Deep-Sea Foraminifera in the South Atlantic Ocean: Ecology and Assemblage Generation

Benthic foraminiferal assemblages of 237 high-quality surface sediment samples from the South Atlantic Ocean, including the Atlantic sector of the circumpolar ocean, were quantitatively analyzed. Comparisons between assemblages of live (stained with Rose Bengal) and dead specimens showed that potential fossil assemblages of dead specimens were markedly impoverished in fragile and non-resistant agglutinated forms compared to the living assemblages. The dead material was grouped into nine principal faunal end-members by multivariate statistics and quantitatively correlated with available environmental variables. This data set is planned to serve as a reference for interpreting benthic foraminifera fluctuations in Pleistocene Southern Atlantic core material and to constrain the reliability of proxies directly derived from benthic foraminiferal shell geochemistry. Multiple regression analysis in concert with the analysis of distinctive and limited distribution areas of specific faunas delineated ecological demands and preferences of well-known cosmopolitan species and the generation of characteristic assemblages. We differentiated between four principal but interdependent groups of environmental agents acting upon the generation and distribution of nine specific potential fossil assemblages: (I1) Lateral advection and bottom water ventilation, (2) primary productivity and organic carbon flux rates, (3) bottom water carbonate corrosiveness and (4) energetic state at the benthic boundary layer.