Sensitivity and Indicator Function of Bioassays

Abstract

In consequence of the reduced and standardized environmental conditions in laboratory testsystems, prediction of pollution impact on a soil ecosystem is difficult. In a bioassay approach organisms at the level of individuals or populations are exposed to soil material to determine the significance of contaminants. An investigation that incorporates community level processes in comparison with toxicity test results can provide a better understanding of the indicator function of bioassays. Nitrifiers are among the most sensitive testorganisms we know and are also ecological sensitive because only a small group of species can carry out the oxidation of ammonium to nitrate in soil. Thus effects to this bacteria are of special interest concerning ecotoxicological consequences of contaminants.