Studies On Plankton And Water Environment In Caged Culturing Area Of Zhelin Lake

This paper investigated the plankton once a month in an aquatic field named "Lushan xihai Chanyong caged culture field" of Zhelin Lake from July 2006 to July 2007, According to the figure of the caged culture area and the species of feeding fish we set sample sites. The main content of study included: many environment factors were measured; a detailed research on the composition and the changing rule of community structure of the plankton were taken; and we used the diversitied formulary to analysis the diversity of the phytoplankton.At the same time we also mensurated the changing rule in one year about chlorophylla and many environment factors in caged culture area. The nutrition status of the caged culture water has also been evaluated related to changing condition of the community and quantity of plankton, and has been analyzied the relation with aquiculture.The main result is:1. The main environment factors in area caged culture: SD, WT (water temperature), pH, DO, TP, NH₄⁺ and NO₂^- were measured and analyzed.2. More than 333 taxa of phytoplankton were identified, which belonged to 98 genera of 8 phyla and included more than 320 species, 11 variations, 2 forms. The year's average biomass was 7.76×10⁶ind/L.The biomass and the number of species of Chlorophyta ranked the first, the number of species of Cyanophyta and Bacillariophyta was also very big. The dominant species of phytoplankton was different in every month .The amount of species was the most at December 2006 and the fewest at July 2006. The biomass of phytoplankton is the most at July 2007 and the fewest at January 2007. The average concentration of the chlorophylla of a year is 0.63mg/m³ and the highest value was present in summer of 2007, the distribution in every site and changing in a year was similar to the biomass of pyhtoplankton.3. More than 160 species of zooplankton were identified, which belonged to 65 genera of 4 phyla, among which there were Rotifera 85 species, Cladocera 21 species, Copepoda more than 10 species and Protozoa 51 species. And there were 14 dominant species including 6 species of Rotifera, 2 species of Cladocera, 2 species of Copepoda and 4 species of Protozoa.The average biomass of zooplankton was 8010.08ind/L.Among the year the species of Rotifera had dominance, it's proportion was 50.90%,The biomass of Protozoa had abosluted dominance, ti's proportion was 92.67%.The most species appear in July 2007,the fewest in December 2006.4. This paper chosed DO, SD, pH and WT (water temperature) made a correspondence analysis with phytoplankton, DO and SD were obviously correlated with phytoplankton, pH and WT (water temperature) had little correspondence with phytoplankton.5. This paper chosed DO, SD, TP, NH₄⁺, NO₂^-, the dominant species and density of phytoplankton,the content of chlorophylla and the TSI (the nutrition parameter) after amended as a criterion,and made a nutrition evaluation to the water in area caged culture of Zhelin Lake. The water was in the poor nutritional status in caged region of Zhelin lake.6. This paper discussed the relationship between aquaculture and plankton, founded the water quality of caged area in Zhelin lake was good, and this place was suitable for carnivorous fish aquaculture.