饥饿和水温对海月水母碟状幼体游泳能力的影响

Effects of Starvation and Temperature on Swimming Ability of Ephyrae of the Scyphozoan,Aurelia aurita s.l.

【目的】研究饥饿持续时间和水温对海月水母Aurelia aurita碟状幼体游泳能力的影响,探讨游泳能力对碟状幼体种群生存和生长的影响。【方法】将刚刚释放的海月水母碟状幼体分别置于9℃,12℃和15℃下,每个温度下放置20只,并使其保持饥饿。每隔10d测量1次碟状幼体的拍动速度。【结果】碟状幼体的最大平均拍动速度为49.3次·min^-1。在长达50d的饥饿时间内,饥饿持续时间对碟状幼体拍动速度的影响极显著（P〈0.01）,而温度及饥饿持续时间交互作用对拍动速度的影响不显著（P〉0.05）。在饥饿10-20d后,碟状幼体的拍动速度显著加快,然而当饥饿时间进一步延长时,拍动速度也随之下降。【结论】海月水母碟状幼体的最大游泳速度为8.9cm·min^-1。碟状幼体主要食物为藤壶Barnacle幼体、轮虫Rotifers及水螅水母Rathkea octopunctata等游泳速度缓慢的浮游动物。碟状幼体的拍动速度在饥饿30d后开始显著下降,因此严重饥饿的碟状幼体可能更容易被天敌捕食,从而造成自然水域中碟状幼体更高的死亡率。

【Objective】The effects of temperature and starvation on their pulsation rates were studied.【Methods】Each of 20 newly released Aurelia auritaephyrae was transferred to 9℃,12℃and 15℃,respectively,and kept starved for up to 60 d.Pulsation rate of each ephyra was measured at every 10-day interval.【Results】The results showed that the maximum pulsation rate of Aurelia auritaephyrae was 49.3beats·min^-1.Over the starvation period up to 50 d,pulsation rates were significant affected by starvation（P〈0.01）,but they were not affected by temperature and their interactions（P〉0.05）.The pulsation increased significantly after10 dand 20dof starvation,and thereafter decreased.【Conclusion】The maximum swimming speed achieved by Aurelia aurita ephyrae was 8.9cm·min^-1,suggesting that their main prey are confined to slow moving zooplankton such as barnacle nauplii,veliger larvae and hydromedusae.The pulsation rate decreased for ephyrae after 30 dof starvation,and hence the heavily starved ephyrae may be exposed to higher predation loss.