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Density-dependent effects of omnivorous stream crayfish on benthic trophic dynamics
Ludlam JP, Banks BT and Magoulick DD 
Published Online: 12/31/2015
Abstract
Crayfish are abundant and important consumers in aquatic food webs and crayfish invasions have demonstrated strong effects of crayfish on multiple trophic levels. Density may be an important factor determining the role of omnivorous crayfish in benthic communities, especially if density alters the strength of trophic interactions. The effect of crayfish density on a simple benthic food web using ceramic tiles was examined in three treatments (crayfish exclusion cage, cage control (open to crayfish), and exposed ceramic tiles) in mesocosms stocked with 6, 12, or 18 crayfish·m-2. We hypothesized that at low densities crayfish consumption of herbivorous chironomids would increase algal abundance, but at high densities crayfish would reduce both periphyton and invertebrates. In the experiment, periphyton and chironomid abundance increased with declining crayfish biomass on day 30 but not day 15. The magnitude of crayfish effects on day 15 periphyton chlorophyll a abundance increased with crayfish biomass, but crayfish effects on day 30 periphyton chlorophyll a or chironomid biomass did not increase with crayfish biomass. In this experiment there was little evidence for a trophic cascade at low crayfish densities and strong omnivory by crayfish dominated trophic dynamics.
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How to Cite
Ludlam JP, Banks BT and Magoulick DD. (2015). Density-dependent effects of omnivorous stream crayfish on benthic trophic dynamics. Freshwater Crayfish 21(1):165-170. doi: 10.5869/fc.2015.v21-1.165
Author Information
Daniel D. Magoulick,* Department of Biological Sciences, Arkansas Coop Resarch Unit, 1 University of Arkansas, Fayetteville, Arkansas, USA72701. E-mail: danmag@uark.edu
John P. Ludlam, Department of Biology and Chemistry, Fitchburg State University, 160 Pearl Street, Fitchburg, Massachusetts, USA01420. E-mail: jludlam@fitchburgstate.edu
Corresponding Author indicated by an *.
Publication History
Manuscript Submitted: 6/10/2015
Manuscript Accepted: 12/1/2015
Published Online: 12/31/2015
Published in Print: 12/31/2015
Funding Information
No specific funding statement is available for this article.