Combined use of chemical, biochemical and physiological variables in mussels for the assessment of marine pollution along the N-NW Spanish coast

• Integrative assessment of pollution in a large region (>2500 km) of N-NW Spain was undertaken.
• Chemical, biochemical and physiological variables in mussels were used.
• Organochlorines and BDEs were identified as the main responsible of the observed toxicity.
• Age and mussel condition masked the relationships between biological responses and pollutants.

This study undertakes an overall assessment of pollution in a large region (over 2500 km of coastline) of the N-NW Spanish coast, by combining the use of biochemical (AChE, GST, GPx) and physiological (SFG) responses to pollution, with chemical analyses in wild mussel populations (Mytilus galloprovincialis). The application of chemical analysis and biological techniques identified polluted sites and quantified the level of toxicity. High levels of pollutants were found in mussel populations located close to major cities and industrialized areas and, in general, average concentrations were higher in the Cantabrian than in the Iberian Atlantic coast. AChE activities ranged between 5.8 and 27.1 nmol/min/mg prot, showing inhibition in 12 sampling sites, according to available ecotoxicological criteria. GST activities ranged between 29.5 and 112.7 nmol/min/mg prot, and extreme variability was observed in GPx, showing activities between 2.6 and 64.5 nmol/min/mg prot. Regarding SFG, only 5 sites showed ‘moderate stress’ (SFG value below 20 J/g/h), and most sites presented a ‘high potential growth’ (>35 J/g/h) corresponding to a ‘healthy state’. Multivariate statistical techniques applied to the chemical and biological data identified PCBs, organochlorine pesticides and BDEs as the main responsible of the observed toxicity. However, the alteration of biological responses caused by pollutants seems to be, in general, masked by biological variables, namely age and mussel condition, which have an effect on the mussels' response to pollutant exposure.