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

Abstract

A limnological survey of 15 lakes and 6 streams was carried out on Byers Peninsula (Living- ston Island, South Shetland Islands, Antarctica) during austral summer 2001-2002. Most of the surface waters had low conductivities (20-105 Sc m i1 ) and nutrients (total phosphorus 0.01-0.24 M), but some coastal lakes were enriched by nutrient inputs from seal colo- nies and marine inputs. Plankton communities in the lakes contained picocyanobacteria (10 2 -10 4 cells ml i1 ), diatoms, chrysophytes and chlorophytes, and a large fraction of the total biomass was bacterioplankton. Zooplankton communities were dominated by Boeck- ella poppei and Branchinecta gainii; the benthic cladoc- eran Macrothrix ciliata was also recorded, for the Wrst time in Antarctica. The chironomids Belgica antarctica and Parochlus steinenii, and the oligochaete Lumbricil- lus sp., occurred in stream and lake benthos. The phyto- benthos 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 monitor- ing environmental change.