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In this study we compared the heavy metal concentration found in different tissues and eggs of the loggerhead sea turtle and evaluated the potential ecotoxicological risk for this important species. Eighteen heavy metal elements were determined in different tissues (liver, gonads, fat, kidney, heart, brain, and spleen) of nine individuals of Caretta caretta found stranded along the coasts of Messina (Sicily, Italy) and in the shell and yolk of six eggs from the island of Linosa (Sicily, Italy). For the analysis of the heavy metals, we used the analytical procedures in accordance with the EPA 200.8 method supplemented by EPA 6020b with three replicates for each measurement. The elements analysed showed different organotropism even if the liver showed higher levels of bioaccumulation. Turtles’ tissues showed the highest values of iron in the liver, followed by zinc in the heart and arsenic in the kidney. Regarding eggs, zinc, iron, and barium were dominant in the yolk and iron, boron, and copper in the eggshell. From the analyses carried out the worrying levels of arsenic and cadmium in the kidneys and liver of C. caretta raise questions about the risk related to exposure to these non-essential elements. This study highlights the importance of multi-element biomonitoring by increasing knowledge on the biodistribution of 18 heavy metals and the related potential risks for C. caretta. We also exploring for the first time the presence of several heavy metals in the eggs and their possible implication for the survival of the species.

New data on the potential impact of environmental parameters and the mineralogical nature of the substrate on the hatching success of the loggerhead sea turtle Caretta caretta on a volcanic beach on Linosa Island in the central Mediterranean Sea are reported. During 2 years of investigation (2018-19), five nests were observed. The temperature and moisture of the nests were determined along with the grain size and mineralogical nature of the substrate. The temperature values of the nests recorded at depths of 5 and 35 cm showed an average temperature incubation of 32.2°C ± 1.4°C and 32.8°C ± 1.6°C, respectively, with peaks close to 37°C. The sedimentological analysis carried out on two cores revealed the prevalence of large sandy particle and sediment moisture of about 35% in the deeper layers. A total of 214 laid eggs were recorded in 2018 with only 44 emerged turtles, whereas 45 turtles emerged from 199 laid eggs in 2019. Both years showed a low hatching success (25%-30%) and a high frequency of anomalies (>60%), which were present in individuals as nonmodal scutes or bifid limbs. Results suggest that environmental parameters such as temperature, sand moisture, and the geological nature of the substrate seem to play an important role in the reproductive success of this species. Some aspects for improving the nesting site and egg development conditions are also discussed.

During the monitoring of Caretta caretta nests on the island of Linosa, 30 unhatched eggs from four nests were collected to study the presence of phthalates in their three components (shell, yolk, and albumen). Four phthalates, namely diethyl (DEP), dibutyl (DBP), di-(2-ethylhexyl) (DEHP), and dioctyl (DOTP) phthalic acid esters (PAE), which are widely used as additives in plastics, were detected in all egg components. The most frequently found phthalate was DBP, followed by DEHP in eggshell and yolk. Dimethyl- (DMP) and butylbenzyl-phthalate (BBP) were below the limits of detection for all samples. The high total phthalate recorded in the yolk suggests that contamination could arise by vitellogenesis. PERMANOVA analysis (p = 0.01) confirmed significant differences in the PAEs contamination profiles in the eggs from the four nests. This study confirms the negative impact of plastic related compounds posing questions about the potential adverse effects on organisms and their conservation status.

In the Mediterranean Sea, bottom trawl, bottom longline and set nets are the fishing gears with the highest impact on marine turtle populations. These demersal gear types are characterised by a variety of metiers (fishing operations targeting a specific assemblage of species, using specific gear, during a precise period of the year and/or within a specific area). Data on fishing methods, target species and turtle bycatch were collected through interviews in three different study areas in the central Mediterranean. The results show that, even in the same fishing area, different metiers of the same gear can have a different impact on turtles. These findings have several implications. First, traditional turtle bycatch estimations and comparisons based on a fishing gear as a whole may be spatially or temporally biased by spatial and temporal differences in metier composition, respectively. Second, the efficiency of conservation measures may be different according to the metiers involved and caution is needed when measures developed in small areas with certain metiers are exported to a wider scale with possibly very different metiers. Third, conservation measures may induce shifts among metiers that may have an impact on other species, but such shifts are difficult to detect. All this suggests that, in the Mediterranean, a metier-based approach is needed to provide realistic estimates of turtle bycatch, to increase the efficiency of conservation measures by targeting only the most relevant metiers and to predict the changes in target species and effort distribution that can be driven by conservation measures. The variability of fishing methods and metiers implies that the most effective management strategies should be identified at relatively small geographical scales.