Environmental factors influencing the gobiid assemblage of a MediterraneanLagoon: Empirical evidence from a long-term study

A severe freshwater inflow during our long-term ichthyological study of the brackish Vaccares lagoon (1993-1998) helped us to assess the impact of sud den environmental changes on the specific biomass composition of the gobiid population and the catches per unit effort of the black goby Gobius niger, the common goby Pomatoschistus microps and the sand goby P. minutus. In 19 93, the composition of the Gobiid fish assemblage of the Vaccares lagoon wa s dominated by the black goby (63%) and finally evolved to an assemblage do minated by the common goby (80%). The black goby disappeared from the Vacca res lagoon 2 years after the inflow, whereas catches of the common goby inc reased significantly after the environmental changes and reached maximum va lues in 1998. Catches of sand goby did not seem to be affected by environme ntal changes and depended on the communication between sea and lagoon. This study showed that evolution of an ecosystem after environmental changes is linked to the reaction that species developed to face perturbations.