受气候变化与人类活动的双重影响，近海生态系统处于动荡的状态之中。近几十年来，水体富营养化，有害藻华频发，水母和大型底栖动物（如海星）的暴发，渔业资源衰退等都表明胶州湾生态系统结构和功能发生了改变。浮游动物在海洋生态系统中处于承上启下的枢纽位置，其种类和数量的变动会引起整个海洋生态系统的变动。由于不同浮游动物类群有不同的生态功能，我们比较关心胶州湾浮游动物类群的长期变化，比如饵料浮游动物桡足类发生了什么变化，胶质类浮游动物水母类、毛颚类等是否增多了。为了有效简化食物网，全面、准确地模拟浮游动物群落的生态过程，我们将浮游动物划分为不同的浮游动物功能群。本文依托胶州湾海洋生态系统研究站于2003-2013年获取的浅水II型浮游生物网采集样品，使用ZooScan图像分析技术研究了胶州湾浮游动物功能群丰度、桡足类粒径的长期变化趋势，夜光虫的动态变化。本文还从胶州湾生态系统对近年来典型生态灾害的响应入手，分析了海月水母(Aurelia sp.1)以及浒苔(Ulva prolifera)暴发对浮游动物群落的影响，以期加深人们对近海生态系统演变的理解，为胶州湾的科学管理提供理论依据。

        从胶州湾浮游动物功能群丰度长期变化研究中得出，2003-2013年湾北、湾中与湾外桡足类的丰度均下降，主要是春、夏、秋季降低；被囊类的丰度降低，主要是春、夏季降低；毛颚类的数量呈现波动的长期变化趋势；小型水母类在湾北和湾中的数量表现为波动的变化趋势，在湾外呈现增加的趋势，以春季增加为主；夜光虫在湾北的变化不明显，在湾中和湾外均呈现增加的趋势，春季增加明显；其他浮游动物的变化趋势均为从2003年开始升高，2008-2009年达到高值，随后下降。
        通过分析湾北、湾中与湾外2004-2012年不同粒径级桡足类的相对丰度的长期变化发现，湾中与湾外桡足类出现“小型化”的现象，具体表现为300-500 μm粒径级桡足类的相对丰度升高，>500 μm粒径级桡足类的相对丰度降低。湾中与湾外不同粒径级桡足类的相对丰度年际间的差异是由夏季桡足类粒径减小引起的。2004-2012年夏季湾中与湾外调查站位海水平均温度升高，桡足类粒径的减小与海水温度的升高有显著的关系，这与全球变暖对变温动物的影响的预期相吻合。 
        胶州湾及邻近黄海沿岸海域夜光虫季节性暴发，通常在每年的春季到初夏大量出现，温度是影响夜光虫季节变化的重要因子。冬末-初春浮游植物的峰值通常早于夜光虫，表明浮游植物为夜光虫的生长提供食物是夜光虫在春季大量出现，甚至暴发的能量基础。夜光虫的生物量有时能超过浮游植物和桡足类，是重要的浮游动物；当夜光虫大量出现的时候浮游植物生物量通常较低，表明夜光虫可能对浮游植物有较大的摄食压力；另外，夜光虫与桡足类有相似生态位，包括季节变化、食物等，因此沿岸海域夜光虫可能通过竞争食物和捕食桡足类的卵和幼体从而对桡足类造成一定的负面影响。
        2009和2011年夏季，胶州湾海月水母(Aurelia sp.1)大量发生，对浮游动物群落产生了显著的影响。相较于海月水母未大量出现的年份（2003-2008、2010、2012-2013），湾北浮游动物丰度季节性峰值在海月水母暴发的年份显著降低；同时，海月水母暴发的年份，春末-夏季（5-8月）浮游动物的平均丰度也显著降低。其中桡足类、被囊类的丰度显著降低，胶质类肉食性毛颚类、水母类的变化不明显。从不同粒径浮游动物的丰度变化得出，海月水母暴发的年份300-1000 μm总浮游动物与桡足类的丰度显著降低，表明海月水母能够大量摄食这个粒径范围的浮游动物。此时，小型桡足类如双刺纺锤水蚤(Acartia bifilosa)和小拟哲水蚤(Paraclanus parvus)是优势种，可以推断小型桡足类的大量出现为海月水母的暴发提供了能量基础。
        从2008年夏季开始，黄海浒苔持续暴发，并入侵青岛近海，对浮游动物群落产生了显著的影响。相较于浒苔未暴发的年份（2005-2007），夏季湾外浮游动物平均丰度在浒苔暴发的年份（2008-2013）显著降低，主要体现在桡足类及无节幼体的显著减少。同时，双壳类幼体和十足类幼体的丰度分别减少了84.7%和54.6%，而棘皮类幼体的丰度增加了95.6%，多毛类幼体丰度变化不明显。此外，相较于浒苔未暴发的年份，浒苔暴发的年份夏季浮游动物群落结构发生明显变化，桡足类丰度所占比例降低了大约10%，胶质类与其他浮游动物比例分别增加了6.3%和3.5%。在阶段性浮游生物组成中，双壳类幼体的丰度比例降低了一倍，多毛类幼体的比例增加了两倍，并取代双壳类成为最有优势的类群，棘皮类幼体的比例升高了六倍。

    Climate change and human activities are destabilizing coastal marine ecosystems. During the past several decades, eutrophication, frequent occurrence of harmful algal blooms, increasing abundance of gelatinous zooplankton, outbreaks of macrobenthos (e.g. starfish), and decline of fishery resources that reported in Jiaozhou Bay, indicating that the structure and function of marine ecosystem has significant changed. Zooplankton play a central role in marine ecosystems, variations in the zooplankton abundance and species composition will alter the whole ecosystem. Different zooplankton species have different ecological function, we concern about the long-term changes in zooplankton taxa. For example, what happened to the fodder zooplankton, like copepods; whether gelatinous zooplankton (e.g. jellyfish, chaetognaths) increase continuously. In order to effectively simplify the food webs, and comprehensively and accurately simulate the ecological processes of zooplankton community, we classify the zooplankton into different functional groups. In this paper, based on the ZooScan Intergrated System and eleven-year (2003-2013) zooplankton samples collected by Jiaozhou Bay Marine Ecosystem Research Station (JBMERS) in north, middle and outside region of the Jiaozhou Bay, we studied the long-term changes in abundance of zooplankton functional groups, long-term change in copepod size, and population dynamics of Noctiluca scintillans. From the perspective of Jiaozhou Bay marine ecosystem responded to the typical ecological disasters in recent years, we studied the impacts of the outbreaks of moon jellyfish (Aurelia sp.1) and green tide (Ulva prolifera) on zooplankton community. It aims to deepen people's understanding of coastal ecosystem evolution, and provide theoretical basis for scientific management of the Jiaozhou bay. 

    During the period of 2003-2013, we found that copepods dominated the zooplankton community, their abundance decreased, with the decrease in spring, summer and autumn. The abundance of appendicularians decreased, with the decrease in spring and summer. Chaetognaths showed a fluctuated variation trend. The abundance of medusae increased at the sampling station that outside the bay, mainly caused by the increase in spring. Noctiluca scintillans exhibited an increasing trend in spring in middle and outside bay. Other zooplankton increased from 2003 and reaching the peak value in 2008-2009, and then decreased.
    By analyzing the relative abundance of two size ranks of copepods during the period of 2004-2012 at the sampling stations in north, middle and outside part of the Jiaozhou Bay, we found that the relative abundance of 300-500 μm size rank increased, while that of >500 μm size rank decreased. The interannual difference between the two size ranks was caused by the variation in summer, with the average volume of total copepods decreased, which was significantly negative correlated with the increased water column averaged temperature. These changes are consistent with predictions of the impact of warming on aquatic ectotherms.
    Seasonal variations in numerical abundance, cell diameter and population carbon biomass of the heterotrophic dinoflagellate Noctiluca scintillans were studied for 10 years from 2004 to 2013 in middle and outside region of the Jiaozhou Bay. In both areas, N. scintillans occurred throughout the year and demonstrated an essentially similar seasonality; the cell abundance increased rapidly from the winter minimum to an annual peak in late spring and early summer, and decreased gradually toward the autumn-winter minimum. The cell diameter also showed a seasonal fluctuation, being larger in spring and early summer than the other seasons. Temperature was an important factor that affected the seasonal phenology of N. scintillans. The peak abundance of phytoplankton in late winter and early spring preceded the massive occurrence of N. scintillans, indicating that phytoplankton provided the energy for the massive occurrence of N. scintillans. Estimated carbon biomass of N. scintillans population reached to a peak as high as 90.3 mg C m^-3, and occasionally exceed over phytoplankton and copepod biomass. Our results demonstrate that N. scintillans in northwestern Yellow Sea displays the seasonal phenology almost identical to the populations in other temperate regions, and play important trophic roles as a heterotroph to interact with sympatric phytoplankton and copepods.
    In the summers of 2009 and 2011, moon jellyfish (Aurelia sp.1) massive occurred in Jiaozhou Bay. In order to find out the impacts of bloom of this large jellyfish on zooplankton community, we analyzed the seasonal variation of zooplankton functional groups from 2003-2013 at the sampling station in north part of the bay. Compared with non-moon jellyfish bloom years, the seasonal peak abundance of total zooplankton in the years of massive occurrence of moon jellyfish significantly decreased. Meanwhile, during the massive occurrence months (May-August) in jellyfish bloom years, the mean abundance of zooplankton also significantly decreased. The blooms of moon jellyfish have significant impacts on copepods and appendicularians, but not chaetognaths and medusae. The abundance of 300-1000 μm size rank of total zooplankton and copepods significant decreased during the jellyfish bloom period, indicating the moon jellyfish exerted severe pressure on this size rank of zooplankton. Small-sized copepods, such as Acartia bifilosa and Paraclanus parvus are the dominate species in late spring and summer, which match the massive occurrence of the moon jellyfish, thus we speculate that small-sized copepods provide the energy for the outbreaks of moon jellyfish.
    From 2008, Ulva prolifera ongoing outbreak in summer in western coastal Yellow Sea and invasion into Qingdao coast, causing a serious impact on local environment and marine ecosystem. In order to find out the impacts of green tide on zooplankton community, we analyzed the seasonal variation of zooplankton functional groups from 2005-2013 at the sampling station outside the bay. Compared with non-green tide bloom years, the abundance of zooplankton in the years with green tide significant decreased, mainly reflected by the dramatic decrease in the abundance of copepods and nauplii. Meanwhile, the abundance of bivalve larvae and decapod larvae decreased 84.7% and 54.6%, respectively, echinoderm larvae increased 95.6%. In addition, compared with non-green tide bloom years, zooplankton community structure in the years with green tide also significant changed. The relative abundance of copepods decreased 10%, gelatinous zooplankton (including appendicularians, chaetognaths and medusae) and other zooplankton increased 6.3% and 3.5%, respectively. In the meroplankton composition, the relative abundance of bivalve larvae reduced a half, polychaeta larvae tripled and replaced the bivalve larvae became the dominant species; moreover, echinoderm larvae increased by 6 times.