Benthic Foraminifera Diversity of the Abyssal Northwest Atlantic

Abstract

The species diversity of benthic foraminifera at four abyssal working areas in the Labrador Sea, Labrador Basin, and Southwest of the Azores is documented. One hundred and fifty taxa (forty-three not assigned to a species) were found and their diversity was recorded. One hundred and twenty-four taxa (fifteen not assigned to a species) were illustrated with optical and/or SEM (Scanning Electron Microscope) images on twelve plates. The material was sampled during RV Sonne cruise SO286 as part of IceDivA2 (Icelandic marine Animals meets Diversity along latitudinal gradients in the deep sea of the Atlantic Ocean 2). IceDivA2 investigated the biodiversity within key groups of the marine benthic abyssal habitats of the North Atlantic. Thirty-two samples from four sliced and three full cores, from six stations sampled with a MUC (Multiple corer), were analyzed. Given low sedimentation rates in such environments the material is assumed to be of Holocene to late Pleistocene age. Due to the scarcity of living specimens this study was based on total assemblages. Four species-based clusters are identified, which correspond to the four working areas. The samples of each cluster show specific characteristics markedly different from those of the samples of the other clusters. It indicates that abyssal faunas are heterogeneous. Three clusters are dominated by Epistominella exigua (Brady, 1884), which is recorded as not rare to dominant in many abyssal plains worldwide. The faunal differences are manifested in the long tail of less important species and differing abundances of E. exigua.