Cyst-based toxicity tests XVII--prefeeding advantages in short-chronic rotifer microbiotests.

Attempts were made to overcome too-low reproductive output in the 48-h short-chronic microbiotest with the rotifer Brachionus calyciflorus fed with microalgae (Pseudokirchneriella subcapitata) from algal beads older than 4 months (Chemosphere 50 (2002a) 365). Prefeeding of freshly hatched rotifers prior to the start of the actual growth experiments resulted in a satisfactory reproduction (i.e., an intrinsic growth rate r > 0.65), even with subsequent feeding of the rotifers with microalgae from beads stored up to 1 year. Rotirich is an attractive alternative inert food compared with the mixture of microalgae and Spirulina, originally used to prefeed the rotifers. When the rotifers were prefed for 2 h with 30 microg/mL Rotirich, it was then not necessary to add Spirulina to the microalgal food from beads. The above findings are a substantial simplification of the testing procedure of the new short-chronic "culture/maintenance-free" Rotoxkit microbiotest.