The Ichthyofauna and Abiotic Hydrological Environment of the Ria de Aveiro, Portugal

Abstract

The abiotic hydrological environment and the community dynamics of the fish fauna were investigated in the Ria de Aveiro, an estuarine coastal lagoon system (43 km2), which has both marine and fluvial influences. Abiotic hydrological and fish community parameters were recorded routinely during 12 months at ten stations. Temperature ranged between 9.5°C and 26.0°C, salinity between 0.0‰ and 32.0‰, dissolved oxygen between 0.8 mg 1−1 and 15.4 mg 1−1, pH between 6.1 and 9.4, and transparency between 4.4% and 100.0%. No significant differences were observed in temperature and dissolved oxygen among stations, or in seasonal variation in transparency. Nineteen thousand thirty-one fish specimens comprising 55 species were sampled. Abundance, biomass, and species richness were highest in summer and late winter at stations near the lagoon entrance. Sedentary species were most numerous, marine migratory species had the highest biomass, and the category “occasional species” had the highest number of species. Atherinidae, Mugilidae, and Gobiidae were the most important families. Eight species represented about 80% of the total fish abundance and biomass but only six species occurred in all the months and at all the stations. It was concluded that the Ria de Aveiro, with high seasonal and spatial abiotic variation, has a very rich and representative fish community compared with temperate and tropical estuaries and estuarine coastal lagoons around the world.