Long-term trends in inflowing chlorophyll <i>a</i> and nutrients and their relation to dissolved oxygen in a large western reservoir

Naymik, Jesse; Larsen, Chris A.; Myers, Ralph; Hoovestol, Chuck; Gastelecutto, Nick; Bates, Dain

doi:10.1080/10402381.2022.2160395

Cited by 4 publications

(43 citation statements)

References 38 publications

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“…57 The upgradient processes controlling the inflow of DOM to the reservoirs, including seasonal DOM mobilization from surficial soils and autochthonous DOM production, largely governed DOC concentration and DOM composition throughout the HCC. Extensive eutrophication and impoundments of the Snake River and contributing tributaries 29 upgradient of the HCC likely dampens the influences of HCC reservoirs on DOC concentration and DOM composition, 31–33,53 as supported by the autochthonous nature of DOM entering the reservoirs and only minor shifts in DOM composition observed across the reservoir system. These observations provide a foundation to interpret DOM controls on Hg( ii ) and MeHg behavior across the HCC.…”

Section: Resultsmentioning

confidence: 99%

“…Dissolved oxygen concentration and temperature heat maps of Brownlee Reservoir that were collected during in-reservoir sampling are available in companion studies. 14,29…”

Section: Resultsmentioning

confidence: 99%

“…13,44 A complete description of the study basin and properties of the reservoirs are provided in Baldwin et al (2020) 13 and Naymik et al (2023). 29 Briefly, the Snake River watershed represents a heavily managed, arid landscape with reservoirs that support flood control, irrigation of neighboring agricultural lands, and hydroelectric power. Brownlee Reservoir, the first reservoir in the HCC, accounts for approximately 86.2% of the total volume capacity of the reservoir complex (with 3.5%, and 10.3% of volume in Oxbow and Hells Canyon reservoirs, respectively), is the deepest (maximum depth of 91 m) and is subject to seasonal drawdown, and has distinct riverine, transition, and lacustrine zones.…”

Section: Methodsmentioning

confidence: 99%

“…In 2017 and 2018, water samples were also collected at 4 locations within Brownlee Reservoir that span the transition and lacustrine zones of the reservoir. 29 Depth profiles were collected between March and December of each year to target seasonal in-reservoir processes from the spring high flows to summer stratified conditions and through the conclusions of reservoir destratification. 14 In-reservoir samples were collected from the water surface (2 meters depth) to above the sediment–water interface using a peristaltic pump and Teflon tubing (100 meters length, pre-cleaned with 1% hydrochloric acid).…”

Section: Methodsmentioning

confidence: 99%

“…Each deployment depth targeted discrete epilimnetic, metalimnetic, and hypolimnetic strata of Brownlee Reservoir based on temperature profiles. 29 Replicate deployments at identical depths ( n = 8) assessed reproducibility. Within 24 h of retrieval, the settling trap material was sieved (retaining material <243 μm) and analyzed for THg, MeHg, and organic matter content by loss on ignition.…”

Section: Methodsmentioning

confidence: 99%

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Biogeochemical and hydrologic synergy control mercury fate in an arid land river-reservoir system

Poulin

Tate

Ogorek

et al. 2023

Environ. Sci.: Processes Impacts

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Section: Resultsmentioning

confidence: 99%

“…Dissolved oxygen concentration and temperature heat maps of Brownlee Reservoir that were collected during in-reservoir sampling are available in companion studies. 14,29…”

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Biogeochemical and hydrologic synergy control mercury fate in an arid land river-reservoir system

Poulin

Tate

Ogorek

et al. 2023

Environ. Sci.: Processes Impacts

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Reservoir Stratification Modulates the Influence of Impoundments on Fish Mercury Concentrations along an Arid Land River System

Willacker,

Eagles-Smith,

Chandler

et al. 2023

Environ. Sci. Technol.

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Impoundment is among the most common hydrologic alterations with impacts on aquatic ecosystems that can include effects on mercury (Hg) cycling. However, landscape-scale differences in Hg bioaccumulation between reservoirs and other habitats are not well characterized nor are the processes driving these differences. We examined total Hg (THg) concentrations of Smallmouth Bass ( Micropterus dolomieu ) collected from reservoir, tailrace, and free-flowing reaches along an 863 km segment of the Snake River, USA, a semiarid river with 22 impoundments along its course. Across three size-classes (putative 1-year-old, first reproductive, and harvestable sized fish), THg concentrations in reservoirs and tailraces averaged 76% higher than those in free-flowing segments. Among reservoirs, THg concentrations were highest in reservoirs with inconsistent stratification patterns, 47% higher than annually stratified, and 144% higher than unstratified reservoirs. Fish THg concentrations in tailraces immediately downstream of stratified reservoirs were higher than those below unstratified (38–130%) or inconsistently stratified (32–79%) reservoirs. Stratification regimes influenced the exceedance of fish and human health benchmarks, with 52–80% of fish from stratifying reservoirs and downstream tailraces exceeding a human consumption benchmark, compared to 6–17% where stratification did not occur. These findings suggest that impoundment and stratification play important roles in determining the patterns of Hg exposure risk across the landscape.

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Metabolically diverse microorganisms mediate methylmercury formation under nitrate-reducing conditions in a dynamic hydroelectric reservoir

et al. 2023

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Brownlee Reservoir is a mercury (Hg)-impaired hydroelectric reservoir that exhibits dynamic hydrological and geochemical conditions and is located within the Hells Canyon Complex in Idaho, USA. Methylmercury (MeHg) contamination in fish is a concern in the reservoir. While MeHg production has historically been attributed to sulfate-reducing bacteria and methanogenic archaea, microorganisms carrying the hgcA gene are taxonomically and metabolically diverse and the major biogeochemical cycles driving mercury (Hg) methylation are not well understood. In this study, Hg speciation and redox-active compounds were measured throughout Brownlee Reservoir across the stratified period in four consecutive years (2016–2019) to identify the location where and redox conditions under which MeHg is produced. Metagenomic sequencing was performed on a subset of samples to characterize the microbial community with hgcA and identify possible links between biogeochemical cycles and MeHg production. Biogeochemical profiles suggested in situ water column Hg methylation was the major source of MeHg. These profiles, combined with genome-resolved metagenomics focused on hgcA-carrying microbes, indicated that MeHg production occurs in this system under nitrate- or manganese-reducing conditions, which were previously thought to preclude Hg-methylation. Using this multidisciplinary approach, we identified the cascading effects of interannual variability in hydrology on the redox status, microbial metabolic strategies, abundance and metabolic diversity of Hg methylators, and ultimately MeHg concentrations throughout the reservoir. This work expands the known conditions conducive to producing MeHg and suggests that the Hg-methylation mitigation efforts by nitrate or manganese amendment may be unsuccessful in some locations.

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Long-term trends in inflowing chlorophyll a and nutrients and their relation to dissolved oxygen in a large western reservoir

Cited by 4 publications

References 38 publications

Biogeochemical and hydrologic synergy control mercury fate in an arid land river-reservoir system

Biogeochemical and hydrologic synergy control mercury fate in an arid land river-reservoir system

Reservoir Stratification Modulates the Influence of Impoundments on Fish Mercury Concentrations along an Arid Land River System

Metabolically diverse microorganisms mediate methylmercury formation under nitrate-reducing conditions in a dynamic hydroelectric reservoir

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