عنوان مقاله [English]
The aim of this study was to investigate the mean time of hatching of D. magna resting eggs under some abiotic factors. To do so, resting eggs were collected from different parts of live food ponds in Sad Voshmgir Cultivation and Breeding Centre of Gorgan, and after isolation, the eggs were kept in dry and wet conditions at 4°C for 2 months in darkness. Following the pre-incubation period, the two aforesaid groups were subdivided into 2 smaller parts and each was floated in 1% NaOCL and distilled water for 5 min. AdaM medium was used to determine the effect of photoperiod levels (continuous illumination, 12h light day-1) and temperature levels (20ºC, 25ºC and 30ºC) on the hatching time of resting eggs and the incubation period last for 15 days. On the obtained results, the incubation of wet eggs of this species and their subsequent exposure to continuous illumination at 20ºC and 25ºC had a significant shortening effect on the mean time to hatch (P<0.05).