Gandy, Cadence, Department of Biology, Susquehanna University, 514 University Avenue , Selinsgrove, PA, 17870, gandy@susqu.edu; Holt, Jack, R, Department of Biology, Susquehanna University, 514 University Avenue, Selinsgrove, PA, 17870, holt@susqu.edu.
Faylor Lake is a reservoir of the west branch of the upper Middle Creek watershed. The volume of Faylor Lake is 0.7x106m3 with a mean depth of 1.24m. This study focuses on the zooplankton communities of Faylor lake through the months of June and July during 2023, 2024, and 2025. Until 2024, the common free-floating vascular plant, Ceratophyllum dermersum, was found throughout the lake. At the beginning of the summer of 2024, however, Ceratophyllum had all but disappeared and was found only in small clumps on the shore of the reservoir. Toward the end of summer 2025, Ceratophyllum returned in small patches near the shore and open water. The zooplankton community of Faylor Lake in 2023 had 10 taxa, which were dominated by widely distributed Cladocera taxa, such as Ceriodaphnia dubia and Bosmina longirostris. However, following the loss of Ceratophyllum in 2024, the zooplankton community shifted to rotifers (e.g. Asplanchna priodonta). Cladocera returned in 2025 dominated by Diaphansoma birgei and Ceriodaphnia dubia. The dominant zooplankters of Faylor Lake are filter feeders (Keratella and Brachionus) and raptorial predators (Asplanchna). The mean Shannon diversity for 2023 was 1.97, fell to 1.45 in 2024, and rose to 1.71 in 2025. We suspect that differences in zooplankton ecology and community complexity in Faylor Lake are connected to the loss and subsequent return of Ceratophyllum dermersum.
Zooplankton , Ceratophyllum dermersum , Aquatic , Lake