The Ecosystem Health Assessment Of Plankton Index And Sensitive Indicator Of Physicochemical Factor In The Three Kinds Of Large Waters Culture Model

YanTan reservoir has a good water quality and rich biodiversity among the nine cascade hydropower stations of the Red River.As the scale of aquaculture being expanded,the pressure of eutrophication in YanTan reservoir's cage culture intensive area is increasing.From the two years monitor of plankton and the main physicochemical factors in the three different types of aquaculture water,including cage culture intensive area(A zone JiangDong)?cage culture inferior intensive area(B zone BaLong Island)and pen fish culture zones(C zone ShangYin Tun),we analyzed the spatial and temporal change characteristics of the main environmental factors in each water and evaluated the health condition of ecosystem by using gray relational analysis and the integrity index of Plankton biological.Further more,by analyzing the relationship between P-IBI value and the physicochemical factors,we proposed the major water environmental factors that affecting the health of aquatic ecosystems in three types of aquaculture areas.Research results are as follows:1.The community structure of plankton and its temporal and spatial variation in the three types of aquaculture waters.(1)The community structure of Plankton8 phylums,71 genera,76 species of phytoplankton were identified in three types of aquaculture waters,most were Chlorophyta which accounts for 28 genera and secondly were Bacillariophyta.There were fewer Xantophyta in the three types of aquaculture waters,which accounts for only 1 genera.The kinds of phytoplankton in three types of aquaculture waters are C point>A point>B point.The dominant populations are Cyanophyta,Bacillariophyta and Chlorophyta.Dominant species are Melosira and Pediastrum.4 classes,59 genera of zooplankton were identified,including 24 genera of rotifer which accounts for 46.68%,16 genera of protozoa which accounts for 27.12%,16 genera of cladocers which accounts for 27.12%,and 3 genera of copepod which accounts for 5.08%.The kinds of Zooplankton in three types of aquaculture waters are also C point>A point>B point.Dominant species are Cyclops,Polyarthra and Calanoida.Seasonal differences exist on the dominant species of plankton.(2)The density and biomass of planktonThe annual average density and biomass of phytoplankton in the three types of waters are 2.78 x 104 ind/L and 0.13 mg/L respectively.Both density and biomass of phytoplankton are highest in the A point,followed by the C point,the B point.The highest value of both biomass and density occurs in 6-8 months,the minimum occurs around December.The annual average density and biomass of zooplankton are 2.71×102 ind/L and 6.33 mg/L respectively.The annual average density of zooplankton is highest in the C point,followed by the B point,the A point.The annual average biomass is highest in the C point,followed by the A point,the B point.The highest value of both biomass and density occurs in around June.(3)Diversity of planktonThe indexes of Shannon-Wiener,Pielou and Margalef of phytoplankton in the three waters are 2.46,0.69 and 0.96 separately.Three kinds of index values are highest in the C point,followed by the A point,the B point.The index of Shannon-Wiener,Pielou and Margalef of zooplankton in the three waters are 2.41,0.78 and 1,14 separately.Three kinds of index values of zooplankton are highest in the C point,followed by the A point,the B point.Generally,the planktons in the three types of waters are diversity.2.The gray correlation analysis of water quality in three types of watersUsing gray relational analysis,we evaluated the water quality in the three types of waters in YanTan reservoir.The overall water quality is between ?-IV class.The water quality became poor in June,there are different levels among point A,B and C,and the water quality is IV.IV and III class respectively.The best water quality appears around october,three kinds of water quality are class ?.The water quality in 2011 was better than the same period in 2012.Based on the type of water quality assessment,water quality of point C is best,followed by point B and A.3.The ecosystem health assessment of YanTan reservoir's three types of waters.We used seven indictors,including screened abundance of cyanobacteria,diversity index of phytoplankton and zooplankton,Richness index of zooplankton,the species of phytoplankton,zooplankton,cladocerans and copepods,and five grade evaluation methods to assess ecosystem health condition in YanTan reservoir's three types of waters.Ecosystem health conditions of A,B and C areas are sub-health,sub-health and wellness respectively.On the change of seasons,August has the best health status.A,B and C water is wellness.December is the worst,the health condition in water A,B and C is good,good and sub-health.The health conditions in 2011 were better than the same period in 2012.The health condition of the point A was best in the three types of waters ecosystems,followed by the point C and B.That is to say the pen fish culture area is the best,followed by the cage culture inferior intensive area and the cage culture intensive area is the worst.4.The correlation analysis between integrity index of plankton and the major physicochemical factors of YanTan reservoir.The grey relational analysis method was used to analyze the relational grade between P-IBI value and the main water environmental parameters in the three types of waters.The results showed that the pH,WT and CODMn were the major factors which influenced P-IBI values,other factors were TP,NH3-N and NO2-N.Correlation between the main Physicochemical factor and P-IBI value in point A are pH>CODMn>WT>TP>DO>NH3-N>NO2-N;Correlation between the main Physicochemical factor and P-IBI value in point B are pH>CODMn>WT>DO>NH3-N>NO2-N;Correlation between the main Physicochemical factor and P-IBI value in point B are pH>CODMn>WT>DO>NH3-N>TP.Physicochemical factors played different roles in affecting the value of P-IBI of the three types of waters.