The effect of photoperiod and light intensity on egg production, hatching rate, maturity time and adult sex ratio in Acartia clausi

The aims of this study were to investigate the effect of photoperiod and light intensity on egg production and hatching rate in Acartia clausi in laboratory conditions. This zooplankton was collected from Caspian coastal waters of Mazandaran province by the use of a 100µ net. All tests were performed in five light treatments (photoperiod) namely 24:00, 18:06, 12:12, 06:18, 00:24 (light / dark), and two light intensities of 50 and 1000 lux. The results showed that the highest level of egg production was observed in 18 and 12 hours light treatment at low light intensity (50 Lux) 20/02±4/31, and the lowest level of egg production was observed in 24 hours light treatment at high light intensity (1000 Lux)8/15±2/15. The highest percentage of hatching was observed in the photoperiod of 18 hours light and high light intensity (83/08±7/1), and a lower percentage of hatching was observed in the treatment of darkness(17±2/7). Regarding the time for maturation this species reached to copepod it stage more quickly, and adult stag (there are this process in both high light intensity and low light intensity). About adult sex ratio there are not any signification difference between treatment.