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案（公法111-5）资助的。过度捕捞正成为对海洋生态系统完整性及其提供的社会服务的最大威胁之一。尽管人们越来越认识到捕食者减少对包括海带森林和珊瑚礁在内的一些研究充分的沿海栖息地的影响，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和有争议。二十多年来，盐沼植被的死亡一直在西大西洋蔓延，威胁着沼泽提供沿海环境的关键苗圃、营养过滤和风暴屏障生态系统服务。这个项目是基于最近描述的马萨诸塞州科德角盐沼死亡的前提，这是由当地的食草蟹造成的，这些死亡对整个周边地区的近岸海洋生态系统构成了广泛而积极的威胁。研究人员概述了一项研究计划，通过探索以下问题来检验过度捕捞远洋海洋捕食者使Sesarma种群从捕食者控制中解脱出来，并引发草食动物驱动的死亡和美国东北部盐沼退化的一般假设：1)食肉动物的区域枯竭是否通过释放草食Sesarma种群而导致美国东北部盐沼的死亡？将进行大规模、区域性的螃蟹和捕食者丰度和沼泽死亡调查，以及捕食压力和螃蟹食草性的实验分析。2)当地的捕捞压力是否引发并加剧了盐沼的死亡？在大量捕捞和附近海洋保护区，捕食和食草的影响将被量化，以探索初步数据，表明当地捕捞压力、食草蟹压力和河滩死亡之间存在很强的因果关系。3)美国东北部盐沼的结构及其提供生态系统服务的能力如何受到河岸死亡的影响？研究人员将绘制和跟踪整个地区的死亡命运，以预测螃蟹驱动的死亡的个体发生和轨迹，以及它们对盐沼提供的生态系统服务的影响。这项工作具有保护意义，因为它将可能控制沼泽植物消费者的捕食者（商业和娱乐收获的螃蟹和鱼）的管理与沿海湿地的健康和长期持久性联系起来，并将提供对这些系统的机械理解，这些系统是管理和持续提供生态系统服务所必需的。这项研究将由一个强大的本科和研究生教育重点和社区外展组成部分加以补充。

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.