South African ecotoxicology — present status and future prognosis

Toxicology studies the interactions of a chemical substance with individual organisms, whereas ecotoxicology is a multidisciplinary approach incorporating ecology and other disciplines, e.g. chemistry, microbiology, etc., to determine responses of individuals, populations and whole ecosystems to stressors such as chemicals. We present here the current status of toxicity testing in South Africa and propose a future prognosis for such tests. We propose a path forward for the development of ecotoxicology in South Africa and also globally. Toxicity testing issues dealt with are the use of surrogate species as opposed to indigenous species, their comparative tolerances, and the selection of relevant endpoints as measures of toxicity. Ecotoxicological considerations need to address the following key ecological realities: tolerance (both physiological acclimation and genetic adaptation), trophic redundancies, resilience, compensation (e.g. density dependence), evolution, and recovery. We believe that predictive ecotoxicology will play a major role in the future management of ecosystems that are constantly changing. We also believe that such management must be proactive to the point of intervention to create desired change, specifically the maintenance of ecosystem services.