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
Flow management for hydropower extirpates aquatic insects, undermining river food websData
Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North AmericaData
Water storage decisions will determine the distribution and persistence of imperiled river fishes
Net-spinning caddisfly distribution in large regulated rivers
Changes in prey, turbidity, and competition reduce somatic growth and cause the collapse of a fish population
Macroinvertebrate oviposition habitat selectivity and egg-mass desiccation tolerances: Implications for population dynamics in large regulated rivers
Food web controls on mercury fluxes and fate in the Colorado River, Grand Canyon
Spatial population structure of a widespread aquatic insect in the Colorado River Basin: Evidence for a Hydropsyche oslari species complex
Bug flows: Don’t count your midges until they hatch
Warm water temperatures and shifts in seasonality increase trout recruitment but only moderately decrease adult size in western North American tailwaters
Brown trout in the Lees Ferry reach of the Colorado River—Evaluation of causal hypotheses and potential interventions
Pulsed flows, tributary inputs, and food web structure in a highly regulated river
Meeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers
A coupled metabolic-hydraulic model and calibration scheme for estimating of whole-river metabolism during dynamic flow conditions
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.
Science and Products
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Flow management for hydropower extirpates aquatic insects, undermining river food websData
Two unique datasets were gathered to document whether flow management for hydropower affects the abundance and diversity of aquatic insect assemblages. The first dataset was collected in Grand Canyon from 2012-2014 by citizen scientists rafting the Colorado River. Simple light traps were set out each night in camp and used to capture the adult life stages of aquatic insects that emerged from the CFlow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North AmericaData
This data is a compilation of fishery monitoring data collected by state agencies over several decades in tailwaters downriver of dams in Colorado, Utah, Montana, Wyoming, Idaho, New Mexico, Arizona, California, and Oregon. Specifically, the data contained herein is summary data used in four generalized linear mixed models that were developed to assess the biological and hydrologic factors that in - Multimedia
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Filter Total Items: 58
Water storage decisions will determine the distribution and persistence of imperiled river fishes
Managing the world’s freshwater supply to meet societal and environmental needs in a changing climate is one of the biggest challenges for the 21st century. Dams provide water security, however, the allocation of dwindling water supply among reservoirs could exacerbate or ameliorate the effects of climate change on aquatic communities. Here, we show that the relative sensitivity of river thermal rAuthorsKimberly L. Dibble, Charles Yackulic, Theodore Kennedy, Kevin R. Bestgen, John C. SchmidtNet-spinning caddisfly distribution in large regulated rivers
Most of the world's large rivers are dammed for the purposes of water storage, flood control, and power production. Damming rivers fundamentally alters water temperature and flows in tailwater ecosystems, which in turn affects the presence and abundance of downstream biota.We collaborated with more than 200 citizen scientists to collect 2,194 light trap samples across 2 years and more than 2,000 rAuthorsAnya Metcalfe, Jeffrey Muehlbauer, Theodore Kennedy, Charles Yackulic, Kimberly L. Dibble, Jane C. MarksChanges in prey, turbidity, and competition reduce somatic growth and cause the collapse of a fish population
Somatic growth exerts strong control on patterns in the abundance of animal populations via effects on maturation, fecundity, and survival rates of juveniles and adults. In this paper, we quantify abiotic and biotic drivers of rainbow trout growth in the Colorado River, AZ, and the resulting impact on spatial and temporal variation in abundance. Inferences are based on approximately 10,000 observaAuthorsJosh Korman, Mike Yard, Maria C. Dzul, Charles Yackulic, Michael Dodrill, Bridget Deemer, Theodore KennedyMacroinvertebrate oviposition habitat selectivity and egg-mass desiccation tolerances: Implications for population dynamics in large regulated rivers
Aquatic insects exhibit complex life cycles that include egg, larval, adult, and, in some instances, pupal stages. Disturbances at any of these life stages can affect overall population dynamics. Yet, efforts to understand the effects of disturbances, such as hydrologic alterations, overwhelmingly focus on the larval life stage of aquatic insects. We evaluated the potential for load-following flowAuthorsScott W. Miller, Matt Schroer, Jesse R. Fleri, Theodore A. KennedyFood web controls on mercury fluxes and fate in the Colorado River, Grand Canyon
Mercury (Hg) biomagnification in aquatic food webs is a global concern; yet, the ways species traits and interactions mediate these fluxes remain poorly understood. Few pathways dominated Hg flux in the Colorado River despite large spatial differences in food web complexity, and fluxes were mediated by one functional trait, predation resistance. New Zealand mudsnails are predator resistant and a tAuthorsDavid Walters, Wyatt F. Cross, Theodore Kennedy, Colden V. Baxter, R. O. Hall, Emma J. RosiSpatial population structure of a widespread aquatic insect in the Colorado River Basin: Evidence for a Hydropsyche oslari species complex
Structural connectivity and dispersal ability are important constraints on functional connectivity among populations. For aquatic organisms that disperse among stream corridors, the regional structure of a river network can, thus, define the boundaries of gene flow. In this study, we used mitochondrial DNA (mtCO1 barcoding gene) to examine the genetic diversity and population structure of a caddisAuthorsAnya N. Metcalfe, Theodore A. Kennedy, Jane C. Marks, Aaron D. Smith, Jeffrey D. MuehlbauerBug flows: Don’t count your midges until they hatch
Usually when people hear about a “bug problem” it’s due to an undesirable overabundance of insects (think plague of locusts). In the Colorado River in Grand Canyon, however, we are faced with the opposite predicament: the river is essentially devoid of bugs. Aquatic insects are a fundamental component of a healthy river ecosystem. Most aquatic insects spend their juvenile life stages (egg, larva,AuthorsAnya Metcalfe, Jeffrey Muehlbauer, Morgan Ford, Theodore KennedyWarm water temperatures and shifts in seasonality increase trout recruitment but only moderately decrease adult size in western North American tailwaters
Dams throughout western North America have altered thermal regimes in rivers, creating cold, clear “tailwaters” in which trout populations thrive. Ongoing drought in the region has led to highly publicized reductions in reservoir storage and raised concerns about potential reductions in downstream flows. Large changes in riverine thermal regimes may also occur as reservoir water levels drop, yet tAuthorsKimberly L. Dibble, Charles B. Yackulic, Theodore A. KennedyBrown trout in the Lees Ferry reach of the Colorado River—Evaluation of causal hypotheses and potential interventions
Over the period 2014–2016, the number of nonnative brown trout (Salmo trutta) captured during routine monitoring in the Lees Ferry reach of the Colorado River, downstream of Glen Canyon Dam, began increasing. Management agencies and stakeholders have questioned whether the increase in brown trout in the Lees Ferry reach represents a threat to the endangered humpback chub (Gila cypha), to the rainbAuthorsMichael C. Runge, Charles B. Yackulic, Lucas S. Bair, Theodore A. Kennedy, Richard A. Valdez, Craig Ellsworth, Jeffrey L. Kershner, R. Scott Rogers, Melissa A. Trammell, Kirk L. YoungPulsed flows, tributary inputs, and food web structure in a highly regulated river
1.Dams disrupt the river continuum, altering hydrology, biodiversity, and energy flow. Although research indicates that tributary inputs have the potential to dilute these effects, knowledge at the food web level is still scarce.2.Here we examined the riverine food web structure of the Colorado River below Glen Canyon Dam, focusing on organic matter sources, trophic diversity, and food chain lengtAuthorsJohn Sabo, Melanie Caron, Richard R. Doucett, Kimberly L. Dibble, Albert Ruhi, Jane Marks, Bruce Hungate, Theodore A. KennedyMeeting the challenge of interacting threats in freshwater ecosystems: A call to scientists and managers
Human activities create threats that have consequences for freshwater ecosystems and, in most watersheds, observed ecological responses are the result of complex interactions among multiple threats and their associated ecological alterations. Here we discuss the value of considering multiple threats in research and management, offer suggestions for filling knowledge gaps, and provide guidance forAuthorsLaura S. Craig, Julian D. Olden, Angela Arthington, Sally Entrekin, Charles P. Hawkins, John J. Kelly, Theodore A. Kennedy, Bryan M. Maitland, Emma J. Rosi, Allison H. Roy, David L. Strayer, Jennifer L. Tank, Amie O. West, Matthew S. WootenA coupled metabolic-hydraulic model and calibration scheme for estimating of whole-river metabolism during dynamic flow conditions
Conventional methods for estimating whole-stream metabolic rates from measured dissolved oxygen dynamics do not account for the variation in solute transport times created by dynamic flow conditions. Changes in flow at hourly time scales are common downstream of hydroelectric dams (i.e. hydropeaking), and hydrologic limitations of conventional metabolic models have resulted in a poor understandinAuthorsRobert A. Payn, Robert O Jr. Hall, Theodore A. Kennedy, Geoff C Poole, Lucy A. MarshallNon-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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