Heterotrophic Nanoflagellates in the Pelagic Zone and Sediments of the Eastern Laptev Sea

• Published in: Oceanology (Washington. 1965) 2019-11, Vol.59 (6), p.881-892
• Main Authors: Kosolapova, N. G., Kosolapov, D. B., Kopylov, A. I., Romanenko, A. V.
• Format: Article
• Language: English
• Subjects: Abundance; Bacteria; Biomass; Coastal waters; Deep sea; Deep sea environments; Deep water; Earth and Environmental Science; Earth Sciences; Flagellates; Freshwater; Inland water environment; Marine Biology; Oceanography; Pelagic zone; Phytoplankton; Plankton; Rivers; Salinity; Salinity effects; Sediment; Sediments; Species composition; Species richness; Vertical distribution; Water circulation; Water column; Water depth; Water salinity
• ISSN: 0001-4370; 1531-8508
• DOI: 10.1134/S0001437019060092

— For the first time, the species composition of heterotrophic nanoflagellates, their quantitative characteristics, and abundance and biomass of their main food objects—bacteria and picophytoplankton, were determined in the water column and sediments of the Laptev Sea. In early autumn, an increase in the number and biomass of planktonic flagellates was recorded on a meridional transect from the Lena River delta to the deep-sea zone in the area of the internal shelf impacted by freshwater input from the Lena River. The pattern of the vertical distribution of planktonic flagellates differed in different parts of the sea, but everywhere their largest number was confined to either the surface or near-bottom layers. The quantitative parameters of planktonic flagellates correlated positively with the temperature, bacterial abundance, and biomass, and negatively correlated with water salinity. The abundance and biomass of heterotrophic flagellates in surface sediments was three to four orders of magnitude higher than in the water column and exceeded those of planktonic flagellates at shallow sites under 1 m 2 . A total of 28 species and forms of heterotrophic flagellates have been identified. Representatives of two taxonomic groups—Kinetoplastea and Stramenopiles, the most tolerant to the salinity—dominated in the community. The species richness of the flagellates decreased with water depth, it was minimum in less saline coastal waters, and it increased in the deep-sea area.