Collaborative Research - Connectivity of 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的发育阶段，这个阶段作为一种媒介，促进了在不动或不动的成年种群之间的扩散和基因流动。关于人口之间联系的空间规模和强度，仍然存在相当大的争论。本研究项目将检查双壳类种群的连通性（定义为当地种群从外部来源获得新成员的程度），物理运输的作用以及超种群后果。由于幼虫阶段非常微小，几乎不可能跟踪个体，也不可能用传统的标签跟踪它们。技术的进步促进了利用微量元素分析来评估一些浮游生物幼虫的起源和轨迹。生物成因碳酸盐地球化学记录了不同海岸水体环境、微量元素特征的空间变异。由于贝壳在浮游生物幼虫发育的整个过程中都有沉积，因此它们有效地记录了幼虫在发育过程中不同栖息地环境特征的变化。对新定居的双壳类所保留的幼虫壳进行分析，可以提供其来源位置的信息。微量元素指纹图谱方法将用于评估马萨诸塞州和南加州海岸双壳类种群之间连通性的空间规模和强度。假设将解决(1)远程幼虫来源相对于本地幼虫来源（自我播种）的相对贡献，(2)循环之间的关系？(3)物种产卵期、浮游期和地点空间间隔对幼虫交换概率的影响。我们的方法包括激光烧蚀电感耦合等离子体质谱法(LA？ICPMS)来解决幼虫壳组成的空间变化，反映了幼虫的招募来源和运输的时间模式。我们将研究新英格兰的蛤蚌Mya arenaria和贻贝Mytilus edulis，以及南加州的贻贝Mytilus galloprovincialis和M. californianus。种群连通性将通过两种元种群方法进行研究，这两种方法从流体动力学模型中估计分散概率。一种是栖息地面积作为繁殖力的代表，另一种是多区域矩阵模型，它使用人口统计框架来描述元人口的动态。我们将测试通过招募来源的微量元素分析确定的实现人口连通性，以反对基于循环和元人口模型的先验预测。更广泛的影响：由此产生的关于源种群和连通性的信息将增强对具有商业价值的双壳类物种超种群动态的理解。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法规的设计来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参与跨学科研究，将沿海海洋物理学、幼虫生态学和超种群理论结合起来。将把微量元素指纹技术（来自鱼类）转移到无脊椎动物扩散领域，并转移到墨西哥的合作者手中。[编辑- JP - 7/7/03]

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.[edited - JP - 7/7/03]