FOOD BASE

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The Aquatic Food Base below Glen Canyon Dam The Colorado River below Glen Canyon Dam has been altered by dam-induced modifications to the river’s flow, temperature, and sediment supply. Nonnative species have also changed the natural system. Nonnative fish are thought to prey on and compete with native fish, including the endangered humpback chub (Gila cypha). These impacts have likely changed both the amount and sources of energy that fuel the aquatic food web and the flows of energy within the food web. Installation of the dam created a relatively clear, cool aquatic environment below the dam that now allows aquatic plants to capture the sun’s energy, and they in turn are now consumed by a few species, including scuds (Gammarus lacustris), midges (Family: Chironomidae), blackflies (Simulium arcticum), and New Zealand mudsnails (Potamopyrgus antipodarum). The first three species can provide food for both native and nonnative fishes, but fish cannot digest the New Zealand mudsnail. Desired Future Condition for the Aquatic Food Base The aquatic food base will sustainably support viable populations of desired species at all trophic levels. Assure that an adequate, diverse, productive aquatic foodbase exists for fish and other aquatic and terrestrial species that depend on those food resources.

EPT as Biologic Indicators of Stream Condition	Algae and Aquatic Macrophytes	Aquatic Macroinvertebrates

Updates https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR19_Kennedy.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR19_Kennedy.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR19_Kennedy.pdf https://www.usbr.gov/uc/rm/amp/twg/mtgs/17jan26/AR19_Kennedy.pdf

Links and Information GCMRC Aquatic Food Base Lab USU Buglab USU Aquatic Macroinvertebrate Key Freshwater Macroinvertebrates of NY Algae and Aquatic Macrophytes Page Nutrients Page Humpback Chub Page Lees Ferry Rainbow Trout Fishery Page Foodbase Projects Oviposition and Egg Desiccation Studies Foodwebs and Bioenergetics Studies Measuring Primary Production in the Lees Ferry Reach The BugFlow Experiment Citizen Science Insect Monitoring Hyporheic Anoxia in the Lees Ferry Reach Downstream Recovery of the Foodbase Community in Several Colorado River Tailwaters Drift and Food Availability Studies Foodbase PEP 2001 Foodbase PEP 2004 Foodbase PEP Papers and Presentations 2018 Caddisfly outbreak on the Colorado River below Davis Dam Laughlin NV / Bullhead City AZ Colorado River Benthic Foodbase Studies in Glen and Grand Canyons PPT (Tapeats Creek study) Shedding light on aquatic insects of the Colorado River Basin with citizen science PPT Colorado River Benthic Foodbase Studies in Glen and Grand Canyons: Anoxic substrates and Tapeats Creek studies PPT Aquatic invertebrate drift patterns downstream of Colorado River Basin dams Sabo et al., 2018, Pulsed flows, tributary inputs, and food web structure in a highly regulated river: Journal of Applied Ecology 2017 Walters et al., 2017, A digital reference collection for aquatic macroinvertebrates of North America: Freshwater Science, v. 36, no. 4, p. 693-697 Muehlbauer et al. 2016. Deleterious effects of net clogging on the quantification of stream drift: Canadian Journal of Fisheries and Aquatic Sciences Fluvial Aquatic Ecology of the Colorado River (… especially Lees Ferry) Floods, Flows and the Aquatic Foodbase PPT The Grand Beyond: Aquatic Foodbase of the Upper Colorado River Basin 2016 Kennedy et al. 2016. Flow Management for Hydropower Extirpates Aquatic Insects, Undermining River Food Webs. BioScience Grand Canyon Monitoring and Research Center Science Updates (BO Compliance, Trout Updates, Green Sunfish, Fisheries PEP, Partners in Science) Aquatic Foodbase of the Little Colorado River 2015 Walters et al. 2015. Mercury and selenium accumulation in the Colorado River food web, Grand Canyon, USA. Environmental Toxicology and Chemistry Invertebrate drift in Glen Canyon 2007-2013 2014 Citizen Science Insect Monitoring: A Powerful Tool for Detecting Ecosystem Change Science Updates - Recent Research on Sand, Bugs, and Fish Foodbase Enhancement Suggestions from Federation of Fly Fishers Foodbase Findings Low flows in Glen Canyon: preliminary geomorphic analysis of the potential effects on fish and food base (Melis) 2013 Kennedy et al. 2013. The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river. Freshwater Biology. Wellard-Kelly et al. 2013. Macroinvertebrate diets reflect tributary inputs and turbidity-driven changes in food availability in the Colorado River downstream of Glen Canyon Dam. Freshwater Science, 32(2):397-410. 2013. Miller and Judson. 2013. Responses of macroinvertebrate drift, benthic assemblages, and trout foraging to hydropeaking. Can. J. Fish. Aquat. Sci. 71: 675–687 GCMRC Update - Status of Resources and Sediment Conditions Annual Reporting Meeting: Foodbase Update Foodbase Update 2012 Temperatures, TCD, and Food Base Final Report of the Aquatic Food Base Study and Protocol Evaluation Panel and PPT Long-term Food Web and Ecosystem Monitoring Foodbase Monitoring and Research: Response to PEP PPT GCMRC Updates and PPT Food Base 2011 KA2 2011 Cross et al. 2011. Ecosystem ecology meets adaptive management: Food web response to a controlled flood on the Colorado River, Glen Canyon. Ecological Applications, 21(6), 2011, pp. 2016–2033 2010 Wellard-Kelly, 2010, Resource Composition and Macroinvertebrate Resource Consumption in the Colorado River Below Glen Canyon Dam. Master's Theses. McKinney et al., 2010, Macroinvertebrate drift in the tailwater of a regulated river below Glen Canyon Dam, Arizona. The Southwestern Naturalist Cross et al. 2010. Invasion and production of New Zealand mud snails in the Colorado River, Glen Canyon. Biol Invasions Short-Term Effects of the 2008 High-Flow Experiment on Macroinvertebrates in Colorado River Below Glen Canyon Dam, Arizona Basal Resources in Backwaters of the Colorado River Below Glen Canyon Dam—Effects of Discharge Regimes and Comparison with Mainstem Depositional Environments 2009 Blinn and Ruiter, 2009, "Caddisfly (Trichoptera) assemblages along major river drainages in Arizona," Western North American Naturalist Oberlin et al., 2009, Watershed Influence on the Macroinvertebrate Fauna of Ten Major Tributaries of the Colorado River through Grand Canyon, Arizona. The Southwestern Naturalist AIF: Grand Canyon Monitoring and Research Center (GCMRC) Update Grand Canyon Monitoring and Research Center updates by Program Managers 2002 Haden et al. 2002. Benthic community structure of the Green and Colorado Rivers through Canyonlands National Park, Utah, USA. The Southwestern Naturalist 2001 Shannon et al. 2001. Aquatic food base response to the 1996 test flood below Glen Canyon Dam, Colorado River, Arizona. Ecological Applications, 11(3), 2001, pp. 672–685. 2000 Blinn et al. 2000. Environmental Conditions Associated with Cladophora glomerata, Oscillatoria spp and Miscellaneous Algae, Macrophytes, and Bryophytes (MAMB). Report to GCMRC. 1999 Oberlin, G. E., J. P. Shannon, and D. W. Blinn. 1999. Watershed influence on the macroinvertebrate fauna of ten major tributaries of the Colorado River through Grand Canyon, Arizona. Southwestern Naturalist 44:17–30. Haden, G. A., D. W. Blinn, and J. P. Shannon. 1999. Driftwood: an alternative habitat for macroinvertebrates in a large southwestern river. Hydrobiologia 397:179–186. Oberlin et al. Watershed influence on the macroinvertebrate fauna of ten major tributaries of the Colorado River through Grand Canyon, Arizona. The Southwestern Naturalist 44(1):17-30. 1998 Stevens, L. E., J. P. Shannon, and D. W. Blinn. 1998. Colorado river benthic ecology in Grand Canyon, Arizona, USA: dam, tributary and geomorphological influences. Regulated Rivers. Blinn et al. 1998. Algal ecology in the tailwater stream communities: The Colorado River below Glen Canyon Dam, Arizona. J, Phycol. M, 734-740 (1998) Stevens et al. 1998. Chironomidae (Diptera) of the Colorado River, Grand Canyon, Arizona, USA, II: factors influencing distribution. Great Basin Naturalist: Vol. 58: No. 2, Article 2 1997 Stevens, L. E., J. P. Shannon, and D. W. Blinn. 1997. Colorado River benthic ecology in Grand Canyon, Arizona, USA: dam, tributary and geomorphological influences. Regulated Rivers: Research and Management 13:129–149. Shaver et al. Effects of suspended sediment and desiccation on the benthic tailwater community in the Colorado River, USA. Hydrobiologia 357: 63–72, 1997. Stevens et al. 1997. Colorado River benthic ecology in Grand Canyon, Arizona, USA: Dam, tributary, and gomorphological influences. Regulated Rivers: Research and Management, Vol. 13, 129–149 (1997) 1994 Shannon et al. 1994. Trophic interactions and benthic animal community structure in the Colorado River, Arizona, U.S.A. Freshwater Biology 31(2):213 - 220. 1991 Blinn, D. W. and G. A. Cole. 1991. Algal and invertebrate biota in the Colorado River: comparison of pre- and post-dam conditions. In: National Research Council, editor, Colorado River ecology and dam management. National Academy Press, Washington, D.C. Pp. 102–123. Haury 1991. Zooplankton of the Colorado River: Glen Canyon Dam to Diamond Creek Blinn and Cole. 1991. Algal and Invertebrate Biota in the Colorado River: Comparison of Pre- and Post-Dam Conditions. In Colorado River Ecology and Dam Management. 1990 Blin and Cole, 1990, Algal and Invertebrate Biota in the Colorado River: Comparison of Pre- and Post-Dam Conditions 1981 Carothers and Minckley. 1981. A survey of the aquatic flora and fauna of the Grand Canyon: A Survey of the Fishes, Aquatic Invertebrates and Aquatic Plants of the Colorado River and Selected Tributaries form Lee Ferry to Separation Rapids. Final Report to DOI 1959 Woodbury et al. 1959. Ecological Studies of the Flora and Fauna in Glen Canyon. Anthropological Papers (Glen Canyon Series Number 7) ,40. Salt Lake City, Ut: University of Utah Press. Other Stuff The interaction of fish, foodbase, and temperature Fish occupying warmer water have higher metabolic demands than individuals in cooler water, and if these demands increase concurrently with a seasonal decline in prey availability, then growth rates may be reduced. [1] Black Flies and Midges fuel fish production below Glen Canyon Dam. Black Flies and Midges respond positively to spring HFE's. Mud Snails were introduced below Glen Canyon Dam around 1995. Notably, several species of cold-tolerant nonnative invertebrates were intentionally introduced into the Colorado River after Glen Canyon Dam was closed in 1963. Altogether 10,000 immature mayflies were secured from a commercial source in Minnesota and released at three sites in the Lees Ferry reach. Also, 10,000 snails, 5,000 leeches, and thousands of insects representing at least 10 families were transported from the San Juan River in New Mexico to the river near Lees Ferry. In addition, 50,000 “scuds” (Gammarus lacustris) were introduced into Bright Angel Creek in 1932 and at Lees Ferry and below the dam in 1968, in addition to 2,000 crayfish taken from the LCR near Springerville, AZ (Blinn and Cole 1991). Gammarus lacustris has thrived in the cold, clear reaches below the dam, but the fate of the other introduced species is unknown.