NE Atlantic benthic foraminifera: modern distribution patterns and palaeoecological significance

Microfaunal evidence is presented from a region in the NE Atlantic Ocean ch aracterized by well-constrained and very uniform physiochemical water mass properties, but a significant gradient in surface ocean productivity. Notab le changes in the species composition of benthic foraminiferal assemblages can be directly related to surface productivity and particulate organic mat ter supply to the deep ocean Boor. Because of the labile nature of much org anic matter as it reaches the sea Boor, it is argued that benthic foraminif era, which exhibit a high preservation potential in most marine sediments, provide a better proxy for estimating past fluxes than bulk sediment organi c carbon (OC) content. Three distinct assemblage groups are recognized: a C assidulina laevigata group which is dominated by infaunal species and a rel atively high sediment OC content; a Rhizammina spp. group which is also dom inated by infaunal species; and an Epistominella exigua group dominated by epifaunal taxa and falling sediment OC content. Significant faunal assembla ge changes appear to be independent of grain size.