Distribution of Seaweed Floras in the Southern Ocean

An earlier phytogeographical analysis of the marine algal floras of the southern oceans using Detrended Correspondence Analysis enabled the recognition of floristic groupings. In the present analysis attention is focused on the floras of islands or coastlines (21 sites) lying within the Antarctic/sub-Antarctic group. The original database has been amended by the addition of new records from Macquarie Island and South Georgia, addition of records from Terra Nova Bay on Antarctica, and account taken of subsequent taxonomic changes. The main axis of variation in the ordination analysis of 480 species indicates a general north-south trend rather than a sharp discontinuity between the floras of the Antarctic and sub-Antarctic regions. Floristic provinces are not apparent, thus islands like South Georgia and Macquarie lie comparatively close in the ordination despite their vast geographical separation. The species-rich floras of Patagonia, Tierra del Fuego and the Falklands appear to form a grouping. The relatively homogeneous distribution of species in the sub-Antarctic region is attributed in part to dispersal by the eastward-moving West Wind Drift.