Study On Macrobenthic Animal And Assay Of Water Quality Of Dongping Lake

Dongping Lake is the study area in this research.Dongping Lake is the second largestfreshwater lake in Shandong Province. And the lake is also a major flood storage water of Southto North Diversion Project. In recent years, due to the impact of human activities, ecologicalenvironment conditions have been varying degrees of damage.The Dongping Lake water qualityis good or bad, will be directly related to the water quality of south to North Water DiversionProject. Through the study of macrobenthos’ species composition and community structure inDongping Lake, not only can know Dongping macrobenthos distribution, diversity, but alsoreflect the water quality from the ecological point of Dongping Lake, combined with the physicaland chemical indicators of Dongping reflect the situation on the water quality comprehensiveevaluation, to provide water security water diversion project to provide theoretical guidance.According to the ecological environment of the hydrological conditions and othercharacteristics of the Dongping Lake, set eight sampling points, each sample taken three parallelsamples, using quantitative methods to collect macrobenthos. Be divided into four quarters:spring, summer, autumn and winter. Bring the samples back to the experiment to classify,statistical count and weight. Learn Dongping macrobenthos species composition and quantitydistribution, analyze various points of the difference in the density and biomas of differentseason, and do further research on macrobenthos community diversity. Use diversity index,biological indies to reflect water quality status in different time, and space, combined with theresult of physical and chemical indicators of water quality, to make a comprehensive evaluationof water quality. Do correlation analysis between Physical and chemical factors and indicatorsmacrobenthos, to explore the correlation between the two. The results are summarized asfollows:1、The survey founded a total of35genera and56kinds of benthic animals of5874, inwhich14genera and15species are aquatic insects, accounted for9.5%of the total;8generaand13species are Oligochaeta, accounted for6.4%of the total;12of27species of mollusks account83.8%of the total amount of quantity; other1genera1species, accounted for about0.3%of the total. Molluscous, whether in number or in the number of species are predominant.Analysising Dongping species composition of each sampling point, founded on the3rd samplenear the cage culture area the number of species up to45kinds. The number of species on the5thpoint is only25kinds, and the average number of species in every point is35kinds about. Onthe season, the difference between four seasons is small, Spring is47species slightly higher thanthe other seasons. The populations of Dongping Lake are mainly mollusks, like oak beans screw,Han horned screw, red bean screw, respectively accounted for29%、13%and10%of the total.2、The average density of the macrobenthos in Dongping Lake of a whole year is about233ind/m2, where the average density of mollusks is dominant about197.5ind/m2; followed byaquatic insects is22.2ind/m2; Oligochaeta’s average density is13.0ind/m2; still there is a smallpart of the leech class, about0.6ind/m2. The biggest number of average density of the samplingpoints throughout the year is the2nd sample near reservoir sluice about755.2ind/m2, the averagedensity of5th sample the entrance of Dawen River is the lowest about97.7ind/m2. In allseasons,density in Spring is the highest322.3ind/m2, the lowest is in Winter137.7ind/m2.Mollusks, aquatic insects densities are higher in Spring than other seasons, only the density ofOligochaeta the Summer is the highest.3、The annual average biomass is163.5g/m2, the annual average biomass of mollusks is158.7g/m2, The annual average biomass of oligochaetes、aquatic insects are3.1g/m2、1.7g/m2,leeches is only about0.1g/m2. Different from density, biomass is highest in summer229.5g/m2,significantly higher than the other seasons. The biomass of Mollusks, oligochaetes are higher insummer than other seasons, only the biomass of aquatic insects is highest in winter. Between thesampling points, the average biomass throughout the year the2nd sampling is the highest537g/m2, the number of5samples ia the lowest only68g/m2.4、Using species diversity indies Shannon-wiener (H ’), evenness index Pielou (E), speciesrichness index Margalef (M) to make comprehensive evaluation on the community structurediversity in Dongping Lake. The3rd sample point close to the cage culture area calculated H’value, E value, M values are the highest in every point. And the results of each value is lowest inthe5th sample Dawen River entrance. While in the2nd sample density and biomass values arehigh, but mainly for mollusks, and the rest kind of less diversity value is not high. H ’value calculation results of the individual samples are about2.50; and the value of E is higher, allpoints are above0.70except for the2nd sample point, which shows that the species compositionand distribution of samples are well-distributed; the values of M are quite different in samplingpoints, in addition to the1st sample starch factory near the outfall and3samples, the rest arebelow6.0. On the season, there is no obvious difference between the results of value.5、Use the minimum percentage of similarity coefficient between the8sampling pointswere analyzed by cluster analysis.Founded that most of the similarity in the range of0.500~0.700are moderate similarity between communities. Similarity is the lowest between the2ndsample near the gate of reservoir release flood waters and the3rd sampling points near the cageculture areas that is moderate dissimilar. The1st sample starch plant outfall and the8th samplenear the entrance of Liuchang River is very similar to the highest similarity. Overall, at the levelof0.75there are only1st sample and8th sample; at the level of0.5~0.75were divided into twogroups, one group is1,8,6,5,2points, another group is3,4points; at the level of0.25~0.5only7samples and other samples point, similarity is about0.491.6、Based on the evaluation of laboratory measured physical and chemical indicators DO,CODmn, NH3-N, TP, TN data, reflecting the various samples and different time periods forwater quality were in good condition, especially the values of DO monitoredⅠwater quality.Except for the values of TN reflected in class Ⅳ~Ⅴclass, the rest of the main indicators forwater quality were in classⅠ~Ⅲ class.So the major pollutants of Dongping Lake is nitrogensource. According to the calculation results diversity index H ’value, E value reflect Dongpingvarious water quality sampling points and the vast majority of the season to clean, and the Mvalue results in addition to the1st sample and the3rd were clean, the remaining were mildpollution. In addition, according to the GBI and biological pollution index BPI reflect DongpingLake to the mild pollution. Combined physical and chemical indicators evaluate the results andevaluation of large benthic animals of water quality can be considered in good condition.7、According to the results of the Pearson correlation coefficient reflects the correlation isnot significant between macrobenthos species number, density and biomass index andtemperature, DO, CODmn, NH3-N and other physical and chemical indicators.Only molluskspecies number and temperature Showed a strong degree of positive correlation. And betweendensity and temperature showed moderately positive correlation, a weak correlation between the rest of the data, not obvious.