Patos Lagoon is the largest (1,036,000 ha) choked lagoon in the world, extending from the city of Porto Alegre (30º30’ S) to Rio Grande (32º12’ S) in southern Brazil, at the Atlantic coast of South America. In the southern reaches, the Patos Lagoon Estuary and Adjacent Coast (PLEA) present high biological productivity and at the same time provide significant ecosystem services including artisanal and industrial fisheries, an industrial conglomerate and is home to an important maritime port.
The hydrology and biology of the ecosystem has been studied since the nineteenth century and the site has been included in the framework of the Brazilian Long Term Ecological Research in 1998. Systematic analysis has been conducted of abiotic and biotic information unraveling the functioning of the ecosystem and their organisms from phytoplankton to marine mammals.
Climatic events and human activities both affect the ecology of the highly dynamic PLEA. This shallow warm temperate estuary is river dominated, and freshwater discharge peaks are strongly associated with El Niño Southern Oscillation - ENSO episodes. Rainfall increases significantly during El Niño periods, while low discharge occurs during La Niña when drought conditions are observed. These phenomena influence salinity, physico-chemical water characteristics and sediment dynamics in the estuary, which in turn influence the biota. Long-term continuous studies (more than 25 years) have demonstrated that significant changes of phytoplankton, zooplankton, macrobenthic fauna and flora, crustaceans, fish and marine mammals in these coastal ecosystems are induced by natural impacts and human-related factors.
Moreover, freshwater water discharge to the Atlantic Ocean has an overriding influence on ecological processes in the adjacent coastal region and vice-versa fishing activities on the coastal region influence the ecology of the estuary. These conclusions were only possible due to long-term continuous studies conducted in the Patos Lagoon estuary and adjacent coastal region, making this dataset the most comprehensive in South America.
