Trophic Interactions Between Xyrichtys novacula (Labridae) And Juvenile Pagrus pagrus (Sparidae) In The Central Mediterranean Sea


Luca Castriota1, Maria Grazia Finoia2, Franco Andaloro1


1 ICRAM (Central Institute for Applied Marine Research), via Emerico Amari 124, 90139 Palermo, Italy.


2 ICRAM, via di Casalotti 300, 00166 Roma, Italy.



Abstract: The trophic relationships between the pearly razorfish Xyrichtys novacula and the juvenile red porgy Pagrus pagrus living in the same area of the Tyrrhenian Sea were investigated. Stomach content analyses revealed that both fishes fed mainly on benthic crustaceans and molluscs. Pagurids, brachyurans and gastropods were preferred prey of red porgy while amphipods, copepods and bivalves were more important in the diet of pearly razorfish. Highly significant differences between predators were found in prey abundance as well as in prey weight. Non significant values of Pianka’s index of niche overlap were obtained for prey abundance, weight and IRI. Co-inertia analysis showed prey separated in one or the other predator; they were not particularly segregated in predator size classes of 15 mm TL, which differed significantly in mean prey weight exploited. This study showed that the two predators living in the same habitat occupy a different trophic role, showing prey partitioning and low diet overlap.


Key words: diet overlap, Pagrus pagrus, resource partitioning, Tyrrhenian Sea, Xyrichtys novacula


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