Comparative dynamics of exploited marine ecosystems

过度捕捞、气候变化和富营养化等人为压力源被认为是大型海洋生态系统（LME）变化的主要驱动因素。这些变化包括全球浮游植物生物量的减少，生物体型的缩小，以及广泛的渔业资源的崩溃。我们研究的长期目标是量化这些和相关压力源在确定LMEs的结构和功能以及它们对扰动的不同脆弱性方面的作用。这种知识对于预测生态系统功能何时、何地以及在何种条件下退化和/或生产力改变到传统管理策略失效或资源产量崩溃的程度至关重要。它也是成功制定和实施以生态系统为基础的管理战略的核心，这些战略旨在避免再次发生大规模的生态灾害，例如1990年代初西北大西洋鳕鱼和其他底栖鱼类物种的崩溃。我们在过去十年的研究大大增强了对lme结构和功能的理解。本建议的重点是发展这种理解的下一个关键因素。将追求四个相互关联的目标：1)评估用于解释LMEs营养结构和功能模式的多个相互竞争的假设。该项目有两个组成部分：a)利用已发表的海洋生态系统功能分析，量化和模拟主要假设的准确性，以解释控制LMEs动态的宏观生态关系的类型和强度的空间格局；b)使用来自特定生态系统的时间序列数据来评估全球海洋营养控制的时间动态。2)使用“降尺度”作为对照实验的替代（在LMEs中不可能）来解耦温度和物种多样性的相对重要性，它们被确定为海洋生态系统结构的潜在主要决定因素。这将通过利用东、西斯科舍大陆架生态系统的不同生物物理特征来实现。3)通过将进化生活史特征作为种群和生态系统水平特性决定因素的重要性这一迅速发展的知识纳入生态系统功能分析，定量评估最近全球范围内初级和次级生产者体型减小对生态系统结构、稳定性和生产力的影响。4)在基于生态系统的渔业管理背景下，评估“平衡捕捞假说”的有效性。该研究计划是专门为博士和PDF级别的研究行为而设计的，同时在全球范围内日益重要的领域显著推进知识

Anthropogenic stressors including excessive harvesting, climate change and eutrophication are recognized as dominant drivers of large marine ecosystem (LME) change. These changes include global declines in phytoplankton biomass, reductions in organism body sizes, and widespread fisheries stock collapses. The long-term goal of our research is to quantify the role of these and related stressors in determining the structure and function of LMEs and their differential vulnerability to perturbation. This knowledge is a critical requirement for forecasting when, where, and under what conditions ecosystem function degrades and/or productivity is altered to the point that traditional management strategies fail or resource yields collapse. It is also central to the successful development and implementation of ecosystem based management strategies designed to avoid recurring large scale ecological disasters such as the collapse of cod and other groundfish species in the northwest Atlantic in the early 1990s. Our research over the past decade has significantly enhanced this understanding of how LMEs are structured and function.***This proposal focuses on the next key elements in the development of this understanding. Four inter-related objectives will be pursued: 1) Evaluation of the multiple competing hypotheses advanced to explain patterns of trophic structure and function in LMEs. This project has two components: a) quantify and model the veracity of  leading hypotheses  advanced to explain spatial patterns in the type and strength of the macro-ecological relationships governing the dynamics of LMEs by drawing on published analyses of marine ecosystem function and b) use time series data from specific ecosystems to evaluate the temporal dynamics of trophic control in the global oceans. 2) Use 'downscaling' as a surrogate for controlled experimentation (impossible in LMEs) to decouple the relative importance of temperature and species diversity, identified as potential primary determinants of marine ecosystem structure. This will be achieved by exploiting the differential, bio-physical characteristics of the eastern and western Scotian Shelf ecosystems. 3) Quantitatively assess the impact on ecosystem structure, stability and productivity of recent global scale reductions in primary and secondary producer body sizes by incorporating into analyses of ecosystem function the rapidly expanding knowledge of the importance of evolved life history traits as determinants of population and ecosystem level properties. 4) Assess the efficacy of the "balanced fishing hypothesis" in the context of ecosystem based fisheries management. This research program is specifically designed to be tractable for the conduct of research at the Ph.D. and PDF levels while at the same time significantly advancing knowledge in an area of increasing worldwide importance.**