Species composition and glacial-interglacial variations in the ostracode fauna of the northeast Atlantic during the past 200,000 years

Sediment core M23414 from the Rockall Plateau (North Atlantic) covering the last two climatic cycles, marine isotope stages (MIS) 7 to 1, was investig ated for glacial-interglacial variations in the deep-sea benthic ostracode fauna. A highly diversified ostracode fauna including 98 species was found. Two climate-related assemblages were identified, associated with interglac ial and peak glacial periods, respectively. The 'interglacial' group occurs during the end of MIS 7, 5 and 1 and is composed of the genera Henryhowell a, Pelecocythere, Echinocythereis, Cytherella, Bradleya, Aversovalva and Eu cytherura. The 'glacial' group consists of the genera Acetabulastoma (which is known as 'sea ice indicator' in the modem Arctic Ocean), Polycope, Byth oceratina, ?Rhombobythere, and some species possibly belonging to the genus Pseudocythere and is found during MIS 6, 4 and 2. These longer-term variat ions within the ostracode fauna seem related to the particular glacial and interglacial climate conditions that affected both deep-water production as well as primary production in the surface waters. However, a detailed comp arison of ostracode abundances with the occurrence of events marked by incr eased ice-rafted debris reveals also much shorter-term climate related chan ges in the ostracode fauna. Thus, the temporal fluctuations within ostracod e assemblages reflect long- and short-term alterations of the deep-sea envi ronment that are clearly linked to climate changes. (C) 2000 Elsevier Scien ce B.V. All rights reserved.