黄海中华哲水蚤繁殖、种群补充与生活史研究

IOCAS-IR > 海洋环流与波动重点实验室

	黄海中华哲水蚤繁殖、种群补充与生活史研究
其他题名	Reproduction,population recruitment and life history of Calanus sinicus in the Yellow Sea
	王世伟
学位类型	博士
	2009-05-14
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	中华哲水蚤繁殖种群补充生活史黄海胶州湾
摘要	中华哲水蚤是黄、东海浮游动物关键种，连接初级生产与较高营养级，在海洋生态系统中占据核心地位。在以往研究基础上，依据2006年3月至2007年8月黄海9个航次、胶州湾11个航次现场调查数据以及大量室内实验数据，本文研究了中华哲水蚤的繁殖、种群补充以及油脂积累的季节变化，期望初步阐明中华哲水蚤在黄海的种群动态及驱动因素、并构建其生活史概念模型。 3、4月份，黄海与胶州湾中华哲水蚤的生殖腺普遍发育成熟、产卵率较高，中华哲水蚤种群进入繁殖、种群补充的活跃期，恰好可以利用此时较好的食物条件。5、6月份，中华哲水蚤在黄海近岸海区仍表现出较高的产卵率，而陆架海区的中华哲水蚤生殖腺成熟度、产卵率逐渐降低，种群逐渐表现出度夏特征—C5占优势、积累大量脂类。整个夏季，中华哲水蚤的繁殖率、种群补充率在整个黄海都较低，尤其在黄海冷水团区：中华哲水蚤生殖腺停滞于未成熟的GS1－GS2期，产卵率为零。10月，中华哲水蚤在冷水团边缘潮汐锋区的繁殖、种群补充活跃，或许可以解释秋、冬季近岸种群的恢复。11月之后，随着垂直混合的加强，黄海冷水团逐渐消失，此时陆架区的中华哲水蚤种群结束度夏过程，并以较低的繁殖率进行种群补充，直到次年3、4月份食物环境转好，中华哲水蚤种群出现新一轮繁殖、补充高峰。本文依据中华哲水蚤雌体密度、产卵率、孵化率等计算了中华哲水蚤的种群潜在补充率，我们发现，陆架区种群仅在3、4月份出现较强补充以及冬季的微弱补充，而近岸海区除夏季外，于各个季节均可进行比较活跃的种群补充，其中春季种群补充规模、强度最大；整体来看，春季是黄海中华哲水蚤种群补充的最重要时期。本文详细研究了中华哲水蚤的繁殖与各种环境、雌体自身因素之间的关系：1、统计结果表明，中华哲水蚤的产卵率与海区食物条件（浮游植物生物量、纤毛虫丰度）之间具有紧密联系，而与油囊体积无关；在饥饿培养条件下，中华哲水蚤只能维持3－6天的产卵，而添加食物2－7天内，即可逐渐恢复产卵；体内积累油脂在饥饿过程中有所消耗，不过仍然不能阻止产卵率的下降；这些结果表明中华哲水蚤繁殖的能量所需主要来自于近期摄食，而体内储存脂类可能主要用于代谢所需，是应对不利条件的一种能量缓冲。2、统计分析表明：产卵率与雌体前体长间具有一定的正相关性，这可能由于体长较长的雌体往往具有较高的怀卵量；产卵率与温度之间没有显著的统计关系，温度可能通过调节中华哲水蚤的代谢率、体长等间接影响到产卵率。3、值得一提的是，本文发现中华哲水蚤的产卵率与其生殖腺成熟度之间具有非常紧密的统计关系，这为通过保存样品估算产卵率以及长期历史样品、数据间的比较提供了可能。春季硅藻水华是黄海及其邻近海域的重要季节性特征。本文针对硅藻水华与中华哲水蚤繁殖的关系进行了多次现场研究，我们发现，硅藻水华因其发生海区、硅藻优势种类不同而对中华哲水蚤繁殖具有复杂多样的影响。2006年3月，胶州湾东部海区发生中肋骨条藻（Skeletonema costatum）水华，中华哲水蚤的产卵率显著增高，但其孵化率相对较低（50%左右）；2007年2月，胶州湾东部发生环纹劳德藻（Landeria annulata）水华，中华哲水蚤卵的孵化率在各种处理下均接近100%；2006年4月，黄海东北部发生太平洋海链藻（Thalassiosira pacifica）水华，产卵率与孵化率均处于调查海区的中等水平；2007年4月，黄海中部海区发生中肋骨条藻水华，中华哲水蚤在此次调查海区平均产卵率高达27.8 卵/雌体/天，远远高于以往同时期的调查结果，孵化率、幼体存活率也普遍较高；此次硅藻水华对于黄海陆架区中华哲水蚤的种群补充具有积极的促进作用。综上，硅藻水华对中华哲水蚤繁殖的影响表现出种类、海区特异性，其具体机理仍需进一步研究。本文研究了黄海中华哲水蚤C5期油脂积累的区域、季节变化，并探讨了油脂积累对中华哲水蚤的生理、生活史的可能作用。黄海近岸区的C5期油囊体积常年较小，而陆架区则表现出明显的季节差异。在陆架区，C5期是中华哲水蚤度夏种群的主要组成部分，其油囊体积与度夏过程有密切联系：最大油囊体积（可占前体部体积的30%以上）出现于度夏准备期（5、6月），随着度夏过程的进行，油囊体积因代谢而不断消耗，至12月时，油囊体积降低到与近岸种群无异。次年4月以后，油脂积累可能随食物条件转好而再次开始积累。我们认为黄海中华哲水蚤所积累油脂除了可以为休眠提供能量以克服较长时期食物缺乏之外，还可能是休眠的诱导因素，对其生活史具有重要意义。黄海近岸海区与陆架海区在水团特征、中华哲水蚤种群丰度与结构、繁殖特征、种群补充、油脂储存策略等方面具有显著差异，因此，本文分别讨论了这两个区域中华哲水蚤的生活史。黄海陆架海区中华哲水蚤在全年共有4－5个世代：11月末，中华哲水蚤结束度夏过程，种群中占优势的C5期个体开始蜕皮为成体、逐渐成熟、繁殖，由此产下的子代可称之为G0，此世代在食物条件较差的冬季发育成熟后可以产下G1；G1于3月初发育成熟，恰逢春季较好的食物条件，于是在3月初－5月中旬很可能发育G2、G3两个世代；假若陆架区食物环境适宜，5月中旬后很可能产生新的世代—G4；G3与G4两个世代的混合种群共同进入度夏过程，期间，一小部分C5蜕皮为成体，大部分C5保持滞育状态；至12月冷水团消退后，G3、G4世代C5蜕皮、成熟，开始新的生活周期。中华哲水蚤生殖腺成熟度、油囊体积的季节变化与上述概念模型具有较好的对应关系，另外，这两个参数简单易用、对环境变化敏感，可以尝试应用于气候变化与桡足类关系等长期研究中。以往的研究更多的关注于黄海陆架区的中华哲水蚤种群，对近岸种群的关注较少，本文初步探讨了近岸种群的种群补充、世代情况。相对于陆架区，黄海近岸区中华哲水蚤的生活史更为复杂，区域差异较大。近岸海区中华哲水蚤产卵率、种群周转率较高；同时，近岸海区是多种鱼类的产卵场、索饵场，该区域的各营养级间的能量流动对黄海海洋生态系统的结构功能至关重要。因此，在将来的研究中，近岸海区中华哲水蚤种群的生态学、生活史应该受到同样的重视。
其他摘要	As the key zooplankton species of the Yellow Sea and East China Sea，Calanus sinicus links the primary production to the higher trophic levels, occupying the central position of the marine ecosystem. Base on the 9 cruises in the Yellow Sea and 11 cruises in the Jiaozhou Bay during March 2006 to August 2007 and several experiments in laboratory, we studied the seasonal variations of the reproduction, population recruitment and oil storage in C. sinicus, hoping to illustrate the population dynamics, clarify the driving factors and construct the conceptual model of its life history. In March-April, C. sinicus showed relatively high gonad maturity and fecundity, and active population recruitment over the Yellow Sea, matching the favorable food and temperature conditions. While the fecundities were still high in the nearshore areas, the population on the continental shelf of the Yellow Sea showed lower fecundity and some features in preparation for the over-summering in the Yellow Sea Cold Water Mass (YSCWM), such as the dominance of C5s and accumulation of lipids in the oil sac. During summer, both the reproduction and population recruitment were not successful in the Yellow Sea, especially in the YSCWM where the gonad development was arrested in the immature stages GS1-GS2 and no spawning was recorded. In October, the reproduction and recruitment in the tidal front areas were active, which might explain the recovery of the nearshore population in autumn-winter. After November, with the increasing of the vertical mixing, the YSCWM gradually disappeared. C. sinicus started to reproduce and recruit at very low rates until the next March-April when the active reproduction begins. Based on the fecundity, hatching success and female abundance, we calculated the potential population recruitment rate of C. sinicus. On the continental shelf, recruitment was restricted in March-April when active recruitment occurred and in winter when the recruitment was very low. In the nearshore areas, however, the population recruitment could occur in every season except for summer. In general, the spring recruitment was most important for C. sinicus population in the Yellow Sea. We studied the relationships between reproduction of C. sinicus and the possible influencing factors. The fecundity was closely related to the food conditions represented by the phytoplankton biomass and the ciliate abundance but not to the oil sac volume. Under starvation, the reproduction of C. sinicus could only sustain for 3-5 days, while it would recover spawning after a few days of food addition. The oil storage was consumed during starvation but could not prevent the decrease of egg production. Based on these results, we conclude that the energy for reproduction was mainly from the recent diet, but not from the inner lipid storage which might be a kind of energy buffer coping for the unfavorable conditions. Fecundity was positively related to the prosome length of females, which was possibly mediated by the relationship between prosome length and clutch size. There was no significant relationship between the fecundity and temperature, however, temperature could affect the egg production indirectly by influencing the metabolic rates and prosome length. It was worthy to note that there was close and significant relationship between the egg production rate of C. sinicus and its gonad maturity. This relationship might enable us to estimate the fecundity by examining the preserved samples and compare the difference in long term studies such as the climate change effect on copepods. Spring diatom bloom was a major seasonal feature in the Yellow Sea and the adjacent areas. Based on the results of several cruises, we found that the effects of diatom bloom on the reproduction of C. sinicus were complex. In March 2006, the diatom bloom consisted by Skeletonema costatum occurred in the eastern Jiaozhou Bay. During this bloom, the fecundity of C. sinicus was high but its hatching success was only ~50%. The diatom (Landeria annulata) bloom occurred in the same area of the Jiaozhou Bay in February 2007, during which time the hatching success was near 100%. In April 2006, the fecundity and hatching success were only moderate during a diatom bloom consisted by Thalassiosira pacifica. In April 2007, a diatom (Skeletonema costatum) bloom occurred in the central areas of the Yellow Sea. The average fecundity of C. sinicus was as high as 27.8 eggs/fem/day, which was much higher than the previous studies. Generally, the hatching success and nuapliar survival was also high. We conclude that this diatom bloom may stimulate the population recruitment for the population on the continental shelf of the Yellow Sea. We studied the regional and seasonal variations of the lipid accumulation in C. sinicus C5. The oil sac volume was generally small in the nearshore areas in the Yellow Sea. However, the seasonal variation of oil sac volume in the population on the continental shelf showed close match with over-summering. The maximum oil sac appeared in May-June when the population prepared for over-summering. Then the oil sac volume gradually decreased possibly consumed by the metabolic needs during the dormancy. In December, the oil storage decreased to the same level as the nearshore population. The oil accumulation restarts in next April when food conditions get better. Besides the energy source for the dormant population, the lipid storage might also provide a cue for the dormancy, which has critical importance during the life history of C. sinicus. Since there were distinct water masses, population abundance and structure, reproductive characteristics, population recruitment and the oil storage strategies in the nearshore areas and the continental shelf in the Yellow Sea, we discussed the life history in the two areas separately. The conceptual life history model of C. sinicus on the continental shelf was as follows. There were possibly 4-5 generations per year. In late December, the dominant C5 began molting and maturing. The offspring of this over-summering generation composed G0, which developed during the winter in food-poor environment and might produce G1 which could mature in March, when the food conditions began to turn better. During March－mid May, there were likely 2 new generations, G2 and G3. When the food environment favors, there would be a new generation G4 after mid-May. G3 and G4 were supposed to enter dormancy after June. It was likely that a small part of the C5s from the G3 and G4 would molt to be adults, while a great portion of the C5s remain under diapause until the termination of over-summering in December, when the C5s of G3 and G4 molted to adults and started the new generation. The gonad maturity and lipid storage could match this conceptual model very well and the 2 parameters showed sensitivity to the environment, so we conclude that the 2 parameters could be applied for the studies concerning the effect of climate change on population and life history. We also discussed the population recruitment patterns, possible generations and life histories of the nearshore population which had not been fully studied. Compared with the population on the continental shelf, the nearshore population had generally higher fecundities and turnover rate. Besides, the nearshore areas provided several spawning and feeding grounds, it was meaningful to fully understand the ecology and life history of the nearshore C. sinicus population in the future.
页数	122
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1537
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	王世伟. 黄海中华哲水蚤繁殖、种群补充与生活史研究[D]. 海洋研究所. 中国科学院海洋研究所,2009.

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