Sea turtles can be considered a sentinel species for monitoring the health of marine ecosystems, acting, at the same time, as a carrier of microorganisms. Indeed, sea turtles can acquire the microbiota from their reproductive sites and feeding, contributing to the diffusion of antibiotic-resistant strains to uncontaminated environments. This study aims to unveil the presence of antibiotic-resistant bacteria in (i) loggerhead sea turtles stranded along the coast of Sicily (Mediterranean Sea), (ii) unhatched and/or hatched eggs, (iii) sand from the turtles’ nest and (iv) seawater. Forty-four bacterial strains were isolated and identified by conventional biochemical tests and 16S rDNA sequencing. The Gram-negative Aeromonas and Vibrio species were mainly found in sea turtles and seawater samples, respectively. Conversely, the Gram-positive Bacillus, Streptococcus, and Staphylococcus strains were mostly isolated from eggs and sand. The antimicrobial resistance profile of the isolates revealed that these strains were resistant to cefazolin (95.5%), streptomycin (43.2%), colistin and amoxicillin/clavulanic acid (34.1%). Moreover, metagenome analysis unveiled the presence of both antibiotic and heavy metal resistance genes, as well as the mobile element class 1 integron at an alarming percentage rate. Our results suggest that Caretta caretta could be considered a carrier of antibiotic-resistant genes.

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In this study, we evaluated the microbiome and the resistome profile of water and fragments of polyethylene (PE) waste collected at the same time from a stream and the seawater in a coastal area of Northwestern Sicily. Although a core microbiome was determined by sequencing of the V3–V4 region of the bacterial 16S rDNA gene, quantitative differences were found among the microbial communities on PE waste and the corresponding water samples. Our findings indicated that PE waste contains a more abundant and increased core microbiome diversity than the corresponding water samples. Moreover, PCR analysis of specific antibiotic resistance genes (ARGs) showed that PE waste harbors more ARGs than the water samples. Thus, PE waste could act as a carrier of antibiotic-resistant microbiota, representing an increased danger for the marine environment and living organisms, as well.

This review is a survey of recent advances in studies concerning the impact of poly- and perfluorinated organic compounds in aquatic organisms. After a brief introduction on poly- and perfluorinated compounds (PFCs) features, an overview of recent monitoring studies is reported illustrating ranges of recorded concentrations in water, sediments, and species. Besides presenting general concepts defining bioaccumulative potential and its indicators, the biodistribution of PFCs is described taking in consideration different tissues/organs of the investigated species as well as differences between studies in the wild or under controlled laboratory conditions. The potential use of species as bioindicators for biomonitoring studies are discussed and data are summarized in a table reporting the number of monitored PFCs and their total concentration as a function of investigated species. Moreover, biomolecular effects on taxonomically different species are illustrated. In the final paragraph, main findings have been summarized and possible solutions to environmental threats posed by PFCs in the aquatic environment are discussed.

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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.

The first determination of presence and biodistribution of PFOA in ninety specimens of sea urchin Paracentrotus lividus from two differently contaminated sites along Palermo’s coastline (Sicily) is reported. Analyses were performed on the sea urchins’ coelomic fluids, coelomocytes, gonads or mixed organs, as well as on seawater and Posidonia oceanica leaves samples from the collection sites. PFOA concentration ranged between 1 and 13 ng/L in seawater and between 0 and 794 ng/g in P. oceanica. The analyses carried out on individuals of P. lividus from the least polluted site (A) showed PFOA median values equal to 0 in all the matrices (coelomic fluid, coelomocytes and gonads). Conversely, individuals collected from the most polluted site (B) showed median PFOA concentrations of 21 ng/g in coelomic fluid, 153 ng/g in coelomocytes, and 195 ng/g in gonads. Calculated bioconcentration factors of log10BCF > 3.7 confirmed the very bioaccumulative nature of PFOA. Significant correlations were found between the PFOA concentration of the coelomic fluid versus the total PFOA concentration of the entire sea urchin. PERMANOVA (p = 0.001) end Welch's t-test (p < 0.001) analyses showed a difference between specimens collected from the two sites highlighting the potential application of P. lividus as sentinel species for PFOA biomonitoring.

Perfluorooctanoic acid (PFOA) has been largely used in the manufacturing industry but a few years ago it turned out to be a dangerous pollutant which is now of concern for terrestrial and aquatic environments. Here, we investigated the bioaccumulation of PFOA in the sea urchin Paracentrotus lividus after exposure to different concentrations of the pollutant for 28 days. We observed rapid uptake of PFOA in the coelomic fluid collected weekly during the exposure period and high bioaccumulation in gonads at the end of the experiment. Interestingly, animals were also able to fast depurate when relocated to a clean environment. In addition, to assess the effect of PFOA on sea urchins’ physiological pathways, we analysed the expression profile of some marker genes both in the gonads and in the embryos obtained from parents exposed to PFOA. Our results suggest that PFOA is a persistent, bioaccumulative compound that adversely affects the health of the exposed organisms and their offspring by causing significant changes in the expression of some key target genes and the occurrence of developmental anomalies in the embryos.