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.

关键词:  海月水母  碟状幼体  饥饿  水温  拍动速度

Key words:  Aurelia aurita  ephyrae  starvation  water temperature  pulsation rate

摘要:

[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曟,12曟和15曟下,每个温度下放置20只,并使其保持饥饿。每隔10 d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50 d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10~20 d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8.9 cm·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30 d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。

Abstract:

[Objective] The effects of temperature and starvation on their pulsation rates were studied.[Methods] Each of 20 newly released Aurelia aurita ephyrae 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 ofAurelia aurita ephyrae was 49.3 beats·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 after 10 d and 20 d of starvation,and thereafter decreased.[Conclusion] The maximum swimming speed achieved by Aurelia aurita ephyrae was 8.9 cm · 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 d of starvation,and hence the heavily starved ephyrae may be exposed to higher predation loss.