Multiple stressors and the potential for synergistic loss of New England salt marshes

Climate change and other anthropogenic stressors are converging on coastal ecosystems worldwide. Understanding how these stressors interact to affect ecosystem structure and function has immediate implications for coastal planning, however few studies quantify stressor interactions. We examined past and potential future interactions between two leading stressors on New England salt marshes: sea-level rise and marsh crab (Sesarma reticulatum) grazing driven low marsh die-off. Geospatial analyses reveal that crab-driven die-off has led to an order of magnitude more marsh loss than sea-level rise between 2005 and 2013. However, field transplant experimental results suggest that sea-level rise will facilitate crab expansion into higher elevation marsh platforms by inundating and gradually softening now-tough high marsh peat, exposing large areas to crab-driven die-off. Taking interactive effects of marsh softening and concomitant overgrazing into account, we estimate that even modest levels...

气候变化与其他人为胁迫因子正共同影响全球各地的海岸生态系统。明晰此类胁迫因子的相互作用如何影响生态系统结构与功能，对海岸规划具有直接的现实意义，但目前鲜有研究对胁迫因子间的交互效应开展量化分析。本研究针对新英格兰盐沼的两类核心胁迫因子——海平面上升与由湿地蟹（*Sesarma reticulatum*）啃食引发的低潮沼衰退——的历史及潜在未来交互作用展开了探究。地理空间分析结果显示，2005至2013年间，蟹类引发的低潮沼衰退导致的盐沼流失量较海平面上升高出一个数量级。然而野外移植实验结果表明，海平面上升可通过淹没并逐步软化当前致密的高潮沼泥炭，推动蟹类向更高海拔的沼滩平台扩张，进而使大片区域暴露于蟹类引发的衰退风险之下。在综合考量盐沼软化与伴随发生的过度啃食的交互效应后，我们估算，即便处于适度水平的……