EFFECTS OF ENVIRONMENTAL FACTORS ON THE HATCHING RATE OF RESTING EGGS OF BRACHIONUS CALYCIFLORUS (ROTATORIA: MONOGONONTA)

The accumulative hatching rate of resting eggs (RE) of rotifer Brachionus calyciflorus was observed under different environmental conditions.The rates of RE stored in medium where they were formed were higher at temperature varying from 20℃ to 30℃ and the highest rate was observed when RE hatched in aerated tap water at 30℃.The rate of RE stored in rotifer culturing medium was highest when hatching in aerated tap water.In contrast the lowest was found in rotifer culturing medium.At 20℃ and 25℃, the rates were similar as in tap water, culturing medium and in filtrated lake water.The rate of RE produced by rotifer fed on green algae chlorella was higher than that produced by rotifer fed on mixed algae.The accumulative rate was not associated with photoperiod.The rates were in range of 45 to 54.2% when stored in dark for 20 to 60 days at 5℃.