REVELATION OF ENDOGENOUS RHYTHMS OF CLADOCERA REACTIVATION FROM RESTING EGGS: EVIDENCE FROM EPHIPPIA OF WLASSICSM PANNONICA (CLADOCERA, MACROTHRICIDAE)

摘要

The hatching rate of Wiassicsia pannonica crustaceans from resting eggs placed in an incubator at 27 degrees C in the absence of light was observed monthly during 32 months. Under the same external conditions, the reactivation of Cladocera from "young" latent eggs showed seasonal periodicity. With an increasing age of the ephippia, the hatching of the crustaceans occurred irrespective of season, while previously noted long periods of deep dormancy were absent. Endogenous rhythms of diapause termination in Cladocera must be considered when conducting research using forced reactivation by external stimuli.