The genus Chaetoceros (Bacillariophyta) in Arctic and Atarctic

A floristic review of the genus Chaetoceros from Arctic and Antarctic waters is undertaken. Taxonomic composition of the Chaetoceros from the Russian Arctic seas, as well as from some regions of the Antarctic was investigated in both water column and sea ice. The genus is rather diverse in both polar regions: 55 species in Arctic and 34 ones in Antarctic. The regions differ in total number of species, number of species belonging to the subgenera Chaetoceros and Hyalochaete and to different sections. Species of the genus are often dominant and the most abundant in Arctic phytoplankton. However, the genus is not prevailing in number of the dominant species as well as in share of the total cell abundance of Antarctic phytoplankton. The importance of the species in sea ice assemblages of the Antarctic is more significant as compared with the Arctic. The Arctic is characterized by cosmopolitan species and those widely distributed in the Northern Hemisphere, more than half of the Chaetoceros taxa are common to all Arctic seas. The Antarctic has a high percentage of endemic Chaetoceros species. Both polar regions are similar in terms of Chaetoceros species composition mainly due to cosmopolitan species.