Quantification of Anoxia and Hypoxia in Water Bodies

Nürnberg, Gertrud K.

doi:10.1002/9781119300762.wsts0081

Cited by 8 publications

(10 citation statements)

References 39 publications

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“…We tested several lake morphometric variables that relate to potential for wind‐driven mixing events during the stratification period (SDR, Fetch, MaxL, MaxW, L : W , OI; Table 1). None of these variables appeared in any of the top 25 ranked models, which was surprising as AF is correlated with OI (Nürnberg 1995), and OI helps to explain some of the variance between TP and AF (Nürnberg 2019). Average depth was also not an important variable for predicting areal extent of anoxia, but it has been a component of models in other studies linking shallower average depth with increased probability of anoxia (Reckhow 1977) and higher DO consumption rates (Cornet and Ringler 1980, Rippey and McSorley 2009).…”

Section: Discussionmentioning

confidence: 97%

Predicting anoxia in low‐nutrient temperate lakes

Deeds

Amirbahman

Norton

et al. 2021

Ecological Applications

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Absence of dissolved oxygen (anoxia) in the hypolimnion of lakes can eliminate habitat for sensitive species and may induce the release of sediment‐bound phosphorus. Lake anoxia generally results from decomposition of organic matter, which is exacerbated by high nutrient loads. Total phosphorus (TP) in lakes is regulated by static aspects of the lake’s watershed, but lake TP can be readily increased by human activities. In some low‐nutrient lakes, basin morphometry may induce naturally occurring anoxia. The occurrence of natural anoxia is especially important to consider in lake water quality assessments that compare observed conditions to expected reference conditions. To investigate the occurrence of natural vs. anthropogenically influenced anoxia, we constructed a logistic regression model to calculate the probability of low‐nutrient lakes (TP < 15 µg/L) developing aerial anoxic extent ≥10% by testing the predictive potential of variables related to basin morphometry, depths of lake thermal strata, epilimnetic TP, and dissolved organic carbon (DOC). Maximum lake depth and the proportion of lake area under the top of the metalimnion were the most important variables to predict the likelihood of hypolimnetic anoxia, which correctly predicted anoxic condition in 84% of lakes (Model 1). Adding TP as a third variable to Model 1 produced a significantly improved model (Model 2) but the prediction success rate was comparable (86%). We also present a model for lakes with limited bathymetric data, which predicts anoxia with 81% accuracy based on maximum lake depth and mean thermocline depth at peak stratification. DOC was relatively low (4.3 ± 1.5 mg/L [mean ± SD]) in the study lakes and its inclusion did not improve model performance. In Model 1, lakes with an anoxic extent ≥10% of lake area had significantly higher epilimnetic TP than lakes with oxic hypolimnia, regardless of prediction category or success. Our results indicate that including TP as a variable helps refine models based on morphometry alone, but lake morphometry and stratification dynamics are the most important factors in the development of anoxic extent in low‐nutrient temperate lakes. Our approach informs studies concerned with identifying key factors that influence regime shifts in a variety of ecosystems.

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Section: Discussionmentioning

confidence: 97%

Predicting anoxia in low‐nutrient temperate lakes

Deeds

Amirbahman

Norton

et al. 2021

Ecological Applications

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“…Conditions remained anoxic (DO < 2 mg L −1 ; Nürnberg 2022) in the BBL throughout the remainder of the 2017 sampling period. The decrease in DO concentrations measured in the BBL was consistent with the development of hypoxia (DO < 5 mg L −1 ; Nürnberg 2022) in the hypolimnion in June, followed by complete anoxia in the hypolimnion in July and August (Fig. 7b).…”

Section: Resultsmentioning

confidence: 99%

In situ flux estimates reveal large variations in methane flux across the bottom boundary layer of a eutrophic lake

D’Ambrosio

Henderson

Nielson

et al. 2022

Limnology & Oceanography

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Methane (CH4) produced in anoxic sediments plays a significant role in the carbon economy of many lakes and reservoirs. CH4 released from sediments first crosses the bottom boundary layer (BBL), the layer of water overlying the lakebed where currents are slowed by friction with the sediments below. Physical and biogeochemical conditions in the BBL, which can fluctuate hourly to daily with basin‐wide internal waves (seiches), likely influence CH4 transport from sediments into the hypolimnion. In this study, we estimated CH4 fluxes across the BBL of a eutrophic lake using a novel in situ flux gradient approach adapted from marine applications. For 2–6 h periods throughout the spring and summer, we estimated CH4 fluxes across the BBL using simultaneous measurements of CH4 concentrations, turbulent mixing, and thermal stratification. Sub‐daily variation in CH4 fluxes was high, and CH4 fluxes sometimes changed several‐fold within hours. These rapid shifts in BBL fluxes were likely influenced by fluctuations in seiche‐driven variations in the intensity of BBL turbulent mixing. Fluxes increased from spring to summer, concurrent with the development of lake stratification, and fueled an accumulation of CH4 below the thermocline. Throughout the summer, CH4 flux across the BBL exceeded CH4 accumulation below the thermocline, suggesting significant methanotrophy in the hypolimnion, consistent with incubation‐based oxidation rates. Our results are the first to demonstrate sub‐daily and seasonal variability in the timing and magnitude of CH4 fluxes within a lake BBL, and highlight a need to quantify such variability in other lentic systems.

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“…A threshold relationship between DO and TP is well supported by previous research across sediment core incubations, in situ sediment chamber measurements, and mass‐balance whole ecosystem analyses (e.g., Anderson et al., 2021; Einsele, 1936; Mortimer, 1942; Orihel et al., 2017). Here, our threshold value of 1.8 mg/L DO, averaged throughout the entire hypolimnion, likely reflects DO conditions of ~0 mg/L near the sediment–water interface (which inherently is challenging to quantify empirically), resulting in enhanced TP loading (Nürnberg, 2019). We note that our identified breakpoint of 1.8 mg/L is also remarkably similar to those identified in previous sediment incubation work (Doig et al., 2017; Matisoff et al., 2016; Orihel et al., 2017).…”

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Anoxic factor (AF) describes the spatial and temporal extent of anoxia within a lake and is therefore a useful metric of deoxygenation in lakes that experience hypolimnetic anoxia (Nürnberg, 1995(Nürnberg, , 2019. AF is expected to increase with increased oxygen demand, and can predict internal TP loading in lakes that experience hypolimnetic anoxia (Nürnberg, 1995(Nürnberg, , 2019; Figure 1). Here, we calculated AF within each lake year following Nürnberg (1988) and Nürnberg et al (2019), modified to address limited data availability across and within lakes (Appendix S5).…”

Section: Anoxic Factormentioning

confidence: 99%

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Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes

Lewis,

Lau,

Jane

et al. 2023

Global Change Biology

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Declining oxygen concentrations in the deep waters of lakes worldwide pose a pressing environmental and societal challenge. Existing theory suggests that low deep‐water dissolved oxygen (DO) concentrations could trigger a positive feedback through which anoxia (i.e., very low DO) during a given summer begets increasingly severe occurrences of anoxia in following summers. Specifically, anoxic conditions can promote nutrient release from sediments, thereby stimulating phytoplankton growth, and subsequent phytoplankton decomposition can fuel heterotrophic respiration, resulting in increased spatial extent and duration of anoxia. However, while the individual relationships in this feedback are well established, to our knowledge, there has not been a systematic analysis within or across lakes that simultaneously demonstrates all of the mechanisms necessary to produce a positive feedback that reinforces anoxia. Here, we compiled data from 656 widespread temperate lakes and reservoirs to analyze the proposed anoxia begets anoxia feedback. Lakes in the dataset span a broad range of surface area (1–126,909 ha), maximum depth (6–370 m), and morphometry, with a median time‐series duration of 30 years at each lake. Using linear mixed models, we found support for each of the positive feedback relationships between anoxia, phosphorus concentrations, chlorophyll a concentrations, and oxygen demand across the 656‐lake dataset. Likewise, we found further support for these relationships by analyzing time‐series data from individual lakes. Our results indicate that the strength of these feedback relationships may vary with lake‐specific characteristics: For example, we found that surface phosphorus concentrations were more positively associated with chlorophyll a in high‐phosphorus lakes, and oxygen demand had a stronger influence on the extent of anoxia in deep lakes. Taken together, these results support the existence of a positive feedback that could magnify the effects of climate change and other anthropogenic pressures driving the development of anoxia in lakes around the world.

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Quantification of Anoxia and Hypoxia in Water Bodies

Cited by 8 publications

References 39 publications

Predicting anoxia in low‐nutrient temperate lakes

Predicting anoxia in low‐nutrient temperate lakes

In situ flux estimates reveal large variations in methane flux across the bottom boundary layer of a eutrophic lake

Anoxia begets anoxia: A positive feedback to the deoxygenation of temperate lakes

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