Collaborative Research: The impact of multiple nursery areas and adult age structure on the population dynamics of marine fishes

许多海洋种群表现出复杂的生活史，其中幼虫和少年阶段与成年人在空间上分开。这是许多沿海产卵，河口依赖鱼类的情况下，利用多个河口作为育苗场，以确保招聘失败，在任何一个单一的河口不转化为总招聘失败的人口水平。对于这些物种来说，产卵的地点和时间被认为是调节幼虫供应到潜在河口苗圃区的模式。此外，许多这些物种表现出年龄依赖性的沿海迁移，随着年龄的增长，幅度增加。因此，种群年龄结构的变化可能会影响幼虫向苗圃区的供应模式，并影响招募模式。调查人员将进行一个综合的经验和模拟的方法来研究的来源，模式和后果的幼虫供应到河口育苗区大西洋鲱鱼（Brevoortia hennus）沿着美国东海岸。第一个目标将是量化这些苗圃地区对海岸范围内招募的贡献。从马萨诸塞州到格鲁吉亚的苗圃地区采集青少年鲱鱼样本，并对其耳石的微量化学成分进行表征。这些化学特征将被用来分配成年鲱鱼在沿海人口的托儿所亲和力。调查人员将检验零假设，即切萨皮克湾仍然是人口最重要的新兵来源。通过确定人口中不同年龄段成年人的托儿所亲和力，他们将评估托儿所的贡献是否随时间而变化或发生变化。第二个目标是使用一个人口模型，以个人为基础的耦合的物理-生物模型的招聘，以评估是否已知的成年鲱鱼的年龄依赖性迁移足以导致所观察到的变化，在分布的幼虫鲱鱼种子潜在的苗圃地区。该模拟模型将有助于评估所观察到的幼年鲱鱼分布变化背后的机制。这项工作将有助于对空间结构海洋种群调节的基本了解。在过去十年中，一些依赖河口的海洋物种的分布范围扩大，其幼虫分散，而另一些物种的长期补充减少。这一综合研究计划旨在探索人口统计学，海洋环流和苗圃地多样性对随后的人口动态的影响。鉴于许多河口苗圃地区栖息地质量的变化，以及气候变化对海洋环流的预期影响，个别物种的分布变化可能会变得更加普遍。此外，鉴于许多依赖河口的物种在许多海洋生态系统中发挥着关键作用，了解分布变化将对它们所属的生态系统的结构和功能产生直接影响。该项目还将在国家目前需要的研究领域（定量渔业生态学、物理海洋学）培训青年科学家。

Many marine populations exhibit complex life histories in which larval and juvenile stages are spatially separated from adults. This is the case for many coastal-spawning, estuarine-dependent fishes which utilize multiple estuaries as nursery grounds to ensure that recruitment failure in any single estuary does not translate to total recruitment failure at the population level. For these species, the location and timing of spawning is believed to regulate the pattern of supply of larvae to potential estuarine nursery areas. Furthermore, many of these species exhibit age-dependent coastal migrations which increase in amplitude with age. Thus, there is the potential that changes in the age structure in the population can affect the pattern of supply of larvae to nursery areas and structure the pattern of recruitment. The investigators will carry out an integrated empirical and simulation approach to study the sources, patterns and consequences of larval supply to estuarine nursery areas for Atlantic menhaden (Brevoortia tyrannus) along the East Coast of the US. The first goal will be to quantify the contribution of these nursery areas to coast wide recruitment. Juvenile menhaden from nursery areas from Massachusetts to Georgia will be sampled and the microchemical constituents of their otoliths will be characterized. These chemical signatures will be used to assign the nursery affinities of adult menhaden in the coastwide population. The investigators will test the null hypothesis that the Chesapeake Bay remains the most important source of recruits to the population. By determining the nursery affinities of adults from different year classes in the population they will assess whether the contribution of nurseries varies or has shifted over time. The second goal is use a population model linked to an individual-based coupled physical-biological model of recruitment to evaluate whether the known age-dependent migrations of adult menhaden are sufficient to cause the observed shifts in the distribution of larval menhaden that seed potential nursery areas. The simulation model will assist in evaluating mechanisms behind observed changes in the distribution of juvenile menhaden.This work will contribute to the fundamental understanding of the regulation of spatially-structured marine populations. The last decade has seen the range extension of several estuarine-dependent marine species with dispersive larvae and the long-term recruitment decline of others. This integrated research program seeks to explore the effects of population demography, oceanographic circulation, and nursery site diversity on subsequent population dynamics. Given the documented changes in habitat quality in many estuarine nursery areas, and the anticipated impacts of climate change on oceanographic circulation, distributional changes in individual species are likely to become more common. Moreover, given the pivotal role that many estuarine-dependent species play in many marine ecosystems, understanding distributional changes will have direct consequences for the structure and function of the ecosystems to which they belong. The project will also train young scientists in areas of research (quantitative fisheries ecology, physical oceanography) for which there is current a national need.