Biomarkers of Oxidative Stress in Aquatic Organisms Exposed to Pollutants

Abstract

Oxidative stress biomarkers serve as sensitive early warning indicators of pollutant impacts on aquatic biota. This review critically examines the induction of reactive oxygen species by heavy metals, pesticides, polycyclic aromatic hydrocarbons, pharmaceuticals, and emerging contaminants, and the consequent responses of enzymatic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase), non-enzymatic thiols, and damage products such as malondialdehyde and protein carbonyls. Species, tissue, and exposure regime dependent patterns are compared across fish, molluscs, crustaceans, and other taxa. Limitations of single-marker approaches, advantages of multi-biomarker batteries, and the integration of omics technologies are evaluated. The synthesis underscores the necessity of standardised protocols and contextual interpretation for reliable environmental risk assessment and monitoring.