An interdisciplinary approach to elucidating the causes of widespread mangrove die-off

基础物种是构成整个生态系统基础的物种，它们极大地改变了所在地区的物理和生物特征。红树林是基础物种中最引人注目的群体之一，提供了我们高度重视的众多生态系统服务，例如，生态和经济重要物种的栖息地、海岸线稳定和碳储存。 因此，全球红树林的减少是最令人关切的问题。 例如，在巴哈马阿巴科岛西侧的一个偏远地区，发现矮红红树林大量死亡。由于该地点的偏远性质，死亡不太可能直接归因于人类活动。尽管该地区基本上无法进入，但在生态和经济上都很重要，例如，它是阿巴科的主要捕鱼区--巴哈马每年的渔业价值超过1.5亿美元。因此，巴哈马的利益攸关方迫切需要确定红树林减少的根本原因，并评估对其他地区红树林的潜在威胁。 为此，将开展一系列活动，包括对最近发现的一种真菌病原体进行广泛调查，开展实验室工作以分离和确定这种病原体，开展卫星图像测绘活动，并进行模拟放牧实验。巴哈马国家信托基金（BNT）目前正在考虑将发生死亡的地区指定为国家公园。研究结果将直接传达给BNT，并用于立即做出管理决策。将与巴哈马的两个环境非政府组织-环境之友和巴哈马珊瑚礁环境教育基金会合作，设计一个以公民科学为基础的真菌病变调查以及一个关于红树林生态学的教育单元。 来自公民科学和学生调查的数据将被整合到巴哈马各地病变发生率的地图中。 公民科学的组成部分，以及与bonefish指南的互动，为进一步整合科学和教育提供了机会。 教育单元将在7月的BREEF夏季教学培训讲习班上介绍。 这一年度活动通常有来自10个岛屿的30名教师参加。调查人员将继续通过阿巴科科学家网站（http：//appliedecology.cals.ncsu.edu/absci/）立即向公众提供我们的所有研究成果。沿海地区生态系统服务的提供主要由红树林、珊瑚和盐沼草等基础物种介导。其中许多物种在世界各地都在大幅减少。这些下降往往是由复杂的，相互作用的，可能难以识别和阐明的压力因素驱动的。尽管困难重重，但解开这些机械驱动因素对于阻止这些生态系统的衰退和制定管理战略至关重要。红树林为沿海社区提供了许多高价值的生态系统服务，但在世界范围内，这些森林正在迅速减少。这种损失大部分与沿着海岸线的各种人类活动有关，但自然生态机制也造成许多地区的减少。在巴哈马群岛阿巴科岛西侧的一个偏远地区，观察到一种广泛的矮红红树林（Rhizophora mangle）死亡。初步观察表明，死亡可能是由于真菌病原体，放牧和物理压力的组合。这种压力的组合是惊人的平行盐沼下降的驱动程序在美国东部和海湾沿岸的日期，不同的真菌菌株从红树林叶已被确定。一种真菌是拟盘多毛孢属（Pestalotiopsis）的物种，一种子囊菌纲真菌，并且该属的成员是已知的植物病原体。在死亡区也有高密度的食草性蟋蟀（Tafilasca eleuthera）。 目前尚不清楚该物种是否最近在该地区定居，密度是否正在增加，或者两者兼而有之。此外，高盐度的沉积物孔隙水在死亡区建议另一个潜在的压力源的植物。一系列的观察和实验研究将被用来检查潜在的机械驱动器的红树林死亡。 首先，将使用配备摄像机的GPS集成无人机进行航空调查，绘制死亡区域的范围。 将利用陆地卫星数据，用1980年代至今（每年）红树林的历史光谱剖面图来审查死亡的进展情况。 第二，将利用一系列公民科学倡议探讨阿巴科岛和整个巴哈马红树林病变的发生率。 第三，真菌的鉴定需要北卡罗来纳州州立大学进行DNA测序和真菌孢子/分生孢子形态学检查。 第四，维护一个食草动物排除实验附近的死亡的位置将提供一个评估的作用，草食动物在这个系统中。 最后，模拟放牧疤痕实验将被用来评估放牧是否真的可以促进真菌感染。

Foundation species are those that form the basis for entire ecosystems, substantially altering the physical and biological characteristics of the areas in which they are found. Mangroves are one of the most conspicuous groups of foundation species, providing numerous ecosystems services which we highly value, e.g., habitat for ecologically and economically important species, shoreline stablilization and carbon storage. As such, global declines in mangroves is of upmost concern. For example, an extensive die-off of dwarf red mangrove has been identified in a remote area on the west side of Abaco Island, The Bahamas. Because of its remote nature of the site, the die-off is unlikely to be directly due to human activities. Despite its largely inaccessible nature, the area is ecologically and economically important, e.g., it is the primary bonefishing area on Abaco - an industry worth more than $150 million annually in The Bahamas. Therefore, it is of pressing concern for stakeholders in The Bahamas to identify the underlying cause(s) of decline and assess potential threat to mangroves in other areas. To do so, a series of activities will be carried out, included widespread surveys for a recently identified fungal pathogen, laboratory efforts to isolate and identify this pathogen, satellite imagery mapping activities, and simulated grazing experiments. The area in which the die-off is occurring is currently being considered for designation as a national park by the Bahamian National Trust (BNT). The results of the study will be directly communicated to the BNT and will be used to make immediate management decisions. In collaboration with two Bahamian environmental NGOs, Friends of the Environment and Bahamas Reef Environmental Education Foundation (BREEF), a citizen science-based survey for fungal lesions, as well as an educational module on mangrove ecology, will be designed. The data from the citizen-science and student surveys will be integrated in a map of the incidence of the lesions across The Bahamas. The citizen-science component, and interaction with bonefish guides, provides the opportunity to further integrate science and education. The educational module will be introduced at the BREEF summer teaching training workshop in July. This annual event typically includes 30 teachers from 10 islands. The investigators will continue to make all of our research findings immediately available and accessible to the public through the Abaco Scientist website (http://appliedecology.cals.ncsu.edu/absci/).Provisioning of ecosystem services in the coastal realm is largely mediated by foundation species, such as mangroves, coral and salt marsh grasses. Many of these species are undergoing substantial declines throughout the world. These declines are often driven by complex, interacting, stressors that may be difficult to identify and elucidate. Despite the difficulty, unraveling such mechanistic drivers is essential for stemming declines and developing management strategies for these ecosystems. Mangroves provide many highly valued ecosystem services to coastal communities, yet worldwide these forests are rapidly declining. Much of this loss is related to various human activities along coastlines, but natural ecological mechanisms contribute to declines in many areas as well. An extensive die-off of dwarf red mangrove (Rhizophora mangle) was observed in a remote area on the west side of Abaco Island, The Bahamas. Preliminary observations suggest the die-off may be due to a combination of fungal pathogens, grazing, and physical stress. This combination of stressors is strikingly parallel to the drivers of salt marsh decline on the East and Gulf coasts of the U.S. To date, different fungal strains from mangrove leaves have been identified. One fungus is a species of Pestalotiopsis, an Ascomycete fungus, and members of this genus are known plant pathogens. There are also high densities of a nocturnally active herbivorous cricket (Tafilasca eleuthera) in die-off areas. It is unclear whether this species has recently colonized the area, is increasing in density, or both. In addition, high salinities in the sediment porewater in the die-off area suggest another potential stressor for the plants. A series of observations and experimental studies will be used to examine potential mechanistic drivers of the mangrove die-off. First, the extent of the die-off areas will be mapped using aerial surveys conducted with a GPS-integrated drone equipped with a video camera. Progression of the die-off will be examined with historical spectral profiles of mangroves from 1980s-present (on an annual basis) using Landsat satellite data. Second, the incidence of lesions on mangroves across Abaco Island and throughout The Bahamas will be explored using a series of citizen science initiatives. Third, identification of fungi will require DNA sequencing and examination of the morphology of fungal spores/conidia at North Carolina State University. Fourth, maintenance of a grazer exclusion experiment near the die-off location will provide an assessment of the role of herbivory in this system. Finally, simulated grazing scar experiments will be used to assess if grazing can indeed facilitate fungal infections.