Collaborative Research: Oceanographic and Topographic Influences on Dispersal of Hydrothermal Vent Species

25年前，当热液喷口群落首次被发现时，生物学家立即认识到扩散在种群动态和持久性中的关键作用。尽管过去10年在这一主题上取得了实质性进展，但关于扩散的机制及其对种群动态、种群遗传学和群落结构的影响，一些非常重要的问题仍然没有得到回答。研究人员假设，幼虫的扩散很大程度上是由物理运输过程推动的。这个项目的主要目标是调查幼虫的行为如何与大洋中脊上受地形影响的水流相互作用，并确定这些相互作用如何影响扩散轨迹、最大扩散距离以及向幼虫和偏远喷口供应的相对概率。已经确定了三个具体的生态问题：1.平流和涡流扩散对给定幼虫寿命的喷口物种的最大扩散距离有什么影响？2.幼虫行为的个体发育变化(即垂直位置)对扩散距离有什么影响？3.幼虫从脊系中消失的可能性如何受地形和水流的影响？轴向顶槽是否会抑制幼虫的离轴运输，并作为宜居喷口之间的管道？该项目还将解决物理海洋学界感兴趣的几个问题，包括：1.大洋中脊附近的平均和时间变化的流动是什么，它们的空间结构和相干性是什么？2.脊顶附近的日扩散系数是多少？3.横向扩散的速度有多快，通过脊顶附近的涡流扩散实现的横向均匀化有多有效？如果没有一套完整的物理和生物方法，这些传播问题就无法得到回答。一个由不同的天文学家和模型师组成的团队已经聚集在一起，研究与海脊相关的海洋学和生物学的相关方面，并将数据组合成扩散的定量模型。该方法包括田间示踪剂释放、海流计测量、水动力-运输模型、田间幼虫位置和阶段的测量以及生物-物理耦合模型。东太平洋海隆(EPR)北纬950.N附近的地区被选为研究地点，该地点过去一直是许多跨学科研究的焦点，并被NSF Ridge 2000计划选为综合研究地点。该项目的广泛影响将通过几项不同的活动来实现。该项目的方法和成果将被纳入研究生课程，并被纳入对当地K-12班的演讲中。两名研究生将得到支持，本科生将通过WHOI暑期学生奖学金计划和NSF REU计划融入社会。这项研究将与基于网络的外展活动联系起来，包括潜水和发现(www.divediscovery)和妇女探索海洋(http://wexo.whoi.edu/).拟议活动对社会的长期益处将通过促进对海洋种群的保留、分散和连通性的总体理解以及对海底地形对流动和混合的影响的更好理解来实现。喷口系统越来越多地被研究人员、游客和工业界使用(例如，提取多金属矿物，以及为天然产品发现和制药应用采样动物)。项目成果将为制定可持续利用喷口生态系统计划的工作提供依据。

When hydrothermal vent communities were first discovered 25 years ago, biologists immediately recognized the key role of dispersal in the dynamics and persistence of the populations. Despite substantial progress on this topic over the past 10 years, some very important questions remain unanswered about the mechanisms of dispersal and their effects on population dynamics, population genetics and community structure. Investigators have hypothesized that larval dispersal is driven largely by physical transport processes. The primary objectives of this project are to investigate how larval behaviors interact with topographically-influenced flows on mid-ocean ridges, and determine how these interactions affect dispersal trajectories, maximal dispersal distances, and relative probabilities of supply to natal versus remote vents. Three specific ecological questions have been identified: 1. What are the influences of advection and eddy diffusion on the maximal dispersal distance of vent species with given larval life spans?; 2. What are the effects of ontogenetic changes in larval behavior (i.e., vertical positioning) on dispersal distances?; and 3. How are the probabilities that larvae will be lost from the ridge system influenced by topography and flow? Might the axial summit trough inhibit off-axis transport of larvae, and serve as a conduit between habitable vent sites? This project will also address several issues of interest to the physical oceanography community, including: 1. What are the mean and temporally varying flows in the vicinity of a mid-ocean ridge crest, and what is their spatial structure and coherence?; 2. What is the magnitude of the diapycnal diffusivity near the ridge crest?; 3. How rapid is lateral dispersion, and how effective is lateral homogenization by eddy diffusion near the ridge crest? These dispersal questions cannot be answered without an integrated set of physical and biological approaches. A diverse team of observationalists and modelers has been assembled to investigate relevant aspects of ridge-associated oceanography and biology, and to combine the data into a quantitative model of dispersal. The approach includes tracer release in the field, current meter measurements, a hydrodynamic- transport model, measurements of larval positions and stages in the field, and a coupled biological-physical model. The region near 9 50.N on the East Pacific Rise (EPR) has been chosen for the study, a site that has been the focus of much interdisciplinary research in the past and has been selected as an Integrated Study Site by the NSF Ridge 2000 program. Broad impact of this project will be achieved through several different activities. The approaches and results from the project will be incorporated into graduate courses, and into presentations given to local K-12 classes. Two graduate students will be supported, and undergraduates will be integrated through the WHOI Summer Student Fellowship program and the NSF REU program. The research will be linked with web-based outreach efforts including Dive and Discover (www.divediscover.whoi.edu) and Women Exploring the Oceans (http://wexo.whoi.edu/). The long-term benefits of the proposed activity to society will be achieved by contributing to a general understanding of retention, dispersal, and connectivity of marine populations, and a better understanding of seafloor topographic effects on flows and mixing. Vent systems are subject to increasing use by researchers, tourists and industry (e.g., extracting polymetallic minerals, and sampling fauna for natural products discovery and pharmaceutical applications). Project results will inform efforts to develop plans for sustainable use of vent ecosystems.