Abstract
Microbial communities within the soil of Great Lakes coastal wetlands drive biogeochemical cycles and provide several other ecosystems services. However, there exists a lack of understanding of how microbial communities respond to nutrient gradients and human activity in these systems. This research sought to address the lack of understanding through exploration of relationships between nutrient gradients, microbial community diversity, and microbial networks among coastal wetlands throughout the Great Lakes. Significant differences in microbial community structure were found among coastal wetlands within the western basin of Lake Erie and all other wetlands studied (three regions within Saginaw Bay and one region in the Beaver Archipelago). Further, within Lake Erie wetlands, chemical and biological structure did not vary with increasing soil depth. Beyond this, alpha diversity levels were highest within Lake Erie coastal wetlands. These diversity differences coincided with higher nutrient levels within the Lake Erie region. Site-to-site variability also existed within the majority of the regions studied, suggesting site-scale heterogeneity may impact microbial community structure. Several subnetworks of microbial communities and individual community members were related to chemical gradients among wetland regions, revealing several candidate indicator communities and taxa which may be useful for Great Lakes coastal wetland management. This research provides an initial characterization of microbial communities among Great Lakes coastal wetlands and demonstrates that microbial communities could be negatively impacted by anthropogenic activities. Anthropogenic impacts to these coastal wetland communities could influence natural biogeochemical cycles which occur within coastal wetland soils, and by extension would directly influence the Great Lakes themselves.