“…where climatic variation such as rain and floods is the only source of freshwater inputs), have been reported to be characterized by marine and brackish species with the dominance of the families Sparidae, Mugilidae, Gobiidae, Atherinidae, Soleidae, Sygnathidae and Blennidae (Pérez-Ruzafa et al 2006, Maci and Basset 2009, Verdiell-Cubedo 2009. On the other hand, fish assemblages of coastal lagoons with artificial freshwater supplies, such as the Vaccarès lagoon (France; Poizat et al 2004) and the Albufera lagoon (Spain; Blanco et al 2003, Blanco andRomo 2006), have families typical of freshwater environments, in addition to the aforementioned brackish and marine species. Our results suggest that the hydrological alteration of the cycle might be the responsible for the current fish community in the Ebro Delta coastal lagoons composed by brackish and marine families such as Gobidae, Mugilidae and Atherinidae and by freshwater species belonging to the families Cyprinidae and Poecilidae (Blanco et al 2003, Poizat et al 2004, Blanco and Romo 2006.…”