Collaborative Research: Microbial influences on Alexandrium populations

被称为麻痹性贝毒(PSP)的有害藻华(HAB)综合征是一个严重且日益严重的世界性问题，对经济和人类健康造成负面影响，有时甚至是毁灭性的影响。亚历山大菌属内的甲藻是许多PSP暴发的原因。在美国东北部和加拿大，亚历山大藻水华出现在两种类型的栖息地--一种是大而广泛的栖息地，覆盖了广阔的沿海开阔水域，另一种是小而局部的栖息地，例如在科德角的盐塘或水壶洞内。这些系统中的水华表现出强烈的“点源”特征，即局部的孢囊萌发接种在上覆水中，导致水华发育并最终在该位置沉积新的包囊，从而导致反复的、自播的水华。由于其地理规模小，与沿海种群的连通性有限，鳕鱼角盐池是一个独特的自然实验室，用于研究亚历山大藻自我生态的许多重要方面，这些方面在开放的沿海水域、较大的河口系统，甚至在中生生物中都很难研究。在这个项目中，伍兹霍尔海洋研究所和海洋生物实验室的研究人员将对两个鳕鱼角盐池中的真菌种群和遗传动态进行协调的野外和实验室研究，并在当地水动力学的背景下调查宿主-寄生虫的相互作用、放牧损失和细菌相关动态。项目假设是亚历山大藻种群动态和结构的突然、短期变化与细菌、寄生虫和/或食草动物的丰度和群落组成的可识别变化有关。将使用比较的方法来揭示两个站点共同的过程，但发生在不同的时间。具体目标是：1)描述两个孤立盐池中亚历山大藻种群的丰度和结构，以及寄生和放牧造成的损失的动态和影响；2)在亚历山大藻开花之前、期间和之后生成和分析相对高分辨率的微生物群落结构数据；3)获得研究区域内的高分辨率水动力数据，并利用这些信息在环境背景下解释微生物网络数据和亚历山大藻种群结构。研究人员过去曾在伍兹霍尔海洋与人类健康中心(WHCOHH)担任PI，他们将共享和合成数据，以确定对真菌种群的主要影响，并利用这些见解为NMS内真菌水华动力学的现有物理/生物模型提供信息。这些也将帮助我们改进我们的缅因湾近海水华模型，对于这些模型，强迫作用和损失项很难分离和量化。更广泛的影响。该研究网站是一个多用户、高价值的资源，包括科德角国家海滨(CACO)的部分地区。由于在过去20年里，捕捞关闭的时间和空间增加，PSP已成为居民和商业贝类渔民的主要关切。产生的数据和分析将对系统中许多问题的政策决策有价值，包括污水处理、地下水质量、水产养殖、贝类繁殖和捕捞关闭政策。该项目还适用于本科生、研究生和博士后培训。

The harmful algal bloom (HAB) syndrome known as Paralytic Shellfish Poisoning (PSP) is a significant and growing problem worldwide, with negative and sometimes devastating economic and human health impacts. Dinoflagellates within the genus Alexandrium are responsible for many of these PSP outbreaks. In the northeastern US and Canada, Alexandrium blooms occur in two types of habitats -- one that is large and widespread, covering vast expanses of open coastal waters and another that is small and localized, such as within salt ponds or kettle holes on Cape Cod. Blooms in these latter systems exhibit strong "point source" characteristics in which localized cyst germination inoculates the overlying waters, leading to bloom development and eventual deposition of new cysts at that location, and thus to recurrent, self-seeding blooms. Due to their small geographic scale and limited connectivity with coastal populations, Cape Cod salt ponds represent a unique natural laboratory for the investigation of many important aspects of Alexandrium fundyense autoecology that are difficult to study in open coastal waters, larger estuarine systems, or even in mesocosms. In this project, researchers at the Woods Hole Oceanographic Institution and the Marine Biological Laboratory will conduct a coordinated field and laboratory study of population and genetic dynamics of A. fundyense in two Cape Cod salt ponds, coupled with an investigation of host-parasite interactions, grazing losses, and bacterial associated dynamics, examined within the context of local hydrodynamics. The project hypothesis is that abrupt, short-term changes in Alexandrium population dynamics and structure are associated with identifiable changes in abundance and community composition of bacteria, parasites, and/or grazers. A comparative approach will be used to reveal processes that are common to both sites, but that occur at different times. Specific objectives are to: 1) Characterize Alexandrium population abundance and structure in two isolated salt ponds, as well as the dynamics and impacts of losses due to parasitism and grazing; 2) Generate and analyze comparative high resolution microbial community structure data before, during, and after Alexandrium blooms; and 3) Obtain high-resolution hydrodynamic data within the study area and use that information to interpret microbial network data and Alexandrium population structure in an environmental context. Having worked together in the past as PIs in the Woods Hole Center for Ocean and Human Health (WHCOHH), the investigators will share and synthesize data to identify the major influences on A. fundyense populations, and use these insights to inform an existing physical/biological model of A. fundyense bloom dynamics within the NMS. These will also help us to refine our models of the offshore blooms for the Gulf of Maine, for which forcing functions and loss terms are difficult to isolate and quantify. Broader Impacts. The study site is a multi-user, high-value resource that includes parts of the Cape Cod National Seashore (CACO). PSP has become a major concern to residents and commercial shell fishermen due to the temporal and spatial increase in harvesting closures over the last two decades. The data and analyses produced will be of value in policy decisions about many issues in the system, including sewage treatment, groundwater quality, aquaculture, shellfish propagation, and harvesting closure policies. This project also lends itself to undergraduate, graduate, and postdoctoral training.