Marine ecosystems are increasingly threatened by pollutants, including trace elements (TEs) such as heavy metals, which bioaccumulate and pose risks to both marine fauna and human health. Sharks and rays are particularly susceptible to metal uptake and retention, making them sentinel species for assessing environmental contamination. This study investigated the bioaccumulation of 16 TEs across 12 elasmobranch species sampled from the Ionian and Tyrrhenian coasts of Calabria, southern Italy, over an 11-year period. Muscle tissue was analyzed for all species, while additional comparisons among skin, muscle, and brain tissues were conducted for Galeus melastomus. Statistical analyses revealed significant variability in TEs concentrations across trophic levels (TRLs), with higher levels observed in species occupying higher trophic positions. Positive correlations were noted for elements such as Al, Ba, and Se, while negative correlations were found for Co, Cu, Mn, and U, indicating species-specific metabolic adaptations. Tissue-specific analyses identified the skin as a primary site for TEs accumulation, likely due to its barrier functions and external exposure. This study highlights the complex interplay of ecological, dietary, and physiological factors influencing TEs bioaccumulation in elasmobranchs and emphasizes the need for further research to understand the implications for marine food webs and conservation strategies.

Marine environmental pollution has been rapidly increasing in Arctic waters, and the release and bioaccumulation of trace elements in Arctic marine species may pose significant risks to both ecosystem health and human well-being. As a top predator, the Greenland shark is an ideal sentinel species for ecotoxicological studies in this region. In this study, trace element analyses were conducted on various tissues from two Greenland sharks—a male and a female—collected in Kulusuk (southeastern Greenland). Eleven trace elements (Mn55, Co59, Cu63, Zn64, As75, Se82, Rb85, Mo98, Ag107, Cd112, and Pb208) were measured in different skin samples from both specimens and in the muscle and fat of the female using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Principal Component Analyses (PCAs) revealed sex-related differences in skin bioaccumulation patterns, likely due to sampling of different skin regions. Notably, skin tissues from both sharks showed the highest concentration of trace elements, especially for As75 (9.39–41.13 ppm) and Zn64 (24.34–50.99 ppm) and with the exception of Ag107. These findings suggest that environmental exposure may play a more significant role than dietary intake in trace element accumulation in this area. This study represents the first investigation of trace element bioaccumulation in Greenland sharks from Kulusuk. While the results offer important preliminary insights into the species’ ecotoxicology, further research involving more specimens and tissues is needed to confirm these trends. These initial findings contribute to filling key data gaps and have implications for both environmental monitoring and public health within the Greenlandic community.

The European eel (Anguilla anguilla), a catadromous species currently listed as Critically Endangered by the IUCN, is undergoing a severe continental decline. Among the multiple contributing factors, chemical contamination of aquatic environments—particularly by heavy metals—plays a major role. This study analyzed the concentrations of 16 trace elements in the muscle tissue of A. anguilla specimens collected from three ecologically distinct sites in Southern Italy: an estuary (Foce del Crati), a lagoon (Laghi di Gizzeria) and a stream (torrente Raganello). Correlations between trace element accumulation and the onset of oxidative stress were also examined. To assess eel health status, oxidative biomarkers were also analyzed in heart, liver, and gill tissues. Statistical analysis among populations revealed significant differences in the bioaccumulation of 10 of the 16 elements, with Cd and As being of particular concern. No significant correlations were found between these two elements and oxidative biomarkers, but Spearman analysis identified both positive and negative correlations with other elements varying by the site of collection. Oxidative biomarkers also showed site- and tissue-specific variation. In particular, SOD activity was highest in the liver and varied across sites; LPO and protein carbonyl levels were generally lower in eels from the Crati River, although heart values deviated from this trend, highlighting tissue-specific response patterns. These results underscore the complex interplay between chemical contamination and the physiology of the European eel, emphasizing the influence of environmental context in modulating tissue-specific oxidative responses.

Directional asymmetry (DA) is a widespread yet often overlooked feature of animal morphology. Here, we report a consistent right-biassed asymmetry in the crystalline lenses of the thornback ray Raja clavata. Across 71 individuals sampled from the Strait of Sicily, 24% exhibited lens asymmetry, and in all cases, the right lens was larger. This pattern, supported by binomial and distributional tests, represents the first evidence of ocular DA in this species. Body size and age emerged as the primary correlates of asymmetry: the odds of exhibiting DA increased significantly with body weight, whereas the effects of sex and sampling site were not significant. The prevalence of asymmetry thus appears to rise with age and ontogenetic growth. Two non-exclusive mechanisms may account for this pattern. First, the association with positive allometry (b = 3.33) suggests that right-lens enlargement could reflect a functional or developmental lateralisation, potentially conferring a visual or ecological advantage to larger individuals. Alternatively, the same right-lens bias could arise through an age-related pathological process, such as oxidative or osmotic lens swelling preceding cataract formation, consistent with asymmetric physiological wear. These findings reveal a novel case of morphological lateralisation in an elasmobranch and highlight the need for comparative, histological, and functional approaches to disentangle adaptive asymmetry from lateralised senescence in the visual system of R. clavata.