DNA damage as a bivalve biomarker.

Bivalves have been used in numerous environmental assessment studies, chiefly because they are sessile deposit or suspension feeding organisms found in or near sites of environmental concern, and they can be easily collected, sorted and deployed at sites of interest. Monitoring studies utilizing bivalves currently rely on the comparison of growth, survival, and contaminant bioaccumulation. Data gathered from 'reference' sites are compared with those of populations at assessment sites. These studies require extended periods of exposure, lasting weeks to months, and the use of a well defined population of test organisms of similar size, age, and condition. In many cases time and resources require researchers to restrict their sampling to the organisms on-hand at a particular site without the benefit of any reference data. Therefore more versatile and sensitive assessment methods are needed. Because effects at higher levels of organization such as growth, development, and survival are initiated at the molecular and cellular levels attempts have been made to identify useful biomarkers at these levels. The proposed advantages of molecular/cellular biomarkers are that they will respond to stress predictably and more rapidly, and will be indicative of the mechanisms of toxicity thereby yielding a rudimentary characterization of the contaminant(s) influencing them. In the following communication we will report on past and current developments in the monitoring of DNAdamage as an environmental biomarker.