【作者】 韩君；

【导师】 魏皓；

【作者基本信息】 中国海洋大学 ， 物理海洋， 2008， 博士

【摘要】 黄海为半封闭陆架浅海,位于中国大陆和朝鲜半岛之间。黄海被确定为是世界50个“大海洋生态系统”之一,是重要的渔场。浮游植物水华是一段时期内浮游植物种群快速、显著增加的过程,每年春秋两次水华是中纬度海域浮游植物年循坏的普遍规律,其对整个海域的初级生产力水平和各生源要素循环等均有重要影响。本文的主要目标是利用一个三维生态模型模拟黄海浮游植物生物的季节变化规律,分析黄海浮游植物水华的特征,讨论环境因子的改变对春季浮游植物水华的影响作用。首先根据2007年4月黄海水华航次的观测资料,分析讨论了浮游植物水华过程中各要素的变化特征及快速衰退的主导因素。春季水华过程中,水体中较高的营养盐浓度不会对浮游植物的生长起限制作用。结合卫星遥感资料图片分析,浮游植物水华的空间变化过程为:首先发生于黄海近岸水域,进而扩展至黄海中部海域,中部海域的水华衰退后,近岸水域生物量又有小的峰值。水华期间,浮游植物呈“斑块”状分布。通过对连续站的分析发现,水平平流作用是水柱内浮游植物生物量快速减少的主导因素。建立了一个与黄海环流、混合过程耦合的三维生态模型对黄海浮游植物的水华过程进行了模拟。模型包括硅藻、鞭毛藻两种浮游植物、氮、磷、硅三种营养盐等状态变量,以反映浮游植物生长过程中的群落演替及不同营养盐对不同种群地限制作用。黄海浮游植物系统各生态变量1994年季节变化的模拟结果表明,黄海浮游植物的年变化呈现“双峰”结构,即每年出现春季、秋季两次水华,秋季水华的强度与范围都较春季水华的弱。浮游植物春季水华一般发生在3月份,4月份为水华强盛期,后由于上层水体中营养盐的消耗及跃层的形成而衰退,5月份水华基本消失。模拟的营养盐与浮游植物的季节变化与实测值较符合,较好的反映了黄海浮游植物生态系统的变化规律。模拟的浮游植物春季水华空间变化舰律为与卫星资料的结果一致,同样体现了近岸水域-中部海域-近岸海域的演变过程。浮游机物的分布同样也呈“斑块”状分布,尺度为十几至几十公里,这主要是由于流场的辐聚辐散造成的。“斑块”尺度、位置及“斑块”浓度大小在短时间内的快速变化主要是由水体的平流作用引起的。通过对环境因子的分析得:2月份,浮游植物的生长主要受到光强的限制;3月份主要受温度的影响。光强增强能够引起浮游植物水华时间提前,持续时间增加。温度通过对生长率的影响作用进而影响了浮游植物的生长,温度的增加或减小能使水华时间提前或推迟,水华持续时间也略有相应的增加或减小。强混合作用使水体的稳定性变差,延迟了浮游植物水华的发生。悬浮颗粒物使得水体中光强衰减加快,能显著影响浮游植物水华的发生时间及水华强度。初级生产力和浮游植物(硅藻和鞭毛藻)的群落结构也会发生相应的改变。更多还原

【Abstract】 The Yellow Sea is semi-enclosed shelf sea located between the mainland of China and the Korea Peninsula.It is one of the world’s 50 so-called ’large marine ecosystems’ and one of the most important fishing areas.An algal bloom is defined as a relatively rapid increase in the biomass of phytoplankton in an aquatic system.The twice bloom in spring and autumn every year is common for mid-latitude phytoplankton annual cycle.Phytoplankton bloom has great effect on the primary production level and biological variable cycle of the whole area region.The main purpose of this paper is 1) to simulate the seasonal variation of phytoplankton by using a three-dimension biological dynamic model,2) to analyze the characteristic phytoplankton bloom in the Yellow Sea,3) to discuss the variations of phytoplankton spring bloom which affected by the change of environment factors.Based on the observation data which were obtained from bloom cruise on April, 2007 in the Yellow Sea,analyze and discuss the characteristics of different biological variables during the bloom process and the reason for rapidly decrease of the bloom. During the bloom process,the nutrient concentration doesn’t restrict the phytoplankton growth.Combined with the remote sensing data,the spatial variation of the phytoplankton bloom appears in shore region at first.Then it extends to the central part of the Yellow Sea.After the central region bloom declined,the chlorophyll concentration has another small peak in the shore region again.The distribution of the phytoplankton bloom reveals the patchiness characteristic which has a wide range of spatial and temporal scales.The horizontal convection is speculated to be responsible for the abrupt decrease in the concentration of chlorophyll at anchor station.A three-dimension biological model is established to simulate the phytoplankton bloom process in the Yellow Sea.The model has two groups of phytoplankton(diatom, flagerlate) and three kinds of nutrients.It could reveal the succession between the two groups during the bloom and the different restriction effect on the two groups from different nutrient.The results are similar to the observation data.The model could reveal the seasonal variation of phytoplankton well.From the simulation results,the phytoplankton concentration has two peaks every year in the Yellow Sea.The bloom appears in spring and autumn separately.The intensity and range of the autumn bloom is weaker and smaller than the spring bloom’s.In general the spring bloom happens in March,strengthens in April and decreases in May due to the consumption of the nutrient.The spatial variation of the phytoplankton bloom process from simulated data coincides with the result from remote sensing data.The distribution of the phytoplankton also has the patchiness characteristic.The spatial scale is ten to tens of kilometers.It is mainly affected by the convergence and divergence of the current field.The horizontal convection is responsible for the rapidly variations of the patch scale,location and concentration.Through analyzing the environment variation,the growth of phytoplankton is mainly restricted by the solar radiation in February.The water temperature has effect on the phytoplankton growth in March.In spring,intensified the radiation could make the bloom happen in advance and the lasting time increase.The temperature could affect the phytoplankton growth through the relationship between the temperature and growth rate.The increase or decrease of the temperature could lead the bloom to happen in advance or delay.The lasting time of the phytoplankton bloom also increases or decreases a little correspondingly.The intensified mixing effect could weaken the water stabilization,therefore the happening time of the bloom will be delayed.The suspended particulate matter could intensify the diffusion the radiation in water column and change the bloom timing and range obviously.The primary production and the phytoplankton community will change correspondingly.更多还原