Physiological Indicators of Waterborne Copper Toxicity in Freshwater Fish

Abstract

<p>Application of safety factors to water quality guidelines are often employed in the environmental management of waterborne metals. These factors extrapolate the available science into areas not reliably defined, such as: 1) acute-to-chronic toxicity, 2) laboratory-to-fielde exposures, and 3) model-to-resident species. Scientific advancements require modifications to the derivation process of water quality guidelines to minimize the arbitrary nature of safety factors. One advancement is the Biotic Ligand Model (BLM), which uniquely incorporates toxicology and physiology. This model, along with the mechanism of acute copper toxicity, forms the foundation of the thesis, with the main objective to reduce the uncertainty associated with the three areas in which safety factors are applied. The research employed laboratory experiments to understand the responses of freshwater fish to waterborne copper. This work was extended to a field situation with wild perch. In conclusion, the usual effect indicators of acute toxicity may be of limited value, in their current form, in evaluating chronic toxicity. The complexicity of chronic toxicity reaches beyond the simple connections between acute effects and mortality. It now requires the translation of subtle physiological effects into an impact on growth, reproduction or fecundity, thereby affecting fish populations or aquatic food chains. The influence of water chemistry on copper bioavailability is one area most advanced in the last ten years, at least in part due to the development of the BLM. However, the influence of water consistuents are likely to cause different effects on acute toxicity, rapid gill surface binding, metal uptake, and metal accumulation. Lastly, the laboratory and field studies using yellow perch, a species endemic to metal contaminated lakes, show that although the mechanism of toxicity may be identical to that of a model species (i.e., rainbow trout), the mechanism of tolerance can greatly alter the physiological indicators used to detect copper toxicity.</p>