Microbial Community Composition Dependence on Season, Site, and Flow Rate in the Macatawa Watershed

The poor condition of the Macatawa watershed has been an area of focus for the greater Holland community for decades. Urbanization and agricultural development are key reasons for the poor water quality as they introduce excess nutrients. These nutrients, such as nitrates and orthophosphates, lead to hypereutrophication of the lake and catalyze the growth of algal blooms and the spread of potentially dangerous bacteria. Hope College has been collecting data to better understand trends and patterns within the lake that affect both levels of nutrients and the bacterial community. We continuously monitor levels of Escherichia coli, orthophosphates, nitrates, total suspended solids (TSS), and other biological and chemical attributes. This poster focuses on investigating the composition of microbial communities under certain conditions such as changing seasons (e.g. winter vs. summer) and different types of sites (e.g. lake vs. stream). These data showed stark differences in the relative abundance of some bacteria when correlated with season and site type. For instance, Cyanobacteria and Cryomorphaceae showed higher abundance in the summer at lake sites. We also analyzed the abundance of microbes during standard flow rates compared with high flow rates. Details of these changes in microbial community structure are presented in this poster. These results ultimately tell us that there are seasonal and flow rate influences on bacterial community composition within the Macatawa watershed.