Collaborative Research: Connectivity in Bivalve Populations: Assessing Sources of Larval Recruits

大多数海洋底栖无脊椎生物的早期生活史都包括一个浮游幼虫发育阶段，这是增加固着或定居的成年种群之间的扩散和基因流动的一个因素。关于人口之间联系的空间规模和强度，仍有相当多的争论。该研究项目将研究双壳类种群的连通性（定义为当地种群从外部来源接收新兵的程度），物理运输的作用以及集合种群的后果。 因为幼虫阶段是微观的，所以几乎不可能跟踪个体，或者用传统的标签跟踪它们。 技术的进步促进了微量元素分析的使用，以评估的起源和轨迹的一些寄生虫幼虫。 不同海岸水体的环境、微量元素特征的空间变异性记录在生物碳酸盐的地球化学中。 由于贝壳在幼体发育的整个过程中沉积，它们有效地记录了幼体在发育过程中所占据的不同生境的环境特征变化。 分析新定居的双壳类所保留的幼虫壳，将提供有关其来源位置的信息。 微量元素指纹方法将被用来评估空间尺度和连接强度的双壳类种群之间的马萨诸塞州和南部加州海岸。假设将解决（1）相对贡献的远程幼虫源与本地的（自我播种），（2）之间的关系循环？（3）种的产卵期、繁殖期和地点的空间分隔在决定幼虫交换概率中的作用。我们的方法涉及激光烧蚀电感耦合等离子体质谱（LA？ICPMS），以解决幼虫壳组成的空间变化，反映新兵的起源和幼虫运输的时间模式。 我们将研究新英格兰的沙生蛤和贻贝，以及贻贝Mytilus galloprovincialis和M.产于加州南部。 人口的连通性将研究两个集合种群的方法，估计从流体动力学模型的扩散概率。 一个涉及栖息地面积作为繁殖力的代理，另一个是一个多区域矩阵模型，使用人口框架来描述集合种群的动态。我们将测试实现人口连通性确定从微量元素分析的招聘起源对先验预测的基础上循环和集合种群models.broader影响：由此产生的信息源人口和连通性将提高理解集合种群动态在商业上有价值的双壳类物种。适用于美国东西海岸的连通性信息将通过改进海洋保护区和渔业条例的设计，促进沿海资源的保护。关键的教育要素包括本科生，研究生和博士后学生，以及早期职业科学家的参与，在跨学科的研究，整合沿海海洋物理学，幼虫生态学和集合种群理论。 将把微量元素指纹技术（从鱼类）转移到无脊椎动物扩散领域，并转让给墨西哥的合作者。

The early life history of most marine benthic invertebrate organisms involves a planktonic larval stage of development that acts as an agent for increased dispersal and gene flow between sessile or sedentary adult populations. There remains considerable debate as to the spatial scale and strength of the connections between populations. This research project will examine connectivity of bivalve populations (defined as the extent to which a local population receives recruits from external sources), the role of physical transport, and the metapopulation consequences. Because larval stages are microscopic, it is all but impossible to follow individuals, or to track them with conventional tags. Technological advances have facilitated the use of trace element analysis to evaluate origins and trajectories of some planktonic larvae. Spatial variability in environmental, trace elemental characteristics of different coastal water masses is recorded in the geochemistry of biogenic carbonates. Because shells are deposited throughout planktonic larval development, they effectively record changes in environmental characteristics of different habitats occupied by larvae through development. Analysis of larval shell retained by newly settled bivalves will provide information about their source locations. Trace element fingerprinting methods will be used to evaluate the spatial scale and strength of connectivity among bivalve populations on the Massachusetts and southern California coasts. Hypotheses will address (1) the relative contribution of remote larval sources versus local ones (self seeding), (2) the relationship between circulation?driven dispersal potential and realized connectivity among bivalve populations and (3) the roles of species spawning period, planktonic period, and spatial separation of sites in determining probabilities of larval exchange. Our approach involves laser ablation inductively coupled plasma mass spectrometry (LA?ICPMS) to resolve spatial changes in larval shell composition that reflect recruit origins and temporal patterns of larval transport. We will work with the clam Mya arenaria and the mussel Mytilus edulis in New England and the mussels Mytilus galloprovincialis and M. californianus in southern California. Population connectivities will be studied with two metapopulation approaches that estimate dispersal probabilities from hydrodynamic models. One involves habitat area as a proxy for fecundity and the other is a multiregional matrix model that uses a demographic framework to describe the dynamics of the metapopulation. We will test realized population connectivity determined from trace elemental analysis of recruit origins against a priori predictions based on the circulation and metapopulation models.Broader impacts: The resulting information about source populations and connectivities will enhance understanding of metapopulation dynamics in commercially valuable bivalve species. Connectivity information applicable to the east and west coasts of the USA will facilitate conservation of coastal resources through the improved design of marine protected areas and fisheries regulations. Key educational elements include the involvement of undergraduate, graduate, and postdoctoral students, as well as early career scientists, in interdisciplinary research that integrates coastal ocean physics, larval ecology and metapopulation theory. There will be a transfer of trace element fingerprinting technology (from fish) into the realm of invertebrate dispersal and to collaborators in Mexico.