Exposure to waterborne copper reveals differences in oxidative stress response in three freshwater fish species

Among species, various strategies in metal handling can occur. Moreover, the same metal concentration, or even the same metal dose, does not always seem to exert the same effect in different species. Here, we have investigated differences in a copper induced oxidative stress response between rainbow trout (Oncorhynchus mykiss),commoncarp (Cyprinus carpio) and gibel carp (Carassius auratus gibelio). Fish were exposed to two sub-lethal Cu concentrations, an identical concentration of 50µg/l for all fish species and an identical toxic dose which was 10% of the concentration lethal to 50% of the fish within 96 h of exposure(LC50 96 h value) for each of the 3 species (20µ/l for rainbow trout, 65µg/l for carp and 150µg/l for gibel carp). Different anti-oxidative enzyme (superoxide dismutase, glutathione reductase and catalase) activities and anti-oxidant (reduced glutathione and reduced ascorbate) concentrations were determined in gill samples collected. Changes in the measured parameters were present in all 3 species, yet a clear differentiation between fish species could be made before and during the exposure. Our research seems to confirm that some fish rely more on glutathione as a first line of defence against metal exposure, while others rely more on metallothionein in combination with anti-oxidant enzymes.