Level III ecoregions of the conterminous United States provide a framework for facilitating environmental understanding and aiding environmental management practices. In southern Minnesota near Mankato, there are two level III ecoregions: to the east is North Central Hardwood Forest (NCHF) and to the west are Western Corn Belt Plains (WCBP). They contained a combined 104 fish species in local lakes. However, little is known about how land use and land cover affect fish assemblages in these lakes, which are indicator fish species, and if any invasive fish species are adversely impacting native fish populations. This study addresses these issues through analyses of published datasets, and field data collection. NCHF lakes have 96 fish species and the WCBP lakes have 77. T-test and Nonmetric Multidimensional Scaling (NMDS) results indicate that fish assemblages are significantly different between NCHF and WCBP lakes, and NCHF lakes have a higher fish species richness per lake area than WCBP lakes. NCHF lakes have eight fish indicator species, and the WCBP have 16 fish indicator species. Analysis of Covariance (ANCOVA) results indicated that mean Trophic State Index (TSI) is negatively related to fish species richness by lake area. In contrast, percent planted, percent forest, and percent developed areas are positively related to fish species richness by lake area. Gill nets and small seine nets caught various fish species in both ecoregions, and small seine nets caught several small body fish species. The NCHF has a higher percentage of insectivore and intolerant fish indicator species than the WCBP. In contrast, the WCBP has a higher percentage of carnivore and omnivore and tolerant fish indicator species than the NCHF. Some rare fish species including Pugnose Shiner (state threatened), Yellow Bass (state special concern), American Eel (state special concern), and Least Darter (state special concern) are observed as indicator species. Common Carp is one of the indicator species in the WCBP. This study shows that WCBP lakes are unique in and of themselves, and not simply degraded relative to NCHF lakes. Future analyses by other researchers and the MNDNR should take this into account.


Donald Friend

Committee Member

Susan Colvin

Committee Member

Fei Yuan

Date of Degree




Document Type



Master of Science (MS)

Program of Study



Geography and Anthropology


Humanities and Social Sciences

Included in

Geography Commons



Rights Statement

In Copyright