The US Army Corps of Engineers (USACE) repairs aging breakwater structures as part of routine maintenance to maintain safe navigation in Great Lakes commercial ports. A USACE repair to an existing breakwater structure in Milwaukee Harbor (WI) implementing Engineering With Nature (EWN) principles created complex rocky habitat by strategically placing cobble-sized stone over conventional 5.4 to 9.1 metric ton boulders, thus creating “control” (boulder) and “treatment” (cobble) habitats. We evaluated the resultant nature-based breakwater (NBBW) developing food web versus an adjacent reference site on the same breakwater and determined that, unexpectedly, locally abundant Hemimysis anomala were impacting the food-web dynamics and feeding ecology of fishes occupying the structure. Fish and forage communities were sampled using gillnets, night scuba diving surveys, rock collections, and a novel trap to capture invertebrates. The resultant NBBW became home to a prolific population of nonindigenous Hemimysis, with indications that they were more abundant on cobble versus boulders, based on rainbow smelt feeding. This lithophilic/cave swelling mysid provided an important new food resource in Milwaukee Harbor for two introduced pelagic prey fishes: alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax). Gillnetting and night scuba diving surveys confirmed that rainbow smelt preferred to forage on the cobble section (p < 0.05). Hemimysis were also the primary food item consumed by nearshore game fishes such as young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris). We propose that those breakwaters that harbor abundant Hemimysis constitute novel ecosystems (ecosystems that include both native and non-native biota) that might benefit harbor fisheries if well-managed. This project demonstrated how a low-cost design modification could be applied during the repair of rubble-mound, breakwater structures to achieve benefits beyond safe navigation. Integr Environ Assess Manag 2022;18:49–62. Published 2021. This article is a US Government work and is in the public domain in the USA.

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改造后的碎石堆防波堤上的半霉菌驱动的新型生态系统：自然工程®示范项目

作为日常维护的一部分，美国陆军工程兵团 (USACE) 修复老化的防波堤结构，以维持五大湖商业港口的安全航行。USACE 对密尔沃基港 (WI) 现有防波堤结构的修复实施了自然工程 (EWN) 原则，通过战略性地将鹅卵石大小的石头放置在传统的 5.4 到 9.1 公吨巨石上，创造了复杂的岩石栖息地，从而创造了“控制”（巨石）和“处理”（鹅卵石）栖息地。我们评估了由此产生的基于自然的防波堤 (NBBW) 发展食物网与同一防波堤上的相邻参考站点，并确定出乎意料地，当地丰富的 Hemimysis 异常正在影响占据该结构的鱼类的食物网动态和摄食生态。使用刺网、夜间水肺潜水调查、岩石收集和捕获无脊椎动物的新型陷阱对鱼类和草料群落进行了抽样。由此产生的 NBBW 成为大量非土着Hemimysis种群的家园，有迹象表明它们在鹅卵石上比在巨石上更丰富，基于彩虹冶炼。这种嗜石/溶洞膨胀的糠秕在密尔沃基港为两种引入的远洋捕食鱼类提供了重要的新食物资源：鲶鱼（Alosa pseudoharengus）和虹鳟鱼（Osmerus mordax）。刺网和夜间水肺潜水调查证实，彩虹鱼更喜欢在鹅卵石路段觅食（p < 0.05)。Hemimysis也是近岸猎鱼消费的主要食物，例如年幼 (YOY) 黄鲈 ( Perca flavescens )、YOY 大嘴鲈鱼 ( Micropterus salmoides ) 和幼鱼 ( Ambloplites rupestris )。我们建议，那些拥有丰富的半裂藻的防波堤构成了新的生态系统（包括本地和非本地生物群的生态系统），如果管理得当，可能有利于港口渔业。该项目展示了如何在修复瓦砾堆、防波堤结构期间应用低成本的设计修改，以实现安全航行之外的好处。集成环境评估管理2022；18：49-62。2021 年发布。本文是美国政府的作品，在美国属于公共领域。