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CHANGES IN SUMMER ZOOPLANKTON COMMUNITY STRUCTURE FOLLOWING THE LOSS OF CERATOPHYLLUM DERMERSUM IN FAYLOR LAKE, A SMALL RESERVOIR IN SNYDER COUNTY, PA

    Gandy, Cadence, Department of Biology, Susquehanna University, 514 University Avenue, Selinsgrove, PA 17870, gandy@susqu.edu; Holt, Jack, Department of Biology, Susquehanna university, 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 0.7×106 m3 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 and 2024. Until 2024, the common free-floating vascular plant, Ceratophyllum dermersum, was found throughout the lake. During the summer of 2024, however, Ceratophyllum had all but disappeared and found only in small clumps on the shore of the reservoir. The zooplankton community of Faylor Lake in 2023 was dominated by widely distributed cladoceran taxa, such as Ceriodaphnia dubia and Bosmina longirostris. The zooplankton community of 2024 was generally dominated by rotifers (e.g. Asplanchna pirodonta) throughout most of the study. The dominant zooplankters of Faylor Lake are coarse filter feeders. Average zooplankton taxa richness for 2023 was 10 and 13 in 2024. We suspect that differences in the zooplankton ecology of the reservoir is connected to the loss of Ceratophyllum dermersum. The zooplankton community changed over the course of two summers with the loss of Ceratophyllum dermersum.

    Zooplankton, Ceratophyllum dermersum, Aquatic, Lake