Influence of exposure conditions on the bioavailability of fluoranthene toDaphnia magna (Cladocera)

A study of the bioavailability of fluoranthene to Daphnia magna (Cladocera) was carried out. Acute toxicity of fluoranthene to Daphnia magna was asses sed in various conditions: co-solvent, darkness, classical laboratory light ing, UV exposure, presence or absence of microalgae. Bioaccumulation of flu oranthene in daphnids was also determined. In the dark, the toxicity of flu oranthene was low. Following a 2-h exposure under UV light (254 nm), toxici ty increased to a great extent. Under fluorescent light, phototoxicity was also observed. The bioaccumulation of fluoranthene in the dark was maximal after 24 h exposure and related to the aqueous fluoranthene content. No dif ferences were found between both co-solvents. in the presence of microalgae , fluoranthene was far less toxic, whereas bioaccumulation was unchanged. A dsorption of fluoranthene on algae could not explain this lower toxicity wh ich might be due to either absorption of light by algae or a protective eff ect of algal carotenoid pigments against phototoxicity.