Theodore Kennedy, Ph.D.
I use food webs to describe ecosystem response to river regulation and biological invasions. I have been with USGS since 2004, providing science in support of the Glen Canyon Dam Adaptive Management Program.
Professional Experience:
11/04 - present. Research Ecologist, Grand Canyon Monitoring and Research Center, Southwest Biological Science Center, US Geological Survey, Flagstaff, AZ
1/04 - 11/04. Postdoctoral researcher, Arizona State University
1/03 - 1/04. Postdoctoral researcher, Grand Canyon Monitoring and Research Center, Southwest Biological Science Center, US Geological Survey, Flagstaff, AZ.
Education:
9/96 - 12/02. Ph.D. in Ecology, Dept. of Ecology, Evolution, and Behavior, University of Minnesota. Dissertation title: The causes and consequences of plant invasions
1/90 - 12/94. B.S. in Ecology, California Polytechnic State University at San Luis Obispo, cum laude.
Science and Products
Building a better sticky trap: description of an easy-to-use trap and pole mount for quantifying the abundance of adult aquatic insects
High diet overlap between native small-bodied fishes and nonnative fathead minnow in the Colorado River, Grand Canyon, Arizona
Barcodes are a useful tool for labeling and tracking ecological samples
The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river
Food-web dynamics in a large river discontinuum
Native and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses
Macroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam
Identification and evaluation of scientific uncertainties related to fish and aquatic resources in the Colorado River, Grand Canyon - summary and interpretation of an expert-elicitation questionnaire
Abiotic & biotic responses of the Colorado River to controlled floods at Glen Canyon Dam, Arizona, USA
Air-water oxygen exchange in a large whitewater river
Regulation leads to increases in riparian vegetation, but not direct allochthonous inputs, along the Colorado River in Grand Canyon, Arizona
Ecosystem ecology meets adaptive management: food web response to a controlled flood on the Colorado River, Glen Canyon
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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Building a better sticky trap: description of an easy-to-use trap and pole mount for quantifying the abundance of adult aquatic insects
Insect emergence is a fundamental process in freshwaters. It is a critical life-history stage for aquatic insects and provides an important prey resource for terrestrial and aquatic consumers. Sticky traps are increasingly being used to sample these insects. The most common design consists of an acetate sheet coated with a nondrying adhesive that is attached to a wire frame or cylinder. These trapAuthorsJoshua T. Smith, Theodore A. Kennedy, Jeffrey D. MuehlbauerHigh diet overlap between native small-bodied fishes and nonnative fathead minnow in the Colorado River, Grand Canyon, Arizona
River regulation may mediate the interactions among native and nonnative species, potentially favoring nonnative species and contributing to the decline of native populations. We examined food resource use and diet overlap among small-bodied fishes in the Grand Canyon section of the Colorado River as a first step in evaluating potential resource competition. We compared the diets of the predominanAuthorsSarah E. Zahn Seegert, Emma J. Rosi-Marshall, Colden V. Baxter, Theodore A. Kennedy, Robert O. Hall, Wyatt F. CrossBarcodes are a useful tool for labeling and tracking ecological samples
Barcodes are used to label and track just about everything these days. Look around your office, in your medicine cabinet, at the package you just received in the mail, or on the shelves of any shop in town, and you will immediately grasp the ubiquity of their use. Interestingly, railroads and supermarkets were the early pioneers of barcode development: the former needing a way to track railway carAuthorsAdam J. Copp, Theodore A. Kennedy, Jeffrey D. MuehlbauerThe relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river
1. Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (# m−3), but the factors that govern invertebrate drift in larger riveAuthorsTheodore A. Kennedy, Charles B. Yackulic, Wyatt F. Cross, Paul E. Grams, Michael D. Yard, Adam J. CoppFood-web dynamics in a large river discontinuum
Nearly all ecosystems have been altered by human activities, and most communities are now composed of interacting species that have not co-evolved. These changes may modify species interactions, energy and material flows, and food-web stability. Although structural changes to ecosystems have been widely reported, few studies have linked such changes to dynamic food-web attributes and patterns of eAuthorsWyatt F. Cross, Colden V. Baxter, Emma J. Rosi-Marshall, Robert O. Hall, Theodore A. Kennedy, Kevin C. Donner, Holly A. Wellard Kelly, Sarah E.Z. Seegert, Kathrine E. Behn, Michael D. YardNative and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses
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 dominatedAuthorsTheodore A. Kennedy, Wyatt F. Cross, Robert O. Hall, Colden V. Baxter, Emma J. Rosi-MarshallMacroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam
Physical changes to rivers associated with large dams (e.g., water temperature) directly alter macroinvertebrate assemblages. Large dams also may indirectly alter these assemblages by changing the food resources available to support macroinvertebrate production. We examined the diets of the 4 most common macroinvertebrate taxa in the Colorado River through Glen and Grand Canyons, seasonally, at 6AuthorsHolly A. Wellard Kelly, Emma J. Rosi-Marshall, Theodore A. Kennedy, Robert O. Hall, Wyatt F. Cross, Colden V. BaxterIdentification and evaluation of scientific uncertainties related to fish and aquatic resources in the Colorado River, Grand Canyon - summary and interpretation of an expert-elicitation questionnaire
Identifying areas of scientific uncertainty is a critical step in the adaptive management process (Walters, 1986; Runge, Converse, and Lyons, 2011). To identify key areas of scientific uncertainty regarding biologic resources of importance to the Glen Canyon Dam Adaptive Management Program, the Grand Canyon Monitoring and Research Center (GCMRC) convened Knowledge Assessment Workshops in May and JAuthorsTheodore A. KennedyAbiotic & biotic responses of the Colorado River to controlled floods at Glen Canyon Dam, Arizona, USA
Closure of Glen Canyon Dam reduced sand supply to the Colorado River in Grand Canyon National Park by about 94% while its operation has also eroded the park's sandbar habitats. Three controlled floods released from the dam since 1995 suggest that sandbars might be rebuilt and maintained, but only if repeated floods are timed to follow tributary sand deliveries below the dam. Monitoring data show tAuthorsJosh Korman, Ted Melis, Theodore A. KennedyAir-water oxygen exchange in a large whitewater river
Air–water gas exchange governs fluxes of gas into and out of aquatic ecosystems. Knowing this flux is necessary to calculate gas budgets (i.e., O2) to estimate whole‐ecosystem metabolism and basin‐scale carbon budgets. Empirical data on rates of gas exchange for streams, estuaries, and oceans are readily available. However, there are few data from large rivers and no data from whitewater rapids. WAuthorsRobert O. Hall, Theodore A. Kennedy, Emma J. Rosi-MarshallRegulation leads to increases in riparian vegetation, but not direct allochthonous inputs, along the Colorado River in Grand Canyon, Arizona
Dams and associated river regulation have led to the expansion of riparian vegetation, especially nonnative species, along downstream ecosystems. Nonnative saltcedar is one of the dominant riparian plants along virtually every major river system in the arid western United States, but allochthonous inputs have never been quantified along a segment of a large river that is dominated by saltcedar. WeAuthorsT.A. Kennedy, B.E. RalstonEcosystem ecology meets adaptive management: food web response to a controlled flood on the Colorado River, Glen Canyon
Large dams have been constructed on rivers to meet human demands for water, electricity, navigation, and recreation. As a consequence, flow and temperature regimes have been altered, strongly affecting river food webs and ecosystem processes. Experimental high‐flow dam releases, i.e., controlled floods, have been implemented on the Colorado River, USA, in an effort to reestablish pulsed flood evenAuthorsWyatt F. Cross, Colden V. Baxter, Kevin C. Donner, Emma J. Rosi-Marshall, Theodore A. Kennedy, Robert O. Hall, Holly A. Wellard Kelly, R. Scott RogersNon-USGS Publications**
Kennedy, T.A., 1998, Patterns of an invasion by Argentine ants (Linepithema humile) in a riparian corridor and its effects on ant diversity: The American Midland Naturalist, v. 140, p. 343-350.Naeem, S., Knops, J.M., Tilman, D., Howe, K.M., Kennedy, T. and Gale, S., 2000, Plant diversity increases resistance to invasion in the absence of covarying extrinsic factors: Oikos, v. 91, p. 97-108, DOI: 10.1034/j.1600-0706.2000.910108.x.Raffaelli, D., Van der Putten, W.H., Persson, L., Wardle, D.A., Petchey, O.L., Koricheva, J., Van Der Heijden, M., Mikola, J. and Kennedy, T., 2002, Multi-trophic dynamics and ecosystem processes, In Loreau, M., Naeem, S., and Inchausti, P., eds., Biodiversity and ecosystem functioning: synthesis and perspectives: Oxford, Oxford University Press, p.147-154.Levine, J.M., Kennedy, T., and Naeem, S., 2002, Neighborhood scale effects of species diversity on biological invasions and their relationship to community patterns, In Loreau, M., Naeem, S., and Inchausti, P., eds., Biodiversity and ecosystem functioning: synthesis and perspectives: Oxford, Oxford University Press, p.114-124.Kennedy, T.A., Naeem, S., Howe, K.M., Knops, J.M., Tilman, D., and Reich, P., 2002, Biodiversity as a barrier to ecological invasion. Nature, v.417, p.636. doi:10.1038/nature00776.Kennedy, T.A., and Hobbie, S.E., 2004, Saltcedar (Tamarix ramosissima) invasion alters organic matter dynamics in a desert stream. Freshwater Biology, v. 49, p. 65-76. doi: 10.1046/j.1365-2426.2003.01166.x.Kennedy, T.A., Finlay, J.C., and Hobbie, S.E., 2005, Eradication of invasive Tamarix ramosissima along a desert stream increases native fish density: Ecological Applications, v. 15, p. 2072-2083.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
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