engleski

Diet overlap in juvenile Sparidae species caught in the south-eastern Adriatic (Croatia)

The diet patterns of three Sparidae species (Sarpa salpa, Boops boops, Diplodus vulgaris) from south-eastern Adriatic were investigated. Samples were collected using demersal trawl net from March to July 2009. During the research length-weight relationship, feeding habits and Schoener index were analyzed for total of 1354 juveniles. Total lengths of analyzed juveniles range from 2.0 to 6.5 cm, and growth in all three species showed positive alometry. Stomach content analysis showed that B. boops and D. vulgaris were feeding mainly on zooplankton while juveniles of Sarpa salpa were feeding on zooplankton until they have reached the total length of about 3.0 cm after which they fed only on plant material. Copepods: Calanoida, Cyclopoida, Harpaticoida, Cyclopoida-Onceae had the largest shares in the total amount of zooplankton prey. The most frequent group of prey in stomach of all three species was Calanoida. Diet overlap was calculated using Schoener´s index, which showed significant diet overlap in May when all three species were present at the same time. In other months competition was not present due to different spawning period. These results confirmed significant level of food competition between these three species when present at the same place.

Sarpa salpa; Boops boops; Diplodus vulgaris; juvenile; diet overlap

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