Preliminary results of an inventory of ascidian faunas in the seas of the Russian Arctic

Abstract

This study examines the taxonomic structure and commonality of species composition of ascidians in the Arctic seas of Russia, where there are currently registered more than 70 representatives of this group. Quantitative analysis of taxa of different ranks inhabiting the study area demonstrates that their abundance decreases from west to east, and species composition in all seas, except Kara Sea, is understudied on average by 13±4%, and understudy increases in the eastern direction. The maximum decrease in the species composition in the mentioned direction is common for the families Polyclinidae and Didemnidae. The richest by number of species are genera Molgula Forbes, 1848 and Dendrodoa MacLeay, 1824. The performed clustering allows us to assume a predominant formation of regional ascidian faunas under the influence of the northeastern Atlantic. The results of finding multiple regression parameters confirm this hypothesis, which show that the actual and theoretically maximum number of species in Ascidiacea faunas of the Arctic seas of Russia depends only on the depth of water bodies and the length of their western and eastern borders (R2adj = 0.814; p = 0.015).