Estuaries include some of the most productive yet anthropogenically impacted marine ecosystems on the planet, and provide critical habitat to many ecologically and economically important marine species. In order to elucidate ecological function in estuaries, we must understand what factors drive community dynamics. Delaware Bay is the third largest estuary in the United States and hosts over 200 species of migrant and resident fishes and invertebrates. The Delaware Division of Fish and Wildlife has conducted two long-term trawl surveys at monthly intervals in Delaware Bay since 1966. The two surveys collect data on environmental conditions, species composition, and number of fishes and macroinvertebrates across different size classes and life histories. Using a suite of multivariate approaches including hierarchical cluster analysis, canonical correlation analysis, and permutational multivariate analysis of variance, we characterized the fish and macroinvertebrate community in Delaware Bay and found that community composition and environmental conditions varied across spatial and seasonal scales. We identified four distinct biogeographic regions, based on environmental conditions and community composition, which were consistent across surveys. We found that the community was driven primarily by gradients in temperature and salinity and that abundant, frequently occurring species in the Bay have well-defined environmental associations. Our work represents the first attempt to use an existing historical survey to better understand how environmental parameters influence diversity and distribution of macrofauna within Delaware Bay, providing insight into how abiotic variables, influenced by climate, may impact the Delaware Bay ecosystem and similar estuarine ecosystems worldwide.

河口包括地球上一些生产力最高但受人为影响的海洋生态系统，并为许多具有生态和经济重要性的海洋物种提供了重要的栖息地。为了阐明河口的生态功能，我们必须了解哪些因素驱动群落动态。特拉华湾是美国第三大河口，栖息着 200 多种候鸟和留鸟鱼类及无脊椎动物。自 1966 年以来，特拉华州鱼类和野生动物部门每月在特拉华湾进行两次长期拖网调查。这两次调查收集有关环境条件、物种组成以及不同体型和生活史的鱼类和大型无脊椎动物数量的数据。我们使用一系列多元方法，包括层次聚类分析、典型相关分析和排列多元方差分析，对特拉华湾的鱼类和大型无脊椎动物群落进行了表征，发现群落组成和环境条件在空间和季节尺度上存在差异。我们根据环境条件和群落组成确定了四个不同的生物地理区域，这在所有调查中都是一致的。我们发现，该群落主要由温度和盐度梯度驱动，并且海湾中丰富且频繁出现的物种具有明确的环境关联。我们的工作首次尝试利用现有的历史调查来更好地了解环境参数如何影响特拉华湾内大型动物群的多样性和分布，从而深入了解受气候影响的非生物变量如何影响特拉华湾生态系统和全球类似的河口生态系统。