According to their life stage, the loggerhead sea turtle (Caretta caretta) is found in a wide range of habitats, from neritic to more oceanic areas. Their feeding habits are expected to change as they develop, along with habitat use. Juvenile sea turtles are hypothesized to feed on pelagic species in oceanic areas, shifting to more benthic prey during the subadult and adult stages. We analyzed the gastrointestinal content from 150 loggerhead sea turtles stranded and/or bycaught along the Adriatic coast of the Abruzzo and Molise regions (n = 89) and the Tyrrhenian coast of the Lazio and Campania regions (n = 61) from 2018 to 2021. Food items were identified to the lowest taxonomic level, and the frequency of occurrence was calculated for each taxon and most recurrent species to assess changes in prey selection during the development. The marine litter was categorized, and the frequency of occurrence was calculated for the ingestion of litter. The most recurrent taxonomic prey group recorded in the Adriatic sample was Arthropoda (94%), followed by Mollusca (63%) and Chordata (34%). In the Tyrrhenian sample, loggerhead sea turtles fed mostly on Mollusca (84%), Arthropoda (38%), and Chordata (26%). Surprisingly, the Adriatic-Tyrrhenian sample groups showed similar feeding behavior between juveniles, subadults, and adults. A similar correlation has been observed concerning the ingestion of litter. Moreover, this study confirms the opportunistic feeding behavior of loggerhead sea turtles and their high adaptability.

Persistent organic pollutants are widespread in the marine environment. They can bioaccumulate and biomagnify in marine organisms through the food web with a potentially toxic effect on living organisms. The sea turtle Caretta caretta is a carnivorous animal with opportunistic feeding behavior. These turtles tend to bioaccumulate pollutants through food, and hence they can be considered an indicator of chemical pollutants in the marine ecosystem. In this study, 44 loggerhead sea turtles were considered, and liver and fat tissue were sampled from each of them to investigate the levels of dioxins (PCDD/Fs) and polychlorinated biphenyls (PCBs) in sea turtles and their potential correlation with sex and size in terms of curved carapace length (CCL). Results suggested that these contaminants were easily bioaccumulated, and PCBs were predominant compared to dioxins in both liver and fat tissue. The congener patterns were similar to those found in sea fish. Moreover, there were no differences in the contamination levels between females and males, nor was there a correlation with the size. There is a need to harmonize the methodological approaches to better evaluate the results and trends over time and to monitor the species and indirectly the health status of the marine environment.

Sea turtles, particularly the opportunistic feeder species loggerhead turtles (Caretta caretta), are increasingly reported as a source of disturbance to mussel farming operations, especially in the Adriatic Sea. Despite the evident damage caused by these interactions, comprehensive national data on the phenomenon are still lacking. This study aimed to address this gap through a survey conducted among Italian mussel farmers, combined with the analysis of gastrointestinal contents from stranded sea turtles along the Adriatic and Tyrrhenian coasts, focusing on the ingestion of Mediterranean mussels (Mytilus galloprovincialis). Survey results revealed frequent turtle sightings in the northern Adriatic (Veneto and Emilia-Romagna) during summer months (June to August), while southern regions (Molise and Puglia) reported more sightings in autumn (September to October), likely influenced by seasonal water temperatures. The Mediterranean mussel was identified as the most commonly ingested mollusk in the Adriatic, with a notable increase in presence from 2018 to 2021. Although mussels are not a targeted prey, they appear to be a consistent dietary component due to adaptive feeding behavior. These interactions are increasingly and consistently reported, leading to significant management challenges for mussel farms. Based on these findings, a broader national and international assessment is recommended to evaluate the overall impact of sea turtles on shellfish aquaculture in the Mediterranean.

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles.

The Adriatic Sea is a critical neritic habitat for juvenile and adult female loggerhead sea turtles (Caretta caretta), where intense anthropogenic pressures and environmental stressors may influence their reproductive biology. Knowledge on the onset of puberty in this population is limited by scarce information on the sub-adult stage, a transitional phase in which reproductive competence is acquired. This study integrated histological analysis and Fourier-transform infrared (FTIR) imaging spectroscopy to provide both structural and biochemical characterization of folliculogenesis, with emphasis on vitellogenesis, in C. caretta from the north-central Adriatic Sea. Histological analysis determined the progression of follicle development, while FTIR imaging, a label-free and spatially resolved technique, mapped the distribution of proteins, lipids, and nucleic acids across ovarian compartments. Logistic regression estimated the size at which 50% of females are sexually mature (L₅₀) at 58.54 cm Curved Carapace Length (CCL). Based on this value, 60% of sub-adult females were already mature, indicating earlier puberty than previously inferred from macroscopic criteria. These preliminary results, along with reports of sporadic nesting in the Adriatic, raise the question of whether this basin may host further nesting events in the future. FTIR imaging proved to be a powerful tool for reproductive biology in non-model marine vertebrates.