塔玛亚历山大藻和东海原甲藻对褶皱臂尾轮虫种群数量的影响

通过对2002年5月东海赤潮原因种一东海原甲藻和亚历山大藻的单一藻种和两种藻混合情况下对褶皱臂尾轮虫种群数量影响的实验研究，发现塔玛亚历山大藻(ATHK)对轮虫有致死作用，其48hLC50为1300cell·ml^-1．藻的各组分毒性比较研究表明，只有藻液和藻细胞具有这种毒害作用，藻在早期生长阶段的毒害作用较强，毒性大小与藻细胞活性相关．东海原甲藻在高密度(4×10^4、5×10^4、10×10^4cell·ml^-1)时对轮虫种群数量在第5d时开始有影响；东海原甲藻在低密度(1×10^4、2×10^4、3×10^4cell·ml^-1)时，轮虫能够以其为食并进行生长繁殖．两种藻混合情况下，东海原甲藻能够减轻塔玛亚历山大藻对轮虫的毒害作用．实验结果表明，此次赤潮对东海的微型浮游动物种群能够产生一定的影响．

Effects of Alexandrium tamarense and Prorocentrum donghaiense on rotifer Brachionus plicatilis population

The effects of Prorocentrum donghaiense and Alexandrium sp., causative species of harmful algal bloom of East China Sea in May 2002, on rotifer Brachionus plicatilis population were studied in the laboratory. The results showed that Alexandrium tamarense (ATHK) had a lethal effect on B. plicatilis and the 48hLC50 was about 1300 cell.ml-1. The toxin comparison of different fractions showed that the algal culture and re-suspended algal cells had the adverse effects, and the alga at earlier growth phases showed a stronger impact, indicating that the inhibitory effect was related with the activity of the living algal cells. P. donghaiense at high densities (4 x 10(4), 5 x 10(4) and 10 x 10(4) cell.ml-1) had an adverse effect on B. plicatilis population, while at low densities (1 x 10(4), 2 x 10(4) and 3 x 10(4) cell.ml-1), the alga could be used as food for rotifer population. When the two algae were mixed, the lethal effect of A. tamarense could be decreased by P. donghaiense. The results indicated that the above HAB event could affect the micro-zooplankton population in the occurrence area of East China Sea.