The EPEA (Estación Permanente de Estudios Ambientales) time series station was started in 2000 and since 2003 belongs to ANTARES (www.antares.ws), a network of Latin American time series stations whose main goal is the study of long-term changes in coastal ecosystems to distinguish those due to natural variability from those due to external perurbations (anthropogenic effects).Different research groups at the INIDEP (the National Institute of Fisheries Research and Development of Argentina) sample at the EPEA station, monitoring chemical, environmental and bio-optical variables as well as the bacterioplankton, phytoplankton, zooplankton, and the icthyoplankton communities. EPEA station is located on the Argentine shelf (38°28'S, 57°41'W), 27.0 nautical miles from Mar del Plata city and 13.5 nautical miles from the coast and has a depth of 50m. EPEA is characterized by a temperate regime, with annual sea surface temperatures between 10°C and 21°C and salinity values ranging between 33.5 and 34.1. Occasionally the site can receive less salty waters coming from the North, influenced by the La Plata River, driving salinity values to less than 31.0. Its oceanographic regime is described as the transition between high salinity coastal waters to the medium shelf (Guerrero et al., 1997).