LTER: Linking Pelagic Community Structure with Ecosystem Dynamics and Production Regimes on the Changing Northeast US Shelf

西北大西洋以多产渔业而闻名，这些渔业依赖于为它们提供能量的浮游生物的复杂食物网。在这些沃茨中-如同在地球仪周围的沿海沃茨中一样-人类活动、环境变异和十年尺度的变化相互交织，对浮游生物食物网产生各种影响。关键是要了解这个网络的结构，它是如何运作的，以及它如何应对季节性的环境变化，以便适当地应对该地区正在加速的长期趋势。然而，由于缺乏足够长时间的系统和详细测量，我们的理解受到限制，因此我们可以观察这些网络对环境扰动的反应，并揭示其根本原因和影响。美国东北大陆架（内斯）长期生态研究（LTER）项目将提供此类观测结果，并使用各种模型进行分析，提高我们预测浮游食物网如何随时间和空间变化的能力，以及这些变化如何影响包括商业重要鱼类在内的较高营养级的生产力。此外，NES-LTER项目将产生多方面的广泛影响，包括与美国国家海洋和大气管理局（NOAA）东北渔业科学中心合作，以支持内斯上基于生态系统的多物种管理。该项目包括一项教育计划，将为广大学习者提供机会，并将通过海洋大气署的国际地球科学网络制定一个影响深远的公共外联部分。虽然该区域的生态系统在四季到几十年中的变化模式已经有了记录，但对物理环境变化、浮游食物网和更高营养级之间的联系的关键机制仍然知之甚少。由于这个原因，预测能力是有限的，管理战略在很大程度上是被动的。为了满足这些需求，NES-LTER战略结合了提供区域尺度背景的观测、沿沿着高梯度跨大陆架样带的过程巡航、大陆架内外位置的高频时间序列、耦合的生物物理食物网模型和目标种群模型。该研究计划以一个总体科学问题为指导：长期环境变化如何影响远洋内斯生态系统，特别是影响组成（例如，物种多样性和大小结构）和聚集体（例如，初级生产率和能量转移到重要饲料鱼类）的变化？通过利用内斯的季节性和年际变化的高水平，研究将研究对环境变化的短期反应，以a）描述低和高出口食物网的特征，B）了解浮游植物和中上层鱼类之间的联系和能量转移，以及c）确定高和低出口群落之间转移的机制。最终，将扩大机械知识，以了解和预测与生态系统中十年尺度强迫趋势相关的影响和反馈。

The northwest Atlantic is renowned for productive fisheries that depend upon a complex food web of planktonic organisms that provide them energy. In these waters -- as in coastal waters around the globe -- human activities, environmental variability, and decadal-scale change intersect to have diverse effects on the planktonic food web. It is crucial to understand the structure of this web, how it functions, and how it responds to seasonal environmental change, in order to respond appropriately to long-term trends that are accelerating in this region. Our understanding, however, has been limited by a lack of systematic and detailed measurements over a sufficient length of time so that we can observe the responses of these webs to environmental perturbations and uncover the underlying causes and implications. The Northeast US Shelf (NES) Long-Term Ecological Research (LTER) project will provide such observations, analyze them with a variety of models, and improve our ability to predict how planktonic food webs change through space and time, and how those changes impact the productivity of higher trophic levels including commercially important fish. In addition, the NES-LTER project will have multifaceted broader impacts, including collaboration with the National Oceanic and Atmospheric Administration's (NOAA), Northeast Fisheries Science Center to support multispecies, ecosystem-based management on the NES. The project includes an education plan that will provide opportunities to a broad range of learners and a far-reaching public outreach component will be developed through NOAA's international Science-On-a-Sphere network. While patterns of ecosystem change over seasons to decades have already been documented in this region, the key mechanisms linking changes in the physical environment, planktonic food webs, and higher trophic levels remain poorly understood. For this reason, predictive capability is limited and management strategies are largely reactive. To address these needs, the NES-LTER strategy combines observations that provide regional-scale context, process cruises along a high gradient cross-shelf transect, high-frequency time series at inner- and outer-shelf locations, coupled biological-physical food web models, and targeted population models. The research plan is guided by an overarching science question: How is long-term environmental change impacting the pelagic NES ecosystem and, in particular, affecting the relationship between compositional (e.g., species diversity and size structure) and aggregate (e.g., rates of primary production, and transfer of energy to important forage fish species) variability? By capitalizing on high levels of seasonal and interannual variability in the NES, the research will study short-term responses to change in the environment to a) characterize low and high export food webs, b) understand the linkages and transfer of energy from the phytoplankton to pelagic fish, and c) identify the mechanisms that underlie shifts between high and low export communities. Ultimately, mechanistic knowledge will be scaled up to understand and predict the impacts and feedbacks associated with trends in decadal-scale forcing in the ecosystem.