Abstract:The effects of different concentrations (400,800 and 1200 mg/L) of melamine on population growth,sexual reproduction,body size and egg size of rotifer Brachionus calyciflorus were investigated.The results showed that the 24 h LC50 value of melamine to B.calyciflorus was 2 627.00 mg/L.Compared with the controls,melamine at 800 and 1 200 mg/L decreased significantly the population growth rate,but increased the resting egg production,body size and egg size,indicating that the rotifers allocate more energy for body growth,and produce bigger but less offspring at higher concentrations of melamine.Melamine at 1 200 mg/L increased significantly the mictic rate and the ratio of mictic females/amictic females.With the increase of melamine concentration,the resting egg production increased,but the population growth rate decreased.The mictic rate and the ratio of mictic females/amictic females were curvilinear correlated with melamine concentration.
