Bug Flows: Improving Food Web Health on the Colorado River Active
Flow Management for Hydropower Extirpates Aquatic Insects, Undermining River Food Webs
Journal article in BioScience
Water experiment to be conducted along the Colorado River while maintaining hydropower production this summer
Bureau of Reclamation news release
Native and desired nonnative fish downstream of Glen Canyon Dam are food limited—meaning that if more or larger invertebrate food items were available, there would be more and larger fish. Aquatic insects have complex life cycles that include egg, larvae, and pupal stages that are aquatic while adults have wings and are typically terrestrial. Aquatic insects are a fundamental component of river food webs and the primary prey for fish and many species of birds, lizards, fish, and even other invertebrates. Identifying the factors that limit production and diversity of the insect prey base is important when making management decisions, especially when those decision affect endangered species, like humpback chub (Gila cypha).
In rivers, many aquatic insects lay their eggs right at the water line. In pre-dam era, water levels did not vary much on hourly or daily time scales, so this strategy ensured that eggs would stay submerged long enough to hatch. However, because of hydropower production at Glen Canyon Dam, the river now experiences a daily “tide” as more water is released during daylight hours to meet higher demand for electricity during the day. Then at night, when energy demand is lower, less water is released from the dam resulting in a drop in water levels. The magnitude of this tide during summer months is 2-3 feet, depending on location. Insect eggs laid along the high-water mark become desiccated and die, typically within a few hours, when river flows drop. USGS research has shown that these daily high and low tides created by hydropower operations are an important factor that contributes to the low abundance and diversity of aquatic insects in Grand Canyon.
Bug flows are experimental releases from Glen Canyon Dam that were designed to increase the abundance (number of individuals) and the diversity (number of types) of insects in Grand Canyon by improving egg laying conditions for insects. The Bug Flow experiment was tested at Glen Canyon Dam on weekends from May through August of 2018-2020 and in 2022. During the experiment, hydropower operations continued as normal during weekdays, resulting in daily tides. On weekends, however, a steady low-flow was released from the dam to try to improve egg laying conditions for aquatic insects. Because demand for electricity is typically low during weekends, the design of the Bug Flow experiment improves egg laying conditions for insects while minimizing negative impacts to hydropower production. The goal of the Bug Flow experiment is to support healthier wildlife populations through increases in the production and diversity of the aquatic insect prey base.
News & Multimedia
External multimedia
- PODCAST: Making Waves River guides are science guides
- PODCAST: BioScience Hydroelectric dams kill insects, wreak havoc with food webs
- PODCAST:Science Moab Aquatic insects of Grand Canyon
- FILM: Freshwaters Illustrated Citizen Science in Grand Canyon
- FILM: Freshwaters Illustrated What you take away Featured in National Geographic
- STORYMAP: Grand Canyon Youth Splashing into Science
In the news
- PBS News Hour (2022) Not all scientists wear lab coats. Volunteers are fueling research nationwide.
- Bureau of Reclamation (2020) Water experiment to be conducted along the Colorado River while maintaining hydropower production this summer
- Associated Press (2019) Changing water flow leads to more bugs in Grand Canyon
- Scientific American (2019) Re-engineering the Colorado River to Save the Grand Canyon
- Associated Press (2018) Scientists hope bug experiment fattens Colorado River fish
- Undark Magazine (2018) Essay about conducting aquatic ecology research in Grand Canyon.
- Science (2016) Scientific reinterpretation of the BioScience hydropeaking paper.
- Arizona Daily Sun (2016) Glen Canyon Dam plan aims to boost native fish, bugs
- National Public Radio KNAU (2016) Study: Hydropower decimates aquatic insects on the Colorado River
- High Country News (2016) New measures could reduce Glen Canyon Dam's impacts on the Grand Canyon - a bit..
- Columbia Basin Bulletin (2016) Study: 'Hydropeaking' of river water levels disrupting insect survival, river ecosystems
- American Fisheries Society (2016) Citizen science reveals how river food webs are affected by hydropower practices
- Conservation Magazine (2016) A hydropeak tweak could make dams less damaging
- USGS press release (2016) River foodwebs threatened by widespread hydropower practice: alternative flows might mitigate negative impacts
- Oregon State University (2016) Hydropeaking of river water levels is disrupting insect survival, river ecosystems
- SciStarter (2014) Is our thirst for energy killing the ecology of the Grand Canyon?
Below are other science projects associated with this project.
Community Science in Grand Canyon
Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
Aquatic Insects
Below are publications associated with this project.
Flow management for hydropower extirpates aquatic insects, undermining river food webs
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
Aquatic–terrestrial linkages provide novel opportunities for freshwater ecologists to engage stakeholders and inform riparian management
Pulsed flows, tributary inputs, and food web structure in a highly regulated river
Deleterious effects of net clogging on the quantification of stream drift
Below are partners associated with this project.
- Overview
Native and desired nonnative fish downstream of Glen Canyon Dam are food limited—meaning that if more or larger invertebrate food items were available, there would be more and larger fish. Aquatic insects have complex life cycles that include egg, larvae, and pupal stages that are aquatic while adults have wings and are typically terrestrial. Aquatic insects are a fundamental component of river food webs and the primary prey for fish and many species of birds, lizards, fish, and even other invertebrates. Identifying the factors that limit production and diversity of the insect prey base is important when making management decisions, especially when those decision affect endangered species, like humpback chub (Gila cypha).
In rivers, many aquatic insects lay their eggs right at the water line. In pre-dam era, water levels did not vary much on hourly or daily time scales, so this strategy ensured that eggs would stay submerged long enough to hatch. However, because of hydropower production at Glen Canyon Dam, the river now experiences a daily “tide” as more water is released during daylight hours to meet higher demand for electricity during the day. Then at night, when energy demand is lower, less water is released from the dam resulting in a drop in water levels. The magnitude of this tide during summer months is 2-3 feet, depending on location. Insect eggs laid along the high-water mark become desiccated and die, typically within a few hours, when river flows drop. USGS research has shown that these daily high and low tides created by hydropower operations are an important factor that contributes to the low abundance and diversity of aquatic insects in Grand Canyon.
Bug flows are experimental releases from Glen Canyon Dam that were designed to increase the abundance (number of individuals) and the diversity (number of types) of insects in Grand Canyon by improving egg laying conditions for insects. The Bug Flow experiment was tested at Glen Canyon Dam on weekends from May through August of 2018-2020 and in 2022. During the experiment, hydropower operations continued as normal during weekdays, resulting in daily tides. On weekends, however, a steady low-flow was released from the dam to try to improve egg laying conditions for aquatic insects. Because demand for electricity is typically low during weekends, the design of the Bug Flow experiment improves egg laying conditions for insects while minimizing negative impacts to hydropower production. The goal of the Bug Flow experiment is to support healthier wildlife populations through increases in the production and diversity of the aquatic insect prey base.
News & Multimedia
External multimedia
- PODCAST: Making Waves River guides are science guides
- PODCAST: BioScience Hydroelectric dams kill insects, wreak havoc with food webs
- PODCAST:Science Moab Aquatic insects of Grand Canyon
- FILM: Freshwaters Illustrated Citizen Science in Grand Canyon
- FILM: Freshwaters Illustrated What you take away Featured in National Geographic
- STORYMAP: Grand Canyon Youth Splashing into Science
In the news
- PBS News Hour (2022) Not all scientists wear lab coats. Volunteers are fueling research nationwide.
- Bureau of Reclamation (2020) Water experiment to be conducted along the Colorado River while maintaining hydropower production this summer
- Associated Press (2019) Changing water flow leads to more bugs in Grand Canyon
- Scientific American (2019) Re-engineering the Colorado River to Save the Grand Canyon
- Associated Press (2018) Scientists hope bug experiment fattens Colorado River fish
- Undark Magazine (2018) Essay about conducting aquatic ecology research in Grand Canyon.
- Science (2016) Scientific reinterpretation of the BioScience hydropeaking paper.
- Arizona Daily Sun (2016) Glen Canyon Dam plan aims to boost native fish, bugs
- National Public Radio KNAU (2016) Study: Hydropower decimates aquatic insects on the Colorado River
- High Country News (2016) New measures could reduce Glen Canyon Dam's impacts on the Grand Canyon - a bit..
- Columbia Basin Bulletin (2016) Study: 'Hydropeaking' of river water levels disrupting insect survival, river ecosystems
- American Fisheries Society (2016) Citizen science reveals how river food webs are affected by hydropower practices
- Conservation Magazine (2016) A hydropeak tweak could make dams less damaging
- USGS press release (2016) River foodwebs threatened by widespread hydropower practice: alternative flows might mitigate negative impacts
- Oregon State University (2016) Hydropeaking of river water levels is disrupting insect survival, river ecosystems
- SciStarter (2014) Is our thirst for energy killing the ecology of the Grand Canyon?
- Science
Below are other science projects associated with this project.
Community Science in Grand Canyon
Aquatic insects are important components of riverine foodwebs as they are prey for fish, birds, bats, lizards, and spiders. The closure of Glen Canyon Dam in 1963 fundamentally altered the hydrology, water temperature, and turbidity of the Colorado River through Grand Canyon. These changes, along with competition with invasive species and limited food availability have led to the decline and...Is timing really everything? Evaluating Resource Response to Spring Disturbance Flows
Glen Canyon Dam has altered ecological processes of the Colorado River in Grand Canyon. Before the dam was built, the Colorado River experienced seasonable variable flow rates, including springtime flooding events. These spring floods scoured the river bottom and enhanced natural processes that sustained the Colorado River ecosystem. Since the dam’s construction in 1963, springtime floods have...Aquatic Insects
Aquatic insects live in the water as larvae most of their lives, then emerge onto land for a brief period as winged adults. Sampling these emerged adults on land is therefore a useful tool for understanding the condition of the aquatic insect population that is in the water, particularly in large rivers where sampling the larvae on the river bed is impractical. Our group uses a variety of methods... - Publications
Below are publications associated with this project.
Flow 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. BaxterSpatial 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 KennedyAquatic–terrestrial linkages provide novel opportunities for freshwater ecologists to engage stakeholders and inform riparian management
Studies of aquatic–terrestrial ecosystem linkages explore the mechanisms by which components of one ecosystem, such as the aquatic insect community in a stream, directly affect components of an adjacent ecosystem, such as the density and diversity of riparian predators. On a human level, research into these linkages allows freshwater ecologists to form novel collaborations with stakeholders and otAuthorsJeffrey Muehlbauer, Christina A. Lupoli, Johanna M. KrausPulsed 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. 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. Sabol - Partners
Below are partners associated with this project.