Annual Comparative Studies On Structure Of Zooplankton Community In The Yeyahu

Zooplankton plays a very important role in the process of freshwater ecosystems.They are not only the consumers of bacteria and algae,but also the food for fish and other aquatic animals.They directly or indirectly influence the cycling of such nutrients like phosphorus and nitrogen through their metabolism and excretion in aquatic ecosystem.The study on annual variation of community structure of zooplankton and the correlation between ecological factors and zooplankton was conducted in Yeyahu in Beijing from Dce.2006 to nov.2007.127 species of zooplankton was identified,among which there were 48 Protozoan species in 40 genera,57 Rotifer species in 30 genera,12 Cladocera species in 9 genera and 10 Copepoda species in 9 genera.65 species were recorded in autumn,46 in spring,47 in winter and 36 in summer,and species appearing all the yearround were 12.The data indicated that the dominant species of zooplankton were Difflugia giobulosa,Strobilidium gyrans,Vorticella convallaria,Zoothamnium arbuscula, Brachionus angularis,Keratella valga,Polyarthra trigl,Pompholyx sulcata, Gastropus minor,Alona quadrangularis,Bosmina coregoni,Daphnia carinata, Mesocyclops leuckarti,Paracyclops fimbriatus.Annual fluctuation of abundance and biomass was close in 6 locations. Abundance was44 to 2765ind/L.Abundance was most at bank to least in center. Abundance was the highest in summer,successively in autumn and spring,the least in winter.Species of zooplankton increased along with temperatuer′s rising,but correlation of species and pH were unobvious in Yeyahu.That of abundance in summer and autumn and dissolved oxygen was obvious than them in spring and winter.