HR: 11:15h
AN: NB22A-04    [Abstracts]
TI: Impacts of Invasive Rusty Crayfish on Stream Ecosystems of the Upper Midwestern U.S.
AU: * Bobeldyk, A M
EM: bobeldyk.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369 United States
AU: Lamberti, G A
EM: lamberti.1@nd.edu
AF: University of Notre Dame, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556-0369 United States
AB: Invasive species can have detrimental effects on structural characteristics of freshwater ecosystems, but relatively few studies have assessed ecosystem-level impacts of invasive species in streams. We studied the effects of invasive rusty crayfish (Orconectes rusticus) on detritus processing and invertebrate and fish abundance in northern Wisconsin and Michigan, USA, streams. We hypothesized that rusty crayfish would increase the rate of detritus processing and reduce fish and invertebrate abundance due to their aggressiveness and competitive superiority for food and habitat. We measured sugar maple (Acer saccharum) decomposition rates in three reaches of a stream with differing densities of rusty crayfish, high (5.05/m²), intermediate (2.27/m²), and none (0/m²) using leaf bags excluding crayfish and open bags allowing crayfish access. We found that open bags decayed significantly faster (k=0.143) than crayfish excluded bags at all sites (k=0.079) (p=0.0005). The reach lacking crayfish had significantly higher densities of invertebrates (p=0.005). We also surveyed an additional 7 streams that contained or lacked rusty crayfish and found significantly higher fish abundance (p=0.019) and biomass (p=0.001) in streams lacking rusty crayfish. Rusty crayfish appear to indirectly affect detritus processing via negative effects on benthic invertebrates, and may have larger-scale impacts on fishes across streams.
DE: 1800 HYDROLOGY
DE: 4804 Benthic processes/benthos
DE: 4815 Ecosystems, structure and dynamics
DE: 4817 Food chains
DE: 4899 General or miscellaneous
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly