Is overfishing triggerng the die-off of New England salt marshes?

该奖项是根据2009年《美国复苏和再投资法》(公法111-5)资助的。过度捕捞正在成为对海洋生态系统及其提供的社会服务完整性的最大威胁之一。尽管对包括海藻森林和珊瑚礁在内的一些经过充分研究的沿海生境的捕食者枯竭的后果越来越得到认识，但过度捕捞对包括盐沼在内的其他有价值的海洋生态系统的风险仍然不确定，也存在争议。二十多年来，盐沼植被的死亡一直在西大西洋蔓延，威胁到沼泽提供沿海环境的关键苗圃地面、营养物质过滤和风暴屏障生态系统服务。该项目的前提是，最近描述的马萨诸塞州科德角盐沼的死亡是由当地草食性螃蟹Sesarma reetatum推动的，这些死亡对周围地区的近岸海洋生态系统构成了广泛和积极扩大的威胁。研究人员概述了一项研究计划，以检验一般假设，即过度捕捞中上层海洋捕食者正在将芝麻种群从捕食者控制中释放出来，并通过探索以下问题来触发食草动物驱动的死亡和美国东北部盐沼的退化：1)捕食者的区域性枯竭是否通过将食草性芝麻种群从捕食者控制中释放出来而导致美国东北部盐沼的死亡？将进行大规模的区域调查，调查螃蟹和捕食者的数量以及沼泽的死亡情况，并进行捕食压力和螃蟹食草性的实验分析。2)当地捕捞压力是否触发和加剧了盐沼的消亡？将量化大量捕捞和附近海洋保育区的捕食和草食的影响，以探索初步数据表明当地捕鱼压力、蟹类草食压力和小溪岸边死亡之间存在强烈的因果关系。3)小溪岸边的消亡如何影响美国东北部盐沼的结构及其提供生态系统服务的能力？研究人员将绘制和跟踪整个地区的物种灭绝的命运，以发展对螃蟹驱动的死亡的个体发生和轨迹及其对盐沼提供的生态系统服务的影响的预测性理解。这项工作具有保护意义，因为它将可能控制湿地植物消费者的捕食者(商业和娱乐捕捞的螃蟹和鱼类)的管理与沿海湿地的健康和长期可持续性联系起来，并将提供对这些系统的机械理解，这些系统是它们管理和继续提供生态系统服务所必需的。这项研究将得到强有力的本科生和研究生教育重点以及社区外联部分的补充。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Overfishing is emerging as one of the greatest threats to the integrity of marine ecosystems and the societal services they provide. Though the consequences of predator depletion are increasingly appreciated for a few well-studied coastal habitats including kelp forests and coral reefs, the risks of overfishing to other valuable marine ecosystems including salt marshes remain uncertain and controversial. For over two decades, die-offs of salt marsh vegetation have been spreading across the Western Atlantic, threatening the critical nursery ground, nutrient filtering and storm barrier ecosystem services that marshes provide coastal environments. This project is based on the premise that recently described salt marsh die-offs on Cape Cod, Massachusetts are being driven by the native herbivorous crab, Sesarma reticulatum, and that these die-offs are an extensive and actively expanding threat to the near shore marine ecosystems throughout the surrounding region. The investigators outline a research program to examine the general hypothesis that overfishing of pelagic marine predators is releasing Sesarma populations from predator control and triggering herbivore-driven die-off and the degradation of Northeastern US salt marshes by exploring the following questions: 1) Is regional depletion of predators causing the die-off of Northeastern US salt marshes by releasing herbivorous Sesarma populations from predator control? Large-scale, regional surveys of crab and predator abundance and marsh die-off and experimental assays of predation pressure and crab herbivory will be conducted. 2) Is local fishing pressure triggering and intensifying salt marsh die-off? Impacts of predation and herbivory in heavily fished and nearby marine conservation areas will be quantified to explore preliminary data suggesting a strong causal relationship between local fishing pressure, crab herbivore pressure and creek bank die-off. 3) How are creek bank die-offs influencing the structure of Northeastern US salt marshes and their ability to provide ecosystem services? The investigators will map and follow the fate of die-offs throughout the region to develop a predictive understanding of the ontogeny and trajectory of crab-driven die-offs and their effect on the ecosystem services provided by salt marshes.This work has conservation implications since it links the management of predators (commercially and recreationally harvested crabs and fish) that may control marsh plant consumers with the health and long-term persistence of coastal wetlands, and will provide a mechanistic understanding of these systems necessary for their management and continued provision of ecosystem services. The research will be complemented by a strong undergraduate and graduate educational focus and a community outreach component.