High Of Shrimp Ponds Water Color And Other Environmental Factors On The Growth Of Litopenaeus Vannamei

This paper investigated the changes of physical, chemical and biological factorsincluding feed, water depth, salinity, transparency(TT), water temperature, pH,dissolved oxygen(DO), NH₃-N, water color(WC), shrimp length, and the species andamount of phytoplankton of 16 shrimp culture ponds in a whole shrimp culture season.By statistical analysis, the results show as follows:In the fore 4 months of culture, the change of average daily feed amountshowed basically as a shape of upended letter U which shows the average daily feedamount increased gradually while the culture time extended. To about 60 days ofculture, the average daily feed amount value reached the most, followed by a platformperiod of 30 days and a reduction thereinafter. By 120¹30days, it reached the least,and then increased up again.The change trend of average water depth was almost same in every pond,which was shallow in the early stage and deep in the later stage.The change trend of salinity was almost the same as low in the early stage andhigh in the later stage , which showed salinity higher as culture time extended.The change trend of transparency(TT) showed: the TT in the morning washigher than in the afternoon;the TT was higher in the early stage than in the laterstage.Water temperature fell down gradually as culture time extended. Watertemperature at 6:30 was lower than at 17:30. And the water temperatures at 6:30 and17:30 showed a parallel change trend.The total change trend of pH showed: pH was high in early stage. With theculture time extended, it became lower gradually. To 90 days pH fell to the least value,and then rise up gradually. pH was lower in the morning than in the afternoon. Thechange trend of pH in the morning and afternoon was parallel meanwhile it existedoccasional fluctuation .The average concentration value of DO at 6:30 increased gradually as theculture time extended. And 17:30 DO was relatively stable in the whole culture season.DO was higher at 17:30 than at 6:30, this trend was more obvious in the early stage.The average concentration value of NH3-N increased gradually as the culturetime extended. In the back culture stage it fluctuated relatively greatly. In the courseof shrimp culture, the average concentration value of NH3-N was higher at 17:30 thanat 6:30.No.9²1 water colors appeared at 6:30, the appearance proportion of themseparately as follows: 0.1%No.9, 0.3% No.10, 1.1% No.11, 0.6% No.12, 1.5% No.13,3.7% No.14, 7.1% No.15, 17.5% No.16, 22% No.17, 15.9% No.18, 13.7% No.19,10.9% No.20, 5.8% No.21. No.11²1 water colors appeared at 17:30, the appearanceproportion of them separately as follows: 0.1% No.11, 0.3% No.12, 1.2% No.13,4.0% No.14, 6.0% No.15, 17.8% No.16, 24.7% No.17, 18.1% No.18, 11.8% No.19,9.7% No.20, 5.7% No.21.67 species of phytoplankton were checked out of 11 types of classical WC.: 16species of phytoplankton in No.11 WC, the dominant species including Pleurosigmanormanii Ralfs (47.1% in total phytoplankton amount of No.11 WC ) andThalassionema nitzschioides(29.8%). 16 species of phytoplankton in No.12 WC, thedominant species including Prorocentrum sp. (40.85% ) and Coscinodiscus Ehrend(20.73%). 16 species of phytoplankton in No.13 WC, the dominant species wasOscillatoria sp.(45.58%). 18 species of phytoplankton in No.14 WC, the dominantspecies including Melosira nummuloides (Dillw.) Agardh (56.73% ) andGoniaulax(=Gonyaulax)Diesing (12.87%). 18 species of phytoplankton in No.15 WC,the dominant species was Pleurosigma normanii Ralfs (64.76% ). 16 species ofphytoplankton in No.16 WC, the dominant species was Melosira nummuloides (Dillw.)Agardh (69.93% ). 14 species of phytoplankton in No.17WC, the dominant speciesincluding Pleurosigma normanii (62.56% ) and Goniaulax (=Gonyaulax Diesing(15.76%) . 21 species of phytoplankton in No.18 WC, the dominant species wasMelosira nummuloides (Dillw.) Agardh(71.19% ).18 species of phytoplankton inNo.19 WC, the dominant species was Coscinodiscus Ehrend (94.99%). 18 species ofphytoplankton in No.20 WC, the dominant species was Coscinodiscus Ehrend(87.14%). 15 species of phytoplankton in No.21 WC, the dominant species includingMelosira nummuloides (59.80%) and Guinardia flaccida(17.57%).Correlation analysis results showed that the main factors to water color werepH at 17:30,cultured bio-mass, NH3-N at 17:30,water transparency, water exchangequantity etc. The main factors to shrimp body length were DO at 6:30,waterexchange quantity, water color at 17:30, salinity, water transparency at 17:30, watertemperature at 17:30 and NH3-N at 6:30。The analysis of morphometric attributes on body weight showed that the bodylength (X1), carapace length (X2), carapace width (X3) and number of lower frontaleminence spine (X6) to the body weight have all reached a level of significance. Theseattributes were very indicative of determining the body weight, among them bodylength (X1) weighted the most (P1=0.428) to the body weight, it is a key effectivefactor, carapace length (X2) and carapace width (X3) weighted the second and third(P2=0.2902, P3=0.2453, significant indirect effect 0.6145, 0.6408 respectively). Thenumber of lower frontal eminence spine (X6), carapace height (X4), number of upperfrontal eminence spine (X5), and tail length (X7) have insignificant direct effect on thebody weight and were neglected.