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SFS Annual Meeting

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CHARACTERIZING COMPLEXITY IN WEBS OF FEAR: ROLES OF PREDATOR TYPE, DIET, AND HABITAT IN THE SPATIAL DISTRIBUTION OF ZOOPLANKTON AND FISH IN LAKES AND RESERVOIRS

Infochemicals (kairomones) of planktivores influence the movement of zooplankton. We investigated the response of Daphnia pulex in the presence or absence of macrophytes to a piscivore (Esox masquinongy), a planktivore (Lepomis macrochirus) with either a diet of zooplankton or crickets, and a control. We observed avoidance of D. pulex to the four fish stimuli in tanks with a barrier restricting fish at the edge of one third of the tank and macrophyte treatments on the opposing side, where D. pulex were introduced. Fewer D. pulex moved from the introduction area in the presence of bluegill with a conspecific diet than in other treatments; avoidance of the fish stimuli was least in the control and muskellunge treatments. Movement out of the introduction area was also greater when macrophytes were there. Movement into the fish zone from the central zone was less frequent in the presence of a predator and macrophytes, suggesting D. pulex prefer edges of macrophytes in the presence of fish to open water or the interior of macrophytes. This study shows that Daphnia response to fish is not conserved and habitat arrangement structures the landscape of fear.

Thomas Detmer (Primary Presenter/Author), University of Illinois, tdetmer@illinois.edu;


David Wahl (Co-Presenter/Co-Author), Illinois Natural History Survey, d-wahl@illinois.edu;