Maternal-fetal transfer of essential and non-essential metals and metalloids in the Brazilian Guitarfish (Pseudobatos horkelii) and its promising use as a sentinel species.

Environmental contamination represents an increasing threat to the reproductive success of marine vertebrates, particularly viviparous species. This study investigated the maternal-fetal transfer, tissue distribution, and potential biological effects of essential, toxic, and potentially toxic metals and metalloids in the critically endangered Brazilian guitarfish (Pseudobatos horkelii), assessing its suitability as a sentinel species for coastal contamination. Liver and muscle tissues from pregnant and non-pregnant females and their embryos collected in southeastern Brazil were analyzed using ICP-MS. Pregnant females exhibited lower concentrations of Ni and Ti in muscle compared to non-pregnant females, indicating maternal offloading. Maternal-fetal transfer of multiple elements was observed, including Cu, Ni, Pb, Se, Ti and Zn. Embryos showed evidence of bioaccumulation, with higher concentrations of Ni, Rb, and Ti in muscle relative to liver. Significant correlations between embryo condition factor and metal concentrations suggested sublethal effects associated with early-life exposure. A strong negative correlation between Se and Hg in embryo muscle, combined with a high Se:Hg molar ratio (147:1), indicates a potential protective effect of Se against Hg toxicity during embryonic development. These results demonstrate that P. horkelii embryos are exposed to multiple contaminants during embryonic development, with implications for population recruitment and supporting the species' value as a sentinel for coastal environmental quality.