I know what you're eating... spying on the plankton food web

Session: Exploring Predator-prey Dynamics and Feeding Ecology in the Great Lakes (1)

Warren Currie, Fisheries and Oceans Canada, [email protected]
John Berges, Univ. of Wisconsin-Milwaukee, Dept. of Biological Sciences and School of Freshwater Scienc, [email protected]
David Gronquist, University of Wisconsin Milwaukee, [email protected]
Nathaniel Thorngate-Rein, University of Wisconsin Milwaukee, [email protected]
Robin Rozon, Fisheries & Oceans Canada, [email protected]
Kelly Bowen, Fisheries and Oceans Canada, [email protected]

Abstract

Zooplankton are key to energy transfer from primary producers to upper trophic levels in aquatic systems. However, determining diet for zooplankton is extremely difficult since zooplankton are “sloppy feeders” in that guts rarely contain intact prey. Instead, we employ a protein immunochemical analysis using polyclonal antibodies, which is inexpensive, sensitive, and quantitative, with advantages over integrator analysis (e.g. stable isotopes). Since antibody reaction indicates recent prey consumption, it is suitable for seasonal diet studies. We examined prey preference for key zooplankton predator species important to the Lake Ontario fisheries food web: Bythotrephes longimanus, Mysis diluviana and Limnocalanus macrurus.

One objective was determining fate of veliger production by Dreissena (Zebra/Quagga Mussels), now often the most numerous plankton collected during early summer-fall in the Great Lakes. Zooplankton was collected from Lake Ontario in 2017 to compare with gut detections. Veligers were detected in all three species indicating veligers are being incorporated into the food web. Desirable prey (e.g. Daphnia galeata mendotae) had higher percent gut detections for both Mysis and Bythotrephes even though they had much lower densities than veligers, indicating active selection. Study results and implications for food web modeling in the Great Lakes will be discussed.

Twitter handle of presenter
DrPlanktonguy