In recent years, harmful algal blooms(HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life history parameters of rotifers(B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom(S keletonema costatum) and four dinofl agellates( Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi cum). Compared with the control treatment(CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production(CT: 20.34 eggs/ind.) reduced to 10.11, 3.22, 4.17, 7.16 eggs/ind., life span(CT: 394.53 h) reduced to 261.11, 162.90, 203.67, 196 h, net reproductive rate(CT: 19.51/ind.) reduced to 3.01, 1.26, 3.53, 5.96/ind., fi nite rate of increase(CT: 1.47/d) reduced to 1.16, 1.03, 1.33, 1.38/d, and intrinsic rate of population increase(CT: 0.39/d) reduced to 0.15, 0.03, 0.28, 0.32/d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the reproduction and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton, resulting in an increase in algal numbers. To examine the eff ects of dif ferent diatom and dinofl agellate HABs, the life (in recent years, harmful algal blooms (HABs) have occurred frequently along the coast of China, and have been exhibiting succession from diatom- to dinofl agellate-dominated blooms. history parameters of rotifers (B rachionus plicatilis Müller) were measured after exposure to dif ferent concentrations of HAB species. The HAB species examined included a diatom (S keletonema costatum) and four dinofl agellates (Prorocentrum donghaiense, Alexandrium catenella, Prorocentrum lima and Karlodinium venefi Compared to the control treatment (CT), the diatom S. costatum showed no adverse impacts on rotifers. Exposure to dinofl agellates at densities equivalent to those measured in the fi eld resulted in a reduction in all the life history parameters measured. This included a reduction in: lifetime egg production (CT: 20.34 eggs / ind.) Reduced to 10.11, 3.22, 4.17, 7.16 eggs / ind., Life span (CT: 394.53 h) reduced to The net reproductive rate (CT: 19.51 / ind.) Reduced to 3.01, 1.26, 3.53, 5.96 / ind., Fi nite rate of increase (CT: 1.47 / d) reduced to 1.16, 1.03 , 1.33, 1.38 / d, and intrinsic rate of population increase (CT: 0.39 / d) reduced to 0.15, 0.03, 0.28, 0.32 / d, for the dinofl agellates P. donghaiense, A. catenella, P. lima and K. venefi cum, respectively. The results showed that the diatom S. costatum had no detrimental consequences on the sale and growth of B. plicatilis, however, the four dinofl agellates tested did show adverse ef fects. This suggests that dinofl agellate HABs may suppress microzooplankton , resulting in an increase in algal numbers.