South Brazilian Continental Shelf: Chlorophyll-A, Primary Production, and the Relationship between Abiotic and Biotic Parameters
The south Brazilian continental shelf presents a complex hydrographic regime due to land drainage influence (Rio de la Plata and Lagoa dos Patos) and the proximity of the Subtropical Convergence Zone. Our aim is to determine the effect of the interacting water masses on biological production. During September 1988, we sampled 53 oceanographic stations between 31°30’S and 34°30’S along the continental shelf. The water masses were identified by TS diagrams and classified according to the Mamaiev mixture triangle method, adapted for continental shelf analysis. Chlorophyll-a and phaeopigments were analyzed by fluorometric methods, and we performed simulated in situ C14 primary production experiments on 13 stations. We also measured chlorophyll-a in three size classes (>20μm, 1 to 20 μm, and <1 μm), dissolved inorganic nutrients (nitrate + nitrite, phosphate, ammonia, and silicate), light intensity, and phytoplankton and protozooplankton abundance and composition.