Abstract: In order to understand the effects of fertilization and water quality control on the planktons in farming waters, an investigation from June to October 2008 was made on the community structure and population dynamics of planktonic ciliate in controlled low salinity enclosure environment. Through living body observation and stained specimen observation, a total of 48 planktonic ciliate species were detected, belonging to 3 classes, 11 orders, and 37 genera, of which, 8 species were of Oligotrichida, 7 species were  peritrichida, and 6 species were of hypotrichida and scuticociliatida. The dominant species mostly enjoyed living in eutrophic water or were pollution-resistant species, e.g., Tintinnopsis cylindrata, Stranbidium globosaneum, Pleuronema marinum, Mesodinium pulex, Coleps hirtus, and Cyclidium citrullus, etc. Different fertilization treatments had significant effects on the community composition and population dynamics of planktonic ciliate. In investigation period, the highest species number of planktonic ciliate in the enclosure environment was averagely 9, and the lowest one was averagely 4. In the test 10 control enclosures, the highest density of planktonic ciliate was averagely 112.30 cells·ml^-1, and the lowest one was averagely 19.50 cells·ml^-1. The average species number and density of planktonic ciliate were 6-7 and 52.56 cells·ml^-1, respectively. In the enclosures applied with organic fertilizer, the ciliates addicted to entrophic water were the dominant species. There was a close relationship between the population dynamics of planktonic ciliates and planktonic algae. Their densities were lower in early and late periods and higher in intermediate period, and the diversity of planktonic ciliates of early and late periods was lower intermediate period while that of planktonic algae was.

Key words: Road ecology, Roadside vegetation, Animal population, Index, Landscape, Road planning