The Ria Formosa lagoon, situated in the South of Portugal, has a tradition of aquaculture, providing excellent conditions for this activity. In January 1985, a study of the benthic populations and of the water quality began in three salt-pans and in a coastal lagoon, near Olhao: Ria Formosa (GAMITO, 986). This study was intented to determine the actual ecological conditions and relate these to the dynamics of water circulation, in order to suggest the modifications necessary in similar sites which could then be either used exclusively for aquaculture, or support mixed fisheries. In this work, the stations have been compared by multivariate analysis, principal component analysis and correspondence analysis. It has thus been possible to characterize and group the stations according to their fauna1 composition and relate this to the water quality. The more confined areas, with great variations of salinity during the year, are characterized by the presence of a few abundant species: Capitella capitata (Fabricius), Hydrobia spp., Cerastoderma glaucum Linnaeus and Chironomid larvae. |