BENTHIC FORAMINIFERAL RESPONSE TO ENVIRONMENTAL-CHANGE IN THE SKAGERRAK, NORTHEASTERN NORTH-SEA

Studies of the benthic macrofauna (both quantitative and qualitative) conducted in the Skagerrak and Kattegat over a period of many years to gether with comparisons made with data collected in 1914 have led to t he conclusion that the area is undergoing eutrophication. The general increase in biomass and densities of macrofauna has been attributed to an increased supply of degradable organic matter to the sediment. In this study, the effect of eutrophication on benthic Foraminifera is sh own in a comparison of foraminiferal data from Recent sediment layers (the upper 2 cm of short sediment cores) with layers deposited more th an 42 years B.P. (24-25 cm core interval). Foraminiferal densities are significantly lower in the Recent sediment with no large scale change s in the assemblage composition. It is proposed that the lower densiti es are a result of increased macrofaunal activity. The (paleo) environ mental significance of this interrelated effect of food availability a nd biological interactions on foraminiferal densities is discussed.