Collaborative Research: An integrated theoretical and empirical approach to across-shelf mixing and connectivity of mussel populations

现有的幼虫运输模型主要关注沿大陆架的运输，很少明确地考虑跨大陆架混合和运输过程的影响。然而，跨大陆架过境（包括向外和向内的腿）是沿海无脊椎动物扩散路径的关键组成部分。该项目将探索跨大陆架混合在缅因州东部蓝贻贝种群连通性中的作用。先前的研究表明，东缅因海岸流（EMCC）开始从大马南海峡西南海岸发散，并在跨大陆架混合和幼虫运输中产生梯度，跨大陆架混合在东北端更常见，在过渡中部地区偶尔发生，然后在缅因湾地区的西南半部变得罕见。因此，研究人员预测东北贻贝种群的种子主要来自上游来源，而西南种群中存在显著的自种（本地保留）成分。在中间的海湾中沉淀的幼虫预计来自当地和上游的混合来源。采用经验和理论相结合的方法，将收集水文、洋流剖面和幼虫垂直迁移数据，并用于开发和验证高分辨率沿海环流模型与幼虫行为模型的耦合。研究人员将利用贻贝繁殖产量和产卵时间的经验数据在不同年份进行模拟。然后，根据该模型预测的连通性将与基于痕量元素指纹的幼虫连通性的独立经验估计进行测试，这些幼虫可以连接到特定的出生栖息地。将确定模型中一致和不一致的区域，以指导额外的数据收集和模型改进。这个迭代过程将确保对幼虫运输模式和过程的理解，并提供对缅因湾蓝贻贝种群连通性的年际变化的估计。该项目将为一些本科生和研究生提供跨学科培训。这三位研究者都有培养本科生或研究生，或两者兼而有之的学生的记录。机构间和跨学科交流将通过每年两次的小型研讨会/静修来促进，来自三个实验室的所有项目参与者将在会上介绍和讨论其项目部分的成果。该项目对缅因州的商业贻贝养殖业也有重要意义，该行业严重依赖自然定居，希望更好地了解幼虫供应模式，以便于选择收集新定居贻贝的地点。

Existing larval transport models focus mainly on along-shelf transport and have done little to explicitly incorporate the effects of cross-shelf mixing and transport processes. Yet cross-shelf transits (both outgoing and incoming legs) are critical components of the dispersal paths of coastal invertebrates. This project will explore the role of cross-shelf mixing in the connectivity of blue mussel populations in eastern Maine. Previous work has shown that the Eastern Maine Coastal Current (EMCC) begins to diverge from shore southwest of the Grand Manan Channel and creates a gradient in cross-shelf mixing and larval transport, with cross-shelf mixing being more common on the northeastern end, episodic in the transitional middle area, and then becoming rare in the southwestern half of the region of the Gulf of Maine. As a result, the investigators predict that northeastern populations of mussels are seeded mostly from up-stream sources, while a significant component of self-seeding (local retention) exists in southwestern populations. Larvae settling in the intervening bays are expected to be derived from a mixture of local and up-stream sources. Using a combined empirical and theoretical approach hydrographic, current profile, and larval vertical migration data will be collected and used to develop and validate a high-resolution coastal circulation model coupled to a model of larval behavior. The investigators will model simulations in different years using the empirical data from mussel reproductive output and spawning times. Connectivity predicted from this model will be then tested against independent empirical estimates of connectivity based on trace element fingerprinting for larvae which can be connected to specific natal habitats. Regions of agreement and discrepancy in the model will be identified to guide additional data collection and model refinement. This iterative process will ensure an understanding of both larval transport patterns and processes, and provide estimates of inter-annual variability in connectivity for blue mussel populations in the Gulf of Maine.The project will provide interdisciplinary training for a number of undergraduate and graduate students. All three investigators have established track records of training students at either the undergraduate or graduate level, or both. Inter-institutional and interdisciplinary exchange will be fostered by a twice per year mini-symposium/retreat at which all project participants from the three laboratories will present and discuss results from their portions of the project. This project also has important implications for the commercial mussel aquaculture industry in Maine, which relies heavily on natural settlement and desires a better understanding of larval supply patterns to facilitate site selection for collecting newly settled spat.