Oxidative Stress-Related Biomarkers in Tissues of the Euryhaline Guppy Poecilia Vivipara Exposed In Situ to a Coastal Water Environment with a Long History of Metal Contamination

We aimed to select reliable biomarkers of metal exposure in the eurhalyne guppy Poecilia vivipara. Individuals were exposed to three different sites in a coastal bay (i.e., Linguado Channel, Babitonga Bay, Southern Brazil), a coastal environment with a long history of metal contamination. Temperature, salinity, pH, dissolved oxygen, and dissolved organic carbon) were measured in seawater from the exposure sites. After exposure, fish were anesthetized and their tissues (i.e., gill and liver) were dissected to evaluate the Ag, Cd, Cr, Cu, Ni, Pb, and Zn concentrations, as well as a suite of biomarkers: antioxidant capacity against peroxyl radicals (ACAP), antioxidant enzyme activities (catalase and glutathione S-transferase), metallothionein-like protein (MTLP) concentration, and lipid peroxidation level (LPO). Seawater physicochemical conditions were similar in the exposure sites. Metal concentrations in tissues did not differ significantly between exposure sites. Principal component analysis indicated close correlations between Ni and ACAP, Ag/Cd and MTLPs, and Zn and LPO in the gills. In the liver, there was a close correlation between Pb and LPO. These findings highlight the importance and need for selecting relevant and suitable tissues and biomarkers for biomonitoring programs that aim to assess and monitor fish exposure to metal contamination in coastal waters. The findings also point to the need for future research focused on the response of oxidative stress‒related biomarkers to long-term in situ exposure of fish to coastal waters contaminated with metals and other inorganic and organic pollutants.