The biology of an Antarctic aquatic moss community

SUMMARY. 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 settleme