The use of the shanny Lipophrys pholis for pollution monitoring: a new sentinel species for the northwestern European marine ecosystems

The contamination of aquatic ecosystems by organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) is a matter of great concern. Mussels have been extensively used as sentinel species in a large number of monitoring programs. However, the use of bivalves as the sole species has some limitations, because they are not as responsive as fish to Aryl Hydrocarbon Receptor agonists. Hence, for many marine areas, there is the need to validate new sentinel fish species that can be used in the assessment of pollution by organic contaminants. The shanny Lipophrys pholis is an intertidal fish that combines many characteristics required in a sentinel species: is abundant and easy to catch, has a wide geographical distribution and restrict home range. After larvae recruitment to the intertidal rocky shores, they remain in the same area for the rest of the life-cycle, thus reflecting local pollutants exposure. In order to evaluate the species sensitivity to organic contaminants under field conditions, L. pholis were collected at six sites reflecting different degrees of anthropogenic contamination. The induction of two biomarkers extensively validated in the assessment of PAHs contamination ethoxyresorufin-O-deethylase activity (EROD) and Fluorescent Aromatic Compounds (FACs) was evaluated. In parallel, mussels were collected at the same locations and levels of 16 PAHs and selected heavy metals determined. Overall, the specimens collected in the urban areas showed a significant induction of EROD and FACs (up to a six-fold induction) if compared with the reference sites. Additionally, a positive correlation was observed between the biomarkers and PAHs levels in mussel tissues. Even though further validation is currently in progress, the available data indicate that L. pholis is responsive to organic contaminants such as PAHs, suggesting its future integration in monitoring programmes designed to evaluate the presence of these contaminants in European marine ecosystems.