Assessment of trace metal toxicity using molecular, physiological and behavioural biomarkers

Laboratory-based assessments of the potentially damaging effects of trace metals in the natural environment are difficult to validate. This is a consequence of the diverse factors which in situ affect metal bioavailability and the susceptibility of organisms to trace metal toxicity. For several years, biomarkers (biochemical responses to contaminant exposure) have been measured in the tissues, body fluids and excreta of a range of organisms to signal chemical exposure. More recently, however, the biomarker concept has been extended to include physiological and behavioural indices of both pollutant exposure and effect. In this paper, a contemporary biomarker approach is outlined and new techniques are described for measuring physiological and behavioural parameters. In particular, biomarkers which indicate changes in Darwinian fitness are discussed. Protocols are outlined concerning how simultaneous measurements of molecular, physiological and behavioural biomarkers might be utilized in biological impact assessment of trace metals (and other pollutants). The potential use of biomarkers as laboratory screening tools and in bioremediation is also addressed.