2023 Early Hearing Detection & Intervention Conference
March 5-7, 2023 • Cincinnati, OH
5/21/2018 | 11:45 AM - 12:00 PM | SEASONAL TOP DOWN EFFECTS OF FISH ON BENTHIC MACROINVERTEBRATES AND PERIPHYON IN A COLDWATER MICHIGAN STREAM | 420 A
SEASONAL TOP DOWN EFFECTS OF FISH ON BENTHIC MACROINVERTEBRATES AND PERIPHYON IN A COLDWATER MICHIGAN STREAM
We conducted a manipulative field experiment to test the seasonal strength of fish predation on benthic macroinvertebrates and periphyton at the patch scale. We hypothesized that excluding predators will increase prey density and the predation effect will be weaker in winter due to decreased metabolic rates of predators. We placed paired exclosure and open-control cages in a 250-m stream reach (n=12 pairs) during late-summer 2015 and winter 2016 for 32 and 31 days, respectively. Periphyton density (chlorophyll-a) from three cobbles in each cage was significantly lower in exclosures than open controls for the late-summer trial. Periphyton density in the winter trial was not significantly different between exclosures and open controls. The most common families in the late-summer trial were Gammaridae, Hydropsychidae, Brachycentridae, Baetidae, and Elmidae (78% of invertebrates); a predation effect was observed in Brachycentridae and Elmidae. The most common families in the winter trial were Gammaridae, Hydropsychidae, Nemouridae, Baetidae, and Ephemerellidae (79% of invertebrates); a predation effect was observed in Hydropsychidae and Nemouridae. Thus, there was evidence of weak top-down control by fishes in the study stream during both seasons.
- Food Webs
- Fish
- Invertebrate
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Presenters/Authors
Travis J. Ellens
(), Grand Valley State University, ellentra@gvsu.edu;
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Carl R. Ruetz III
(), Annis Water Resources Institute, Grand Valley State University, ruetzc@gvsu.edu;
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Steven L. Kohler
(), Western Michigan University, steve.kohler@wmich.edu;
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