| From May to November in2011, we carried out three experiments in Fengxiandistrict of Shanghai which were research on artificial seawater quality in the Penaeusvannamei larval breeding ponds, research on the water quality of Penaeus vannameiaquaculture ponds with different water treatment technologies and research on theimpacts of salinity on Penaeus vannamei muscle quality. The results were as follows:1. From May30thto June13th, we added seawater crystal and coarse salt to thenatural freshwater from adjacent river for Penaeus vannameito breeding in Fengxiandistrict of Shanghai. During the breeding period, we monitored water quality everydayand the results were as following: DO was7.3±0.10mg/L, pH was8.00±0.04,temperature was28.2±0.2℃, the concentrations of PO-4-P, TP, NO2-N, NO-3-N,TNH4-N, TN and CODMnwere0.88±0.14,1.46±0.14,0.21±0.02,1.52±0.10,2.88±0.34,7.01±0.36and18.05±1.40mg/L respectively.2. We compared the water quality of aquaculture ponds in which the source ofshrimp were different. One was self-cultivated shrimp, and the other was from Hainanthrough air transportation. Differences of PO4-P concentration was significant, and theDO, TP, and CODMnwas very significant, while the otherwater quality indicatorsshowed no significant differences. In self-cultivated shrimp ponds, DO wassignificantly lower than that in Hainan shrimp ponds. Inorganic nitrogen and totalnitrogen showed no significant difference, while total phosphorus and reactivephosphorus had significant differences. 3. June30thto September15th, we monitored water quality of outdoor shrimpponds. Each pond was rectangular, the area was500m2approximately and the depthabout2m. There were three kinds of water treatment technologies: bottom oxygenfilling only, bottom oxygen plus paddlewheel aerator filling, and bottom oxygen fillingplus artificial biofilm. Significant difference was observed among DO (P <0.05). DOwas significantly lower in ponds with artificial films than that in ponds without films.Paddle wheel aerators showed no effects on DO promoting. Different watertreatment did not affect the pH(P>0.05). CODMnkept increasing and showed nosignificant difference among ponds (P>0.05).Proposed method by CCME was used to evaluate the water quality of above pondsand the following Water quality indicators and the standard values were selected whichwere as following: DO>5mg/L, pH6-9, TNH4-N<1mg/L,TP<0.2mg/L, TN<1mg/L, CODMn<6mg/L. The scores in the pool with bottomfilling plus artificial biofilm and one pool only with bottom oxygen filling were slightlyhigher than the scores in the other ponds. Which meant the water quality in the formertwo ponds was better than that in the other ponds. In fact, disease broke out in thoseponds before the harvest season which showed that CCME index could indicatereasonable results when it was used to evaluate shrimp pond water quality.4. In August2011, we added seawater crystal and coarse salt to natural freshwaterto prepare artificial seawater at the salinity of2.5,5,10and15respectively. Afreshwater pond was prepared as control.3000shrimps (3.1±0.4cm) cultivated byourselves were put into the five ponds.30shrimps were sampled from each pool at1st,7th,14th,21st and28thday. Free amino acids and hydrolysis amino acids in shrimpmuscle were detected. The types of hydrolysis amino acids in shrimps cultured underdifferent salinity were comprehensive and the contents of total amino acids (TAA) werehigh. The composition and contents of hydrolysis amino acid showed no differenceamong shrimp samples under different salinity and did not change significantly withthe time. Free amino acids concentration in shrimp muscle was much lower than thehydrolyzed amino acids. Total free amino acids did not differ significantly (P>0.05).Essential amino acid, semi-essential amino acids, non-essential amino acids and umamiamino acids showed no significant differences(P>0.05) and did not change significantly(P>0.05) with the time. |
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