A preliminary study of benthic diatoms in contrasting lake environments

Eleven of the 17 freshwater lakes from Signy Island, South Orkney Islands, Antarctica were sampled by snorkel divers. A list of diatom taxa identified from benthic samples is presented. Most freshwater taxa listed were rare and only a few taxa were observed abundantly in many lakes. Assemblage composition varied between three broad lake categories: (1) proglacial; (2) oligotrophic; and (3) mesotrophic lakes. Assemblage composition also changed with lake depth in the larger lakes. A second, more detailed study was undertaken on an oligotrophic and a mesotrophic lake. No seasonal trends could be identified. The limitation of the methods used are discussed, and spatial and temporal variability in Antarctic lakes is considered.