Ecological Transitions in the California Current Ecosystem: CCE-LTER Phase II

加州洋流生态系统（CCE） LTER站点是一个多产的沿海上升流生物群落，由远程和本地物理强迫以及海洋水柱中的生物相互作用构成。CCE站点建立在CalCOFI 60年来广泛的时间序列测量基础上，旨在了解该生态系统不同状态之间转换的潜在机制，以及它们的推论：生态系统恢复力。在CCE资助的第一阶段，该地点的研究人员发现了北太平洋（NPGO）的一种新的气候模式；发现海上风应力旋度与经典海岸边界上升流域的食物网结构存在显著差异；检测了胶状食草动物（远洋被囊动物）、光学特性、硝化深度、缺氧发生率、分层和其他生态系统特征的长期变化；初级生产铁与铁-光共限显示带；建立了ROMS模型，并将其应用于生态系统变迁的后验因果诊断和拉格朗日过程巡航的预测；开发了异速生长的食物网建模方法；发现物理时间序列与生物时间序列在非线性程度上的差异；证明了捕鱼的不稳定影响；启动新的数据实践；和更多。第一次努力的结果指出了CCE空间结构的重要性，特别是在中尺度上。在这次更新中，LTER研究人员瞄准了构成CCE生态扰动机制重要组成部分的中尺度锋和涡旋。研究人员发现，这些特征在CCE地区的年际和年代际尺度上都有变化，他们假设这些特征随时间的变化可能有助于生态系统的转变。该项目将继续在CCE LTER进行研究。下一阶段研究提出的首要问题是：导致沿海远洋生态系统不同状态的机制是什么？海洋气候变化、群落结构和生态系统动态之间的相互作用是什么？为了解决这些问题，研究人员建议研究可能导致生态系统转变的4种机制：反常的沿岸平流；原位食物网随分层和养分供应的变化；跨岸运输的变化；以及捕食压力的改变。他们还将测试与中尺度过程作用有关的3个假设，特别是它们在改变营养通量和捕食者-猎物相互作用方面的作用，中尺度锋和涡旋在CCE地区的综合生物地球化学效应以及这些特征与更大尺度气候变率的关系。拉格朗日过程巡航、实验工作、时间序列测量、建模、数据合成和耦合的人-自然系统研究的组合将用于解决这些问题。该项目还将继续测量5个LTER核心变量。更广泛的影响：在南加州沿海海洋提供的生态系统服务中，值得注意的是该地区吗？对许多商业上重要的鱼类和海洋无脊椎动物的产卵和/或收获具有重要意义。该研究将为理解基于生态系统的渔业管理相关属性的时空变异性提供关键的科学基础。当管理者开始处理海洋酸度变化、分层和缺氧对资源种群和社区的影响时，这些信息是必不可少的。ISSE（社会与环境综合科学）研究将与一名经济学家、研究生和科学家合作开发一种生物经济模型，以检查生态系统变化与渔民之间的相互作用。决策和资源分配。此外，CCE调查人员将进一步发展和加强DataZoo，这是我们信息管理和数据共享环境的核心信息系统。他们将实施新的网络访问工具，以促进数据可视化，并将CCE结果传达给学生、各级教师、科学家、管理人员、政策制定者和广大公众。一个教育、推广和能力建设（EOCB）项目将包括一个由数十名研究生参与的场地科学和交流的有力项目。一名研究生将作为EOCB协调员的研究联络人，帮助将CCE科学转化为K-12课程计划。CCE LTER将与一个多元化城市学区的当地教师合作，将CCE科学带入课堂，并将继续与非营利性海洋研究所（ocean Institute）开展外联活动和沿海海洋时间序列活动。这个LTER网站将扩展他们成功的RET和海上教师计划，使教师能够直接与学生交流科学探究的过程。他们的REU项目将继续针对代表性不足的本科生，以扩大进入海洋科学的管道。

The California Current Ecosystem (CCE) LTER site is a productive coastal upwelling biome structured by remote and local physical forcing, as well as biotic interactions in the ocean water column. The CCE site, building upon 60 years of extensive time-series measurements by CalCOFI, seeks to understand the mechanisms underlying transitions between different states of this ecosystem, as well as their corollary: ecosystem resilience. In the first phase of CCE funding investigators at this site uncovered a new climate mode for the North Pacific (NPGO); found marked differences in food web structure between the offshore wind stress curl and the classical coastal boundary upwelling domains; detected long-term changes in gelatinous grazers (pelagic tunicates), optical properties, nitracline depths, prevalence of hypoxia, stratification, and other ecosystem characteristics; revealed zones of iron and iron-light co-limitation of primary production; developed a ROMS model and used it in hindcast mode to diagnose causality of ecosystem transitions and forecast mode to guide Lagrangian process cruises; developed an allometric approach to food web modeling; discovered differences between physical and biotic time series in degree of nonlinearities; demonstrated the destabilizing effects of fishing; initiated new data practices; and more. Findings from this first effort point to the importance of spatial structuring of the CCE, especially on the mesoscale. In this renewal the LTER investigators target mesoscale fronts and eddies, which constitute an important part of the CCE ecological disturbance regime. CCE Investigators have found that such features vary on interannual and decadal scales in the CCE region and they hypothesize that their variability over time may contribute to ecosystem transitions. This project will continue studies at the CCE LTER. The overarching questions posed in this next phase of the study are: What are the mechanisms leading to different states in a coastal pelagic ecosystem? What is the interplay between changing ocean climate, community structure and ecosystem dynamics? To address these questions, the investigators propose to examine 4 mechanisms that could contribute to ecosystem transitions: anomalous alongshore advection; in situ food web changes in response to stratification and nutrient supply; changes in cross-shore transport; and altered predation pressure. They will also test 3 hypotheses related to the role of mesoscale processes, specifically concerning their role in altering nutrient fluxes and predator-prey interactions, the integrated biogeochemical effects of mesoscale fronts and eddies over the CCE region and the relationship of such features to larger scale climate variability. A combination of Lagrangian process cruises, experimental work, time series measurements, modeling, data synthesis, and a coupled human-natural system study will be used to address these questions. The project will also continue to measure the 5 LTER core variables.Broader Impacts: Notable among the ecosystem services furnished by the coastal ocean off southern California is the region?s importance for spawning and/or harvesting of many commercially important fishes and marine invertebrates. This research will provide a key scientific foundation for understanding time and space variability of properties relevant to ecosystem-based fisheries management. This information is essential as managers begin to address the consequences of changing ocean acidity, stratification, and hypoxia for resource populations and communities. ISSE (Integrated Science for Society and the Environment) studies will partner an economist, graduate student, and scientists in the development of a bioeconomic model to examine the interplay between ecosystem variability and fishers? decision-making and resource allocation. In addition, the CCE Investigators will further develop and enhance DataZoo, the information system central to our Information Management and data sharing environment. They will implement new web-accessible tools to facilitate data visualization and communication of CCE results to students, teachers across all levels, scientists, managers, policy-makers, and the broader public. An Education, Outreach, and Capacity Building (EOCB) program will include a vigorous program of involvement of tens of graduate students in site science and communication. A graduate student will serve as a research liaison with the EOCB coordinator, to help translate CCE science into K-12 lesson plans. CCE LTER will work with local teachers in a diverse urban school district to bring CCE science into the classroom, and will continue outreach and coastal ocean time series activities with the nonprofit Ocean Institute. This LTER site will expand their successful RET and Teacher-at-Sea programs, to enable teachers to communicate the process of science inquiry directly to students. Their REU program will continue targeting under-represented undergraduates to expand the pipeline into the ocean sciences.