LTER: Nonlinear transitions in the California Current Coastal Pelagic Ecosystem

该奖项将在加州洋流系统的沿海上升流生物群落中建立一个LTER长期生态研究基地。研究将侧重于导致大洋生态系统不同状态之间暂时过渡的机制。从CalCOFI（加州合作海洋渔业调查）沿海海洋时间序列的观测，目前在其第55年，证明了外部强迫的远洋生态系统在多个时间尺度上的重要性，包括：厄尔尼诺，几十年的太平洋十年振荡，和几十年的长期变暖趋势。这种强迫和生物相互作用的相互作用可能导致非线性生态系统的反应，可以表示为相对突然的过渡。这项工作将评估这种生态系统过渡的四种假设机制：持续的，异常沿岸平流的不同组合; -在原地食物网的变化，以改变分层和营养供应; -在跨海岸运输和损失/保留的生物的变化;和-改变捕食压力。加州当前生态系统（CCE）LTER站点将通过具有三个主要要素的综合研究计划来解决这些假设：（1）实验过程研究最初将侧重于原位食物网变化的假设。(2)时间序列研究将使用空间分辨时间序列测量来评估替代假设，包括在不同近岸位置的高频时间测量，卫星遥感，以及在海上的广泛的季度测量计划，该计划将利用并显着增强CalCOFI时间序列。(3)建模和综合研究将有助于量化观测背后的动态;通过数值实验和过程模型提供假设检验平台;提供空间和时间观测之间动态插值的手段;并有助于优化实地方案。拟议的研究区域是建立长距离接触试验点的理想地点：该区域具有CalCOFI提供的50年的气候背景;该区域处于海洋学边界区域，使其成为气候变化的早期前哨;该区域在相对较小的地理区域内具有明显的空间梯度;其缺氧盆地为古海洋学研究提供了独特的联系;该区域现有的四维物理海洋环流模型将使生态系统过渡的耦合生物物理模型的开发取得迅速进展。该网站将允许LTER网络比较沿海水层上升流生态系统与其他生物群落方面：模式和控制的初级生产，空间和时间分布的人口选择代表营养结构，模式的无机输入和运动的营养物质，模式和频率的干扰。更广泛的影响：该项目将拥有最先进的信息和数据管理，以便在内部向LTER合作伙伴、教育工作者、公众和决策者提供数据。一个积极的教育和推广计划将与CA-COSEE和外部合作伙伴合作，让K-12社区参与这项研究的过程和从中获得的理解。 他们将培养本科生，研究生和博士后学者跨越学科界限。通过与非正式科学教育组织的合作，他们每年将接触到数百名K-12学童，包括当地低收入和少数民族学生。教师和学生将参加实地考察，并获得海洋科学方面的培训。他们还将协助编制新的学校课程。

This award will create a LTER-Long-Term Ecological Research site in the coastal upwelling biome of the California Current System. The research will focus on mechanisms leading to temporal transitions between different states of the pelagic ecosystem. Observations from the CalCOFI (California Cooperative Oceanic Fisheries Investigations) coastal ocean time series, currently in its 55th year, demonstrate the importance of external forcing of the pelagic ecosystem on multiple time scales, including: El Nino, the multi-decadal Pacific Decadal Oscillation, and a multi-decadal secular warming trend. Interactions of such forcing and biotic interactions can lead to nonlinear ecosystem responses that may be expressed as relatively abrupt transitions. The work will evaluate four hypothesized mechanisms for such ecosystem transitions:?-Sustained, anomalous alongshore advection of different assemblages; -In situ food web changes in response to altered stratification and nutrient supply; -Changes in cross-shore transport and loss/retention of organisms; and-Altered predation pressure. The California Current Ecosystem (CCE) LTER site will address these hypotheses with an integrated research program having three primary elements: (1) Experimental Process Studies will initially focus on the hypothesis of in situ food web changes. (2) Time Series Studies will evaluate alternative hypotheses using space-resolving time series measurements, including high frequency temporal measurements at different nearshore locations, satellite remote sensing, and an extensive quarterly measurement program at sea that will capitalize on and significantly enhance the CalCOFI time series. (3) Modeling and synthesis studies will help quantify the dynamics underlying the observations; provide a platform for hypothesis testing through numerical experiments and process models; provide a means for dynamic interpolation between observations in space and time; and help optimize the field program. The proposed study region is an ideal location for an LTER site: it has 5 decades of climate context provided by CalCOFI; it is in a biogeographic boundary region, making it an early sentinel of climate change; it has pronounced spatial gradients in a relatively small geographic area; its anoxic basins provide a unique connection to paleoceanographic studies; and the extant 4-D physical ocean circulation model of the region will permit rapid advances in the development of coupled bio-physical models of ecosystem transitions. The site will allow the LTER network to compare coastal pelagic upwelling ecosystems with other biomes with respect to: Pattern and control of primary production, Spatial and temporal distribution of populations selected to represent trophic structures, Patterns of inorganic inputs and movements of nutrients, and Patterns and frequency of disturbances. Broader Impacts: The project will have state of the art Information and Data Management to serve data internally, to LTER partners, educators, the general public, and policy makers. An active Education and Outreach program will team scientists with CA-COSEE and external partners to engage the K-12 community in both the process of and the understanding gained from this research. They will train undergraduates, graduate students, and postdoctoral scholars across disciplinary boundaries. Through collaborations with informal science education organizations, they will reach hundreds of K-12 schoolchildren each year, including local low-income and minority students. Teachers and students will participate in field studies and gain training in oceanographic science. They will also assist in the development of new school curricula.