A Preliminary Study On The Effect Of Water Quality In Ecological Farming Crab

Chinese mitten crab (Eriocheir sinensis) is a famous freshwateraquaculture species, Chinese mitten crab farming has become one of theimportant pillars of the aquaculture industry in China.Chinese mitten crabaquaculture make full use of aquatic plants, purify water quality.Inaquaculture water， all biological form a three-dimensional multi-levelfarming ecological system.Aquatic plants not only provide a good habitatecological environment for crabs and at the same time，it could absorbthe a large amounts of nitrogen and phosphorus in water, reduce theeffect of aquaculture on water environment.Chinese mitten crab farmingnot only increase agricultural income, while it can reduce the pollution ofthe water environment, to achieve good economic and ecologicalbenefits.Chinese mitten crab life cycle include zygote-zoea-megalopa,megalopa-button crab, button crab-mature crab, three life stages.Thispaper reports the Chinese mitten crab breeding water quality variationlaw of the two life stages.This paper will analyze the relationshipbetween culture ponds and water source in the three life stage, at the sametime,according to the "surface water environmental quality standards" in the3standards and "fishery water quality standard", we can get the finalanalysis that Chinese mitten crab breeding impacts to the natural waterenvironment.In recent years，there have been many research on river crabecological breeding technology, but the water quality changing law incrabs ecological aquaculture is still little research.However, the variationof water quality is very important to the development of ecological crabculture and natural water environment protection,In order to study thewater quality change rule in crabs ecological aquaculture and its theinfluence on the natural water environment, We investigated waterquality in aquaculture pond and water source form clasp crab breedingcycle to crab breeding cycle.In June2012-October period, we have monitored the larvaeculture ponds water quality and water sources water quality inShanghai’s Songjiang Maogang district. During the entire monitoringprocess,nitrate(NO3--N) concentration in water source were substantiallyhigher than the clasp crab culture ponds.Nitrite(NO2--N) concentration inwater source ponds was higher than the clasp crab culture ponds,however，the concentration of nitrite(NO2-—N) in the water sourcewas obviously lower than the concentration of the clasp crab cultureponds on June26of the experiment. And at the early stage of theexperiments, Phosphate(PO43-—P) concentration in water sources was higher than the clasp crab culture ponds. After a period of theexperiment,the concentration of phosphate(PO43-—P) in the clasp crabculture ponds was hihger than the water resources (P<0.05).Throughoutthe breeding cycle, the concentration of ammonia（NH4+-N） in the claspcrab culture ponds were slightly lower than the water resources, but nosignificant difference.the concentration of CODMnin the clasp crabculture ponds keep growing trend，which concentration were significantlyhigher than the water source。In March2013-October period,we have monitored the rivercrab eco-culture ponds water quality and water sources water quality inShanghai’s Songjiang Maogang district.Nitrite(NO2--N)concentration inriver crab eco-culture ponds was lower than the water sources， Theconcentration of Nitrite(NO2--N) in river crab eco-culture ponds haskept the declining trend in the experiment。 In the middle of theexperimental period, the concentration of nitrite(NO2--N) in watersource achieve highest, then gradually declined。 In the wholeexperimental section，the nitrate(NO3--N) concentration in water sourcewere substantially higher than the river crab eco-culture ponds. Nitrogen（NH4+-N）concentration in river crab eco-culture ponds was lower thanthe water source, nitrogen （NH4+-N） concentration in river crabeco-culture ponds has kept the declining trend in the experiment. Thewater source and river crab eco-culture ponds had been above the "surface water environmental quality standards" in the3standards inentire experiment，and the heighten indexes are total nitrogen(TN)andtotal phosphorus(TP),and,the maximum amplitude exceed the standardrespectively reached434.2%,208.9%.