Biochemical biomarkers in barnacles Balanus improvisus: Pollution and seasonal effects

• Glutathione S-transferase activity was increased in barnacles from polluted sites.
• GST, TOSC and LPO seasonal responses were associated to water temperature.
• Lipid peroxide levels were decreased in barnacles from polluted sites.
• Biochemical biomarkers were evaluated in the cosmopolitan barnacle Balanus improvisus

Biochemical biomarkers were evaluated in the barnacle Balanus improvisus (Crustacea: Cirripedia) sampled from both polluted and reference sites in the Patos Lagoon Estuary, Southern Brazil. During winter, higher glutathione S-transferase (GST) activity was recorded in the barnacles from the polluted sites, indicating environmental exposure to contaminants. Relatively low lipid peroxide levels (LPO) were also observed in barnacles from polluted sites, indicating that oxidative stress by lipid peroxidation was not a major threat in barnacles from those sites. Seasonal differences in the GST and total oxyradical scavenging capacity (TOSC) could have contributed to the low LPO levels in the summer relative to the levels in the winter. Catalase activity and metallothionein levels were not affected by contamination or seasonality. The seasonal changes observed in biomarker responses were paralleled by the differences in temperature, which could have affected physiological responses, including the balance between pro-oxidants and antioxidants.