Temporal Population Dynamics of Zooplankton Drifting in Great Plains Reservoirs

Zooplankton play a significant role in aquatic food webs; however, their population dynamics in the Great Plains have not been thoroughly documented or studied. To understand potential controls on zooplankton populations, we have conducted monthly samplings of two reservoirs near a medium-sized city (Lincoln, NE). We hypothesize that zooplankton populations will be affected by seasonal variables, such as temperature and light, and available chemical energy including total nitrogen, phosphorus, and other stoichiometric variables. Each month, zooplankton samples were identified, counted, and analyzed for carbon, nitrogen, and phosphorus content. Additionally, water samples were collected for phytoplankton biomass and nitrogen and phosphorus content. Our initial findings suggest zooplankton populations are dynamic over winter. In both reservoirs, between October and January, Bosmina became less prevalent (from 61% down to 3%) while calanoids progressively made up a larger percentage of all zooplankton (up to 72%). Initial observations suggest complex interactions between environmental and stoichiometric variables drive zooplankton populations in Great Plains reservoirs. These ongoing observations will help reveal how zooplankton, a key lentic food web component, may be impacted by eutrophication, climate change, and shifts in hydrologic regimes in understudied freshwater systems of the Great Plains.

Primary Presenter: Joshua Matthews, University of Nebraska-Lincoln (jmatthews6@huskers.unl.edu)

Authors:

Daniel Gschwentner, University of Nebraska Lincoln  (dgschwentner2@huskers.unl.edu)

Carly Olson, Univsersity of Nebraska-Lincoln  (colson41@unl.edu)

Alan Warden, University of Nebraska-Lincoln  (awarden3@unl.edu)

Jessica Corman, University of Nebraska-Lincoln  (jcorman3@unl.edu)