N/P比失衡对海洋浮游生物的影响及其沿食物网的传递

	N/P比失衡对海洋浮游生物的影响及其沿食物网的传递
	陈蕾
学位类型	硕士
导师	李超伦
	2015-05-10
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	生物工程
关键词	海洋浮游生物富营养化生态化学计量学食物网
摘要	近半个世纪以来，近海富营养化问题日益突出，富营养化水体营养盐数量和比例均发生显著变化，由此引起的海洋生态系统演变过程、机制及趋势是当前研究的前沿问题。生态化学计量学（Ecological stoichiometry）理论从元素计量平衡限制角度为了解富营养化对海洋生态系统的影响机制提供了一个新的视角和研究方法。然而，海洋生态化学计量学的研究起步较晚，国内研究尚少。为了更好的探究N/P比失衡（本文中将偏离Redfield比定义为N/P比失衡）对海洋浮游生物的影响及其沿食物网的级联效应，本文针对N/P比失衡对浮游植物的影响、浮游植物元素组成的变化是否影响浮游动物以及沿食物链的级联效应开展室内实验研究，以期为揭示富营养化对海洋浮游生态系统的影响途径及机制提供科学依据。研究结果表明： N/P比失衡条件下，三角褐指藻（PT)、中肋骨条藻（SC)、小球藻（CV）和球等鞭金藻（IG）的元素组成受到显著影响。高N/P比条件下，微藻P含量显著降低，同时微藻N含量也有一定程度的降低；低N/P比条件下微藻的N含量显著降低。微藻N含量较P含量表现出了更强的稳定性。微藻的营养组成也受到N/P比失衡的影响。低N/P比条件下PT和SC的总脂肪酸（TFA）、多不饱和脂肪（PUFA）、单不饱和脂肪酸（MUFA）和饱和脂肪酸（SFA）的含量均增加。PUFA含量与DIP存在正相关性，而MUFA和SFA含量与DIN存在负相关性。蛋白质、氨基酸以及必需氨基酸的含量也受到N/P比失衡的影响，其中低N/P比条件影响效应更显著。同时，N/P比失衡条件下，中肋骨条藻和海链藻群体的粒径出现减小的趋势，高N/P比条件下这一趋势更为显著。中华哲水蚤、蒙古裸腹水溞和褶皱臂尾轮虫三种浮游动物对N/P比失衡的饵料没有主动回避的能力，其对不同N/P比饵料的摄食无显著差异。N/P比失衡饵料培养条件下，三种浮游动物的生长均出现降低现象，但是繁殖活动的变化存在一定的种间差异。蒙古裸腹水溞的怀卵率在低N/P比饵料条件下升高，在高N/P比饵料条件下降低；而褶皱臂尾轮虫的怀卵率在低N/P比和高N/P比饵料条件下均呈现降低现象；中华哲水蚤的产卵率在低N/P比饵料条件下降低，在高N/P比饵料条件下升高，其孵化率在低N/P比和高N/P比饵料条件下均呈现降低现象。褶皱臂尾轮虫体内C、N和P元素在高N/P比和低N/P比条件下均呈现降低的现象，高N/P比的降低幅度更大。高N/P比饵料条件下，褶皱臂尾轮虫的TFA、PUFA、MUFA和SFA含量均呈现增加趋势，但PUFA在TFA中的百分比降低；高N/P比和低N/P比条件下褶皱臂尾轮虫的氨基酸和蛋白质含量均呈现降低现象，高N/P比的降低幅度更大。由如上结果推论，N/P比失衡效应会由浮游植物向植食性浮游动物传递。关于肉食性浮游动物，从生长状态来看，饵料N/P比失衡对牙鲆仔鱼的影响大于海月水母碟状幼体。牙鲆仔鱼的生长在高N/P比和低N/P比条件下均呈现较大程度的降低，而水母海月水母碟状幼体的生长在高N/P比条件下存在一定程度的降低，但是在低N/P比条件下却呈现一定程度的升高。在N/P比失衡饵料条件下，牙鲆仔鱼达到LT10的时间较海月水母碟状幼体短。从元素组成来看，N/P比失衡饵料对牙鲆仔鱼的影响大于海月水母碟状幼体，海月水母碟状幼体可能具有比牙鲆仔鱼更强的耐受性。由此，N/P比失衡可以沿食物网向肉食性浮游动物传递，存在食物网的级联效应。综上所述，N/P比失衡效应可以由浮游植物向植食性浮游动物，进而向肉食性浮游动物传递，存在食物网级联效应。但是，传递过程会因生物不同产生不同的传递效应。因此，富营养化的生态效应研究中，不仅要关注营养元素结构改变引起的浮游植物的种类组成以及数量变化，亦要关注浮游植物的元素组成和营养结构的变化，以及这些变化沿食物网的级联效应，有助于全面系统地认识富营养化对生态系统结构与功能的影响途径和机制。
其他摘要	For nearly half a century, coastal eutrophication problems have become increasingly prominent. Quantity and proportion of nutrients in the eutrophication water are significantly changed. The evolutionary process, mechanism and trends of marine ecosystems resulting from the eutrophication are leading edge issues in current research. Ecological stoichiometry provides a new perspective and research methods from the perspective of the equilibrium theory to understand the impact of eutrophication on the marine ecosystems. However, marine ecological stoichiometry research started late and domestic studies are rare. Therefore, in order to provide a scientific basis for revealing the eutrophication effects on marine ecosystems, we conducted laboratory research aiming at N/P ratio imbalance effects on marine plankton and the cascading effect along the food web. The results are as follows: Under the condition of N/P ratio imbalance, the elementary composition of Phaeodactylum tricornutum(PT), Skeletonema costatum(SC), Chlorella vulgaris(CV) and Isochrysis galbana(IG) is significantly affected. High N/P ratio condition not only significantly reduces P content of phytoplankton, but also reduces N content of phytoplankton. Low N/P ratio condition significantly reduces N content of phytoplankton. N content of phytoplankton shows greater stability than the P content. Phytoplankton nutritional composition has also been influenced by the N/P ratio imbalance. Low N/P ratio promotes the total fatty acid, PUFA, MUFA and SFA content of PT and SC. High N/P ratio inhibits the main content of the PUFA. PUFA content is positively correlated with the DIP. MUFA and SFA content show negative correlation with the DIN. Content of protein, amino acids and essential amino acids is inhibited by the N/P ratio imbalance, wherein the low N/P ratio condition shows stronger inhibitory effect. N/P ratio imbalance promotes SC and Thalassiosira sp. to evolve towards low particle size. Therefore, N/P ratio imbalance has a strong influence on the food quality of phytoplankton. N/P ratio imbalance shows no significant effect on the filtration rates of Calanus sinicus. The same statistical results are also found in the feeding rates of Moina mongolica, mixed food selectivity of Moina mongolica, feeding rates of Brachionus plicatilis and mixed food selectivity of Brachionus plicatilis. N/P ratio imbalance inhibits the growth of three zooplankton. Low N/P ratio promotes the egg-laying rates of Moina mongolica , while inhibits the egg-laying rates of Brachionus plicatilis and Calanus sinicus’s spawning rates and hatching rates. High N/P ratio suppresses the egg-laying rates of Brachionus plicatilis and Moina mongolica, while promotes the spawning rates of Calanus sinicus. C, N and P elements of Brachionus plicatilis are subject to N/P ratio imbalance and high N/P ratio shows stronger inhibitory effect. High N/P ratio promotes the total fatty acids, PUFA, MUFA and SFA content of Brachionus plicatilis, but suppresses the percentage of PUFA in the total fatty acids. N/P ratio imbalance inhibites the total amount of amino acids and proteins, and high N/P shows stronger inhibitory effect. Therefore, N/P ratio imbalance effect may transfer to the herbivorous zooplankton from the phytoplankton, but herbivorous zooplankton make adjustments. From the point of the growth state, N/P ratio imbalance has a greater impact on the ephyra than the fish larva. N/P ratio imbalance has a greater inhibition in the growth of the fish larvae. However, the growth of ephyra is promoted by the low N/P ratio and inhibited by the high N/P ratio. From the point of deformity or mortality rates, the larvae reaches LT10 faster than the ephyra. From the point of elemental composition, N/P ratio imbalance inhibites the C, N and P elements of the larvae. However, high N/P ratio promotes C and N elements of the larvae and low N/P ratio promotes its C element content. Thus, from the perspective of ecological stoichiometry, the ephyra may have a stronger competitive advantage than the larvae. In summary, the effect of N/P ratio imbalance can transfer to herbivorous zooplankton from phytoplankton, and then to carnivorous zooplankton. It has the cascading effect along the food web. However, the transfer process may be specific due to the biological effects. Therefore, in order to explore the ecological effects of eutrophication, we need to pay more attention to the changes of elemental composition and nutrient structure of phytoplankton, and their cascading effect along food web. This can contribute to the overall understanding of eutrophication impacts on the structure and function of ecosystems.
学科领域	海洋生态与环境科学
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/23265
专题	海洋生态与环境科学重点实验室
作者单位	中国科学院海洋研究所
第一作者单位	中国科学院海洋研究所
推荐引用方式 GB/T 7714	陈蕾. N/P比失衡对海洋浮游生物的影响及其沿食物网的传递[D]. 北京. 中国科学院大学,2015.

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