Feeding ecology of the white seabream, Diplodus sargus, and the ballan wrasse, Labrus bergylta, in the Azores

To make a first approach in the assessment of the sea urchin predators in the Azores, the diet of white seabream (Diplodus sargus) and ballan wrasse (Labrus bergylta), were studied by the analyses of their stomach contents. The white seabream is a diurnal omnivore, feeding on algae, sea-urchins, worms, gastropods and amphipods, while ballan wrasse fed mainly on echinoderms (sea-urchins), gastropods and decapods. Both species tended to feed on harder prey, such as echinoderms and gastropods, as they grew. Although both species feed upon similar resources, the diet overlap was low. This study shows that the white seabream and the ballan wrasse are important predators of sea-urchins in Azorean coastal habitats. Furthermore, larger fish account for most of the predation on sea-urchins. Thus, a reduction in the abundance and mean size of fishes, which is a typical consequence of fishing, may significantly decrease predation on sea-urchins and could thus facilitate their proliferation.