BENTHIC FORAMINIFERAL FAUNAS IN SURFACE SEDIMENTS OFF NW AFRICA: RELATIONSHIP WITH ORGANIC FLUX TO THE OCEAN FLOOR

Abstract

Benthic foraminiferal thanatocoenoses were studied in 29 sediment surface samples off NW Africa, between 19 degrees and 27 degreesN, and from water depths between 506 and 3314 m. The results were compared with estimated values of the downward organic flux and measured bottom water oxygen concentrations. Although the latter 2 parameters show a strong negative correlation in the study area, we argue that the organic flux is the main controlling ecological factor. On the basis of an R-mode multivariate statistical analysis, 6 species clusters are recognized, which are separated geographically by differences in organic flux and water depth. The combined sample scores on the first 2 principal component axes show a strong positive correlation with the estimated downward organic flux (R(2) = 0.83). It is suggested that this relationship can be used on a local scale as a proxy for paleo-export production, as long as bottom water oxygenation does not fall below a critical level.