How does the presence of top predators impact zooplankton and phytoplankton communities in small ponds?

Authors: Ella Warner, Kelly Wessell

SUNY Campus: Tompkins Cortland Community College

Presentation Type: Poster

Location: Old Union Hall

Presentation #: 42

Timeslot: Session A 9:00-10:00 AM

Abstract: Trophic dynamics in aquatic ecosystems can be driven by bottom-up control due to resource availability. This is particularly important given the impact human land use–especially non-point source pollution from agricultural activities in the watershed. However, in many cases, top-down control of lower trophic levels by top predators are often important as well in determining ecosystem composition. My research pertains to the study of trophic cascades and the cascading effect they have on the composition of our ecosystems. I examined pond food webs and the differences in their composition as impacted by the presence or absence of piscivorous fish and how this impacted zooplankton and phytoplankton communities. I hypothesized that zooplankton populations would be greater and more diverse in the pond without fish and phytoplankton abundance would be greater in the pond with fish. I took water samples from each pond and analyzed the differences in zooplankton diversity and chlorophyll a.samples. The data collected refute my hypothesis and revealed higher zooplankton diversity and abundance in the fish pond, and higher chlorophyll a levels in the fishless pond. This indicates that there could be other factors influencing the quantity of each population such as nutrient and light availability, the size of each pond, as well as spatial heterogeneity due to differing amounts of macrophytes in each pond. Additional research addressing these variables needs to be done to better understand the ecological impacts of fish removal on aquatic ecosystem dynamics.