Abstract
Environmental management is inevitably complicated by the large variation in susceptibility to chemical toxicity exhibited by the living components of ecosystems, a significant proportion of which is determined by genetic factors. This paper examines the concept of genetic susceptibility in ecosystems and suggests the existence of two distinct forms reflecting genetic changes at the level of the individual and at the level of population and community. The influence of genetic susceptibility on exposure-response curves is discussed and the consequent accuracy of data used for toxicity test-based risk assessments examined. The paper concludes by describing a possible biomarker-based approach to future studies of susceptibility in ecosystems, suggesting the use of modern molecular genetic methods.