Various freshwater habitats, some slightly under brackish water influence, have been investigated from Vaigach Island, Mestnyi Island, Matveev Island and the Yugorsky Peninsula in north - west Siberia. In only 17 samples with obviously different water quality conditions 490 taxa or "Sippen" (i.e. morphodemes currently having no formal taxonomic rank), were found in this very small area of the Arctic.