In order to clarify the effects of restoration and disappearance of submerged macrophytes upon structure and biodiversity of protozoan community,the mesocosm experiments were conducted in Lake Donghu,Wuhan.When the submerged macrophytes were restored in the enclosures,some species of protozoans which were recorded in the 60's but disappeared from the lake waters afterwards were to be reappeared.There were richer species,lower densities and higher biodiversity indeces in the two macrophytic enclosures.The se...