Dataset Information

Effects of an Experimental Water-level Drawdown on Methane Emissions from a Eutrophic Reservoir.

ABSTRACT: Reservoirs are a globally significant source of methane (CH₄) to the atmosphere. However, emission rate estimates may be biased low due to inadequate monitoring during brief periods of elevated emission rates (that is, hot moments). Here we investigate CH₄ bubbling (that is, ebullition) during periods of falling water levels in a eutrophic reservoir in the Midwestern USA. We hypothesized that periods of water-level decline trigger the release of CH₄-rich bubbles from the sediments and that these emissions constitute a substantial fraction of the annual CH₄ flux. We explored this hypothesis by monitoring CH₄ ebullition in a eutrophic reservoir over a 7-month period, which included an experimental water-level drawdown. We found that the ebullitive CH₄ flux rate was among the highest ever reported for a reservoir (mean = 32.3 mg CH₄ m^-2 h^-1). The already high ebullitive flux rates increased by factors of 1.4-77 across the nine monitoring sites during the 24-h experimental water-level drawdown, but these emissions constituted only 3% of the CH₄ flux during the 7-month monitoring period due to the naturally high ebullitive CH₄ flux rates that persist throughout the warm weather season. Although drawdown emissions were found to be a minor component of annual CH₄ emissions in this reservoir, our findings demonstrate a link between water-level change and CH₄ ebullition, suggesting that CH₄ emissions may be mitigated through water-level management in some reservoirs.

SUBMITTER: Beaulieu JJ

PROVIDER: S-EPMC6445499 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Effects of an Experimental Water-level Drawdown on Methane Emissions from a Eutrophic Reservoir.

Beaulieu Jake J JJ Balz David A DA Birchfield M Keith MK Harrison John A JA Nietch Christopher T CT Platz Michelle C MC Squier William C WC Waldo Sarah S Walker John T JT White Karen M KM Young Jade L JL

Ecosystems (New York, N.Y.) 20170905 4

Reservoirs are a globally significant source of methane (CH4) to the atmosphere. However, emission rate estimates may be biased low due to inadequate monitoring during brief periods of elevated emission rates (that is, hot moments). Here we investigate CH4 bubbling (that is, ebullition) during periods of falling water levels in a eutrophic reservoir in the Midwestern USA. We hypothesized that periods of water-level decline trigger the release of CH4-rich bubbles ...[more]

PMID: 31007569

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Project description:Dams and reservoirs alter natural water flow regimes with adverse effects on natural ecosystems. Quantifying and reducing these effects are important as global demands for energy and water, and the number of dams and reservoir, increase. However, costs and logistic constraints typically preclude experimental assessment of reservoir effects on the environment. We developed a stochastic individual-based model (IBM), parameterized using empirical data, to estimate the annual productivity of yellow warblers that breed in riparian habitat within the footprint of the Arrow Lakes Reservoir in British Columbia, Canada. The IBM incorporated information on breeding phenology, nest site selection, brood parasitism, daily nest survival, re-nesting probabilities and post-fledging survival. We used the IBM to estimate the effect of four different water management scenarios on annual productivity. We found that the IBM accurately estimated average nest success (0.39 ± 0.10 SD), the proportion of females that produced at least one fledgling during a breeding season (0.56 ± 0.11), and annual fledging success (2.06 ± 0.43) under current conditions. The IBM estimated that reservoir operations currently reduce the annual productivity of this population by 37%, from an average of 1.62 to 1.06 independent young/female. Delaying when reservoir water levels reach 435m asl (the minimum elevation occupied by yellow warblers) by approximately 2 weeks was predicted to increase annual productivity to 1.44 independent young/female. The standardized effect on annual productivity of reducing the maximum elevation of the reservoir so that yellow warbler habitat is not inundated (Cohen's d = 1.52) or delaying when water is stored (Cohen's d = 0.83) was primarily driven by inundation effects on post-fledging survival. Reservoir operation effects on breeding birds will be species specific, but this IBM can easily be modified to allow the environmental impacts on the entire breeding bird community to be incorporated into water management decisions.

Dataset Information

Effects of an Experimental Water-level Drawdown on Methane Emissions from a Eutrophic Reservoir.

Publications

Effects of an Experimental Water-level Drawdown on Methane Emissions from a Eutrophic Reservoir.

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