Oxidative stress response in an endangered goodeid fish (Girardinichthys viviparus) by exposure to water from its extant localities

The oxidative stress response in Girardinichthys viviparus after exposure to water from its extant habitants was evaluated. The distribution range of this endangered species is currently restricted to a single lake, which receives domestic and industrial wastewater treated to a secondary level, but this is also contaminated with PCBs. Fish were exposed to water from Lake Texcoco, its extant habitat or another one, the Lake Zumpango proposed as a candidate to re-introduction. To predict the damage induced by sublethal increases in PCBs, assessment is also made of fish response to water from these localities enriched with PCB mixtures. Adult fish born in the laboratory were exposed to filtered surface water or to the PCB-enriched water for 1, 2, 4, 8 and 16 days. An assessment of the oxidative stress response in G. viviparus revealed four characteristic response patterns that were frequently observed: (1) increased lipid-peroxidation (LPOX), depressed SOD and increased CAT; (2) an increase in all three biomarkers; (3) reduced LPOX, unchanged SOD and increased CAT; (4) increased LPOX and depressed SOD and CAT. Our results demonstrate the complexity stress response of this endangered species while indicating that preventive measures are urgent to control the discharge of pro-oxidants in its environment.