Relazioni trofiche tra le specie ittiche residenti in tre laghi costieri del parco nazionale del Circeo.

In order to describe diet, use and allocation of available food resources, and feeding relationships of resident fish species in the coastal lakes of the Circeo National Park, stomach contents of 1729 fish have been examined, belonging to the species Aphanius fasciatus, Atherina boyeri, Gobius niger and Knipowitschia panizzae. Fish have been collected in the coastal lakes of Fogliano, Monaci and Caprolace in the course of four seasonal samplings carried out between 2003 and 2004, that have also allowed to collect, in the same moments and in the same sites, samples relative to zooplankton and to zoobenthic community. Occurrence frequencies of preys and correspondence analysis used for comparing the food spectra with the available resources have revealed alimentary choices of the fish and their feeding strategies in the three coastal lakes studied. The two pelagic species, A. boyeri and A. fasciatus were mainly zooplanktivorous. Copepods were the prey item most frequent, while larvae of bivalves and chironomids, this last one only for big-scale sand smelt specimens, were common prey. G. niger and K. panizzae showed definite benthic habits. Crustaceans, in particular amphipods, were the most important item in the diet of both benthonic fish, while larvae of chironomids were only secondary prey item. Instead small fishes were a common prey item only for the black goby specimens. Planktonic feeders had a similar spectrum, quite narrow as it presented a reduced number of items. The two benthic species showed a broader spectrum, with G. niger showing a wider-ranging diet with respect to K. panizzae.