Study On Ecological Conditions' Optimization Of Chinese Mitten Crab,Eriocheir Sinensis Culture Pond In Gucheng Lake Reclamation Area

1.Effects of different sediment treatment methods on water quality and yield of crab culture pond in the front of Bellamya quadrata throwingOn the basis of aquaculture practice,the effects of three different methods of sediment improvement,Deltamethyrin or Pesticide disinfection,common disinfectant(Calcium hypochlorite or Chlorination disinfection)and Quicklime,on water quality index and production in the front of Bellamya quadrata throwing were tested and recorded by the method of practical detection in pond mouth.The results showed that:1.The indexes of nitrite and ammonia nitrogen in the experimental group using Deltamethyrin or Pesticides were significantly higher than those in the other two experimental groups(P<0.05);The pH and D.O values of the test group using Deltamethyrin or Pesticides were significantly lower than those of the other two groups(P<0.05).2.The yield of the experimental group using Deltamethyrin or Pesticides in pond cleaning was significantly lower than that of the other two experimental groups(P<0.05).The results showed that the water quality index and final yield n in the front of Bellamya quadratathrowing of common disinfectant(Calcium hypochlorite or Chlorination disinfection)in the culture conditions of three different treatment groups were better than those of the other two experimental treatment groups.2.Effects of stocking density on the benefits of adult crab cultureBased on the same culture environment,the effects of different stocking densities(800 ind/667m~2,1000 ind/667m~2 and 1200 ind/667m~2)on the yields,costs and economic benefits of farming were investigeted.The results showed that there were significant differences in the yields of three different stocking-densities groups(P<0.05).Among them,the highest yields and costs were in the stocking-density group of ind/667m~2;The best farming benefits could be obtained from the ponds with the stocking-density(1000 ind/667m~2)by comprehensive analysis of breeding costs and yields.3.Effect of aquatic grass cultivation on the benefits of adult crab cultureBased on the same culture environment,the effects of three different experimental groups on the water quality index and culture benefit of crab pond were studied,Elodea nuttallii in whole pond,Hydrilla verticillata in whole pond,Planting Hydrilla verticillata in Sakata and Elodea nuttallii planted in ring ditches.The results showed that:1.The pH value and ammonia nitrogen content of the whole pond Elodea nuttallii test group were significantly different from those of the other two test groups(P<0.05);2.The survival rate and yield of the whole pond Elodea nuttallii test group were significantly different from those of the other two test groups(P<0.05).The results showed that the water quality index and ultimate aquaculture benefit of planting Elodea nuttallii in Ring ditchs and Hydrilla verticillata in Sakata were better than those of other aquatic plants planting modes.4.Effects of Bellamya quadrata on Water Quality and Growth of Water Grass in Crab PondsBased on the same aquaculture environment,the effects of Bellamya quadrata throwed on the Growth of aquatic plants and beneficial plankton biomass in ponds were studied in three different periods:mid-March(15 March-17 March),early April(4April-7 April)and mid-April(17 April-18 April).The results showed that:1.The average values of ammonia nitrogen and nitrite in the experimental group of Bellamya quadrata in mid-March were significantly higher than those in the other two experimental groups(P<0.05);The values of pH and D.O in the Bellamya quadrata test group were higher than those in the other two test groups in the middle and late April(P<0.05).2.The beneficial plankton biomass of the experimental group in late April was significantly higher than that of the other two groups(P<0.05).3.In the middle of March,the growth rate of water and grass in the Bellamya quadrataexperimental group was significantly lower than that in the other two experimental groups;In mid-March,the yield of the Bellamya quadrataexperimental group was significantly lower than that of the other two experimental groups(P<0.05).The results showed that:the most important influence of the time of Bellamya quadrata throwed on crab culture is the growth of aquatic plants.The time of snail feeding should not be too early in the reclamation area of Gucheng Lake.The water quality of the experimental group with Bellamya quadrata in mid-April is obviously better than that of other experimental groups.5.Effects of different aeration methods on dissolved oxygen and survival of crab culture in pondsBased on the same aquaculture environment,the effects of pump aeration,microporous aerator aeration and water truck aerator aeration on the changes of dissolved oxygen and stress resistance in crab pond during adverse weather were studied.The results showed that:1.Under the stimulation of high concentration of 10%povidone iodine,the number of deaths in the pump oxygenation group was significantly higher than that in the other two groups.2.In bad weather,the difference of dissolved oxygen in the morning and evening of the pump oxygen enrichment test group was significantly higher than that of the other two test groups.The results show that pump aeration can not meet the requirements of pool aeration,and the hypoxic oxygen stress caused by pump aeration is the greatest;microporous aeration equipment can improve the dissolved oxygen in water to a certain extent,but its aeration efficiency is not high enough to meet the needs of pool dissolved oxygen in bad weather;water truck aerator can effectively ensure the stability of dissolved oxygen in water and reduce the stress of cultured animals.