Benthic foraminifera in surface sediments, South Atlantic

• Main Authors: Schmiedl, Gerhard, Mackensen, Andreas, Müller, Peter J
• Format: Dataset
• Language: English
• Published: PANGAEA 1997
• Subjects: Accumulation rate; total organic carbon; Angola Basin; ANT-IX/4; Calcium carbonate; Calculated; Campaign of event; Cape Basin; Carbon; organic; total; Counting >125 µm fraction; Date/Time of event; DEPTH; sediment/rock; Element analyser CHN; Elevation of event; Event label; Foraminifera; benthic; number of species; standing stock; benthic dead; benthic living; GeoB; GeoB1013-2; GeoB1014-2; GeoB1015-2; GeoB1016-2; GeoB1017-3; GeoB1021-3; GeoB1022-3; GeoB1023-2; GeoB1024-3; GeoB1025-2; GeoB1026-3; GeoB1027-2; GeoB1028-4; GeoB1029-1; GeoB1030-3; GeoB1031-1; GeoB1032-2; GeoB1033-3; GeoB1034-1; GeoB1035-3; GeoB1036-3; South Atlantic Ocean
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.53139; https://doi.org/10.1594/PANGAEA.53139

Sixty surface sediment samples from the eastern South Atlantic Ocean including the Walvis Ridge, the Angola and Cape basins, and the Southwest African continental margin were analysed for their benthic foraminiferal content to unravel faunal distribution patterns and ecological preferences. Live (stained with Rose Bengal) and dead faunas were counted separately and then each grouped by Q-mode principal component analysis into seven principal faunal end-members. Then, multiple regression technique was used to correlate Recent assemblages with available environmental variables and to finally differentiate between four principal groups of environmental agents acting upon the generation of benthic foraminiferal assemblages: (1) seasonality of food supply and organic carbon flux rates, together with oxygen content in the pore and bottom waters; (2) lateral advection of deep-water masses; (3) bottom water carbonate corrosiveness; and (4) energetic state at the benthic boundary layer and grain size composition of the substrate. Food supply and corresponding dissolved oxygen contents in the pore and bottom waters turned out to be the most important factors which control the distribution pattern of the Recent benthic foraminifera. At the continental margin, in the zone of coastal upwelling and its mixing area, benthic foraminiferal assemblages are dominated by stenobathic high-productivity faunas, characterized by elevated standing stocks, low diversities and a large number of endobenthic living species. At the continental shelf and upper continental slope the live assemblages are characterized by Rectuvigerina cylindrica, Uvigerina peregrina s.1., Uvigerina auberiana and Rhizammina spp. while the dead assemblages are characterized by Cassidulina laevigata, Bolivina dilatata, Bulimina costata and B. mexicana. At the lower continental slope strong influence of high organic matter fluxes on the species composition is restricted to the area off the Cunene river mouth, where the live assemblage is dominated by Uvigerina ...