Combined Effects Of Temperature, Salinity And PH On The Phsiological Features Of The Juveniles Of Pinctada Martensii (Dunker)

The combined effects of temperature, salinity, pH on the oxygen consumption （OR）,ammonia excretion （AE）, clearance rate （CR）, filtration rate （FR）, digestive enzymeactivities （Proteinase, PRS; Lipase, LPS; Amylase, AMS）, Acid phosphatase activity（ACP）and Alkaline phosphatase activity （AKP） of the juveniles of Chinese pearl oysterPinctada martensii （Dunker） by using of Box-Behnken Design and response surfacemethod were studied. This study aimed to investigate the influence of simultaneousvariation in temperature, salinity and pH on these physiological responses of P.martensii,to establish the equations of three responses to enviromental factors and to find out theoptimal conditions through optimization technique. The results showed as that:1) Liner effects of temperature and pH, and quadratic effects of temperature, salinityand pH on the oxygen consumption and ammonia excretion were highly significant（P<0.01）. Liner effect of salinity, interaction effect of temperature and pH on oxygenconsumption were significant （P<0.05）, but not significant in the ammonia excretion（P>0.05）. Interaction effect between salinity and pH was highly significant （P<0.01）, andinteraction effect between temperature and salinity was significant （P<0.05）. The modelequations of the oxygen consumption and ammonia excretion towards temperature salinityand pH ware established, with R²being0.9948,0.9897, respectively, and could be used forforecasting the oxygen consumption and ammonia excretion of the P. martensii juveniles.The OC and AE varied with increasing temperature salinity and pH in a curvilinear way.The optimization showed that the optimal factor combination was28.14°C/29.47/8.62, atwhich the maximum oxygen consumption (0.7045mg·g^-1·h^-1), ammonia excretion(61.2296μg·g^-1·h^-1) were reached, with the desirability of1.2)The liner effect of temperature, interaction effect between temperature and pH,interaction effect between salinity and pH, the quadratic effects of temperature, salinity andpH on the clearance rate of juveniles of P. martensii were highly significant （P<0.01）. Theliner effects of salinity and pH, the interaction effect between temperature and salinitywere not significant （P>0.05）. The clearance rate model was derived, with the R²being0.9950. The Predictive R²for the model reached0.9284, showing that it could be employedto forecast the CR of the juveniles of P. martensii. The optimization results showed that the optimal factor combination was26.95°C/29.69/8.09, at which the maximum clearance rate,1.4894×10^-3L/h, was arrived, with the desirability of0.9886.3) Liner effect of temperature, quadratic effects of temperature, salinity and pH on thefilitration rate were highly significant （P<0.01）. Interaction effect between salinity and pHon the FR was significantly （P<0.05）; liner effects of salinity and pH were not significant（P>0.05）, which also appeared in the temperature salinity interaction and temperature pHinteraction. The model equation of the FR towards temperature salinity and pH wasestablished, with R²being0.9898and Pred. R²being0.8474, which could be used forforecasting the FR of the juveniles of P. martensii. The FR varied with increasingtemperature salinity and pH in a curvilinear way. The optimization results showed that theoptimal factor combination was26.76°C/29.54/8.11, at which the maximum FR（16.493×10³cell/h） was reached, with the desirability of0.992.4) Liner effects of temperature and pH, interaction effect between temperature andsalinity, interaction effect between temperature and pH, quadratic effects of temperaturesalinity and pH on PRS were highly significantly （P<0.01）. Interaction effect betweensalinity and pH on PRS was significantly （P<0.05）. Liner effect of salinity on PRS was notsignificant （P>0.05）. Liner effect of pH, interaction effect between temperature and salinity,quadratic effects of temperature salinity and pH on LPS were highly significantly （P<0.01）.Liner effects of temperature and salinity, interaction effect between temperature and pH,interaction effect between salinity and pH on LPS were not significant（P>0.05）. Linereffects of temperature and pH, interaction effect between temperature and salinity,quadratic effects of temperature salinity and pH on AMS were highly significantly（P<0.01）. Liner effect of salinity, interaction effect between temperature and pH,interaction effect between salinity and pH on AMS were not significant （P>0.05）. The PRS,LPS and AMS model were derived, with the R²being0.9934,0.9828and0.9939,respectively. The Predictive R²for the model reached0.9015,0.9064and0.9264,respectively, showing that it could be employed to forecast the PRS, LPS and AMS of thejuveniles of P. martensii. The optimization results showed that the optimal factorcombination was26.89°C/30.62/7.84, at which the maximum degestive enzyme activities,PRS,0.376U/mgprot, LPS,0.184U/mgprot and AMS,0.863U/mgprot, were arrived, withthe desirability of0.9774.5) Liner effect of temperature on ACP was significantly （P<0.05）, and on AKP washighly significantly （P<0.01）. Liner effect of salinity, pH and quadratic effects oftemperature salinity and pH on ACP and AKP were highly significant （P<0.01）. Interactioneffect between temperature and salinity on the ACP and AKP were highly significant （P<0.01）. Interaction effect between temperature and pH on the ACP and AKP were nothighly significant （P<0.01）. Interaction effect between temperature and pH on the AKPwas highly significantly （P<0.01）, but not exsited in ACP. The ACP and AKP model werederived, with the R²being0.9959and0.9972, respectively. The Predictive R²for the modelreached0.9539and0.9589, respectively, showing that it could be employed to forecast theACP and AKP of the juveniles of P. martensii. The optimization results showed that theoptimal factor combination was26.92°C/30.38/7.68, at which the minimum ACP and AKPactivities,0.171U/gprot and0.189U/gprot, were arrived, with the desirability of0.9895.