EGG PREDATION BY COPEPODS IN DAPHNIA BROOD CAVITIES

Both field observations and enclosure experiments show that juvenile c opepods enter Daphnia brood cavities to feed on Daphnia eggs and embry os. The ability to perform such in vivo exploitation is reported for b oth cyclopoid and calanoid copepods. Copepodites of Acanthocyclops rob ustus (G.O. Sars) were found to eat eggs in brood cavities of D. magna , D. pulex and D. pulicaria in experimental enclosures rich in algae. Copepodites of Eudiaptomus gracilus (G.O. Sars) were found in brood ca vities of D. hyalina in a mesotrophic lake. The copepods' intrusions i nto brood cavities caused dramatic declines in the clutch size of infe sted Daphnia, and this predation effect could easily be confused with the effect of severe food limitation.