强壮水螅对凤尾鱼苗的危害

在200mL培养液中放入1～5只强壮水螅(Hydra robusta)，然后再放入1只1～7d的凤尾鱼(Coilia mystus)鱼苗，以研究水螅对鱼苗早期生长发育的危害作用。对实验数据的双因素方差分析表明：随着水螅密度的增加，鱼苗死亡率极显著增加，直至鱼苗死亡，而鱼苗平均体重极显著降低；当水螅密度不变时随着鱼龄的增加，鱼苗死亡率极显著降低，而鱼苗平均体重极显著增加。显然，强壮水螅对凤尾鱼鱼苗早期的生长发育有极大的危害作用，但随着鱼龄的增长，危害程度降低，不过仍然影响鱼苗体重的增长。

Hazards of Hydra robusta to Coilia mystus Fry

To investigate the hazards of Hydra robusta to fish fry of Coilia mystus at the earlier development stage,we designed an experiment to put a fish fry (1-7 days of age) in the cultured solution of 200 milliliter contained 1-5 polyps.Results of experimental data analyzed by two-way analysis of variance showed that:With the polyps density increased,the death rate of fish fry increased (up to died) and the average weight of fish fry was decreased significantly (P<0.01).With the age of fish fry increased,the death rate was decreased and the average weight was increased significantly (P<0.01).It is concluded that the hazards of Hydra robusta to fish fry of Coilia mystus is extremely serious,but becomes lower and lower with development of fish fry,however,it finally influences the increase in fish weight.