Biomarker responses in the freshwater shrimp Caridina nilotica as indicators of persistent pollutant exposure

Abstract

Biomarkers are applied as early warning indicators of organisms' exposure to pollutants. The aim of this study was to utilise a multi-biomarker approach in the freshwater shrimp Caridina nilotica (Decapoda: Atyidae) as indicators of persistent pollutant exposure. A suite of biomarkers was selected to cover oxidative stress and damage, and energetics of the organisms. Five sites, representing an agricultural and pesticide application gradient, were sampled during two flow related hydro-periods in rivers of the Phongolo floodplain, north-eastern South Africa. Cytochrome P450 (CYP) activity was significantly higher in shrimp at sites directly adjacent to regions of increased human activity. Increased oxidative responses, i.e. catalase (CAT; p < 0.01) and protein carbonyl (PC, p < 0.01) were also found at these sites. The energetics biomarker did not show any influence of increased contaminant exposure. We demonstrated that the biomarkers of exposure (CYP) and effect (CAT, PC) were suitable to detect effects of stressors, probably persistent pollutants