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 and Certifications
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
Filter Total Items: 15
No Result Found
Filter Total Items: 62
Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA Mercury 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...
Authors
David Walters, E.J. Rosi-Marshall, Theodore A. Kennedy, W.F. Cross, C.V. Baxter
Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon Turbidity, 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...
Authors
Robert O. Hall, Charles Yackulic, Theodore A. Kennedy, Michael D. Yard, Emma Rosi-Marshall, Nicholas Voichick, Kathrine Behn
Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America Flow 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...
Authors
Kimberly Dibble, Charles Yackulic, Theodore A. Kennedy, Phaedra Budy
Building a better sticky trap: description of an easy-to-use trap and pole mount for quantifying the abundance of adult aquatic insects 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...
Authors
Joshua Smith, Theodore A. Kennedy, Jeffrey Muehlbauer
High diet overlap between native small-bodied fishes and nonnative fathead minnow in the Colorado River, Grand Canyon, Arizona High 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...
Authors
Sarah E. Zahn Seegert, Emma Rosi-Marshall, Colden V. Baxter, Theodore A. Kennedy, Robert O. Hall, Wyatt Cross
Barcodes are a useful tool for labeling and tracking ecological samples Barcodes 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...
Authors
Adam Copp, Theodore Kennedy, Jeffrey Muehlbauer
The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river The 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...
Authors
Theodore A. Kennedy, Charles Yackulic, Wyatt Cross, Paul Grams, Michael D. Yard, Adam Copp
Food-web dynamics in a large river discontinuum Food-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...
Authors
Wyatt Cross, Colden V. Baxter, Emma Rosi-Marshall, Robert O. Hall, Theodore A. Kennedy, Kevin Donner, Holly A. Wellard Kelly, Sarah Seegert, Kathrine Behn, Michael D. Yard
Native and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses Native 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...
Authors
Theodore A. Kennedy, Wyatt Cross, Robert O. Hall, Colden V. Baxter, Emma Rosi-Marshall
Macroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam Macroinvertebrate 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...
Authors
Holly Wellard Kelly, Emma Rosi-Marshall, Theodore A. Kennedy, Robert O. Hall, Wyatt Cross, Colden V. Baxter
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 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
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...
Authors
Theodore A. Kennedy
Abiotic & biotic responses of the Colorado River to controlled floods at Glen Canyon Dam, Arizona, USA Abiotic & 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...
Authors
Josh Korman, Ted Melis, Theodore A. Kennedy
Non-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.
Science and Products
Filter Total Items: 15
No Result Found
Filter Total Items: 62
Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA Mercury 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...
Authors
David Walters, E.J. Rosi-Marshall, Theodore A. Kennedy, W.F. Cross, C.V. Baxter
Turbidity, light, temperature, and hydropeaking control primary productivity in the Colorado River, Grand Canyon Turbidity, 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...
Authors
Robert O. Hall, Charles Yackulic, Theodore A. Kennedy, Michael D. Yard, Emma Rosi-Marshall, Nicholas Voichick, Kathrine Behn
Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America Flow 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...
Authors
Kimberly Dibble, Charles Yackulic, Theodore A. Kennedy, Phaedra Budy
Building a better sticky trap: description of an easy-to-use trap and pole mount for quantifying the abundance of adult aquatic insects 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...
Authors
Joshua Smith, Theodore A. Kennedy, Jeffrey Muehlbauer
High diet overlap between native small-bodied fishes and nonnative fathead minnow in the Colorado River, Grand Canyon, Arizona High 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...
Authors
Sarah E. Zahn Seegert, Emma Rosi-Marshall, Colden V. Baxter, Theodore A. Kennedy, Robert O. Hall, Wyatt Cross
Barcodes are a useful tool for labeling and tracking ecological samples Barcodes 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...
Authors
Adam Copp, Theodore Kennedy, Jeffrey Muehlbauer
The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river The 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...
Authors
Theodore A. Kennedy, Charles Yackulic, Wyatt Cross, Paul Grams, Michael D. Yard, Adam Copp
Food-web dynamics in a large river discontinuum Food-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...
Authors
Wyatt Cross, Colden V. Baxter, Emma Rosi-Marshall, Robert O. Hall, Theodore A. Kennedy, Kevin Donner, Holly A. Wellard Kelly, Sarah Seegert, Kathrine Behn, Michael D. Yard
Native and nonnative fish populations of the Colorado River are food limited--evidence from new food web analyses Native 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...
Authors
Theodore A. Kennedy, Wyatt Cross, Robert O. Hall, Colden V. Baxter, Emma Rosi-Marshall
Macroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam Macroinvertebrate 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...
Authors
Holly Wellard Kelly, Emma Rosi-Marshall, Theodore A. Kennedy, Robert O. Hall, Wyatt Cross, Colden V. Baxter
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 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
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...
Authors
Theodore A. Kennedy
Abiotic & biotic responses of the Colorado River to controlled floods at Glen Canyon Dam, Arizona, USA Abiotic & 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...
Authors
Josh Korman, Ted Melis, Theodore A. Kennedy
Non-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.