STUDY ON THE PLANKTON COMMUNITIES AND ITS BIOMANIPULATION IN THE EUTROPHICATED BEACH PONDS

This paper studied the influence of different treatments which were respectively＂Phragmitis and calamus planting＂,＂silver carp－ cultrure＂ and＂ EM- inoculation＂ on the communities, quantity and biomass of algae and zooplankton in the eutrophicated aquatic ecosystem along the coastal area. Algae species group was different in each treatment, there was no Xanthophyta and Cryptophyta in CK and silver carp-cultrure treatment water, but other treatment was 7 phylum of algae. Phragmitis and calamus planting, EM-inoculation diversified algae species and reduce Cyanophyta biomass proportion. Silver carp-cultrure reduced　algae species but increased Cyanophyta biomass proportion, the dominant species group was Microcystis aeruginosa K?tz, Rhabdoderma lineare Schm. andDactulococcopsis acicularis Lemm., etc. There was more Protozoa species in CK and Silver carp-cultrure aquatic ecosystem than that of the other treatment, and protozoa biomass proportion was higher. Comparing with each treatment, the zooplankton density and biomass in＂EM-inoculation＂aquatic ecosystem was highest and the main communities was　Rotifera and Cladocera. The treatment of＂ EM- inoculation＂ could decrease the aquatic ecosystem concentrations of TN, NH+4-N and TP obviously, which was respectively only 57.1%, 42.7%, 57.9% of these in CK. Meanwhile, it could decrease the COD　while increased the dissolved oxygen and transparency of the water. In conclusion,＂Phragmitis and calamus hydrophyte planting＂and＂ EM- inoculation＂ could improve the aquatic micro- ecosystem and ecosystem．