ECOLOGICAL STUDIES ON AQUATIC MACROPHYTES IN LAKE DONGHU, WUHAN Ⅱ.THE DYNAMICS OF AQUATIC MACROPHYTES AND PROPERTIES OF WATER BODY IN SUBLAKE HOUHU

The present paper deals with the dynamics and the restoration strategies of aquatic macrophytes in Houhu, a sublake of Lake Donghu of Wuhan.There are 47 species of aquatic vascular plants found in this sublake, and several species such as Ottella alismofdes, which are susceptible to water pollution and have been extinct from other sublakes of Lake Donghu, can be found in Houhu.The primary factor limiting macrophyte proliferation may be the overgrazing of herbivorous fish stocked by the fishery, and it is believed that the nutrient levels and light properties of water body should allow for the spontaneous recovery of macrophytes at present.The dramatic changes in macrophyte biomass and distribution area are also considered to be due to the grazing of fish.The ceasing of herbivorous fish stocking combined with the artificial lowering of water level and transplanting of macrophytes may accelerate the restoration of the aquatic macrophytes in Houhu.The water qualities under macrophyte dominance and phytoplankton dominance have also demonstrated respectively.It is suggested that Potamogeton maackianus and Elodea canadensis should be introduced artificially into Houhu to enhance the stability and resource value of aquatic macrophytes.