Light and flow regimes regulate the metabolism of rivers

Bernhardt, Emily S.; Savoy, P.; Vlah, Michael J.; Appling, Alison P.; Koenig, Lauren E.; Hall, Robert O.; Arroita, Maite; Blaszczak, Joanna R.; Carter, Alice M.; Cohen, M. J.; Harvey, Judson W.; Heffernan, James B.; Helton, Ashley M.; Hosen, Jacob D.; Kirk, Lily; McDowell, William H.; Stanley, Emily H.; Yackulic, Charles B.; Grimm, Nancy B.

doi:10.1073/pnas.2121976119

Cited by 95 publications

(105 citation statements)

References 44 publications

(67 reference statements)

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“…Water temperature is a key environmental variable linked to stream primary productivity, macroinvertebrate trait-based sensitivities, and growth rates for fishes (for primary productivity Bernhardt et al, 2022;for macroinvertebrates Poff et al, 2006;in fishes Bjornin and Reiser, 1991). Cold-water fishes are of particular management concern at restoration sites in the Pacific Northwest because many species of salmon and trout listed under the U.S.…”

Section: Water Temperaturementioning

confidence: 99%

Rehabilitating Valley Floors to a Stage 0 Condition: A Synthesis of Opening Outcomes

Flitcroft

Brignon

Staab

et al. 2022

Front. Environ. Sci.

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Degraded floodplains and valley floors are restored with the goal of enhancing habitat for native fish and aquatic-riparian biota and the protection or improvement of water quality. Recent years have seen a shift toward “process-based restoration” that is intended to reestablish compromised ecogeomorphic processes resulting from site- or watershed-scale degradation. One form of process-based restoration has developed in the Pacific Northwest, United States, that is intended to reconnect rivers to their floodplains by slowing down flows of sediment, water, and nutrients to encourage lateral and vertical connectivity at base flows, facilitating development of dynamic, self-forming, and self-sustaining river-wetland corridors. Synergies between applied practices and the theoretical work of Cluer and Thorne in 2014 have led this form of restoration to be referred to regionally as restoration to a Stage 0 condition. This approach to rehabilitation is valley scale, rendering traditional monitoring strategies that target single-thread channels inadequate to capture pre- and post-project site conditions, thus motivating the development of novel monitoring approaches. We present a specific definition of this new type of rehabilitation that was developed in collaborative workshops with practitioners of the approach. Further, we present an initial synthesis of results from monitoring activities that provide a foundation for understanding the effects of this approach of river rehabilitation on substrate composition, depth to groundwater, water temperature, macroinvertebrate richness and abundance, secondary macroinvertebrate production, vegetation conditions, wood loading and configuration, water inundation, flow velocity, modeled juvenile salmonid habitat, and aquatic biodiversity.

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Section: Water Temperaturementioning

confidence: 99%

Rehabilitating Valley Floors to a Stage 0 Condition: A Synthesis of Opening Outcomes

Flitcroft

Brignon

Staab

et al. 2022

Front. Environ. Sci.

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“…Metabolic troughs occurred during the winter and early spring, when low temperatures, low insolation, and high flows from snowmelt can suppress river metabolism to very low levels (O'Donnell & Hotchkiss, 2020). These patterns are typical of the "bright and stable" river typologies identified by Bernhardt et al (2022) that are characterized by high rates of, and broad correlation between, GPP and ER. Indeed, the wide cross section of the middle section of the Grand River and shallow depth (typically < 1 m during summer baseflows), with minimal riparian shading, results in large metabolic responses to light, air temperature, and nutrient availability during the summer growing season (Venkiteswaran et al, 2015).…”

Section: Seasonal Dynamics In River Metabolismmentioning

confidence: 70%

River metabolic fingerprints and regimes reveal ecosystem responses to enhanced wastewater treatment

Jarvie

Macrae

Anderson³

et al. 2022

J of Env Quality

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Although many studies have examined how improvements in wastewater treatment impact river nutrient concentrations and loads, there has been much less focus on measuring river metabolism to evaluate the wider aquatic ecosystem benefits of reducing nutrient inputs to rivers. The objectives of this study were to evaluate the effects of enhanced wastewater treatment (nitrification) on river metabolism in the Grand River, Canada's largest river draining into Lake Erie. Metabolic fingerprints and regimes (calculated from high-frequency dissolved oxygen [DO] measurements) were used to visualize whole-river ecosystem functional responses to these wastewater treatment upgrades. There was a 60% reduction in ecosystem respiration during summer, in response to reductions in effluent total ammonia inputs, causing a shift from net heterotrophy to net autotrophy, and contraction of river metabolic fingerprints. This resulted in major improvements in summer DO concentrations, with reductions in the percentage of days during summer that DO minima fell below waterquality guidelines for protection of aquatic early life stages, from 88% to ≤16%. The results also point to potential cascading impacts on coupled phosphorus and nitrogen cycles, which may generate further improvements in river water quality. During the summer, high rates of river metabolism and nutrient retention may result in measured water-column nutrient concentrations potentially underestimating nutrient pressures. This study also demonstrates the value of combining river metabolism with nutrient monitoring for a more holistic understanding of the role of nutrients in river ecosystem health and function.

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“…Warming also induces phenological mismatches between consumers and resources in highly seasonal environments, potentially destabilizing food chain structure (Woodward et al, 2010;Shipley et al, 2022). Moreover, increase in water temperature and streamflow alterations by climate change may interact with land-use modifications to increase autotrophic productivity (Bernhardt et al, 2022) and the dominance of species that prefer warm-and slow-water habitats, reorganizing the structure of freshwater communities (Comte et al, 2021).…”

Section: Current and Future Climate Change Threatsmentioning

confidence: 99%

Time for decisive actions to protect freshwater ecosystems from global changes

Oberdorff

2022

Knowl. Manag. Aquat. Ecosyst.

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Freshwater ecosystems and their biodiversity provide fundamental services to humans such as nutritional resources production, water provisioning, water purification, recreation, and more globally climate regulation. Anthropogenic impacts on freshwater ecosystems and their biodiversity are already strong and will most probably increase in the near future. Anthropogenic drivers are widely known and include in particular, climate change, habitat shrinking and/or modification due to land-use (e.g. water abstraction for human and agricultural consumption, urbanization), habitat fragmentation and homogenization in stream flow dynamics due to the damming of rivers, introduction of non-native species, dumping of nutrient or organic loadings increasing eutrophication processes, and biodiversity over-exploitation. Here, I review the current and future effects of these anthropogenic drivers on freshwater ecosystems and their biodiversity and provide some few examples of existing solutions, either technological, nature-based or policy-based, that could be applied globally to halt and/or minimize their negative consequences. However, success will require systemic changes across public policy and a sufficient political will to do so.

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Light and flow regimes regulate the metabolism of rivers

Cited by 95 publications

References 44 publications

Rehabilitating Valley Floors to a Stage 0 Condition: A Synthesis of Opening Outcomes

Rehabilitating Valley Floors to a Stage 0 Condition: A Synthesis of Opening Outcomes

River metabolic fingerprints and regimes reveal ecosystem responses to enhanced wastewater treatment

Time for decisive actions to protect freshwater ecosystems from global changes

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