Temperature and Salinity Regulation Model In Embryonic Development and Hatching Rates of Humpback Grouper Cromileptes altivelis
Two important water quality parameters of temperature and salinity have been thought play important role in affecting embryogenesis of eggs and hatching rates in humpback grouper Cromileptes altivelis. High temperature has been determined impairing molecular reactions whilst low salinity caused osmotic imbalance (hypotonicity) between intra- and extra-cellular blood cell that may exert metabolic disruptions. Hence, a factorial design ANOVA (high temperature at 31°C; low salinity at 28 ppt, and control) with two replications eggs were observed in every 2 h within two days sampling. It shows that temperature has marginal effects on embryonic development (P<0.05) of Cromileptes’s eggs but not for salinity. In contrast, when temperature and salinity were paired with progressive time development of eggs, it was found that salinity*timeare significantly affected the development of eggs, but not the temperature. Further regression analysis was also made to assess whether the eggs analysed were produced by the same brood stock of C. altivelis. It was found that the rates of eggs development were significantly different between day-1 and day-2. It is thought that eggs of day-1 and day-2 were coming from different brood stocks. In this regards, eggs collected in day-2 were more viable and better progressive time development and survival rates than day-1 eggs. Even though salinity has more challenges in embryonic development and hatching rates of humpback grouper C. altivelis, however the ability in controlling these two factors might accelerate embryogenesis and hatching rates of this species.