【摘要】 对厦门港中华哲水蚤(Calanus sinicus)的卵型进行观察和研究,获得主要结果如下:(1)厦门港中华哲水蚤仅存在一种基本卵型,属于无鞘卵,但卵表面具有透明、柔软的胞膜(blister),胞膜呈褶皱结构;(2)胞膜可因外力而脱落,但胚胎仍可以正常发育;(3)在实验室水温为16~22℃条件下,受精卵均可正常孵化与发育;(4)胞膜的厚度有一定的变化,它随着水温的升高有减小的趋势.卵型分析与孵化实验均证实:厦门港中华哲水蚤不存在休眠卵(dormant egg)或滞育卵(diapause egg).更多还原

【Abstract】 Calanus sinicus,an independent species divided from C.pacificus,dominated in all main seas of China,plays the same role in China neritic ecosystem as C.finmarchicus in Atlantic.As a mega-copepod, C.sinicus has been widely studied because of its connecting link between the preceding and the following in marine food webs.In Xiamen Harbor,located opposite of Taiwan Island,C.sinicus usually appears in the late autumn or early winter and disappears at the beginning of summer.Then how can they spend the summer? Did they move into deeper waters or produce dormant eggs for oversummering? The present paper studies the egg types of C.sinicus in order to discuss whether C.sinicus produced dormant eggs.We collected female of C.sinicus by horizontal hauls with a 50cm diameter net equipped with a 500 μm mesh in Xiamen Harbor every 10~15 d from January to May in 2003 and 2004.In the laboratory,healthy females were chosen and placed individually in twenty-four wells tissue culture plate with full of sea water pumped from beach(salinity of 28~31) and filtered with fine sand.No food was supplied during culture.On the second morning,all eggs(except died eggs) newly released by the females were immediately transferred into glass slide.And the thickness of blister was measured under Olympus BH2 LM.In addition,some eggs which were allowed to develop into blastula stage were examined for analysis of egg types and taken photos under LM and ESEM.The results revealed that C.sinicus produced only one kind of eggs.Instead of egg case,there were transparent and soft envelopes(blister) around egg surface which make the eggs also different from smooth eggs.Blister made the egg surface take on spines under LM,while foldlike processes are evident under ESEM.Most eggs have blisters with much foldlike,while minority have a little one.Outer envelopes can be removed from the egg by whiffing gently again and again with a sucker.And the embryo losing outer envelopes can develop having synchronization with those normal ones.So the outer envelopes(blister) will not determine the embryo development of C.sinicus.We can infer that waves might lead outer envelopes to fall off from eggs,and the eggs without blister can not be regarded as dormant eggs.In laboratory,almost all fertilized eggs can hatch and develop at 16~22 ℃ and no dormant eggs were found.The studies of both egg types and hatch experiment showed that C.sinicus will not produce dormant eggs or diapause eggs in Xiamen Harbor.Additionally,we found the thickness of blister will vary slightly.The blister becomes thicker as the water temperature declines.We conclude blister may have relationship with the sinking of eggs.In low temperature the time that egg hatchment needed will be elongated and wider blister may advantaged egg floating in water column to make sure that the eggs will hatch before they reached the sea bottom.While the narrower blister was disadvantageous for egg floating so it helped to reduce the injury of higher temperature in surface water on the embryos.更多还原