Dietary Preferences of Loggerhead Sea Turtles (Caretta caretta) in Two Mediterranean Feeding Grounds: Does Prey Selection Change with Habitat Use throughout Their Life Cycle?

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.

Exposure of Mytilus galloprovincialis to Microplastics: Accumulation, Depuration and Evaluation of the Expression Levels of a Selection of Molecular Biomarkers.

Microplastic contamination is a growing marine environmental issue with possible consequences for seafood safety. Filter feeders are the target species for microplastic (MPs) pollution because they filter large quantities of seawater to feed. In the present study, an experimental contamination of Mytilus galloprovincialis was conducted using a mixture of the main types of MPs usually present in the seawater column (53% filaments, 30% fragments, 3% granules) in order to test the purification process as a potential method for removing these contaminants from bivalves intended for human consumption. A set of molecular biomarkers was also evaluated in order to detect any variations in the expression levels of some genes associated with biotransformation and detoxification, DNA repair, cellular response, and the immune system. Our results demonstrate that: (a) the purification process can significantly reduce MP contamination in M. galloprovincialis; (b) a differential expression level has been observed between mussels tested and in particular most of the differences were found in the gills, thus defining it as the target organ for the use of these biomarkers. Therefore, this study further suggests the potential use of molecular biomarkers as an innovative method, encouraging their use in next-generation marine monitoring programs.

New protocols to improve the deposition and hatching of Sepia officinalis' eggs.

The objective of this study was the development of hatching protocols in controlled conditions to obtain juveniles, in order to restock and increase the resource of Sepia officinalis. The study was divided into the following phases: development and application of artificial surfaces at specific sites of the Molise coast in Italy; induction of eggs hatching and juveniles maintenance under controlled condition; juveniles introduction into specific sites and assessment their increment; experimental data elaboration. The obtained results concerned both the effectiveness of the artificial surfaces tasted during the study and the importance of the recovery of the eggs laid on artificial surfaces (artefacts and fishing gear) for preservation and the management of the Sepia officinalis resource. The induction tests conducted on eggs hatching under controlled conditions confirmed what described in the extant literature. Water salinity was detected as the only limiting factor, with values ≤ 20% related to the absence of hatching. The described practices for harvesting and induction of hatching for the production of juvenile cuttlefish may be endorsed by the operators at relatively low cost and throughout the year, with obvious economic benefits.

Study of the efficacy of a closed cycle depuration system on bivalve molluscs.

The aim of this study was to develop and apply protocols for the microbiological depuration of bivalve molluscs (Chamelea gallina and Mitylus galloprovincialis). The study was divided into the following phases: preparation of two closed-circuit tanks fitted with mechanical, chemical and biological filtration systems for the depuration of bivalve molluscs, mollusc contamination and depuration, analyses of molluscs and depuration waters (biometric and microbiological tests) and statistical processing of the experimental data. The Escherichia coli challenge revealed the high efficacy of the depuration system and thus the possibility of preparing the molluscs for sale in a relatively short period of time. Depuration tests against Salmonella Typhimurium were effective only after 72 h to 84 h. Results for Vibrio parahaemolyticus revealed only a small reduction in the bacterial load during the entire observation period. However, depuration times were shorter in trials with mussels: V. parahaemolyticus was no longer detected after 36 h to 48 h.