Using biomarkers to address the impacts of pollution on limpets (Patella depressa) and their mechanisms to cope with stress

Contaminant discharges, derived from human activities, are major concerns as they exert a continuous ecological pressure on aquatic systems, causing in fact cascading community effects. Although with associated ecological and fitness costs, physiological and biochemical defense mechanisms may restore the organism's internal balance. Several studies have pointed biomarkers as tools to assess contamination levels, and also to understand potential mechanisms to cope with stress. In the present study, the fitness costs of limpets Patella depressa located in two different contaminated sites and when transplanted into a different common environment - with no known historical contamination - were assessed through the measurement of oxidative stress, energy metabolism responses, and fatty acid profile changes. Integrated biomarker response index (IBR) revealed differences in responses between organisms of the different origin sites, with greater antioxidant and detoxification activities in the site with the higher contamination life-history (higher IBR index). Moreover, different abilities of this species to deal with the new environmental condition were also observed. After the transplant, and despite the differences in the initial profiles, response patterns became similar between both populations (similar IBR index), with organisms from the less contaminated site suffering a higher impact with a demarked increase in their detoxification and antioxidant defenses, as well as higher changes on fatty acid abundance/composition. Through an integrated biomarker profile analysis in a transplant context, this work provides a distinct insight on the mechanisms of response and tolerance to environmental stress, and fitness costs of this potential sentinel marine species in the context of environmental contamination changes.