Assessment of freshwater mussel communities in the Bass Creek watershed, Rock County, Wisconsin

Abstract

Within North America, freshwater mussels have endured large population declines and threatened to extirpation and extinction. Many factors contribute to the causes of imperilment, from overharvest to poor water quality and altered hydrological conditions. Mollusks are of ecological importance; they provide many aquatic functions and are indicators of stream health. Tools, like the Mussel Classification Assessment Tool (MCAT), have been created to guide mussel conservation in the Upper Midwest. Bass Creek in Rock County, Wisconsin, serves as my case study to: 1) access the viability of freshwater mussel community presence in Bass Creek, which currently has no mussels documented; 2) evaluate the abundance and community diversity of mussels in Bass Creek, where there is a lack of data; 3) apply MCAT to compare mussel assemblage health; and 4) to determine if other extrinsic parameters contribute to spatial differences in mussel communities. I performed mussel surveys in Bass Creek in September 2021. I also measured water quality parameters: water temperature, conductivity, pH, velocity, and dissolved oxygen. I found the three-ridged mussel (Amblema plicata) was the most dominant species, plain pocketbook was the most dominant live species and found farthest from Rock River confluence, and I found the highest mussel abundance closest to the confluence with the Rock River. I used MCAT protocols on Bass Creek; my replication indicated low recruitment, low species abundance, and low species evenness on a smaller spatial scale. My analysis from surveys and water quality point toward extrinsic factors, hydrological alterations, and habitat degradation as the primary driving factors of low mussel abundance. Although hydrological connectivity has been enhanced by removing Afton Dam, conservation implementation is still needed. My MCAT results illustrate mussel populations in Bass Creek are unstable but serve as a baseline for future studies.