Factors Affecting Aquatic Invertebrate Community Composition in a Managed Wetland System
Wildlife Ecology and Management Ella Follman
Invertebrates are common bioindicators for aquatic systems due to their sensitivity to pollution and important ecosystem roles. Most studies on these communities focus on freshwater streams and lakes, prompting interest in further analysis of invertebrate composition in wetlands. Horicon National Wildlife Refuge is a 22,000-acre freshwater marsh located in Wisconsin. Management includes periodically draining impoundments and using prescribed fires to control invasive cattail. Within Horicon’s Luehring impoundment, a total of 160 invertebrate samples were collected over 4 sampling periods from May-August in 2024 and 2025. Samples were collected at 20 sites. Counts were standardized to a set volume of 23 liters. Invertebrates were identified by taxa, enabling analyses of abundance, diversity, functional feeding groups, and community-level stress tolerance. Approximately 26,000 invertebrates were identified across 44 taxa. Across dates, invertebrate diversity was high, but evenness was low, potentially indicating a system affected by pollution, unable to support healthy populations of many species (M evenness = 0.18, SD evenness = 0.08). Species stress tolerance per sample was weighted by count and showed a dominance of moderately tolerant taxa (n low = 28.0, n moderate = 16544.0, n high = 3454.5; p < 0.001). Stress tolerance values range from 0-10, 0 indicating extreme intolerance and 10 indicating extreme tolerance to pollutants. Across all samples, average tolerance ranged from 4.0 to 8.0 (M = 5.4, SD = 0.9). Tolerance values also increased across sampling dates (p < 0.001). Analyses of potential sources of pollution, including surface water inputs and precipitation runoff, are ongoing.
Advisors: Marie Perkins, Ph.D. Amy Kopec
Subject Area: Wildlife
Type: Oral
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Jim and Katie Krause CNR Student Research Symposium
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