Collaborative Research: The interplay of nitrogen loading and ecosystem sustainability in threatened wetlands: an extension of the WETFEET project

在过去的十年里，佛罗里达州河口的污染已经造成了可怕的后果，比如赤潮和鱼类和海洋哺乳动物的大规模死亡。这组研究人员与佛罗里达州东北部的土地管理人员密切合作，后者寻求数据驱动的指导，以减轻污染并帮助维持这些湿地。由于海平面上升，湿地边缘的侵蚀和内陆的“积水”正在逐渐丧失重要的湿地栖息地。随着海平面和污染的增加，保护佛罗里达州人口免受大风暴侵袭的绿色薄带植被正在从盐碱地草丛变成红树林。为了确定这些湿地在未来海平面更高、营养物质输入更多、植物更大的情况下会如何，该项目将结合实地实验、测绘和数学建模。将获得关于沿海湿地如何帮助去除氮的信息，氮是沿海水域中的一种常见污染物。研究人员将调查湿地的减少是否导致目前营养水平的上升，威胁到人类和其他动物的健康。最后，该团队将利用他们与佛罗里达州东北部土地管理者、政府官员和修复从业者建立的关系，帮助规划瓜纳托洛马坦萨斯国家河口研究保护区(GTMNERR)和其他地区这些受到威胁的湿地的未来。该项目的数据将用于绘制GTMNERR营养热点的地图，并培训本科生和研究生研究沿海湿地的研究并规划其恢复。在佛罗里达州东北部，沿海湿地生态系统面临海平面上升和污染负荷，并正在经历气候驱动的植被从沼泽植物向红树林的戏剧性转变。氮(N)富营养化和海平面上升分别会对沿海湿地造成严重影响。该项目将探索海岸湿地反馈如何将这两个问题联系在一起，这是该项目三个核心假设的基础：(1)过量的N负荷可能中断维持湿地的土壤积累机制；(2)沼泽向红树林的转化大大增强了N需求，这可能会缓解邻近水道的N污染；(3)N富营养化可以通过满足红树林比沼泽植物更大的N需求，加速沼泽向红树林的转化。过去的研究表明，氮素的添加可以通过刺激有机质的流失来阻碍湿地跟上海平面上升的能力，而另一些研究表明，氮素的添加可能会促进植物的生长，从而有助于滨海湿地的维持。这种差异可能是由于湿地边缘和内部的生物地貌过程的显著差异造成的。该项目将直接解决这一差异，利用现有的基础设施在河边和内部位置进行试验性氮添加，并首次比较氮对沼泽和邻近红树林为主的地块的影响。将检验关于N如何改变海拔增加和红树林侵蚀整个景观的机制的新假设，以及关于湿地持续丧失和沼泽转变为红树林如何对沿海N预算产生显著影响的假设。在最近的一次沿海脆弱性研讨会(2021年9月)上，GTMNERR管理层将研究氮对湿地对海平面上升的复原力的影响确定为一项研究优先事项。这组研究人员将利用GTMNERR水质数据和我们自己从该项目收集的数据，在海岸脆弱性地图上建立一个新的营养层，这将有助于为GTMNERR遗址规划的保护和恢复行动确定优先顺序。研究成果将通过与GTMNERR的环境教育中心合作，为参观者和营地制作展览和课程，向公众传达。对年轻科学家的跨学科培训也将在三所机构--维拉诺瓦大学、佛罗里达中部大学和罗斯福大学进行。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Over the last decade, pollution in Florida estuaries has had dire consequences such as red tides and massive die-offs of fish and marine mammals. This team of researchers has worked closely with land managers in northeastern Florida who seek data-driven guidance on strategies to mitigate pollution and help sustain these wetlands. Critical wetland habitats are increasingly being lost to erosion at the edges, and "ponding" in the interior due to sea level rise. As sea levels and pollution are increasing, the thin green strips of vegetation that protect Florida’s human population from big storms are changing from salt marsh grasses to mangrove forests. To determine how these wetlands will fare in a future with higher seas, more nutrient inputs, and larger plants, this project will use a combination of field experiments, mapping, and mathematical modeling. Information will be obtained on how coastal wetlands can help remove nitrogen, a common pollutant in coastal waters. The researchers will investigate whether wetland decline is contributing to the current uptick in nutrient levels that threatens the health of humans and other animals. Finally, the team will use the relationships that they have built with northeastern Florida land managers, government officials and restoration practitioners to help plan for the future of these threatened wetlands in the Guana Tolomato Matanzas National Estuarine Research Reserve (GTMNERR) and beyond. Data from this project will be used to map nutrient hotspots in the GTMNERR, and to train undergraduate and graduate student researchers in the study of coastal wetlands and plan for their restoration. In northeastern Florida, coastal wetland ecosystems are faced with rising seas and pollution loads, and are undergoing dramatic climate-driven vegetation conversion from marsh plants to mangroves. Nitrogen (N) eutrophication and rising sea levels each individually can severely impact coastal wetlands. This project will explore how these two problems may be linked by coastal wetland feedbacks, which underlie the project's three central hypotheses: (1) Excess N loading may interrupt the mechanisms of soil accumulation that sustain wetlands; (2) Conversion of marsh to mangrove greatly enhances N demand which may mitigate N pollution of adjacent waterways; (3) N-eutrophication can accelerate transformation of marsh to mangrove by satisfying the greater N demand of mangroves compared to marsh plants. Past studies have shown that N addition can hinder the ability of wetlands to keep up with sea level rise by stimulating loss of organic matter, whereas others have shown that N addition may promote plant growth, which can help sustain coastal wetlands. The discrepancy may result from stark differences in biogeomorphic processes between wetland edges and interiors. This project will address this discrepancy directly by leveraging established infrastructure to conduct experimental N addition at both creekside and interior locations, in addition to comparing N effects on marshes and adjacent mangrove-dominated plots for the first time. New hypotheses will be tested about how N may alter mechanisms of elevation gain and mangrove encroachment across the landscape as well as hypotheses about how ongoing loss of wetlands and conversion of marshes to mangroves could have dramatic effects on coastal N budgets. Examining N influences on wetland resilience to sea level rise was identified as a research priority by the GTMNERR management at a recent coastal vulnerability workshop (September 2021). This team of researchers will work with the GTMNERR water quality data and our own data collection from this project to build a new nutrient layer onto a coastal vulnerability map that will help prioritize GTMNERR sites for planned conservation and restoration initiatives. Research findings will be conveyed to the public by working with the environmental education center at the GTMNERR to produce an exhibit and curricula for visitors and camps. Interdisciplinary training of young scientists will also take place at three institutions- Villanova University, University of Central Florida and Roosevelt University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.