中华原钩虾的胚胎发育及其与水温的关系

The embryonic development of Eogammarus possjeticus and its relationship with variation in incubation temperature

采用发育生物学和生态学方法,观察描述了中华原钩虾的胚胎发育过程,研究了胚胎发育与水温的关系。结果显示,中华原钩虾的抱卵量与雌体体长呈正相关,抱卵雌虾通过抱卵板附着胚胎,在育卵袋内孵化幼体。水温15~27°C范围内,随着温度的升高,胚胎发育历期缩短,发育速率加快;21°C恒温条件下,中华原钩虾胚胎发育全程大约需要220 h,离体培养受精卵和亲体抱卵孵化基本同步。根据有效积温法则公式计算出胚胎的发育温度阈为6.02°C,有效积温为137.30°C·d。研究表明,中华原钩虾的前几次卵裂为全裂,后转为表面卵裂,初孵幼体与成体形态相似;温度对其胚胎发育历期和发育速率的影响差异极显著。

Detailed observations of the embryonic developmental stages of E. possjeticus were obtained by using vivo light microscopy. The embryonic development and its relationship with incubation temperature were studied.The results indicated that there was a positive linear relation between the fecundity and female body length. E.possjeticus displays a direct development, with the eggs developing inside a ventral brood pouch, where they hatch as larvae. The duration of embryonic development was about 220 hours at the constant temperature 21 °C. There were two types of observations for embryonic development. One was isolated culture and the other was the fertilized egg carried by the female. The result showed that the fertilized egg of the isolated culture and the fertilized egg carried by the female developed almost simultaneously in the same conditions. In a word, eggs undergo total cleavage for the first few times, and then turn to the superficial cleavage. Early total cleavage appears to be a general feature of amphipod embryogenesis. The hatched larvae had similar morphological characters to those of adults. Temperature showed significant influence on the embryonic development time. Within range of water temperature 15–27 °C, the duration of embryonic development decreased with the increase of temperature,while the developmental rate increased. Based on the developmental time at the different temperature, the developmental threshold temperature was calculated to be 6.02 °C, and sum of effective temperature was137.30 °C·d.