Studies On The Effects Of Physical And Chemical Factors In Water Environment On The Reproductive Performance And Larval Development In Cherax Quadricarinatus

1.The influence of temperatureWhen the temperature is below 18℃,Cherax quadricarinatus do not lay eggs, when the temperature rose to above 18℃,Cherax quadricarinatus begin to mature and breed, with the temperature, the holding eggs rate linear increase.Suitable temperature for the growth of 24～30℃,its growth limit of 34℃,the eggs cap may be 34℃.Below 30℃, maintain a high water temperature is a key factor in improving the rate of eggs.Improve the water temperature will prompt holding eggs very quickly, we should focus on breeding, brood stock must be made within the shortest possible time for holding eggs. When the water temperature is 18℃,Cherax quadricarinatus eggs can developed, but the extremely long incubation period, when over 30℃,the embryo malformation rate increased, the hatching rate showed a downward trend. Out the effect of temperature on embryo development time, at 22℃,the juveniles leave the mother's need after 84 days, while in 32℃,the juveniles leave the mother's need after 28 days.In the water temperature of 18～33℃,the temperature on the survival rate of juveniles is less, but a greater impact on the growth rate,24℃below the growth of a slower,27℃or so growth at the best condition, 30℃and above the growth rate of a sharp decline.2. The impact of dissolved oxygenCherax quadricarinatus from egg-laying, the embryo developed to the seedling stage, the dissolved oxygen must meet the 5mg/l or above in order to achieve a satisfactory rate of egg-laying, hatching and nurturing rate.This is because the dissolved oxygen is to promote the Cherax quadricarinatus gonadal conversion factor, one must reach a certain level of dissolved oxygen, gonadal maturation can hold eggs;hatching when the low dissolved oxygen caused by the abnormal embryonic development, some embryos can not be a normal hatch out; and low dissolved oxygen also create obstacles to seedling growth, resulting in nurturing rate is low. Another low dissolved oxygen conditions, the embryonic development of slow, incubation time longer than normal.3. PH effectsThe holding eggs rate, hatching rate and nurturing rate is affected greatly by pH in juveniles Cherax quadricarinatus. The breeding is not suitable for Cherax quadricarinatus in acidic water and high alkaline water. Where water pH value is 7.0-8.5,incubation and breeding can be processed, high alkalinity of water is not suitable for farming Cherax quadricarinatus.4. Sodium chloride salinityNo significant impact was observed on effect of salinity on the holding eggs rate.The hatching rate and hatching time in the 2‰salinity below, showed no difference;while in 2 %osalinity above, the hatching rate has declined and extend the incubation time.Cherax quadricarinatus is one of fresh water shrimp, but have some tolerance to salinity.