Freshwater invertebrates from Livingston and Horseshoe Islands, Maritime Antarctica

Various processes trigger the formation, disappearance or expansion of lakes and ponds in Antarctica. Such dynamic ecosystems are a challenging environment for their inhabitants. We studied aquatic invertebrates in lakes and ponds on Livingston and Horseshoe Islands, Antarctica. Invertebrate fauna was either poor, in terms of diversity, or completely lacking. The taxa we found were of the polyphyletic group Protozoa; phylla Nematoda, Tardigrada, Annelida (subclass Oligochaeta) and Arthropoda (subclass Collembola, classes Insecta, Branchiopoda and Copepoda). Whenever a species dominated the communities, it was the copepod Boeckella poppei. When other taxa were recorded, their density was relatively low with few exceptions (Macrothrix oviformis, Branchinecta gaini). High density of B. poppei was recorded in circa 65% of all samples and the majority of the lakes/ponds with fauna. Most of the studied water bodies were oligotrophic, likely among the reasons for the poor faunal diversity, together with the harsh environmental conditions in Antarctica, e.g. low temperatures and long periods during which the lakes are frozen or completely dried out. The formation of new lakes and ponds poses the question on the pathways of distribution of aquatic organisms and why some ponds and lakes are densely populated, while others are deprived of aquatic invertebrates.