Macrobenthos Distribution in the Laptev Sea in Relation to Hydrology

Abstract

As a results of six joint expeditions to the Laptev Sea in 1993, 1994 and 1995, 150 invertebrate species were added to the list of species known from this high-Arctic region, comprising now 1235 species in total. Most of these species (987) are macrozoobenthic. The geographic distribution of macrobenthic species numbers and biomass exhibited a pronounced increase to the north up to 77°N. In terms of biogeographic composition, Boreal-Arctic species accounted for most of the species, primarily widespread Boreal-Arctic species in the southern and central Laptev Sea at depths from 10 to 75 m and primarily Atlantic Boreal-Arctic species in the northern Laptev Sea at depths of 90 to 1100 m. Only in depths of more than 2000 m, as well as in estuarine and brackish coastal waters, Arctic forms had significant species shares. On sandy and silty bottoms, nine major communities and two trophic zones were distinguished. The distribution of species numbers, biomass and faunal composition is discussed in relation to water depth, seabed sedimentology and near-bottom water salinities. The latter are supposed to be the major environmental factor regulating the distribution and structure of macrobenthic communities. An ecological-biogeographical zonation scheme is proposed, combining the current information about the distribution of macrobenthic communities and brackish water masses.