Date Approved

1-3-2024

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Annis Water Resources Institute

First Advisor

Dr. Carl R. Ruetz III

Second Advisor

Dr. Matthew J. Cooper

Third Advisor

Dr. Megan M. Woller-Skar

Academic Year

2023/2024

Abstract

Coastal wetlands in the Laurentian Great Lakes are important habitats for many fish species. The geographic scale of the watershed and the diversity of land uses in the region result in substantial environmental variation among coastal wetlands. During 2011-2020, annual surveys were conducted as part of the Great Lakes Coastal Wetland Monitoring Program (GLCWMP) to better understand the status and trends of coastal wetlands. Fish sampling consisted of fyke netting in monodominant vegetation zones. During this time, 1225 unique monodominant plant zones in coastal wetlands were sampled, resulting in 584,125 fishes captured that consisted of 113 different species. Yellow Perch (Perca flavescens) was the most abundant species collected (30.9% of the catch), and Bluegill/Pumpkinseed (Lepomis macrochirus/Lepomis gibbosus) were collected the most frequently (present in 68.4% of sampling events). The purpose of the study was to evaluate how fish assemblages in Great Lakes coastal wetlands are associated with Great Lake basin, monodominant vegetation type, hydrogeomorphic type, and sampling year. Fish characterized based on size in the field as young-of-year (YOY) comprised 69.7% of the total catch and 95.7% of the Yellow Perch collected, suggesting coastal wetlands may be important nursery habitats. I found that basin, hydrogeomorphic type, monodominant vegetation type, and sampling year influenced variation in fish assemblages with basin and monodominant vegetation type showing the strongest association with fish assemblages among the variables investigated. While significant patterns were identified, the variables evaluated explained small amounts of variation associated with fish assemblages in Great Lakes coastal wetlands. Fish assemblages in the oligotrophic Lakes Michigan, Huron, and Superior appeared more similar to each other than the more mesotrophic Lakes Erie and Ontario. Yellow Perch was the strongest indicator of coastal wetland by basin, being most abundant in the catch of Lake Michigan and least abundant in the catch of Lake Erie. Fish assemblages were significantly associated with monodominant vegetation type, but the associations varied depending on basin. While fish assemblage structure in Great Lakes coastal wetlands have substantial amounts of variation, patterns were identified that further define how fish assemblages vary across the Great Lakes basin.

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