Study on the relationship between trace elements and microbiological profiles in organs and tissues, for an innovative ecological perspective on the health of sea turtle Caretta caretta

Environmental factors, particularly exposure to marine contaminants, can compromise immune function in marine species, including sea turtles, increasing their susceptibility to bacterial and viral infections. In this context, the present study analyzes trace element bioaccumulation and bacterial presence in organs and tissues of stranded loggerhead turtles (Caretta caretta) from the Tyrrhenian coast of Southern Italy and explores the potential associations between contaminant levels and bacterial infections. Liver, kidney, muscle, and blood from 36 loggerhead turtles were analyzed for 17 trace elements, classified as essential (e.g., zinc and selenium) and non-essential (toxic) elements (e.g., cadmium, lead, mercury). Results highlighted organ-specific differences in trace element concentrations, attributable to the roles of these organs in detoxification and storage mechanisms. Bacteriological analyses revealed a wide range of bacterial species, mainly gram-negative strains of the families Vibrionaceae, Enterobacteriaceae and Shewanellaceae, as well as some gram-positive bacteria of the families Enterococcaceae and Streptococcaceae. No statistically significant correlation was observed between toxic element concentrations and bacterial presence; however, mercury levels exhibited a slight tendency to be associated with bacterial colonization, warranting further investigation. This study provides valuable data on the accumulation of contaminants and bacterial profiles in Caretta caretta. These results will contribute to ecological risk assessments and improve conservation strategies aimed at reducing the impact of pollution on marine species.