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Metcalfe, A.N., T.A. Kennedy, G.A. Mendez and J.D. and Muehlbauer. 2022. Applied citizen science in freshwater research. WIREs Water e1578:1-11. https://doi.org/10.1002/wat2.1578
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Abstract
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Publisher Website
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January 2022
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Worldwide, scientists are increasingly collaborating with the general public. Citizen science methods are readily applicable to freshwater research, monitoring, and education. In addition to providing cost-effective data on spatial and temporal scales that are otherwise unattainable, citizen science provides unique opportunities for engagement with local communities and stakeholders in resource management and decision-making. However, these methods are not infallible. Citizen science projects require deliberate planning in order to collect high data quality and sustain meaningful community partnerships. Citizen science practitioners also have an ethical responsibility to ensure that projects are not putting the safety of participants at stake. We discuss here how citizen science is being applied in freshwater research, emerging challenges in project planning and implementation, as well as how citizen science is shaping public understanding, policy, and management of freshwaters.
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Metcalfe, A. N., J. D. Muehlbauer, M. A. Ford, and T. A. Kennedy. 2023. Colorado River Basin. Pages 462-509 in M. D. Delong, T. D. Jardine, A. C. Benke and C. E. Cushing (editors). Rivers of North America. Academic Press, San Diego, California, USA.
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April 2023
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Metcalfe, A. N., C. A. Fritzinger, T. J. Weller, M. J. Dodrill, J. D. Muehlbauer, C. B. Yackulic, P. B. Holton, C. M. Szydlo, L. E. Durning, J. B. Sankey, and T. A. Kennedy. 2023. Insectivorous bat foraging tracks the availability of aquatic flies (Diptera). The Journal of Wildlife Management 87:e22414. https://doi.org/https://doi.org/10.1002/jwmg.22414
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Abstract
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May 2023
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Approximately 70% of bats are insectivores and are commonly observed foraging over rivers and streams, presumably feeding on emergent aquatic insects. In this study, we collaborated with recreational river runners and other citizen scientists in Grand Canyon, Arizona, USA to record bat activity and sample riparian insects for one hour at dusk from April through October in 2017-2020. Citizen scientists collected 1,428 paired samples on 611 sampling nights at 410 sampling sites throughout a 470 km segment of river. Light traps collected a total of 71 insect taxa and acoustic monitors detected 19 bat species. We hypothesized that bat activity would be positively related to insect catch rates. Additionally, we predicted that bat activity in the riparian zone would be unrelated to terrestrial insect abundance. We fit Bayesian regression models to test these hypotheses as well as other competing hypotheses regarding the potential effects of quantify the relation between and environmental variables including time-of-year, time-of-day, distance downstream from Glen Canyon Dam, channel width, riparian vegetation density, air temperature, and lunar phase. We found that bat activity was positively related to the abundance of aquatic flies (Diptera), which outcompeted other prey categories in our models. We also found that activity of small Myotis (Myotis californicus and M. yumanensis) was higher later in the evening and that canyon bats (Parastrellus hesperus), conversely, were more active earlier in the evening. Activity of canyon bats also varied seasonally, with peak activity in August. Our results highlight the importance of aquatic flies as prey for bats along a large, regulated river corridor and demonstrate the power of citizen science as a tool for ecosystem monitoring.
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Kennedy, T.A., A.N. Metcalfe, B.R. Deemer, M.A. Ford, C.M. Szydlo, C.B. Yackulic, and J.D. Muehlbauer. 2022. Little bugs, big data, and Colorado River adaptive management—Preliminary findings from the ongoing bug flow experiment at Glen Canyon Dam. Boatman's Quarterly Review. 35:26-31.
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Publisher Website
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October 2022
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Deemer, B.R., C.B. Yackulic, R.O. Hall, M.J. Dodrill, T.A. Kennedy, J.D. Muehlbauer, D.J. Topping, N. Voichick, and M.D. Yard. 2022. Experimental reductions in sub-daily flow fluctuations increased gross primary productivity for 425 river kilometers downstream. Proceedings of the National Academy of Sciences Nexus pgac094. https://doi.org/10.1093/pnasnexus/pgac094
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Abstract
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Publisher Website
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June 2022
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Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves sub-daily changes in water releases proportional to fluctuations in electrical power demand. This flow regime causes an artificial tide, wetting and drying channel margins and altering river depth and water clarity, all processes that are likely to affect primary production. In collaboration with dam operators, we designed an experimental flow regime whose goal was to mitigate negative effects of load following on ecosystem processes. The experimental flow contrasted steady-low flows on weekends with load following flows on weekdays. Here, we quantify the effect of this experimental flow on springtime gross primary production (GPP) 90-to-425 km downstream of Glen Canyon Dam on the Colorado River, AZ, USA. GPP during steady-low flows was 41% higher than during load following flows, mostly owing to non-linear reductions in sediment-driven turbidity. The experimental flow increased weekly GPP even after controlling for variation in weekly mean discharge, demonstrating a negative effect of load following on GPP. We estimate that this environmental flow increased springtime carbon fixation by 0.27 g C m<sup>–2</sup> d<sup>–1</sup>, which is ecologically meaningful considering median C fixation in 356 U.S. rivers of 0.44 g C m<sup>–2</sup> d<sup>–1</sup> and the fact that native fish populations in this river are food-limited.
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Abernethy, E.F., J.D. Muehlbauer, T.A. Kennedy, J.D. Tonkin, R. Van Driesche and D.A. Lytle. 2021. Hydropeaking intensity and dam proximity limit aquatic invertebrate diversity in the Colorado River Basin. Ecosphere 12: e03559, 1-12. https://doi.org/10.1002/ecs2.3559
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Abstract
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Publisher Website
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June 2021
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River biodiversity is threatened globally by hydropower dams, and there is a need to understand how dam management favors certain species while filtering out others. We examined aquatic invertebrate communities within the tailwaters 0–24 km downstream of seven large hydropower dams in the Colorado River Basin of the western United States. We quantified aquatic invertebrate dominance, richness, abundance, and biomass at multiple locations within individual tailwaters and across the basin and identified biological community responses associated with dam operations and distance from dam. We found that each tailwater was dominated by 3–7 invertebrate taxa, accounting for 95% of total abundance. Half of these dominant taxa were non-insect, non-flying species and thus were unavailable to terrestrial consumers. Consistent with previous studies, aquatic insects and sensitive taxa were negatively associated with hydropeaking intensity (magnitude of daily flow fluctuations associated with hydropower generation), which limits the composition and potentially the quality of the invertebrate food base. While total invertebrate abundance and biomass did not change with increasing distance downstream from dams, insect and sensitive taxa richness, abundance, and biomass all increased, suggesting that impacts of hydropeaking are most acute immediately downstream of dams. Our results demonstrate that tailwaters experiencing hydropeaking support high abundances of aquatic invertebrate, but the diversity of these communities is low.
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Abernethy, E. F., J. D. Muehlbauer, T. A. Kennedy, K. E. Dziedzic, H. Elder, M. K. Burke, and D. A. Lytle. 2023. Population connectivity of aquatic insects in a dam‐regulated, desert river. River Research and Applications 39:364-374. https://doi.org/10.1002/rra.3972
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Abstract
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Publisher Website
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March 2023
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Humans have exaggerated natural habitat fragmentation, negatively impacting species dispersal and reducing population connectivity. Habitat fragmentation can be especially detrimental in freshwater populations, whose dispersal is already constrained by the river network structure. Aquatic insects, for instance, are generally limited to two primary modes of dispersal: downstream drift in the aquatic juvenile life stages and flight during the terrestrial winged adult stage. Yet the impacts of large hydropower dams can make rivers uninhabitable for incoming (drifting) juvenile insects, with remaining refugia found only in tributaries. The ability of adult aquatic insects to traverse such river stretches in search of suitable tributary habitat likely depends on factors such as species-specific dispersal ability and distance between tributaries. To explore the intersection of natural and human-induced habitat fragmentation on aquatic insect dispersal ability, we quantified population genetics of three taxa with varying dispersal abilities, a caddisfly (Hydropsychidae, <i>Hydropsyche oslari</i>), a mayfly (Baetidae: <i>Fallceon quilleri</i>), and a water strider (Veliidae: <i>Rhagovelia distincta</i>), throughout tributaries of the Colorado River in the Grand Canyon, Arizona, USA. Using 2bRAD reduced genome sequencing and landscape genetics analyses, we revealed a strong pattern of isolation by distance among mayfly populations. This contrasts with caddisfly and water strider populations, which were largely panmictic. Analysis of thousands of informative single nucleotide polymorphisms showed that realized dispersal ability may not be accurately predicted by species traits for these widespread species. Principal components analysis revealed a strong division between caddisfly populations upstream and downstream of Havasu Creek (279 km through the 390 km study reach), suggesting that the geography of the Grand Canyon imposes a dispersal barrier for this species. Our use of genetic tools in the Grand Canyon to understand population structure has enabled us to elucidate dispersal barriers for aquatic insects. Ultimately, these data may be useful in informing effective conservation management plans for understudied organisms of conservation interest.
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