[Objective] The aim was to establish the water quality evaluation index system for freshwater aquaculture pond.[Method] The expert survey,DELPHI,field research and other methods were *** on the analysis of factors inf...
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[Objective] The aim was to establish the water quality evaluation index system for freshwater aquaculture pond.[Method] The expert survey,DELPHI,field research and other methods were *** on the analysis of factors influencing water quality of freshwater aquaculture pond,and the importance degree of 14 factors influencing water quality of freshwater aquaculture pond was ***,five factors were selected as index to establish the water quality evaluation index system of freshwater aquaculture with the determination for thresholds of these factors.[Result] The importance degree of water quality of freshwater aquaculture pond showed an order of Dissolved oxygenpHPhytoplankton biomassSecchi depthTotal NitrogenZooplankton biomassWater temperatureBiochemical Oxygen DemandWater colorSalinityTotal hardness;according to the value of importance degree,the dissolved oxygen,pH,secchi depth,phytoplankton biomass and total nitrogen these five factors were selected as the index system of water quality evaluation of *** level of water quality of freshwater aquaculture pond was divided into five,and the tolerance range of fish to each index was obtained by expert observation.[Conclusion] This study had provided a scientific basis for water quality evaluation system of freshwater aquaculture pond.
The NEW GIFT Nile tilapia （Oreochromis niloticus niloticus L.） is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new...
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The NEW GIFT Nile tilapia （Oreochromis niloticus niloticus L.） is a nationally certificated new strain selected over 14 years and 9 generations from the base strain of GIFT Nile tilapia, introduced in 1994. This new variety has been extended in most of areas of China. The management of genetically improved strains, including the genetic markers for identification is needed urgently. RAPD analysis was conducted and their conversion to SCAR markers was developed. From NEW GIFT Nile tilapia, two strain-specific RAPD bands, S304624 bp and S36568 bp were identified. The strain-specific RAPD bands were gel-purified, cloned, and sequenced. Locus-specific primers were then designed to amplify the strain-specific bands. PCR amplification was conducted to test the variations in allele frequencies of two converted SCAR markers among the NEW GIFT Nile tilapia and its base strains, as well as 7 additional farmed strains worldwide. The frequency of SCAR marker Ⅰ （553 bp） was 85.7% in NEW GIFT Nile tilapia, but 16.7% in the base strain. The frequency of SCAR marker Ⅱ （558 bp） was 91.4% in NEW GIFT Nile tilapia, but 0% 70% in the 7 other strains. In order to confirm the utility of these two markers, an examination was conducted for a wild population from Egypt, resulted the frequency of SCAR Ⅰ and Ⅱ was 10% and 70%, respectively, much lower than that of New GIFT strain. The increase in allele frequency of these two SCAR markers suggests that these markers might be genetically linked to the quantitative trait loci （QTL） underlining the performance traits by long term selection, and indicate the bright potential of SCAR marker technology for tracking generations during selection progress and for distinguishing among genetically improved strain and other strains.
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