How Daphnia cope with algae selected for inedibility in longrunning microcosms

Abstract

Macro video records of restrained feeding Daphnia enabled us to measure 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 latter selected by long-term Daphnia grazing in oligotrophic microcosms. Inedible algae slowed the filtering process and influenced the carapace gape (widening at low concentration and narrowing at high), but did not affect the rejection rate.