COLLABORATIVE: US-GLOBEC NEP PHASE IIIA-CCS: SCALE-DEPENDENT DYNAMICS OF TOP-TROPHIC PREDATORS AND PREY - TOWARD PREDICTING PREDATOR RESPONSE TO CLIMATE CHANGE

已知顶级捕食者在构建群落和影响陆架系统中碳流方面的生态作用是重要的。人们不太清楚的是，中尺度强迫的时空变化如何影响中营养群落的跨陆架和沿陆架结构，以及浮游动物和鱼类向顶级捕食者的碳转移。研究人员将利用2000年和2002年在俄勒冈州和加利福尼亚北部海域进行的GLOBEC NEP多船调查中收集的数据集，研究北加州洋流系统（CCS）中顶级捕食者（海洋哺乳动物、海鸟）、猎物和物理生物过程之间的中尺度和精细尺度空间和时间关系。由于气候在时间尺度上的变化，从日（上升流）到年际（ENSO）再到年代际（太平洋年代际涛动，PDO）， CCS的生产力变化非常大。虽然这些趋势可以从大规模的角度来看，但从中尺度或精细尺度的角度来看，捕食者正在利用可用的猎物斑块。本文将检验两个主要的零假设：1)改变沿岸上升流锋和赤道急流的中尺度强迫不影响跨陆架和沿陆架的密度和顶级捕食者群落结构；②浮游生物和浮游生物分布的空间尺度，通过空间自相关测量，处处与物理参数具有可比性；反过来，浮游生物或鱼类分布的空间尺度分别与浮游生物和鱼类分布的尺度相当。研究人员将基于2000年的数据构建影响顶级捕食者分布因素的预测模型，并将使用2002年的数据对其进行测试。他们还将使用一般的加性模型来估计捕食者的丰度和分布，并构建一个碳流模型来估计上层营养水平的碳排放、呼吸和封存（以及迁徙者带走的碳）。将使用几种建模方法来确定在一定范围内猎物对应或消耗的大小和重要性。空间异质性将在生态系统的两个层面进行研究：相对于海洋物理特征的猎物密度或斑块大小，以及相对于猎物的捕食者密度。本文提出的综合方法为本世纪初提供了一个有价值的基线，用于研究北部CCS中几种尺度和变异性来源的顶级捕食者反应。此外，该综合展望了CCS中顶级捕食者（其中许多是濒危物种）发生模式的预测生物物理模型的长期发展。这些模型的进化将有助于美国西海岸北加州洋流生态系统的资源管理和人类活动规划（例如，主要渔业、5个海洋保护区、运输和商业）

The ecological roles of top predators in structuring communities and affecting the flow of carbon in shelf systems are known to be significant. What is less well understood is how the spatial and temporal variability in mesoscale forcing influences cross-shelf and along-shelf structure of mid-trophic communities and the transfer of carbon from zooplankton and fish to top predators. The investigators will examine mesoscale and finer-scale spatial and temporal relationships between top predators (marine mammals, seabirds), their prey and physical-biological processes in the northern California Current System (CCS) with data sets collected during the multi-ship GLOBEC NEP effort that surveyed waters off Oregon and northern California in 2000 and 2002. Variability in the productivity of the CCS is notably large owing to climate variability on time scales ranging from days (upwelling) to interannual (ENSO) to decadal (Pacific Decadal Oscillation, PDO). While these trends can be best seen from a large-scale view, it is at the mesoscale or finer-scale perspective that predators are exploiting the patches of prey that become available. Two major null hypotheses will be tested: 1) mesoscale forcing, that alters the alongshore upwelling front and equatorward jet, does not affect the cross-shelf and along-shelf density and community structure of top predators; and 2) the spatial scale of plankton and nekton distribution, measured by spatial autocorrelation, is everywhere comparable to that of physical parameters; in turn, the spatial scale of planktivore or piscivore distributions is comparable to the scale of plankton and fish distributions, respectively. The investigators will construct a predictive model of factors affecting top-predator distribution based on 2000 data and will test it using 2002 data. They will also estimate predator abundance and distribution using general additive models and construct a carbon flow model to estimate carbon egested, respired and sequestered by upper trophic levels (as well as carbon removed by migrants). Several modeling approaches will be used to determine the magnitude and significance of prey correspondence or depletion at a range of scales. Spatial heterogeneity will be examined at two levels of the ecosystem: the density or patch size of prey relative to physical oceanographic features and the density of predators relative to their prey. The syntheses proposed herein provide a valuable baseline, for the early part of this century, on top predator response to several scales and sources of variability in the northern CCS. In addition, the synthesis forwards the longer-term development of predictive biophysical models of occurrence patterns of top-predators (many of which are endangered species) in the CCS. Evolution of such models will assist with resource management and planning of human activities (e.g., major fisheries, 5 marine sanctuaries, transportation and commerce) in the northern California Current ecosystem off the west coast of the U.S.