Unveiling the egg microbiota of the loggerhead sea turtle <i>Caretta caretta</i> in nesting beaches of the Mediterranean Sea

Microbes have central roles in the development and health of animals, being the introduction of specific microbial species a potential conservation strategy to protect animals from emerging diseases. Thus, insight into the microbiota of the species and their habitats is essential. In this manuscript, we report for the first time the bacterial composition of all the components (eggshells of hatched and unhatched eggs, internal content of unhatched eggs, intestinal content of hatchling and pipping sea turtles, and sand) of three nesting beaches of Caretta caretta along the Italian coasts of the Mediterranean Sea. The analysis of 26 amplicon samples was carried out using next-generation sequencing analysis, targeting V3-V4 regions of the bacterial 16S rRNA gene. Samples featured mainly Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes, whose percentages depended on the sample type. Our results showed that, although from different sampling sites, the internal content of the unhatched eggs, intestinal content of hatchling and pipping sea turtles share the microbiota, which was yet different from that of eggshells and sand of the same nesting beach. This study suggests the maternal and environmental influence alongside a protective role of eggshells in shaping the egg microbiota of Caretta caretta sea turtles

Impact of Heavy Metals in Eggs and Tissues of C. caretta along the Sicilian Coast (Mediterranean Sea)

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