Exploring the presence of pollutants at sea: Monitoring heavy metals and pesticides in loggerhead turtles (Caretta caretta) from the western Mediterranean.

Marine turtles are considered good sentinel species for environmental assessment because of their long lifespan, feeding ecology, habitat use and migratory nature. In the present study, we assessed presence of cadmium, lead and mercury, together with organic pollutants, both in fat and muscle tissue of 25 stranded loggerhead turtles (Caretta caretta) stranded along the Valencian Community coast (East Spain) (43.7 +/- 13.5 cm). Mean concentrations of Cd, Pb and Hg were 0.04 mu g/g w.w., 0.09 mu g/g w.w. and 0.03 mu g/g w.w. in fat and 0.05 mu g/g, 0.08 mu g/g and 0.04 mu g/g in muscle, respectively. These measures indicate a relatively low mean heavy metal concentration, which may be explained by juvenile size and developmental stage of the turtles analysed. A preliminary non targeted analysis (using time-of-flight (TOF) technology), made for the first time in marine turtles, allowed to detect 39 different pesticides, most of them previously undetected in this species. Most of the organic substances detected are used in agricultural activities, and the use of 15 of them (38.5%) is not approved in the European Union. Our sample did not show any trend on pollutant contents in relation to turtle size or stranding location, probably because of the high diversity of pollutants found. However, the potential for a positive latitudinal gradient should be explored in future studies due to riverine inputs and high agricultural and industrial activities in the area. Despite the high diversity of pollutants found here, comparative studies of pollutants in other matrices at sea are needed to ascertain whether the loggerhead turtle is a good sentinel of chemical pollution in the western Mediterranean. (C) 2017 Elsevier B.V. All sights reserved.