Rose, Michael, Ecology Program, Susquehanna University, 514 University Ave, Selinsgrove, PA 17870, rosem@susqu.edu; Holt, Jack, Department of Biology, Susquehanna University, 514 University Ave, Selinsgrove, PA 17870, holt@susqu.edu.
Faylor Lake, a reservoir within the west branch of the upper Middle Creek watershed, has a total volume of 0.7 × 10⁶ m³ and a mean depth of 1.24 m. This study examines the phytoplankton communities during the months of June and July in 2023 and 2024. In 2023, phytoplankton was dominated by Chlorophyta when weighted by biovolume, indicating a stable and uniform assemblage. The average importance of Cyanobacteria increased from .02% in 2023 to 27.68% in 2024. The observed shifts in phytoplankton communities correspond with the near disappearance of Ceratophyllum demersum, a common free-floating vascular plant that had been abundant throughout the lake in 2023 but was found only in small clumps along the shoreline in 2024. This loss of Ceratophyllum demersum likely impacted nutrient cycling, habitat availability, and light penetration in the water column, contributing to the shift toward an increase in Cyanobacteria and an overall increase in phytoplankton biovolume in 2024.
Phytoplankton, Reservoir, Cyanobacteria, Ceratophyllum