Identifying the microbial community and uncovering seasonal trends of Tellico Reservoir, a reservoir in East Tennessee, USA

Tellico reservoir is one of many manmade reservoirs in the Tennessee Valley Region. Rainfall upwards of 130 cm per year resulted in the flooding of cities in the Tennessee valley. To prevent flooding, the Tennessee Valley Authority (TVA) created several reservoirs that can hold the precipitation. Although the TVA does monitor the reservoirs for some ecological factors (including chlorophyll), the microbial status of the reservoir is widely unknown. In collaboration with a citizen group, Tellico Reservoir was sampled every three weeks from April until November 2023 for a total of 10 times. Six stations were selected and grouped into land use categories, which presumably influenced them. The primary land use inside the watershed of the land use categories correlated with the assigned label. The three land use categories were agriculture, developed and control. Primary land use inside the control category was forest. Physicochemical parameters showed a clear distinction between the three land use categories. It is unclear, however, if stations are influenced by land use, or distance to the main channel, due to the low retention time of the reservoir. Overall, chlorophyll was higher in stations influenced by agriculture. No differences were detected between control sites and stations influenced by urban development. This is also true for several nutrients that were measured. 16S/18S rRNA gene analyses showed Actinobacteria, Cyanobacteria and Proteobacteria were the most dominant phyla throughout the year, as well as at each land use category. Even with clear separation of physicochemical parameters, nMDS analyses of the microbial community show no trend between land use categories. Strong seasonal trends were observed. Spring is distinctly different than summer and fall, which are not different from each other. The most important parameter correlating with this separation was water temperature. With climate change increasing surface water temperatures, it is vital to study how the microbial community responds so we can plan for the future.