Importance of consumptive and non-consumptive prey mortality in a coupled predator–prey system |
| |
Authors: | MALCOLM MCKEE,FREDERICK WRONA,GARRY SCRIMGEOUR,& JOSEPH CULP |
| |
Affiliation: | Aquatic Ecology Group, Division of Ecology, Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4,;National Hydrology Research Institute, 11 Innovation Boulevard, Saskatoon, Saskatchewan, Canada S7N 3H5,;Sustainable Forest Management Network of Centres of Excellence, G-208, Biological Sciences Building, University of Alberta, Edmonton, Alberta, Canada T6G 2E9 |
| |
Abstract: | 1. Laboratory experiments were completed to identify the mechanisms by which the predatory flatworm, Dugesia tigrina , imposes mortality on its Aedes aegypti and Daphnia magna prey. Feeding trials were completed in glass microcosms which contained one of three – nine densities of small or large individuals of each prey species. 2. Mortality by Dugesia on small and large Aedes followed a type II functional response, whereas the mortality of Daphnia resembled a type III functional response. Prey mortality imposed by Dugesia consisted of consumptive and non-consumptive elements. Non-consumptive mortality occurred when prey individuals trapped in mucus trails subsequently died but were not ingested. 3. Additional experiments were conducted to quantify consumptive (capture followed by ingestion) and non-consumptive mortality (death not followed by ingestion). 4. Consumptive mortality followed a type II functional response for small and large individuals of both prey species, whereas non-consumptive mortality increased with prey density, although the relationships differed with prey species and size. The non-consumptive mortality of large Daphnia increased at an accelerating rate with prey density and exceeded consumptive mortality at intermediate prey abundances. In contrast, non-consumptive mortality of small Aedes and small Daphnia was lower than consumptive mortality and either increased with prey density at a decelerating (small Aedes ) or accelerating (small Daphnia ) rate. 5. These results suggest that the importance of consumptive and non-consumptive mortality to total prey mortality needs to be considered when modelling predator–prey dynamics. |
| |
Keywords: | |
|
|