engleski

Diet composition of the loggerhead sea turtle, Caretta caretta, in the northern Adriatic Sea : a preliminary study

Croatian waters of the Adriatic Sea have been recognised as an important migration corridor for Caretta caretta, originating primarily from the Greek nesting population. Furthermore, analyses of bycatch and size classes points out on the significance of this waters as a developmental and feeding habitats for the species. A general necropsy was preformed on caracasses of four loggerheads (CCL: avg.= 68.2 cm, SD = 19.1), collected in the Northern Adriatic Sea, Croatia. The esophagus, stomach, and intestinal tract were removed guts contents were rinsed through fine-mesh sieve, and preserved in 76% ethanol. Food items were sorted in laboratory, and identified to the lowest possible taxon. Percent occurrence and percent dry weight were also calculated. Results showed that: (1) The loggerheads in the northern Adriatic have a chiefly carnivorous diet regime. They primarily feed upon a variety of benthic invertebrates and, occasionally, fish. (2) Echinoids and sponges seems to be the two highest ranked prey categories in the dietary composition of the loggerheads in the northern Adriatic Sea (Croatia), with 100% and 50% occurrence, and 67% and 15% of total dry weight. (3) Results support the theory of the opportunistic feeding habits of the loggerhead sea turtle. Even more, it seems that the same population in different sub-regions consumes different types of food, depending on the diversity of local benthic communities. (4) The presence of Aphrodita aculeata (Polychaeta, Annelida), the exclusive species of community of coastal detritical bottoms, suggest a preferred benthic community for the feeding of loggerheads in the northern Adriatic. Communities of coastal detritical bottoms and biocoenosis of coastal terrigenous ooze seem to present important feeding habitats of C. caretta in northern Croatian waters. These communities are common in the northern Adriatic, especially within the channels of Kvarner region and in the Velebit Channel. These waters may represent a loggerhead foraging area in the Adriatic Sea.

sea turtles; foraging ecology; Croatia

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