Monitoring the Milwaukee Harbor Breakwater: An Engineering With Nature (EWN registered) Demonstration Project
Abstract
The US Army Corps of Engineers (USACE) maintains breakwaters in Milwaukee Harbor. USACEs Engineering With Nature (EWN) breakwater demonstration project created rocky aquatic habitat with cobbles (1020 cm) covering boulders (68 metric tons) along a 152 m section. A prolific population of Hemimysis anomala, an introduced Pontocaspian mysid and important food source for local pelagic fishes, was significantly (p < .05) more abundant on cobbles versus boulders. Food-habits data of alewife (Alosa pseudoharengus) and rainbow smelt (Osmerus mordax) provided evidence that H. anomala were a common prey item. Night surveys and gill netting confirmed O. mordax preferred foraging on the cobbles (p < .05) and consumed more H. anomala than at the reference site (p < .05). H. anomala comprised a significant portion of the diets of young-of-the-year (YOY) yellow perch (Perca flavescens), YOY largemouth bass (Micropterus salmoides), and juvenile rock bass (Ambloplites rupestris) caught on the breakwater. The natural features construction on the breakwater increased the available habitat for this benthopelagic macroinvertebrate and created a novel ecosystem benefiting forage fish and a nursery habitat benefiting nearshore game fish juveniles. These data will encourage the application of EWN concepts during structural repairs at other built navigation infrastructure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 19, 2021
- Accession Number
- AD1125409
Entities
People
- Burton C Suedel
- Eric J. Geisthardt
- John A. Janssen
Organizations
- Engineer Research and Development Center
- University of Wisconsin–Milwaukee