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

基础物种是那些构成整个生态系统基础的物种，它们极大地改变了它们所在地区的物理和生物特征。红树林是最显著的基础物种群之一，提供了许多我们高度重视的生态系统服务，例如生态和经济上重要物种的栖息地，海岸线稳定和碳储存。因此，全球红树林的减少是最令人担忧的。例如，在巴哈马阿巴科岛西侧的一个偏远地区，已经发现了大面积的矮红树死亡。由于该地点地处偏远，这种灭绝不太可能是人类活动直接造成的。尽管这个地区基本上是人迹罕至的，但它在生态和经济上都很重要，例如，它是阿巴科岛的主要剔骨捕捞区- -该行业在巴哈马每年价值超过1.5亿美元。因此，巴哈马的利益相关者迫切关注的是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的广泛调查、分离和鉴定这种病原体的实验室工作、卫星图像测绘活动和模拟放牧实验。巴哈马国家信托基金（BNT）目前正在考虑将发生灭绝的地区指定为国家公园。研究结果将直接传达给BNT，并将用于立即做出管理决策。将与两个巴哈马环境非政府组织，即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损害调查，以及一个关于红树林生态的教育模块。来自公民科学和学生调查的数据将被整合到巴哈马群岛的病变发生率地图中。公民科学的组成部分，以及与骨鱼导游的互动，提供了进一步整合科学和教育的机会。该教育模块将在7月份的BREEF夏季教学培训研讨会上推出。这个一年一度的活动通常包括来自10个岛屿的30名教师。研究人员将继续通过Abaco科学家网站（http://appliedecology.cals.ncsu.edu/absci/）.Provisioning)向公众提供我们所有的研究结果，沿海地区的生态系统服务主要由基础物种介导，如红树林、珊瑚和盐沼草。在世界范围内，这些物种中有许多正在急剧减少。这些下降通常是由复杂的、相互作用的、可能难以识别和阐明的压力源驱动的。尽管困难重重，但解开这些机制驱动因素对于阻止这些生态系统的衰退和制定管理策略至关重要。红树林为沿海社区提供了许多极具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海地区的各种人类活动有关，但自然生态机制也导致了许多地区的下降。在巴哈马阿巴科岛西侧的一个偏远地区，观察到矮红树（Rhizophora mangle）大面积死亡。初步观察表明，死亡可能是由于真菌病原体、放牧和身体压力的综合作用。这种压力因素的组合与美国东部和墨西哥湾沿岸盐沼退化的驱动因素惊人地相似。迄今为止，已经从红树林树叶中发现了不同的真菌菌株。一种真菌是拟盘多毛菌，一种子囊菌真菌，该属的成员是已知的植物病原体。在死亡地区也有高密度的夜间活动的食草蟋蟀（Tafilasca eleuthera）。目前尚不清楚该物种是最近在该地区定居，还是密度正在增加，还是两者兼而有之。此外，死亡区沉积物孔隙水的高盐度表明植物的另一个潜在压力源。一系列的观察和实验研究将用于检查红树林死亡的潜在机制驱动因素。首先，将使用配备有摄像机的gps集成无人机进行空中调查，绘制死亡区域的范围。将利用陆地卫星数据，利用从1980年代至今（每年）红树林的历史光谱剖面来研究死亡的进程。其次，将通过一系列公民科学倡议来探索阿巴科岛和整个巴哈马群岛红树林的损害发生率。第三，鉴定真菌将需要DNA测序和检查真菌孢子/分生孢子的形态在北卡罗莱纳州立大学。第四，在死亡地点附近进行食草动物排除实验，可以评估食草动物在该系统中的作用。最后，模拟放牧疤痕实验将用于评估放牧是否确实可以促进真菌感染。

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.