Phytoplankton biomass, chemical parameters and hydrology were studied in a transect 101.6 km long off Cabo Frio (RJ), Southeast Brazil, during summer (December 29 to 31, 1991) and winter (June 27 to 30, 1992). Wind induced upwelling events are frequently observed in the area during summer, becoming rare during winter. By the summer cruise a bloom of phytoplankton was observed in surface, close to the coast, with chlorophyll concentrations reaching 25.55 mg Chl-a m-3, uncoupled from the cold, nutrient rich waters of South Atlantic Central Water (SACW), found below 40 m depth. During the winter cruise, the SACW raised at the surface waters in front of Cabo Frio depicting an upwelling event. However, in spite of high surface nitrate concentrations (up to 7.7 f.1M) chlorophyll-a were lower than 2 mg Chl-a m-3. The phytoplankton biomass, meteorological and hydrological data suggest a probable upwelling event immediately before the summer cruise, and an ongoing one during winter time. Cluster analyses and principal component analyses (PCA) were applied to summer and winter data, pointing out multidimensional fronts in the area during both seasons.
Chlorophyll; Water Masses; Upwelling; Spatial Distribution; Cabo Frio; Brazil