The relevance of molecular biomarkers as a component of a weight-of-evicence aaproach to marine monitoring

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Integrated monitoring programmes measuring the biological effects of contaminants in our seas are now fully incorporated into national and international monitoring activities; with the key aim of identifying and understanding anthropogenic changes in ecosystem health. As part of these monitoring activities we have sampled two well characterized indicator species from sites around the UK and compared these directly with pristine sites in Iceland. Samples were analysed with a suite of traditional biomarkers (measurements included condition index, comet assay, stress, histopathology, and enzyme-based assays) and assessed for the presence of chemical contaminants. Alongside these traditional biomarker techniques we also used real-time PCR to assess gene expression, which has previously been associated with increased levels of contaminants. Genes studied in flounder include CYP1A, vitellogenin, metallothionein, and thyroid receptors, expression of which are induced by polynuclear aromatic hydrocarbons (PAHs), endocrine disrupters, heavy metals, and brominated flame retardants, respectively. Genes studied in mussels include heat-shock proteins, glutathione-S-transferases, and catalase and can elucidate responses to stress. Molecular techniques are coming of age and previous work, based around lab exposure studies, has demonstrated their worth. These results demonstrate, however, that gene expression is also a key tool within environmental monitoring programmes and where possible should be incorporated as part of a weight-of-evidence-based approach. Data are presented to demonstrate the relevance of molecular markers within systematic monitoring programmes and identify which markers are most useful when classifying sites according to biological effects of contaminants.