The biology of an Antarctic aquatic moss community

Two species of aquatic moss (Calliergon sarmentosum and Drepanocladus sp.) occur in deep water in Moss Lake, Signy Island (60° 43′S, 45° 38′W). Their elongate stems support a structurally complex community of epiphytic algae and associated invertebrates which has a greater diversity than the surrounding benthic algal communities. Qualitative differences in the distribution and abundance of the epiphytic algae are described. Two groups of algae present on both mosses are distinguished–‘habitual’ and ‘casual’ epiphytes. On Calliergun, algae are most abundant in the leaf axil. The succession of epiphytes down the stem and the progressive deterioration of the moss plant are used to characterize six stem zones. The invertebrates are benthic and most move actively among the moss. Six species of rotifers are more or less permanently attached and show a preference for the middle stem zones where epiphyte cover is highest. Four species favour the leaf axil, the other two colonize the bare underside of the leaf. A settlement experiment has shown the importance of wind‐induced mixing in summer for the transport of some epiphytic species from shallow parts of the lake. The settlement of sessile rotifers is effected by their larvae. Photosynthesis declines from the stem apex to the dead old stem. Much of the primary production of the community is algal. The respiration maximum occurs where the highest concentration of epiphytic algae and invertebrates is found. Interrelationships between the invertebrates and the epiphytic algae are suggested and a comparison is made between these data and other studies

The Acari of fresh- and brackish water habitats in the Antarctic and sub-Antarctic regions

Neither the benthic Halacaroidea nor nektonic Hydrachnidia, characteristic of temperate and tropical freshwater mite faunas are represented among the twenty four species and sub-species of Acari recorded from the Antarctic and sub-Antarctic. The mites collected from the streams, lakes or brackish/freshwater pools of the region are either terrestrial species blown by wind into freshwater or interlopers from the marine littoral which have invaded coastal brackish pools. The present study reports on new collections of mites obtained from lakes and pools at a number of locations from both Continental and Maritime Antarctica, as well as from several sub-Antarctic islands. It reviews all published records for the region and the combined ‘fauna’ is then compared with that of temperate and tropical regions

The non-marine Crustacea of Antarctica and the islands of the Southern Ocean: biodiversity and biogeography

A total of 101 verified species and eight ordinal taxa represent the non-marine Crustacea on Antarctica and the islands of the Southern Ocean. The largely terrestrial Isopoda and Amphipoda are confined to some sub-Antarctic and cool temperate islands while the predominantly freshwater Anostraca, Anomopoda, Copepoda (=Calanoida, Cyclopoida, Harpacticoida) and Ostracoda (Podocopida) occur throughout the region. Holocene sea-level rises fragmented freshwater and terrestrial species ranges on New Zealand, Auckland, Campbell, and possibly other South Pacific islands, leaving a legacy of vicariant taxa. Tertiary species probably survived Pleistocene glaciation in aquatic refugia on the New Zealand/South Pacific, Falkland, Crozet and Kerguelen archipelagoes, but there are no valid records of Tertiary Antarctic Crustacea. All 40 Continental and Maritime Antarctic freshwater records can be ascribed to the historic introduction of anthropogenic aliens, Holocene immigration of colonists, returning re-colonists and marine species 'marooned' in epishelf and other coastal lakes

Characteristics and classification of the lakes of Signy Island, South Orkney Islands, Antarctica

The lakes of Signy Island (60° 43′S, 45° 38′W), South Orkney Islands, Antarctica, provide a unique laboratory for the study of many processes including natural eutrophication. Current relationships between the lakes have been examined by principal components analysis of environmental data from a long‐term monitoring programme. The results from the analysis have been combined with some biological data to provide a classification scheme for the lakes. The study has produced a valuable baseline for use in future research