Use of more or less universal parameters, which can be measured in a wide range of species, can provide a key to the understanding why a certain species is, and another species is not, vulnerable to the toxic action of a chemical. The authors recommend that when studying the toxicity mechanism of chemicals suspected of causing adverse ecological effects, particular attention should be given to potential interference in biochemical/endocrinological control mechanisms of physiological processes that are important for the survival of populations, such as growth, reproduction, energy utilization and osmoregulation. -from Authors