RAPID: COLLABORATIVE RESEARCH: Mechanisms of seagrass community injury and resilience post Hurricane Florence: implications for increasingly stormy coasts

海草草甸是许多河口和近岸环境的显著特征。据估计，这些草甸每年平均每公顷贡献2万美元的商品和服务。这些包括养分循环、沉积物稳定、碳埋藏以及为幼鱼、蟹和虾提供苗圃栖息地。令人担忧的是，海草受到多种环境和人类驱动的压力因素的威胁，海草栖息地的丧失仍然是保护和可持续发展计划的一个关键问题。在许多气候变化模拟情景下，预计风暴（频率和强度）和降雨量会增加，这使得了解飓风对宝贵的沿海栖息地（如海草草牧场）的影响在地方、国家和全球尺度上都很重要。事实上，对于飓风活动增加的影响，海草草甸可能会成为“煤矿里的金丝雀”，因为它们位于较浅的深度，受浊度和盐度的影响；海草也很容易受到大风暴的掩埋或侵蚀。海草(1)包括一系列具有独特生长和繁殖策略的物种；(2)生活在不同大小和斑块程度的草地上；和(3)呈现不同的季节周期。这代表了一个巨大的机会，可以探索导致海草对飓风的恢复能力或脆弱性的条件和属性，作为更广泛的沿海生态系统响应的模型。9月14日，飓风“佛罗伦萨”在北卡罗来纳州海岸登陆。佛罗伦萨在接近海岸时停滞不前，风暴相关的大风/降雨在北卡罗来纳州东南部持续了4天（13日至16日）。随后，在北卡罗莱纳州海岸线观测到创纪录的高海平面（浪涌+潮汐）。此外，佛罗伦萨成为2017年仅次于哈维的美国第二潮湿风暴，在陆地上倾泻了65万亿升的降雨，使河口盐度下降了一个多月。北洋海草主要有三种：鳗草、浅滩草和江蓠。草甸以多元文化或单一文化的形式存在，呈现出多种多样的空间格局。草甸也被强烈的季节性所定义：由于热应激，大叶藻在夏天会衰老，这些地方要么变成以浅滩草为主的草甸，要么变成泥滩。在枯死之后，大叶藻依靠种子库和存活的顶端分生组织的结合来进行每年冬天的再生。利用研究小组收集的近40个受佛罗伦萨影响的草甸的关键海草数据集，研究了几个基本的生态问题：(1)有性（大叶草：种子库）和无性（浅滩草：营养生长和片段定植）的生活史如何促进海草对干扰的易感性或恢复力；(2)草甸景观配置和植物多样性如何调节风暴对种子库保留的影响；(3)草甸干扰（强烈的物理和更长期的物理化学驱动因素）如何影响群落动态，特别关注植物生产力和海草栖息地的关键“苗圃作用”；(4)季节性和物种特征如何放大或减弱强烈干扰对海草的影响。本研究通过考虑飓风、景观配置和生物多样性对生态系统反应的相互作用，扩展了之前的飓风后研究。它还利用正在进行的美国国家科学基金会支持的沿德克萨斯州海岸的工作来比较和对比不同海草物候/生长策略对风暴干扰的反应（例如，德克萨斯州的海龟草全年都是“叶片”物种，而北卡罗来纳州的大叶草和浅滩草在生物量上都表现出强烈的季节性）。总的来说，这项工作将产生更普遍的沿海生态适应风暴的模型。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Seagrass meadows are conspicuous features of many estuarine and nearshore environments. By some estimates, these meadows contribute an average of $20,000 per hectare per year in goods and services. These include nutrient cycling, sediment stabilization, carbon burial, and provision of nursery habitat for juvenile fishes, crabs, and shrimps. Alarmingly, seagrasses are threatened by several environmental and human-driven stressors, and loss of seagrass habitat remains a key concern for conservation and sustainable development programs. Anticipated increases in storminess (frequency and intensity) and rainfall under many climate change modeling scenarios make understanding hurricane impacts on valuable coastal habitats such as seagrass meadows important on local, national, and global scales. Indeed, seagrass meadows potentially serve as a 'canary in the coal mine' regarding the effects of increased hurricane activity as they are found at shallow depths and are affected by turbidity and salinity; seagrasses are also vulnerable to burial or erosion due to large storms. Seagrasses (1) include a suite of species with distinct growth and reproductive strategies; (2) live in a range of meadow sizes and degrees of 'patchiness;' and (3) present divergent seasonal cycles. This represents a tremendous opportunity to explore the conditions and attributes that result in seagrass resilience or vulnerability to hurricanes as a model for coastal ecosystem responses more broadly. Hurricane Florence made landfall along the NC coast on September 14, 2018. Florence stalled approaching shore, and storm-related winds/rains persisted for 4 days (13th-16th) in southeastern NC. Subsequently, record high sea-level stands (surge + tide) were observed across the NC coastline. Furthermore, Florence became the second wettest US storm, behind only Harvey in 2017, dumping 65 trillion L of rain over land that depressed estuarine salinities for over a month. NC seagrasses are dominated by three species: eelgrass, shoalgrass, and widgeon grass. Meadows exist as polycultures or monocultures, and exhibit a diverse range of spatial configurations. Meadows are also defined by strong seasonality: eelgrass shoots senesce in summer due to heat stress, with sites transformed either into shoalgrass-dominated meadows or mudflats. Subsequent to dieback, eelgrass depends upon a combination of seedbank and surviving apical meristems for regeneration each winter. Using key seagrass datasets collected by the research team dating back decades across ~40 Florence-impacted meadows, several fundamental ecological questions are being addressed: (1) how sexual (eelgrass: seedbank) v. asexual (shoalgrass: vegetative growth and fragment colonization) life histories promote susceptibility or resilience of seagrass to disturbance; (2) how meadow landscape configuration and plant diversity modulate the effect of storms on seedbank retention; (3) how meadow disturbance (intense physical v. more chronic physiochemical drivers) affected community dynamics, with special focus on plant productivity and the critical 'nursery role' of seagrass habitat; and (4) how seasonality and species traits amplify or attenuate the effects of intense disturbance on seagrasses. This research expands upon previous post-hurricane studies by considering the interactive effects of hurricanes, landscape configuration, and biodiversity on ecosystem responses. It also leverages ongoing, NSF-supported work along the TX coast to compare-and-contrast the responses of different seagrass phenology/growth strategies to storm disturbance (e.g., turtlegrass in TX is a "leaf-on" species throughout the year while eelgrass and shoalgrass in NC both exhibit strong seasonality in biomass). Collectively, this work will result in more generalizable models of coastal ecological resilience to storminess.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.