Mechanisms involved in the proliferation and distribution of phytoplankton in the Patagonian Sea, Argentina, as revealed by remote sensing studies

Abstract

Studies about the mechanisms that control the dynamics of phytoplankton in terms of surface chlorophyll patches by means of remote sensing information were encouraged in the Patagonian Sea (South Atlantic Ocean). Over this sea, circulation of the Patagonian Current and Malvinas Current, originated in the Circumpolar Antarctic Current, has much to do in the distribution of algal biomass. The study confirms the existence of three ecosystems: Coastal system, Shelf waters system and Shelf break. In the former, algal blooms are detected mostly between March and August. Later, the patches move inside the shelf area, the second ecosystem, towards NNE direction from approximately August to December under the influence of the Patagonian Current to reach the Malvinas Current, which circulates along the shelf break. The third ecosystem, Malvinas system, may be divided into the Malvinas Islands, where an intense algal bloom from December to January could be verified, and the Malvinas Current that shows a high concentration of algal pigment in the same period, although evidences support the hypothesis that the latter has mainly an allochthonous character. At about 37°S–39°S and 53°W–56°W, variable position, the confluence between Malvinas Current and Brazil Current takes place. As a result, the chlorophyll that functions as a tracer indicates that the impact has the characteristics of being an elastic collision, since the Malvinas Current identity was preserved afterwards. Special events, such as the climatic conditions that prompt changes in the annual behavior of the phytoplankton distribution, are discussed.