HOW DAPHNIA COPE WITH ALGAE SELECTED FOR INEDIBILITY IN LONG-RUNNING MICROCOSMS

Macro video records of restrained feeding Daphnia enabled us to measur e simultaneously carapace gape, claw rejection rate, filter limb beat rate, and mandible movement rate. We compared the effects of high and low concentrations of highly edible algae and of inedible algae, the l atter selected by long-term Daphnia grazing in oligotrophic microcosms . Inedible algae slowed the filtering process and influenced the carap ace gape (widening at low concentration and narrowing at high), but di d not affect the rejection rate.