Benthic foraminifera in the surface sediments of the deep-sea Arctic Ocean

Abstract

Modern distributions of Arctic deep-sea benthonic foraminifera were examined from four expeditions-CESAR, LOREX, Fram II and III. The samples covered a broad water depth range (800-4,200 m) and a wide range of Arctic environments from near the Fram Straits to the Alpha Ridge in the central Arctic basin. For the first time, diverse agglutinated assemblages were found in deep-sea Arctic material, near the Fram Strait in 800-1,000 m of water. We also observed a fauna unique to the deep Eurasian Basin (> 3,700 m) with 95% Stetsonia arctica (Green); we believe this fauna to be representative of Arctic deep bottom water. Other faunas we observed are similar to those reported in previous studies but with higher than average numbers of specimens compared to other deep sea areas. Comparison of this deep Arctic fauna to published core stratigraphies from the Alpha Ridge suggests that it has only been present for the last 400,000 years. Prior to that, a fauna similar to the deep Arctic fauna in the present Eurasian Basin dominated even at shallower depths. A species common to Pleistocene sediments in deep-sea Arctic cores, Bolivina arctica Herman, is rare in our surficial sediments. We have described two new species, Glabratella arctica and Trochammina pseudoinflata, and emended the genera Stetsonia and Robertinoides. We also present, for the first time, scanning light micrographs (SLM) of some species as well as scanning electron micrographs (SEM).