Continuous collection of shrimp-breeding pond water samples was respectively done and detected in 6 ponds(H1-H6) in aquaculture base located in Dongfang

Hainan from May to July 2014

as well as 9 ponds(Z1-Z9) in Zhuhai

Guangdong. Detect the concentration of ammonia nitrogen

nitrite nitrogen

nitrate nitrogen as well as other physical and chemical factors were also detected in these shrimp farming ponds. The weather

feeding management

the outbreak of hepatic pancreas necrosis syndrome(HPNS) and its response management were recorded during the period of aquaculture. Result of the statistical analysis showed that ammonia and HPNS was significantly correlated. Three different forms of nitrogen had a significant change in the aquaculture period. With the increase of time and amount of feeding

ammonia and nitrogen in the aquaculture water showed an upward trend. In the first 70~85 days of aquaculture

HPNS successively occurred in varying degrees in H1-H6. The H1-H6 ammonia nitrogen ranged 0.29~0.74 mg/L when the HPNS occurred. The highest value of ammonia ranged 0.42~1.02 mg/L during the onset. After the feeding control taken in H1-H6 when the HPNS outbreak

the ammonia nitrogen concentration in five days was 60.03%~84.89% lower than its highest concentration during onset

respectively. HPNS was effectively controlled. The ammonia nitrogen of H1-H6 were less than 0.2 mg/L at the two days before raining days and the ammonia nitrogen increased dramatically after rain. The ammonia nitrogen in H5 which has increased least was 0.477 mg/L and the ammonia nitrogen in H3 which has increased most was 1.35 mg/L. Z1-Z9 experiment results showed that the average concentration of ammonia at the day before the typhoon was 0.2 mg/L whereas the average concentration of ammonia at the third day after the typhoon reached 0.66 mg/L. After typhoons

vannamei appeared jejunogastric and inappetence which are obvious symptoms of HPNS. The concentration of ammonia rose significantly and was accompanied with the occurrence of HPNS when the ponds were over-feeded or when typhoon or rain came.