ABSTRACT
This chapter demonstrates the importance of choosing the appropriate test organism of known physiological state and the appropriate physical and chemical test conditions in order to obtain meaningful toxicity assessments. Potential detrimental impacts of environmental contaminants on the photosynthetic microalgal community, the primary producers at the base of the aquatic food web, must be reliably assessed in order to avoid disastrous consequences at higher levels in the food chain. The most important step in conducting microalgal toxicity tests is to select an appropriate test organism. The choice of a microalgal species which can be expected to occur in the natural ecosystems most likely to be affected by the toxic substance will provide more ecologically relevant assessments of potential toxicity. The selection of a test species should involve consideration of: the taxonomy of the test organism; its ecological preferences; its physiological requirements; and its availability from culture collections or other reliable sources.
