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,
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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