Density-dependent effects of omnivorous stream crayfish on benthic trophic dynamics

Freshwater Crayfish
By: , and 

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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.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Density-dependent effects of omnivorous stream crayfish on benthic trophic dynamics
Series title Freshwater Crayfish
DOI 10.5869/fc.2015.v21-1.165
Volume 21
Issue 1
Year Published 2015
Language English
Publisher International Association of Astacology
Contributing office(s) Coop Res Unit Atlanta
Description 5 p.
First page 165
Last page 170
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