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，其中幼虫和幼虫阶段在空间上与成虫分开。这是许多沿海产卵、依赖河口的鱼类的情况，它们利用多个河口作为育苗场，以确保在任何一个河口的补充失败不会转化为种群水平的完全补充失败。对于这些物种，产卵的地点和时间被认为调节了向潜在的河口苗圃地区供应幼虫的模式。此外，这些物种中的许多物种表现出依赖年龄的沿海迁徙，这种迁徙的幅度随着年龄的增加而增加。因此，种群年龄结构的变化可能会影响向托儿所供应幼虫的模式，并影响招募模式。调查人员将采取综合的经验和模拟方法，研究美国东海岸大西洋文昌鱼(Brevoortia Tyrannus)幼体供应给河口苗圃地区的来源、模式和后果。第一个目标将是量化这些托儿所地区对沿海地区招聘的贡献。从马萨诸塞州到佐治亚州的托儿所地区的幼年男子将被抽样，并将对他们耳石的微化学成分进行表征。这些化学特征将被用来分配整个海岸种群中成年男子的育儿期亲缘关系。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的成年人与托儿所的亲和力，他们将评估托儿所的贡献是否随着时间的推移而变化或改变。第二个目标是使用与基于个体的物理-生物招募耦合模型相联系的种群模型来评估已知的成虫年龄相关迁徙是否足以导致观察到的幼虫分布的变化，这些幼虫分布在种子潜在的托儿所区域。该模拟模型将有助于评估观察到的幼鱼分布变化背后的机制。这项工作将有助于从根本上理解海洋种群空间结构的调节。在过去的十年里，一些依赖河口的海洋物种的活动范围扩大，幼体分散，而其他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、海洋环流和苗圃地点多样性对随后的种群动态的影响。鉴于记录在案的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常见。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的关键作用，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。该项目还将培训青年科学家从事目前国家需要的研究领域(定量渔业生态学、物理海洋学)。

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.