Application of Biomarkers in the Analysis of Sublethal Exposures to Different Metals in an Amazonian Ostracod,...

Metals reach aquatic ecosystems through various anthropogenic activities, posing risks to aquatic life. This study investigated oxidative stress and detoxification biomarkers in Strandesia rondoniensis, an Amazonian ostracod, after 96 h of exposure to sublethal concentrations of CuSO₄, ZnCl₂, CdCl₂, and HgCl₂. Significant increases in superoxide dismutase, glutathione, and metallothionein activity were observed in response to Zn, Cd, and Hg, indicating the induction of reactive oxygen species (ROS). In contrast, copper exposure did not alter biomarker activity. Lipid peroxidation increased following exposure to Zn, Cd, and Hg, damaging cell membranes and leading to DNA damage, suggesting the antioxidant defense system was insufficient to counteract oxidative stress. The results demonstrate the sensitivity of S. rondoniensis to environmentally relevant metal concentrations, supporting its application as a neotropical model organism in ecotoxicological assessments. Furthermore, the findings underscore the need to revise Brazil's environmental legislation on permissible metal concentrations in aquatic environments.