The freshwater fauna of the South Polar Region: A 140-year review

Abstract

The metazoan fauna of Antarctic and sub-Antarctic freshwaters is reviewed. Almost 400 species, notably rotifers, tardigrades and crustaceans have been identified. Sponges, molluscs, amphibians, reptiles and fishes are absent though salmonid fishes have been successfully introduced on some of the sub-Antarctic islands. Other alien introductions include insects (Chironomidae) and annelid worms (Oligochaeta). The fauna is predominately benthic in habitat and becomes increasingly depauperate at higher latitudes. Endemic species are known but only a few are widely distributed. Planktonic species are rare and only one parasitic species has been noted.

Spatial distribution of freshwater crustaceans in Antarctic and Subantarctic lakes

“…The relevance of distance was also revealed by our partial redundancy analysis (which showed that spatial autocorrelation among regions explained a large amount of variance), and it is most likely related to patterns of dispersal. Dispersal among nearby islands occurs mainly via migratory seabirds, which can transport resistant eggs within the gut or in mud adhering to feet 1,6,10,16,17 . Distance among regions is often a key determinant in the distribution of freshwater fauna 18 , which may help explain some inconsistencies in the definition of biogeographic provinces.…”

“…We elaborated a presence/absence matrix of all freshwater crustacean species reported for Antarctic and Subantarctic lakes, based on two major literature reviews 6,10 , which contained all the available information to date. We divided each biogeographic province into regions following the above two reviews: CA comprised the En (30°E–90°E), Wi (90°E–150°E) and Sc (150°E–150°W) sectors; MA included the Pa, Ss and So; SA included Sg, Pe, Mc, Hd, Cr and Kr; and SCT included Ca and Ak from New Zealand and Fa from South Atlantic ocean (Table 1, Fig.…”

“…Crustaceans are the most diverse and well-documented freshwater invertebrates in Antarctic and Subantarctic lakes, where the eight major crustacean orders are represented 6 . Most taxa are common components of zooplankton, where they occupy a wide range of ecological niches, and can respond quickly to environmental change, including temperature increase 7 .…”

“…Thus, they are considered sentinel organisms which can help understanding climate change effects 8,9 . The occurrence of crustacean species in Antarctic and Subantarctic lakes has been reported in many publications and compiled in two major reviews 6,10 , but no attempt has been made to explore whether their distribution is explained mostly by biogeography or whether climate is a main determinant. We explored this question using published information and tested the hypothesis that variation in crustacean species composition across regions within Antarctica is determined by (i) biogeography (i.e., regions from the same biogeographic province will have more similar species composition than regions from different provinces), (ii) spatial autocorrelation among regions (i.e., regions closer to each other will have more similar species composition than more distant regions due to higher dispersal among them) and (iii) climate (due to species-specific environmental constraints).…”

Evidence of strong small‐scale population structure in the Antarctic freshwater copepod Boeckella poppei in lakes on Signy Island, South Orkney Islands

“…The fauna is dominated by small ( 200 μm to 5 mm) and inconspicuous invertebrates, usually associated with simple vegetation (lichens, mosses, algae). At least 12 species of Crustacea, including copepods, cladocerans, ostracods, and an anostracan, have been reported from freshwater lakes of the Antarctic continent, Antarctic Peninsula, and the maritime Antarctic South Shetland Islands and South Orkney Islands (Pugh et al 2002;Gibson and Bayly 2007;Dartnall 2017;Diaz et al 2019). There has been a long debate about the origin of the Crustacea that inhabit Antarctic lakes.…”