Toxicant interactions with the biotic and abiotic environment of freshwater rotifers: Implications for ecological risk assessment

The process of ecological risk assessment is dependent upon the data generated by standardized toxicity tests. However, the conditions under which these tests are conducted frequently fail to account for factors in natural ecosystems that may modify the toxicity of chemicals and/or provide data on only a limited number of possible effects. Toxicants may adversely affect processes associated with the biotic environment of aquatic ecosystems, such as intra- and interspecific interactions. In addition, physical and chemical conditions of the abiotic environment may alter the toxicity of chemicals to organisms by acting as physiological stressors or by altering toxicant bioavailability. Understanding the implications of such interactions on populations of aquatic organisms is essential for providing accurate estimates of ecological risk to environmental managers. A variety of ecotoxicological studies with freshwater rotifers are discussed, including toxicant effects on rotifer predator-prey interactions and the effects of ultraviolet radiation and fluid motion on the toxicant sensitivity of rotifers.