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
Trends in Rainbow Trout recruitment, abundance, survival, and growth during a boom-and-bust cycle in a tailwater fishery
Deleterious effects of net clogging on the quantification of stream drift
Scientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan
Water clarity of the Colorado River—Implications for food webs and fish communities
Phenology of the adult angel lichen moth (Cisthene angelus) in Grand Canyon, USA
Flow management for hydropower extirpates aquatic insects, undermining river food webs
Prey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model
Evaluating potential sources of variation in Chironomidae catch rates on sticky traps
Seasonal and spatial patterns of growth of rainbow trout in the Colorado River in Grand Canyon, AZ
Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA
Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America
Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand 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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Trends in Rainbow Trout recruitment, abundance, survival, and growth during a boom-and-bust cycle in a tailwater fishery
Data from a large-scale mark-recapture study was used in an open population model to determine the cause for long-term trends in growth and abundance of a Rainbow Trout Oncorhynchus mykiss population in the tailwater of Glen Canyon Dam, AZ. Reduced growth affected multiple life stages and processes causing negative feedbacks that regulated the abundance of the population, including: higher mortaliAuthorsJosh Korman, Micheal D. Yard, Theodore A. KennedyDeleterious effects of net clogging on the quantification of stream drift
Drift studies are central to stream and river ecological research. However, a fundamental aspect of quantifying drift — how net clogging affects the accuracy of results — has been widely ignored. Utilizing approaches from plankton and suspended sediment studies in oceanography and hydrology, we examined the rate and dynamics of net clogging across a range of conditions. We found that nets clog nonAuthorsJeffrey D. Muehlbauer, Theodore A. Kennedy, Adam J. Copp, Thomas A. SabolScientific monitoring plan in support of the selected alternative of the Glen Canyon Dam Long-Term Experimental and Management Plan
IntroductionThe purpose of this document is to describe a strategy by which monitoring and research data in the natural and social sciences will be collected, analyzed, and provided to the U.S. Department of the Interior (DOI), its bureaus, and to the Glen Canyon Dam Adaptive Management Program (GCDAMP) in support of implementation of the Glen Canyon Dam Long-Term Experimental and Management PlanAuthorsScott P. Vanderkooi, Theodore A. Kennedy, David J. Topping, Paul E. Grams, David L. Ward, Helen C. Fairley, Lucas S. Bair, Joel B. Sankey, Charles B. Yackulic, John C. SchmidtWater clarity of the Colorado River—Implications for food webs and fish communities
The closure of Glen Canyon Dam in 1963 resulted in drastic changes to water clarity, temperature, and flow of the Colorado River in Glen, Marble, and Grand Canyons. The Colorado River is now much clearer, water temperature is less variable throughout the year, and the river is much colder in the summer months. The flow—regulated by the dam—is now less variable annually, but has larger daily fluctuAuthorsNicholas Voichick, Theodore A. Kennedy, David Topping, Ronald E. Griffiths, Kyrie FryPhenology of the adult angel lichen moth (Cisthene angelus) in Grand Canyon, USA
We investigated the phenology of adult angel lichen moths (Cisthene angelus) along a 364-km long segment of the Colorado River in Grand Canyon, Arizona, USA, using a unique data set of 2,437 light-trap samples collected by citizen scientists. We found that adults of C. angelus were bivoltine from 2012 to 2014. We quantified plasticity in wing lengths and sex ratios among the two generations and acAuthorsAnya N. Metcalfe, Theodore A. Kennedy, Jeffrey D. MuehlbauerFlow management for hydropower extirpates aquatic insects, undermining river food webs
Dams impound the majority of rivers and provide important societal benefits, especially daily water releases that enable on-peak hydroelectricity generation. Such “hydropeaking” is common worldwide, but its downstream impacts remain unclear. We evaluated the response of aquatic insects, a cornerstone of river food webs, to hydropeaking using a life history–hydrodynamic model. Our model predicts thAuthorsTheodore A. Kennedy, Jeffrey D. Muehlbauer, Charles B. Yackulic, D.A. Lytle, S.A. Miller, Kimberly L. Dibble, Eric W. Kortenhoeven, Anya N. Metcalfe, Colden V. BaxterPrey size and availability limits maximum size of rainbow trout in a large tailwater: insights from a drift-foraging bioenergetics model
The cold and clear water conditions present below many large dams create ideal conditions for the development of economically important salmonid fisheries. Many of these tailwater fisheries have experienced declines in the abundance and condition of large trout species, yet the causes of these declines remain uncertain. Here, we develop, assess, and apply a drift-foraging bioenergetics model to idAuthorsMichael J. Dodrill, Charles B. Yackulic, Theodore A. Kennedy, John W HayeEvaluating potential sources of variation in Chironomidae catch rates on sticky traps
Sticky traps are a convenient tool for assessing adult aquatic insect population dynamics, but there are many practical questions about how trap sampling artefacts may affect observed results. Utilising study sites on the Colorado River and two smaller streams in northern Arizona, USA, we evaluated whether catch rates and sex ratios of Chironomidae, a ubiquitous aquatic insect, were affected by spAuthorsJoshua T. Smith, Jeffrey D. Muehlbauer, Theodore A. KennedySeasonal and spatial patterns of growth of rainbow trout in the Colorado River in Grand Canyon, AZ
Rainbow trout (Oncorhynchus mykiss) have been purposely introduced in many regulated rivers, with inadvertent consequences on native fishes. We describe how trout growth rates and condition could be influencing trout population dynamics in a 130 km section of the Colorado River below Glen Canyon Dam based on a large-scale mark–recapture program where ∼8000 rainbow trout were recaptured over a 3-yeAuthorsMicheal D. Yard, Josh Korman, Carl J. Walters, T.A. KennedyMercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA
Mercury (Hg) and selenium (Se) biomagnify in aquatic food webs and are toxic to fish and wildlife. The authors measured Hg and Se in organic matter, invertebrates, and fishes in the Colorado River food web at sites spanning 387 river km downstream of Glen Canyon Dam (AZ, USA). Concentrations were relatively high among sites compared with other large rivers (mean wet wt for 6 fishes was 0.17–1.59 μAuthorsDavid M. Walters, E.J. Rosi-Marshall, Theodore A. Kennedy, W.F. Cross, C.V. BaxterFlow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America
Rainbow and brown trout have been intentionally introduced into tailwaters downriver of dams globally and provide billions of dollars in economic benefits. At the same time, recruitment and maximum length of trout populations in tailwaters often fluctuate erratically, which negatively affects the value of fisheries. Large recruitment events may increase dispersal downriver where other fish speciesAuthorsKimberly L. Dibble, Charles B. Yackulic, Theodore A. Kennedy, Phaedra E. BudyTurbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon
Dams and river regulation greatly alter the downstream environment for gross primary production (GPP) because of changes in water clarity, flow, and temperature regimes. We estimated reach-scale GPP in five locations of the regulated Colorado River in Grand Canyon using an open channel model of dissolved oxygen. Benthic GPP dominates in Grand Canyon due to fast transport times and low pelagic algaAuthorsRobert O. Hall, Charles B. Yackulic, Theodore A. Kennedy, Michael D. Yard, Emma J. Rosi-Marshall, Nicholas Voichick, Kathrine E. BehnNon-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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