Limnological characteristics of the freshwater ecosystems of Byers Peninsula, Livingston Island, in maritime Antarctica

A limnological survey of 15 lakes and 6 streams was carried out on Byers Peninsula (Livingston Island, South Shetland Islands, Antarctica) during austral summer 2001–2002. Most of the surface waters had low conductivities (20–105 μS cm−1) and nutrients (total phosphorus 0.01–0.24 μM), but some coastal lakes were enriched by nutrient inputs from seal colonies and marine inputs. Plankton communities in the lakes contained picocyanobacteria (102–104 cells ml−1), diatoms, chrysophytes and chlorophytes, and a large fraction of the total biomass was bacterioplankton. Zooplankton communities were dominated by Boeckella poppei and Branchinecta gainii; the benthic cladoceran Macrothrix ciliata was also recorded, for the first time in Antarctica. The chironomids Belgica antarctica and Parochlus steinenii, and the oligochaete Lumbricillus sp., occurred in stream and lake benthos. The phytobenthos included cyanobacterial mats, epilithic diatoms and the aquatic moss Drepanocladus longifolius. These observations underscore the limnological richness of this seasonally ice-free region in maritime Antarctica and its value as a long-term reference site for monitoring environmental change.