Temporal and spatial variation in the trophic ecology of the banded puffer fish Colomesus psittacus (Tetraodontiformes: Tetraodontidae) in the Amazon coastal zone

Tidal cycles and spatial and seasonal variations in salinity have a marked effect on foraging and feeding patterns of fishes in tropical estuaries. We quantified spatiotemporal variations in the diet of one of the most abundant fish of the Amazon estuary, the Tetraodontidae banded puffer fish Colomesus psittacus, in relation to macrotidal cycles and salinity changes. Monthly samplings were performed at three sites in the Amazon coastal zone in tidal creeks with different salinity levels (Mosqueiro Island, Maiandeua Island and Ajuruteua Beach). Feeding intensity was higher during the spring tide at both Maiandeua and Ajuruteua islands, which can be accounted for by the wider foraging area for the species and higher prey availability. The diet was composed primarily of the cirriped Amphibalanus, Brachyura crustaceans and the mollusc Lilloraria unguliftru Lamarck, 1822. Diet composition varied spatially and temporally by periods of the year, sampling site, tides and the size of individuals. However, this variation was more pronounced in the area with high and relatively stable salinity (Ajuruteua), in contrast with the polyhaline environment at Maiandeua Island, where seasonal fluctuations in salinity result in the mixing of freshwater, estuarine and marine invertebrates.