ИСТИНА

Harpacticoida is one of the most numerous and diverse group of marine meiobenthos, inhabiting all types of sediments from clayed mud to rocky and shelly grounds at all depths and latitudes. However, harpacticoids of Laptev Sea are so far studied very little. The goal of this study therefor was to compose checklist of Harpacticoida species from the Laptev Sea based on original data and published sources and to compare species composition with fauna from other arctic seas in order to evaluate trends of species spread and possible biogeographic relationships. Study was conducted on three main sites in the central and western parts of the Laptev Sea and in the area near the Lena River Delta in the summer 2015. Original data and literature sources allowed identifying 76 species belonging to 41 genera, and 15 families. Four of them were considered as species new to science. Overall, the richest families were Ectinosomatidae (16 species) and Ameiridae, Argestidae, Pseudotachidiidae (9 species each). Epibenthic harpacticoids (inhabiting silt substrates and the surface of soft sediments) dominated and comprised 85% of all species. The diversity of phytal and facultative interstitial fauna was very low (5% and 2% respectively). Only one species, Microsetella norvegica (Boeck, 1865), was considered planktonic. Obligate interstitial species were totally absent. Provisional endemics constituted almost 20% of the fauna. There was observed a high similarity between the fauna of the Laptev, Kara and East Siberian seas. The main factors determining the distribution of fauna groups (temperature and current system) were distinguished.