Free-living heterotrophic flagellates of the sublittoral and bathyal zones of the Kara Sea

Abstract

The first data are presented on the species diversity and community structure of deep-sea benthic heterotrophic flagellates in the Arctic (the Kara Sea). Thirty-three species and forms of heterotrophic flagellates were found, with kinetoplastids, stramenopiles, apusomonadids, and choanoflagellates being predominant. The species diversity of the studied region was characterized by a high beta-diversity and a low alphadiversity, which is indicative of a substantially higher potential species richness of flagellates in the Kara Sea. The total number of species of flagellates decreased with increasing depth (from 15 to 554 m); peculiar features of the species composition of deep-sea flagellates were not revealed. However, the flagellate communities within two different biotopes (the upper layer of the bottom sediments and the loose, flocculent layer on the surface of sediments together with near-bottom suspended matter) had similar taxonomic and trophic structures, but differed in the ratio of species with different feeding strategies. Attached or free-swimming flagellates were predominant in the loose surfacelayer, whereas rapidly gliding species that are able to actively search for and capture food predominated in the bottom sediments.