Topographical and hydrographical impacts on zooplankton community structure in the Abrolhos Bank region, East Brazil

The shelf region of Abrolhos is considered to be under the direct influence of the Tropical Waters (TW) of the Brazil current. The project had the obj ective to investigate the influence of the oceanographic and topographic co nfiguration on the zooplankton community. The samples for this study were c ollected during the 9th leg of the cooperational cruise "Joint Oceanographi c Projects - JOPS-II" of the German RV "Victor Hensen" from April 25th to M ay 6th, 1995. Twelve transects perpendicular to the coast have been worked up continously during the cruise. Samples were collected with a 300 mu m Bo ngo net. Based on the taxonomic composition at 56 stations, cluster and mul tidimensional scaling analyses were performed to describe the zooplankton c ommunity. The species composition showed that the whole area is influenced by TW, inducing low production and biomass. Only those areas, which are rea ched by South Atlantic Central Water-upwelling branches showed higher bioma ss values and elevated productivity. Two major communities were found in th e area: one neritic cluster influenced by upwelling waters in the southwest and on the Abrolhos Bank, and one oceanic cluster dominated by the warm an d oligotrophic Tropical waters at the offshore stations. The impact of the coast was negligible.