Combined effects of temperature and salinity on growth and survival of (GIFT) Nile tilapia larvae (Oreochromis niloticus)

Abstract

We evaluated the effects of temperature and salinity on specific growth rate(SGR) and survival of Nile tilapia larvae(Oreochromis niloticus).We used response surface methodology(RSM) based on a two-factor Cen-tral Composite Rotatable Design(CCD) of experiments to optimize the level of these two factors within the range 18–37℃ and 0–16.The linear and quadratic effects of temperature and salinity had a significant effect on SGR and survival(P0.05).larval growth and survival increased then decreased with as temperature or salinity in-creased.In addition,the interaction between temperature and salinity had a significant effect on growth and sur-vival(P0.05).SGR and survival were higher at 18–20℃ between salinities 8 and 9 and at 27–32℃ between salinities 5 and 7.In contrast,SGR and survival were higher at ~salinity 4 at between 35–37℃.The resulting for-mula was corrected for its coefficient of determination,yielding values of 0.979 6 and 0.982 1(P0.01),and had good predictive value.Temperature had a great influence on SGR than salinity,whereas the pattern was reversed for survival.Solving the regression equation for temperature equal to 29.1℃ and salinity equal to 5.4,the opti-mum predicted value for specific growth rate and survival is 10.08%?d?1 and 91.34%,respectively(value of de-sirability is 0.973).Thus,our data suggest the growth and survival of tilapia larvae can be improved by rearing the species at an optimal combination of temperature and salinity