Study on the growth and survival of Hemifusus tuba (Gmelin) Juvenile at different salinity

Under the water temperature that ranges between 28.6 and 29.5℃ and pH 8.2,the growth and survival of Hemifusus tuba juveniles [shells high(19.5±1.23) mm,weight(661.4±48.6) mg] at different salinity were studied.The goal is to find out the range of optimal survival salinity and optimal growth salinity to H.tuba juveniles by two-point method.The results show that the suitable survival salinity and optimal survival salinity are 17.7‰ 40.8‰ and 25.1‰ 35.9‰,and that the growth suitable salinity and growth optimal salinity were 17.5 39.9‰ and 27.8 33.2‰,respectively.In the range of growth optimal salinity,the average daily growth rate of shells and weight were 0.358 0.397 mm.d 1 and 44.64 49.09 mg.d 1,respectively.The survival rate and the average daily growth rate of shells fell obviously when the range of salinity optimal survival salinity was exceeded.Moreover,the tolerance of salinity by H.tuba Juvenile was related to the original environmental salinity.The survival rate was 84.0% in 72h when the juveniles were adapted for 20d in the salinity of 17.0‰ and then transported to the salinity of 14.0‰,and the survival rate was 96.0% when the juveniles were adapted for 20d in the salinity of then transported to the salinity of 45.0‰.However,the survival rates were 8.0% and zero in 72h when the juveniles were transported from the salinity of 30.5‰ to 14.0‰ and 45.0‰,respectively.Both the suitable range and the tolerance of salinity can be increased when the juvenile was domesticated in gradually changing conditions.