The Daphnia bioassay: a critique

Daphnia magna is used widely as a standard ecotoxicological indicator organism, and protocols exist for its use in assessing the toxicity of substances under acute and chronic experimental conditions. Problems exist in repeatability of such bioassays between laboratories. Sources of variation are identified using a simple quantitative genetics model. Presenting specific examples, we conclude that these problems are tractable, but only if the genotype and culture conditions prior to and during tests are strictly controlled.