Recent Benthic Foraminiferal Assemblages in the Western Part of the East Siberian Sea

Abstract

Benthic foraminiferal assemblages were studied in twenty surface sediment samples collected in the western part of the East Siberian Sea in the framework of the expedition of the R/V “Ivan Kireev” in 2004. Rose Bengal treatment allows us to separate “living” and “dead” individuals. Taxonomic analyses reveal that “living” calcareous foraminifers dominate in the study region with the exception of the New Siberian Islands area and area to the northeast from the Indigirka river mouth where agglutinated tests constitute up to a half of the assemblage. Little amount of dead individuals points to a rapid dissolution of calcareous tests immediately after death of organism. Taxonomic composition of the studied assemblages is similar to river-proximal benthic foraminiferal assemblage previously determined for the Kara Sea. In the East Siberian Sea, the most commonly occurred species are E-lphidium clavatum, Elphidiella groenlandica, Haynesina orbiculare, E. incertum и Lagenammina atlantica. Less abundant species are Gordiospira arctica, Buccella frigida, E. bartletti, Reophax curtus, R. scorpiurus and polymorphinids. As a result of statistical treatment, four areas with specific BF assemblages have been distinguished: area of the Indigirka River mouth, zone affected by Siberian Coastal Current, area located to the north of the Siberian Coastal Current and zone situated close to the New Siberian Island archipelago together with an area located to the northeast from the Indigirka river mouth. Such a distribution of BF assemblages in the study area seems to be related to the distance of the river discharge area, type of sediments and fresh organic matter content.