Keeping Daphnia out of the surface film with cetyl alcohol

Some Daphnia species are difficult to culture due to a tendencyto become trapped in the surface film. A low level of cetylalcohol (1.26 0.12 mg) was shown to be highly effective inreducing the surface film entrapment of a Daphnia species typicallysusceptible to such a problem (D.rosea). In a species that doesnot exhibit surface film problems (D.pulicaria), a low levelof cetyl alcohol had no effect, indicating that this substanceis not toxic to Daphnia in low quantities. However, a high level(10.6 1.0 mg) of cetyl alcohol was shown to decrease the survivalof both species and reproduction of the susceptible species.