Relationship of alkaline stress and acute copper toxicity in the snail Goniobasis livescens (Menke).

Organism response to toxic compounds is routinely tested in highly controlled laboratory tests conducted under rigorous standards (AMERICAN PUBLIC HEALTH ASSOCIATION [APHA] et al. 1976, AMERICAN SOCIETY FOR TESTING AND MATERIALS, 1980). Toxicants are rarely present in nature in singular doses, and stresses on particular organisms may come from a variety of natural and anthropogenic sources. A number of studies have shown alteration of responses to toxicants as a result of multiple assaults (CAIRNS et al. 1975) or prior stress (CAIRNS et al. 1976). The purpose of this study was to evaluate the effect of prior sublethal stress (in this case, alkaline pH) on the subsequent toxicity of copper. The initial hypothesis was that elevated pH stress would increase susceptibility of test organisms to copper toxicity. Although pH excursions into acid ranges have normally attracted attention, industrial process waters commonly range to pH 11.7 (USEPA 1976). Excursions to pH above 7 may also increase the relative toxicity of other compounds, e.g., ammonia (EUROPEAN INLAND FISHERIES ADVISORY COMMISSION 1979).