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Food Web Studies

Slow reaches like this pool in Marble Canyon tend to have low invertebrate drift concentrations, because benthic densities and shear stress are small in pools.

Slow reaches like this pool in Marble Canyon tend to have low invertebrate drift concentrations, because benthic densities and shear stress are small in pools.

 


Food web studies are important to ongoing fisheries management in Glen and Grand Canyon, because they provide a basis for predicting responses of both predators and prey to management actions. 

Recent food web studies (field work conducted from 2006-2009) conducted in collaboration with University of Wyoming (http://www.uwyo.edu/bhall/site/home.html), Montana State University http://www.montana.edu/wcross/Cross_website/Home.html, Idaho State University (http://www.isu.edu/departments/strmecol/fac_cbaxter.shtml), and the Cary Institute for Ecosystem Studies (http://www.caryinstitute.org/science-program/our-scientists/dr-emma-j-rosi-marshall) revealed that fish populations in the Colorado River downstream from Glen Canyon Dam appear to be limited by the availability of high-quality invertebrate prey. Midge and blackfly production is low and nonnative rainbow trout in Glen Canyon and native fishes in Grand Canyon consume virtually all of the midge and blackfly biomass that is produced annually. In Glen Canyon, the invertebrate assemblage is dominated by nonnative New Zealand mudsnails, the food web has a simple structure, and transfers of energy from the base of the web (algae) to the top of the web (rainbow trout) are inefficient. The food webs in Grand Canyon are more complex relative to Glen Canyon, because, on average, each species in the web is involved in more interactions and feeding connections. Based on theory and on studies from other ecosystems, the structure and organization of Grand Canyon food webs should make them more stable and less susceptible to large changes following perturbations of the flow regime relative to food webs in Glen Canyon. In support of this hypothesis, Grand Canyon food webs were much less affected by a 2008 controlled flood relative to the food web in Glen Canyon.

 

Nighttime electrofishing for rainbow trout in Glen Canyon.

Nighttime electrofishing for rainbow trout in Glen Canyon.

 

Publications:
Cross, W.F., C.V. Baxter, E.J. Rosi-Marshall, R.O. Hall Jr., T.A. Kennedy, K.C. Donner, H.A. Wellard-Kelly, S.E.Z. Seegert, K.E. Behn, and M.D. Yard, 2013.  Food-web dynamics in a large river discontinuum.  Ecological Monographs 83: 311-337.

Kennedy, T.A., Cross, W.F., Hall, R.O., Jr., Baxter, C.V., and Rosi-Marshall, E.J., 2013, Native and nonnative fish populations of the Colorado River are food limited—evidence from new food web analyses: U.S. Geological Survey Fact Sheet 2013–3039, 4 p., (http://pubs.usgs.gov/fs/2013/3039/).

H.A. Wellard Kelly, E.J. Rosi-Marshall, T.A. Kennedy, R.O. Hall Jr., W.F. Cross, and C.V. Baxter, 2013.  Macroinvertebrate diets reflect longitudinal and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam.  Freshwater Science 32: 397-411.

Hall, R.O., T.A. Kennedy, and E.J. Rosi-Marshall, 2012.  Air-water oxygen exchange in a large whitewater river. Limnology and Oceanography: Fluids and Environments 2: 1-11.  DOI: 10.1215/21573689-1572535

Kennedy, T.A. and B. Ralston, 2012.  Regulation leads to increases in riparian vegetation, but not direct allochthonous inputs, along the Colorado River in Grand Canyon, Arizona.  River Research and Applications 28: 2-12 DOI: 10.1002/rra.1431

Cross, W.F., C.V. Baxter, K.C. Donner, E.J. Rosi-Marshall, T.A. Kennedy, R.O. Hall Jr., H.A. Wellard Kelly, and R.S. Rogers.  2011.  Ecosystem ecology meets adaptive management: food web response to a controlled flood on the Colorado River, Glen Canyon.  Ecological Applications 21: 2016-2033. doi:10.1890/10-1719.1

Donner, K. C. 2011. Trophic basis of production of fishes in the Colorado River, Grand Canyon: an assessment of potential competition for food. M.S. Thesis, Department of Biological Sciences, Idaho State University, Pocatello, Idaho, USA.

Seegert, S. E. Z. 2010. Diet overlap and competition among native and non-native small-bodied fishes in the Colorado River, Grand Canyon, Arizona. Master’s Thesis. Department of Biology, Loyola University Chicago, Illinois, USA.

Wellard-Kelley, H.A. 2010. Resource composition and macroinvertebrate resource consumption in the Colorado River below Glen Canyon Dam. Master’s Thesis.  Department of Biology, Loyola University Chicago, Illinois, USA.

Rosi-Marshall, E. J., T. A. Kennedy, D. W. Kincaid, W. F. Cross, H. A. W. Kelly, K. A. Behn, T. White, R. O. Hall, Jr., and C. V. Baxter. 2010. Short-term effects of the 2008 highflow experiment on macroinvertebrates in the Colorado River below Glen Canyon Dam, Arizona. Open-File Report 2010-1031. U.S. Geological Survey, Reston, Virginia, USA. [http://pubs.usgs.gov/of/2010/1031/]

Behn, K.E., T.A. Kennedy, and R.O. Hall, 2010. Basal resources in backwaters of the Colorado River below Glen Canyon Dam—effects of discharge regimes and comparison with mainstem depositional environments: U.S. Geological Survey Open-File Report 2010-1075, 25 p. [http://pubs.usgs.gov/of/2010/1075/].

Hall, R.O., T.A. Kennedy, E.J. Rosi-Marshall, W.F. Cross, H.A. Wellard, C.V. Baxter, 2010.  Aquatic production and carbon flow in the Colorado River Pages 105-112 in Proceedings of the Colorado River Basin Science and Resource Management Symposium, November 18–20, 2008, Scottsdale, Arizona. Eds T.S. Melis, J.F. Hamill, L.G. Coggins, P.E. Grams, T.A. Kennedy, D.M. Kubly, and B.E. Ralston U.S. Geological Survey Scientific Investigations Report 2010–5135. [http://pubs.usgs.gov/sir/2010/5135/]

Cross, W.F., E.J. Rosi-Marshall, K.E. Behn, T.A. Kennedy, R.O. Hall, A.E. Fuller, C.V. Baxter, 2010.  Invasion and production of New Zealand mud snails in the Colorado River, Glen Canyon.  Biological Invasions 9: 3033-3043. DOI 10.1007/s10530-010-9694-y

 

For questions or comments about any of these projects, please send an email to citizen_science@usgs.gov

 

Photo credit: Freshwater Illustrated/ US Geological Survey

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Last Update: November 3, 2011