Shifting Seas - a gene landscape approach to understanding saltmarsh vulnerability and resilience to sea-level rise

Saltmarsh是所谓的基于自然的解决方案（NbS）的重要组成部分，以海岸防御，这是制定英国政府政策的核心作用，旨在更好地管理，保护和恢复这个栖息地在未来25年。为了实现这一政策，以及由此产生的更广泛的生态系统和社会效益，我们必须了解海平面上升（SLR）和相关的沿海洪水和侵蚀对沿海栖息地的风险和机会。“海洋转移”采用基因到景观尺度的方法来阐明盐沼对SLR的反应，结合了最先进的跨学科方法，包括潮汐流体动力学、地貌学和沉积学、植物遗传学、盐沼生态学、野外实验和生态建模。我们探讨了以下四个objectivesObjectives 1 -盐沼地带是由不同的，但重叠，个别物种的范围，反映了他们的能力，容忍与潮汐淹没相关的因素。由于海拔和淹没频率施加主要控制一个物种的“基本”和“实现”的生态位，通过SLR潮汐范围的变化可能会产生后果盐沼社区的结构和功能。盐沼将进行调查，以确定组成物种的范围，但特别侧重于典型的高，中，低沼泽物种，以及如何关键的物理变量变化串联。这提供了一个基线，每个物种的海拔生态位可以通过无人机调查，水位测量和潮汐建模相结合确定的潮汐框架中的当前位置（即淹没频率，淹没持续时间，出现持续时间）。这些数据将建立一个生态位模型来预测盐沼植物可能发生或入侵一个地区的程度和过程控制人口和社区结构下不同的ACC和管理scenaries.Objective2-沼泽海拔可以影响组成物种的遗传多样性，并与它恢复持续SLR和相关的环境因素。此外，植物对模拟海水淹没的响应的基因型变化标志着洪水作为一个潜在的选择性过滤器，可以消除关键物种，减少功能的可持续性，生态系统的恢复能力，SLR，并为海防的贡献。从目标1，我们选择了两个网站，代表典型的“高弹性”（泥沙淤积相匹配的SLR）和“高脆弱性”（泥沙淤积滞后SLR）的情况。我们将使用基因型测序方法在多倍体中发现SNP，以确定在选定的“高弹性”和“高脆弱性"地点的沼泽海拔上选定物种的种群结构、遗传多样性和分化。再加上对关键组成植物物种的局部分布、它们的遗传多样性以及对海水浸泡和沉积物沉积的反应的了解，可以揭示盐沼对SLR的适应。“使用‘沼泽器官’技术，我们将在海拔梯度上种植不同基因型的目标植物物种，结果为预测物种和遗传多样性如何影响沼泽对SLR的恢复力/脆弱性的模型提供信息。目标4 -我们将提供一个空间上明确的‘机会映射工具’，为支持保护适应途径所需的管理干预提供信息，恢复和保护盐沼生态系统。通过阐明SLR适应的一些（遗传，水动力，生态）障碍，我们提供了预测盐沼生态系统和物种的变化和风险所需的关键证据，并反过来针对长期海平面变化的解决方案。

Saltmarsh is a vital component of so-called Nature based Solutions (NbS) to coastal defence, a role central to developing UK Government policy, that aims to better manage, protect and restore this habitat over the next 25 years. In order to deliver this policy, and the wider ecosystem and societal benefits that accrue, we must understand the risks and opportunities to coastal habitats from sea level rise (SLR) and associated coastal flooding and erosion. 'Shifting Seas' takes a gene to landscape scale approach to elucidate saltmarsh response to SLR, incorporating state of the art, interdisciplinary approaches including tidal hydrodynamics, geomorphology and sedimentology, plant genetics, saltmarsh ecology, field experiments and ecological modelling. We explore the following four objectivesObjective 1 - Saltmarsh zonation is generated by the different, but overlapping, ranges of individual species, reflecting their ability to tolerate factors associated with tidal submergence. Because elevation and inundation frequency exerts primary controls on a species 'fundamental' and 'realised' niche, changes to tidal range through SLR could have consequences for saltmarsh community structure and function. Saltmarshes will be surveyed to determine the range of component species, but with a particular focus on typical high- , mid-, and low- marsh species, and how key physical variables vary in tandem. This provides a baseline from which the elevation niche of each species can be set against present day position in the tidal frame (i.e. inundation frequencies, inundation duration, emergence duration) determined through a combination of UAV survey, water level measurements and tidal modelling. These data will build a niche model to predict the extent to which saltmarsh plants may occur or invade an area and the processes controlling population and community structure under different ACC and management scenarios.Objective 2 - Marsh elevation can influence the genetic diversity of component species and with it resilience to continued SLR and associated environmental factors. Moreover, genotypic variation in plant response to simulated seawater inundation signpost flooding as a potential selective filter that could eliminate key species and reduce functional sustainability, ecosystem resilience to SLR, and contribution to coastal defence. From Objective 1, we select two sites to represent typical 'high resilience' (sediment accretion matches SLR) and 'high vulnerability' (sediment accretion lags SLR) scenarios. We will use a genotype by sequencing approach for SNP discovery in polyploids to determine the population structure, genetic diversity and differentiation of selected species across the marsh elevation at the selected 'high resilience' and 'high vulnerability' sites.Objective 3 - Elucidation of the hydrodynamic properties operating at 'high resilience/vulnerability' sites, coupled with an understanding of the local distribution of key component plant species, their genetic diversity, and response to seawater immersion and sediment deposition, may reveal much about saltmarsh adaptation to SLR. 'Using the 'marsh organ' technique, we will plant different genotypes of the target plant species across an elevational gradient, the results informing a model forecasting how species- and genetic-variably influences marsh resilience / vulnerability to SLR.Objective 4 - We will deliver a spatially explicit 'opportunity mapping tool' informing management interventions necessary to support adaptation pathways for the conservation, restoration and protection of saltmarsh ecosystems. By elucidating the some of the (genetic, hydrodynamic, ecological) barriers to SLR adaptation, we provide crucial evidence needed to predict changes and risks to saltmarsh ecosystems and species, and in turn target solutions resilient to long-term sea-level change.