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U.S. Department of the Interior U.S. Geological Survey Dammed and Adrift: Patterns of invertebrate drift throughout Colorado River Basin tailwaters Jeff Muehlbauer, Ted Kennedy Grand Canyon Monitoring and Research Center, Southwest Biological Science Center, USGS
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What is invertebrate drift? (And why should you care?) Entrainment of bugs in water column Critical life stage/behavior Food for fish Mmm, drifting bugs…
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Key components of drift Related to time of day Related to discharge (floods/seasonality) Need benthic source population
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But that’s for small, “natural” streams What about drift in a large-river, consistently cold-temperature, fluctuating water-level, no source-population environment? AKA, a Tailwater
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Key components of drift Related to time of day Related to flow (floods/seasonality) Need benthic source population Dam tailwaters ? ? Dam
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Drift in tailwaters Measureable response to dam impacts Drift still fundamental, even in tailwaters Does flow manipulation affect downstream recovery? How do flows alter community dynamics?
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Glen Canyon Dam, Grand Canyon, Arizona 0 EPT taxa. Only 2 insects Drift related to distance downstream River mile # / m 3 Accumulation with distance from Dam 0 (Dam) 51015 0 (Dam) 51015 One “unique” ecosystem Big dam Big river Big canyon Is this normal for tailwaters? How can we tell?
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Sampling drift 6 tailwaters in Colorado River Basin X X X X X X X Fontenelle Flaming Gorge Navajo Glen Canyon Hoover Davis Parker
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Sampling drift 6 tailwaters in Colorado River Basin 15-mile reaches, sampled every mile
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Sampling drift 6 tailwaters in Colorado River Basin 15-mile reaches, sampled every mile Spring, summer, fall 2015
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Sampling drift 6 tailwaters in Colorado River Basin 15-mile reaches, sampled every mile Spring, summer, fall 2015 Also collected benthics -- Erin Abernethy, P119 (poster session tonight!!)
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Are there seasonal patterns to the data? 59,378 invertebrates later… Yes! But bigger story is dam-to-dam variation
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Is downstream recovery consistent? Dam-to-dam variation Not at all! Local factors hugely important Sediment loading Trib inflow Blackfly abatement
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Does context matter? Dams vary notably in several ways TailwaterLatitudeDischarge (Q)HI Fontenelle42.02460.01 Navajo36.81100.02 Flaming Gorge40.91540.13 Glen Canyon36.943600.17 Davis35.205210.36 Parker34.303340.40 Hoover36.014120.56 HI: Hydropeaking index = mean daily CV in Q (Dibble et al. 2015 EcoApps)
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Response metric Focusing on ratio of insects : non-insects (for now) Insects: Egg-laying vulnerable to hydropeaking Kennedy et al. 2016 BioScience Talk Wed. 13:45, S10 :
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Latitude Meh
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Discharge Well, it’s better than latitude
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Hydropeaking Index (HI) Darn good predictor Matters far more than latitude or Q (classic predictors)
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Summary Season and context affect tailwater drift Still searching for “unified theory of tailwaters” Hydropeaking bad for insects Not such a big deal for non-insects? Season Context Hydropeaking
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Thanks to a startlingly large group of really smart, good people USGS Flyco lab: Adam Copp, Moriah Evans, Anya Metcalfe, Tom Quigley, Eric Kortenhoeven, Ali Ingram, Dallana Garcia-Pena, David Goodenough, Megan Daubert, Dave Foster, Kim Dibble USU Bug Lab: Scott Miller, Matt Schroer OSU Lab: Dave Lytle, Erin Abernethy, Richard Van Driesche …and Colden Baxter Funding from: US Bureau of Reclamation Western Area Power Administration
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Related SFS 2016 presentations on hydropeaking in Colorado River Basin tailwaters Scott Miller: C10, Sun, 14:00 Anya Metcalfe: S22, Mon, 14:00 Moriah Evans: S25, Poster 73 Erin Abernethy: C06, Poster 119 Jesse Fleri: C06, Poster 118 Ted Kennedy: S10, Wed, 13:45 Holy cow, you can still see these!
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