Ontogenetic diet shifts and food partitioning between two small sympatric skates (Chondrichthyes, Rajidae) in the Southwestern Atlantic

BARBINI, SANTIAGO A.; LUCIFORA, LUIS O.

MARINE AND FRESHWATER RESEARCH

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2012 vol. 63 p. 905 - 913

1323-1650

Knowing howsympatric species partition their resources is very important for understanding themechanisms that influencemarine community structure.We test the hypothesis of resource partitioning between two sympatric, closely related, morphologically similar, small skates, Psammobatis bergiandP. extenta. The diets of the two species were different.P. bergifed predominantly on crabs, amphipods, isopods and polychaetes. P. extentaconsumed mainly amphipods and shrimps. Changes in the diet with body size, maturity stage and season varied among species. The consumption of amphipods decreased with increasing size of both species. The consumption of crabs increased with increasing size ofP. bergi, but decreasedwith increasing size ofP. extenta. The consumption of cumaceans increasedwith size ofP. extentaand decreased with size ofP. bergi. Adults preyed on isopods more heavily than juveniles for both species.P. extentapreyed on shrimps more heavily in the warm season and, on the contraryP. bergipreyed on shrimps more often in the cold season. The dietary breadthwas higher inP. bergithan inP. extentaandwas higher in females than in males. Our results showed that these sympatric and closely-related species have clearly different trophic traits.