|
Résumé :
|
During a two-year period in Mar Chiquita coastal lagoon (Buenos Aires, Argentina), the diet of juvenile Paralichthys orbignyanus and Oncopterus darwinii sorted according to size, area, and season was analyzed. Sampling was carried out using a beach seine net in three zones of different salinity. The small size of the individuals collected and the high percentage of full stomachs, corresponding with high food availability in the lagoon, indicated that Mar Chiquita is used as a nursery ground. The diet of P orbignyanus consisted of crustaceans and polychaetes, whereas O. darwinii fed predominantly on small crustaceans (gammarid amphipods, harpacticoid copepods, mysids, and ostracods); polychaetes were less important. Diet of both flatfish species varied with length. Smaller individuals were microphagous, while bigger specimens included larger prey in their diet. Prey taxa number increased for both species, seawards to the mouth of the lagoon, probably related to the salinity gradient. Prey diversity for P. orbignyanus was highest in autumn and spring, and the lowest percentage of stomachs with food occurred in winter. Prey diversity was lowest for O. darwinii in spring and die highest percentage of empty stomachs was found in autumn.
|