The use of biomarkers in aquatic biomonitoring: the example of esterases

1. The term biomarker refers to the physiological, biochemical. and histolo gical changes used as indicators of exposure to chemical contaminants and/o r of its effects at the suborganismal or organismal level. Recently the dev elopment of sensitive biochemical markers for monitoring environmental qual ity in aquatic ecosystems has raised a great deal of interest. 2. Selected biochemical markers measured in feral organisms can provide sen sitive indexes, or early warning signals, of potential ecosystem degradatio n caused by contaminants. Compared with chemical residue analysis, biomarke rs have the advantage of measuring the stress on the organism. thus being m ore biologically relevant. 3. Some of the most frequently used biomarkers in aquatic biomonitoring in different countries are briefly described. 4. The use of cholinesterase activity as a biomarker of pesticide exposure for biomonitoring in estuarine areas is also given as an example. Copyright (C) 2001 John Wiley & Sons, Ltd.