Study On The Structure Of Phytoplankton Community And Its Relationships With The Environmental Factors In Yuanhe River

Yuanhe River is a first level branch of the Lower-Middle of GanJing River. Physical and chemical index are monitored all year around. But there is not any study on the structure of biological community yet. Many compounds which have potential synergy effect and toxic effects to aqueous environment are hard to be tested by physical and chemical monitor. And planktonic algae which is important aquatic resources can reflect the regularity of water change because of its short growth cycle and sensibility to environment. And it is scientific to synthetically value the water quality of Yuanhe River. This paper study on the planktonic algae of the river, and has 17 sample sites, sample every quarter of a year from Mar.2010 to Dec.2010, it is four times. Study and monitor the structure of community and its change as the season go on based on the monitor of physical and chemical index. This paper analyze and value the aquatic environment of Yuanhe River by species of planktonic algae, structure of community, indicator species, abundance, biomass and Diversity Index etc., along with the physical and chemical index. And the study supplies a scientific evidence for the comprehensive treatment and protection of Yuanhe River. The main research results are as follows.1. The low temperature of Yuanhe River was 9.17℃throughout the year, the annual average temperature was 18.32℃, and the river was alkaline slightly, the annual average pH was 7.70, the conductivity was 200μs/cm, and CODMn was 2.33mg/L, TN was 1.82mg/L, TP was 0.08mg/L2. There were 98 species of phytoplankton in Yuanhe River, which belonged to 51 genera of 7 phyla. Chlorophyta was the main phytoplankton, Bacillariophyta was the second one. Cyanophyta was the third one. Other phytoplankton phyla were in less biomass.3. The average phytoplankton abundance was 55.13 X 104 cells/L. Phytoplankton abundance had obvious change with seasons, more in June, less in September. There were obvious differences in different sampling points, more in Huixiantai, less in Longwangtan. 4. The average phytoplankton biomass was 0.3269mg/L. Phytoplankton biomass had obvious change with seasons, more in June, less in September. And the trend of phytoplankton biomass was similar to phytoplankton abundance. There were obvious differences in different sampling points, more in Huixiantai, less in Longwangtan.5. The annual average concentration of chlorophyll a was 0.62μg/L, there was a big difference among the different sample points. And the changes of chlorophyll a, the phytoplankton abundance, the biomass go with the same trend. The concentration of chlorophyll a seasonal changes obviously, and stays at a low trough in September, which is different from the cross-section of phytoplankton abundance and biomass.6. The dominant phytoplankton species of Yuan River were:Cryptomonas erosa, Cryptomonas, Scenedesmus obliquus, Scenedesmus, Anabeana, Melosira varians, Fragilaria capucina, Synedra acus, Cyclotella, Navicula cuspidate, Cocconeis, Euglena oxyuris, Peridinium.7. The environmental quality was evaluated comprehensively on the Yuan he River, and the indicators were:dissolved oxygen (DO), potassium permanganate index (CODmn, total phosphorus (TP), total nitrogen (TN), phytoplankton abundance, dominant species, the indicating algae and the diversity index. The result showed that the water quality is low-grade polluted.8. Analyze the correlation between several environmental factors and phytoplankton community structure, the result showed that Chl.a,DO,TN,CODMn had a marked correlation on the species and density of phytoplankton; and TP,SD had no effect on phytoplankton community structure.