high richness of many marine taxa in the Indo-West Pacific (IWP) area seems to be caused by the presence of large numbers of rare and small-sized species in the shallows (Bouchet et al 2002), rare species are far less well represented in the few polar assemblages studied to date (Clarke 2009).…”

New data on the distribution of stenothoid amphipods (Crustacea) from Scotia Arc, West Antarctic

“…Furthermore the studies of the benthos have usually been restricted only to the particular locality or habitat. Also most research has focused on animal groups of big size and easy iden− tification (Barnes 2008;Barnes et al 2006Barnes et al , 2009c. This paper presents the results of a study of one Amphipod family, the Stenothoidae.…”