Ecotoxicology Beyond Sensitivity: A Case Study Involving “Unreasonableness” of Environmental Change

Abstract

Aquatic ecotoxicology has been devoted to research that would allow for protection of the environment by proxy. For example, single-species tests for toxicity often are conducted to determine, with great precision, levels of permissible discharge; often then a “safety” factor is applied in hopes that natural ecosystems are no more than some arbitrary factor more sensitive than the most sensitive species tested. On the ecological side, many studies focus on the search for early-warning indicators within nature; these indicators then would serve as surrogates, signaling the upcoming ecological changes of actual concern. With either the traditional toxicological or ecological approach, there are obvious problems with extrapolation across the range of natural ecosystems and across the range of potential stresses. Since both approaches rely on uncertain extrapolation, and this is an uncomfortable situation, a concern has been to conduct tests with the “most sensitive species” and to evaluate response in ecosystems by the “most sensitive indicator.” The philosophy of protection by proxy can be simply stated: in ignorance of the response of most natural ecosystems to most chemical stresses, we had better try to hedge our bets as much as possible.