Study On Characteristics Of Planktonic Diatomcommunities And Correlation With Their Environmental Factors In Karst Cave

Diatom is a kind of single-cell algae,and responds to changes of water environment condition sensitively like the changes of p H, temperature and trophic structure and many other environment variables, all will give rise to the variety of diatom assemblages and species numbers. Karst cave groundwater as a special water has the function of corrosion and erosion, and a certain difference from surface watersuch as rivers.So it is of great significance to research on diatom assemblages distribution in karst cave groundwater on basicdata supplement in karst cave groundwater ecosystem with monitoring and protecting karst cave groundwater environment. The water samples and diatom samples were collected in 3 caves was as sample points in Yulong Village, Cengtai Town of Bijie City from April to December 2014 and 31 sample points in Wujiang in September2013.The relationship between the diatom species numbers and density and environment factors were analyzed by Canoco:Correlation analysis and cluster analysis. The distributional characteristics of planktonic diatom communities, dominant species of diatom and biological diversity were studied simultaneously, and the transfer functions between planktonic diatom and water environment factors was built. Following are the main results:1. Karst cave planktonic diatoms were identified 256 species, belonging to 2 Classes, 5Orders, 11 Families and 25 Genus, and IV p lanktonic diatomsidentifiedbelonged to 2 Classes, 6Orders, 11 Families and 27 Genus and totally 222 species were identified in Wujinag.2. According to the measuring towards TN, TP, Si O2,T and so on of karst cave groundwater, finding each index distribution existed obvious discrepancy in different caves and seasons.3. The relativity between the species numbers of planktonic diatoms and TN was 0.752(P<0.01), highly significant differences,and theregression equation wasy=-14.841+18.860x; the relativity between the density and Si O2was-0.813(P<0.01), and its regression equation was y=162.427-17.921 x.4. The results of the analysis showed that the highest index of richness was sample S1 in April(13.6156), the lowest one was sample S2 in December(1.5417).Thehighestindexof diversitywas sample S1 in April(3.6701), the lowest one was sample S2 in December(1.2770). The highest index of evenness was sample S2 in December(0.9755), the lowest one was sample S1 in September(0.6602).5. The species numbers of planktonic diatom in krast cavewasmore than Wujiang rive, but diatom density less than Wujiang. TN and Si O2 were ascertained to be prominent factors influencing Thecomposition and growth planktonic diatoms using correlation analysisand cluster analysis, the could be regarded as the criterion for evaluating the water quality of karst cave, and the overall assessment was that water quality was best in June, worst in December by means of Shannon-Wiener index.