The influence of growth medium composition on the toxicity of chemicals to algae

Algal growth inhibition tests are an important part of monitoring programmes designed to predict the environmental impact of new substances. This study investigated the effects of varying growth medium composition on the toxicity of four chemicals (morpholine, nitrilotriacetic acid, o-dichlorobenzene and triphenyl phosphate) to three species of freshwater green algae recommended for use in standard algal growth inhibition tests: Selenastrum capricornutum, Scenedesmus subspicatus and Chlorella vulgaris. Bold's basal, OECD and EPA media were used. The toxic values obtained from the tests suggest that medium composition significantly affected the sensitivity of the test algae to the four chemicals, but not in a predictable fashion.