HR: 0800h
AN: OS51A-0552    [Abstracts]
TI: Spatial Distribution of Organic-walled Dinoflagellate Cysts in Surface Sediments of the Benguela Upwelling System and Their Relationship to Environmental Parameters
AU: * Holzwarth, U
EM: holzwarth@rcom-bremen.de
AF: University of Bremen, Research center ocean margins, P.O. Box 330440, D-28334, Germany, Bremen, 28334 Germany
AU: Esper, O
EM: oesper@awi-bremerhaven.de
AF: Alfred Wegener Institute (AWI), Columbusstrsse, 27568 Bremerhaven, Germany, Bremerhaven, 27568 Germany
AU: Zonneveld, K
EM: zonnev@uni-bremen.de
AF: University of Bremen, Research center ocean margins, P.O. Box 330440, D-28334, Germany, Bremen, 28334 Germany
AU: Willems, H
EM: willems@micropal.uni-bremen.de
AF: University of Bremen, Research center ocean margins, P.O. Box 330440, D-28334, Germany, Bremen, 28334 Germany
AB: The Benguela upwelling system along the west coast of Southern Africa is one of the most productive areas of the world ocean. This is not only important for the fishing industry but also for the accumulation of organic carbon which is a factor of major importance in relation to the global carbon cycle and as such to global change. The mechanisms of changes in intensity and permanence of the Benguela coastal upwelling are not sufficiently understood. The south-east trade winds are the driving force for the upwelling process in this region. Filaments of cold, nutrient-rich water regionally extend from the region of coastal upwelling far into the more oligotrophic open ocean. To understand how this system and the accumulation of organic carbon changed in the past detailed reconstructions are required. Organic-walled dinoflagellate cysts have become a valuable tool for palaeoclimatic and palaeoceanographic reconstructions. To use them as a proxy for oceanographic conditions it is necessary to gain as much knowledge as possible about the relationship between modern assemblages in the sediment and oceanographic parameters. Although the amount of such information increased considerably during the last decade for open oceanic it is extremely limited for coastal regions especially those that are characterised by upwelling. With the investigaton of 58 inshore surface sediment samples on organic-walled dinoflagellate cysts we focus on the continental shelf in detail. Ecological preferences are analyzed by relating the spatial distribution of organic-walled dinoflagellate cyst species to the oceanographic parameters in the upper water column at the sample sites 38 taxa could be identified. Most samples are dominated by cysts of Protoperidinium spp., Protoceratium reticulatum and Spiniferites spp. Statistical analyses have been carried out to separate different groups of indicator species for productivity parameters of the upper water column such as turbulence and/or the position and intensity of upwelling. The detrended canonical analysis reveals a clear inshore-offshore-gradient most likely related to temperature, salinity and nutrients.
UR: http://www.rcom-bremen.de/Einzelprojekt_A_1.1.html
DE: 4815 Ecosystems, structure, dynamics, and modeling (0439)
DE: 4855 Phytoplankton
DE: 4890 Zooplankton
SC: Ocean Sciences [OS]
MN: Fall Meeting 2005