Abstract

The purposes of this study are to 1) quantify the shifts in the macrophyte community structure of five lakes in Sibley County, and 2) to assess the relationships between the macrophyte communities and abiotic factors in these five lakes. In both the early and late growing season of 2019, point-intercept surveys were conducted on High Island Lake, Titlow Lake, Schilling Lake, Silver Lake, and Clear Lake. At each point, water depth was recorded, and all macrophytes sampled were identified and recorded as “present.” There was not a late season survey conducted for High Island Lake in 2019 due to a dewatering event in the middle of the growing season. The macrophyte community shifts in individual lakes during the growing season were quantified by comparing the species presence/absence and mean species richness in the early season to the late season. Additionally, in the early season, a sediment core was retrieved at each point for analysis. All sediment cores were analyzed for particle size and sediment organic matter using the hydrometer method and loss on ignition respectively. In order to assess the relationships between the macrophyte community and abiotic factors at individual lakes, generalized linear regressions were ran with the mean species richness as the dependent variable and water depth, distance from shore, percent sand, percent silt, percent clay, and percent sediment organic matter as explanatory variables. In models where the residuals were spatially autocorrelated, a geographically weighted regression was ran using the variables of the highest performance model. The analyses of the macrophyte community shifts suggest that macrophyte phenology is a primary factor that affects the shifts in community structure over the growing season. The generalized linear regressions identify water depth, distance from shore, and percent silt as significant predictors of mean species richness in multiple models. Water depth and distance from shore are both negatively related to mean species richness in multiple models. Whether silt is positively or negatively related to mean species richness is dependent on the species composition of that lake.

Advisor

Ryan M. Wersal

Committee Member

Matthew A. Kaproth

Committee Member

Mark W. Bowen

Date of Degree

2021

Language

english

Document Type

Thesis

Degree

Master of Science (MS)

Department

Biological Sciences

College

Science, Engineering and Technology

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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