Dispersion of didymosphaenia geminata in the flowing waters of southern Poland : new sites of species occurrence in the orawska watershed and the Orawska basin

To date, Didymosphaenia geminata has been recorded in boreal and montane regions in Europe, Asia and North America. It has been recorded only rarely in central Europe in cold, oligotrophic montane water bodies with a moderately low electrolyte content. In Poland, it occurred in the streams in the Tatra Mountains and in the Dunajec River but abundance was low. During the 1990s this species appeared in the Carpathian tributaries of the Vistula River (Soła, Skawa and Raba). Very high Didymosphaenia geminata abundance was noted in the San River below the dams in mezotrophic environments. Didymosphaenia geminata was recorded for the first time in mezotrophic environments in the Czarna Orawa River and its tributaries, most of which - Zubrzyca, Sylec and Lipnica - come from Babia Góra Mountain. The highest abundance was noted in the Zubrzyca stream where there were macroscopic aggregations. The most common species in these aggregations were Navicula capitatoradiata, N. lanceolata, Cymbella minuta, Achnanthes biasolettiana var. biasolettiana, Fragilaria arcus var. arcus, F. ulna, Diatoma vulgaris and Cocconeis placentula var. euglypta