AQUATIC HYPHOMYCETES OF 21 RIVERS IN SOUTHERN IRELAND

Foam was collected from 21 rivers in southern and western Ireland in a utumn 1993 and 1994 and early spring 1994, and aquatic hyphomycete spo res were enumerated and identified. Sixty-eight aquatic hyphomycete sp ecies were identified, with a significantly greater number of species being recorded from rivers with a riparian vegetation of woodland than from rivers with a more herbaceous vegetation. The number of species recorded in this study was comparable to numbers recorded from Europe and North America. However, the mean number of taxa recorded per river (26.5) was comparatively low. Detrended correspondence analysis showe d that rivers of contrasting water hardness and conductivity could be differentiated on the basis of differences in the composition of their aquatic hyphomycete spora. Assemblages of associated species were als o detected, such as those confined to soft-water livers. TWINSPAN anal ysis also distinguished a core assemblage of species that were widely distributed.