Studies On The Community Distribution And Ecological Functional Of Periphytic Algae In Wuli Lake

Periphytic algae is one of the most sensitive biological indicator to the change of water environment. Its density and community structure, biodiversity can better reflect the quality of water environment, and is the important factor of the hydrobiology evaluation. This study was aimed at provideing feasible bases for using periphytic algae to proceed biological monitoring of water quality assessment, providing certain scientific basis for ecological management, as well as providing some reference for seeking development causes and trend of eutrophication of Wuli Lake. To achieve the above purpose, we observed the spatial and temporal variations of community structure characteristics and diversity of periphytic algae in artificial medium of Wuli Lake, the spatial and temporal variations of biomass, and their relation with environmental factors. In addition, we also detected the absorption effect of artificial matrix on nitrogen and phosphorus pollutants in the eutrophic water under the condition of laboratory environment.We were studied the community species composition, quantity and space-time difference of periphytic algae in Wuli Lake, through continuous monitoring for the whole year to the algous community on artificial matrix of Wuli Lake during May2012to April2012. Results showed that5Phylums34Genuses and43Species were detected in Wuli Lake. Bacillariophyta is sorted out dominant Phylum throughout the year,12Genuses and24Species, accounted for55.81%. The density range of periphytic algae was0.88×104ind./cm2-2.73×104ind./cm2, with a1.95×104ind./cm2annual average. Moreover, the annual average density in the silt bottom waters was up to3.90×104ind./cm2, and a minimum of1.82×104ind./cm2in sand bottom waters from the perspective of space. We found that the numbers of species and density of periphytic algae in Wuli Lake presented obvious seasonal difference, and the performance was the summer> autumn> spring> winter. The annual variation range of Pielou evenness index and Shannon-Wiener diversity index were respectively2.12-2.94and0.76-0.88, but highest in summer. Those demonstrated that the community structure of periphytic algae was rich, and the community structure was in a state of relatively complete in Wuli Lake.We proceeding principal component analysis (PCA) to10water quality indexes, extracting the main factors that affects the water quality, tried to confirm the key factors affecting the algae community parameters, combining with the algae community parameters. Results showed that the algae density was significant positive correlation with temperature (P<0.05), and also was significantly positively related to orthophosphate and chlorophyll a (P<0.05). On the contrary, density was significantly negative correlation with electrical conductivity, transparency, total nitrogen content. Three principal components extracting by the PCA to water quality parameters of Wuli Lake, principal component one was mainly on behalf of water conductivity, content of PO43-P and Chla, reflecting the condition of nutrients content and eutrophication; principal component two represented the concentration of CODmn and NH4+-N relating to the content of organic matter and ammonium ions in water; principal component three standed for water temperature and the content of TP, reflecting changes in water temperature and phosphorus pollution. PCA1and PCA2had obvious influence on the density of periphytic algae. It showed that we assessed the situation of water eutrophication by the changes of bio mass of periphytic algae in Wuli Lake.The results form our study of the absorption effect of artificial matrix on nitrogen and phosphorus pollutants in the eutrophic water showed that, the periphytic algae can eliminated the nitrogen and phosphorus pollutants by55.32%-96.86%. Therein, the TN absorption rate range from77.12%to76.97%, and the average rate was75.27%; the NH4+-N absorption rate range from55.32%to73.33%, and the average rate was62.05%; the TP absorption rate range from92.46%to92.46%, and the average rate was93.98%; Of PO43-P absorption rate range from95.25%to96.86%, and the average rate was95.90%. The experimental results showed that the absorption effect of periphytic algae to PO43--P was the best, followed by TP, and the absorption effect of TN was inferior to TP. Finally, absorption effect of periphytic algae to NH4+-N was the worst. In our study,1μg/cm2of periphyton could absorb0.042mg/L of TN,0.049mg/L of NH4+-N,0.0047mg/L of TP,0.0025mg/L of PO45-P in water.