Abstract
Integrated otolith chemistry and muscle tissue stable isotope analyses were performed to allocate juvenile Diplodus puntazzo and Diplodus vulgaris to nurseries in the Adriatic Sea. Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was used to quantify the concentrations of chemical elements in the otoliths. Fish muscle samples were analysed for δ13C and δ15N. In general, Ba/Ca and Sr/Ca ratios and isotopes varied between sites and species. Values of δ13C and δ15N were significantly different between species and sites. Multivariate analysis detected a significant difference in the element signature between species while there was no evidence for a significant interaction for sites. A clear pattern across the four groups of interest, D. puntazzo_Estuary > D. vulgaris_Estuary > D. puntazzo_Coastal > D. vulgaris_Coastal, following decreases in δ13C, and increases in δ15N were found. It seems that these species are feeding on the same local food web within more productive estuarine site while at costal site, feeding segregation among investigated species is evident. Both species were re-allocated correctly to the estuarine waters based on the otolith chemistry and stable isotopes information and higher value of δ15N. Combining otolith chemistry with tissue isotope ratios of juvenile fish provided complementary information on nursery habitat use at different spatial scales and elucidated ecological and environmental linkages.
Highlights
Elucidating movement and life-history characteristics of marine organism is of crucial importance for their management and conservation [1,2,3] and the knowledge gap still represents a challenge to scientists working on this issue
Settled juveniles of sharpsnout seabream, Diplodus puntazzo and common two-banded sea bream Diplodus vulgaris were collected from two sites along the eastern
Juveniles of D. vulgaris ranged in total length (TL) from 4.3 to 7.1 cm
Summary
Elucidating movement and life-history characteristics of marine organism is of crucial importance for their management and conservation [1,2,3] and the knowledge gap still represents a challenge to scientists working on this issue. Coastal ecosystems are highly structured and fragile environments, and many valuable coastal systems are under high anthropogenic pressures, resulting in species loss and habitat degradation [6,7,8]. Mediterranean coastal areas are becoming progressively degraded, and increasing anthropogenic pressures and destructive and illegal fisheries are causing severe repercussions [9]. Synthetic glass NIST SRM 612 (National Institute of Standards and Technology; Gaithersburg, Maryland, United States ) was used to calibrate element concentrations of otolith samples and quality control materials (QCMs) (USGS MACS-3, USGS BCR-2G, NIST SRM 610). (Table 2) were used to monitor accuracy and precision of the LA-ICP-MS analysis applying the preferred values available from the GeoReM database ([66], application version 26; compared with [67,68,69]). The concentration of 43 Ca as an internal standard in otoliths was taken as 38.8%
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