In situ assessment of health status and heavy metal bioaccumulation of adult Pelophylax ridibundus (Anura: Ranidae) individuals inhabiting polluted area in southern Bulgaria

Abstract

• We study the health effects of heavy metal pollutants and their accumulation in frogs. • The frogs from the polluted area were anemic, with a suppressed hematopoiesis. • The frogs from the polluted area had a weakened immunity. • The tissues in frogs from the polluted area have significantly higher levels of heavy metals. In this study an assessment is made of how the marsh frog P. ridibundus individuals, being long-term inhabitants of an anthropogenically polluted habitat, are affected and what changes toxicants induce in the organism of anurans. In situ measurements of several morphophysiological and hematological parameters were performed to assess the health status of frogs, and after that the bioaccumulation of Pb, Cd, Zn and Cu in their bodies (muscles and liver) was determined. Moreover, P. ridibundus individuals were separated by sex to evaluate this mark as an inherent source of variability. The results revealed that the P. ridibundus individuals inhabiting an area polluted with industrial waste were anemic, with suppressed hematopoiesis and weakened immunity. In the tissues of frogs of both sexes inhabiting the polluted site, high levels of heavy metals and metalloids (Pb, Cd, Cu, Zn, As and Se) were found as compared to samples from a reference site. Furthermore, the levels of all metals and metalloids in these frogs were higher in the liver than in the muscles. Quantity differences were ascertained in the bioaccumulation of frogs inhabiting the polluted site: higher values of heavy metals in the tissues of females, and metalloids in the tissues of males.