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Otolith geochemistry of Diplodus puntazzo and Diplodus vulgaris from marine waters and estuaries in the eastern Adriatic Sea

Studies of fish otolith geochemistry have contributed to the understanding of the life history, segregation, connectivity and nursery identification of different fish species in many areas of the world. Otoliths are calcified structures located in the inner ear of fish that are composed of calcium carbonate. They represent archive of information on life histories in a chronological manner, making it possible to retrieve information on environmental conditions experienced by individual fish from hatching to capture. Otolith chemical signature in the core (young stage) may reflect nurseries areas, while the edge (adult stage) could indicate the presence of geographic management units. Differences in otolith geochemistry of sharpsnout seabream, Diplodus puntazzo and two-banded seabream, Diplodus vulgaris, which inhabited coastal waters and estuary, were determined to evaluate movement patterns. Juvenile fish of D. puntazzo and D. vulgaris were collected by beach seine net on two locations (estuary of river Pantan near Split and cove Sovlja near Šibenik) in the eastern Adriatic during June 2018. Upon collection fish were kept frozen and transported to the lab were the length and weight of each specimen were measured, the otoliths have been extracted, cleaned and prepared for transverse sections through the otolith core with a low-speed saw. On the predetermined sections of otoliths with visible cores and growth marks, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to quantify concentrations of 12 chemical elements along maximum growth rates. Among them, Zn, Na, Mg, Sr, Ba, Mn, Li showed differences between the individuals and locations. Obtained concentrations and peaks could be related to the different habitats and certain part of the otoliths for each individual. The results represent the first geochemical study of Diplodus puntazzo and Diplodus vulgaris otoliths in the Adriatic and reveal the potentials of this method for the interpretation of ontogenetic movements.

Otolith geochemistry, Diplodus puntazzo, Diplodus vulgaris, Adriatic Sea

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