Histopathological alterations in the gonads of wild white clams Dosinia ponderosa inhabiting a former copper mine locality in the Gulf of California

Objective: Prolonged exposure to heavy metals, such as Pb, Hg, or Cu, has multiple adverse effects on marine organisms at the cellular, physiological, and population levels. Bivalves' histopathology provides a sensitive biomarker of pollutant-induced stress and environmental health. Gonad tissue deterioration is of particular concern, as it affects the reproductive success of a species. This study aimed to examine the histopathological alterations caused by metal exposure in the gonad of the white clam Dosinia ponderosa. Methods: Organisms were sampled from three locations in the Gulf of California: Santa Rosalia (SR), a former Cu mining town; San Lucas beach (SL), a nearby site influenced by pollution; and Escondida beach (EB), which served as a control site. Histological and histochemical stains were used, and the prevalence and intensity level of each alteration were calculated. Result: The prevalence of alterations was higher in the ovaries of SR clams (92% compared to 60% in SL clams and 32.7% in EB clams), during spawning (91.4% compared to 20% in SL clams and 4.7% in EB clams), and in winter (93.5% compared to 30% in SL clams and 17.4% in EB clams). Conclusion: These findings suggest a significant deterioration in the gonads of white clams from SR, probably linked to the chronic exposure to high concentrations of Cu and possibly other heavy metals; hence, the reproductive health of the clams is likely compromised.