Mercury bioaccumulation, genotoxic and biochemical biomarkers reveal the health status of yellow-spotted Amazon River turtles (Podocnemis unifilis) in an environmental protection area in the Amazon

Abstract

Chelonians are considered good bioindicators of environmental quality. The assessment of the health status of chelonian populations in the Amazon is important because they are traditionally consumed in large numbers in riverine communities and sustainable use reserves. The present study aimed to evaluate the health of Podocnemis unifilis (Testudines, Podocnemididae) in an environmental protection area in the Amazon region in Brazil. We analyzed the biomarkers lipoperoxidation, carbonylation of proteins, occurrence of micronuclei and erythrocytic nuclear abnormalities, quantified metallothioneins, and evaluated mercury bioaccumulation. We generated pioneering data regarding biomarkers in wild Amazonian freshwater turtles. All biomarker responses did not vary significantly between the sexes. The occurrence of oxidative and genotoxic damage, as well as concentrations of metallothioneins was low compared to other studies. In addition, the bioaccumulation of mercury in the muscle of the animals was below the limit recommended for human consumption by the World Health Organization. Our results provide baseline data on mercury bioaccumulation and biomarker responses that can be useful for future comparisons with other freshwater turtles. The data also provide evidence that the sustainable exploitation of these turtles in the study area (Piagaçu-Purus Sustainable Development Reserve) does not pose a risk to local riverine communities, as the detected mercury concentrations are safe for human consumption. In this sense, our results highlight the importance of protected areas for the conservation of healthy turtle populations, at the same time ensuring the health of the human populations that use them as a food resource.

Total Mercury Content in the Tissues of Freshwater Chelonium (Podocnemis expansa) and a Human Health Risk Assessment for the Amazon Population in Brazil

“…Research conducted in a sustainable development reserve in Amazonas, Brazil evaluated THg concentration in P. unifilis. The study found an average THg concentration mean of 0.011 mg•kg −1 in six muscle samples [49].…”

Toxicological manifestations in gills, liver, kidney and muscles of Channa punctatus exposed to mercuric chloride

“…The study of histological anomalies in the gill, liver, kidney and muscle helps to assess the effects of pollutant present in the aquatic ecosystem (Balali-Mood et al, 2021;Garai et al, 2021). Many studies have documented the toxic effects of mercury in aquatic organisms; however, insufficient relevant data is present on mercury-induced oxidative stress, genotoxicity and histopathological manifestations in fish; hence, it must be investigated further (Borges et al, 2022;Trivedi et al, 2022). Thus, in this study, a freshwater food fish with high nutritional and low-cost value, Channa punctatus was taken as a test organism to investigate the effects on the health of fish exposed to HgCl 2 .…”