Effects of Biophysical Processes on Diel-Cycling Hypoxia in a Subtropical Estuary

Duvall, Melissa S.; Jarvis, Brandon M.; Hagy, James D.; Wan, Yongshan

doi:10.1007/s12237-021-01040-y

Cited by 12 publications

(8 citation statements)

References 49 publications

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“…Our model simulation and associated signal analyses revealed that physical transport is a primary driver of DO variability on hourly timescales in the shallow Corsica River system. These tidal-scale impacts on DO variability reflect that mixing and advection of DO across space is an important feature of hourly-scale DO variability (e.g., Duvall et al, 2022). The transfer of DO signals across space depends on the heterogeneity in DO distribution, and both our simulation and the synoptic surveys showed that heterogeneity is a strong characteristic in DO distribution (Figure 5).…”

Section: Physical Impacts On Do Variabilitymentioning

confidence: 51%

“…A significant number of continuous water quality electronic sensors have been deployed in the shallow regions in Chesapeake Bay, which provide unprecedented continuous highfrequency monitoring data (CONMON). The sensor data have revealed high-frequency variability in water quality in shallow systems with large amplitude variations within hours (Shen et al, 2008;Graziano and Jones, 2017;Duvall et al, 2022). The highfrequency variability represents a fundamental challenge to our concept and understanding of ecosystem function and water quality dynamics, which were previously based on an extrapolation from deep water Bay studies.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

et al. 2022

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Understanding shallow water biogeochemical dynamics is a challenge in coastal regions, due to the presence of highly variable land-water interface fluxes, tight coupling with sediment processes, tidal dynamics, and diurnal variability in biogeochemical processes. While the deployment of continuous monitoring devices has improved our understanding of high-frequency (12 - 24 hours) variability and spatial heterogeneity in shallow regions, mechanistic modeling of these dynamics has lagged behind conceptual and empirical models. The inherent complexity of shallow water systems is represented in the Corsica River estuary, a small basin within the Chesapeake Bay ecosystem, where abundant monitoring data have been collected from long-term monitoring stations, continuous monitoring sensors, synoptic sensor surveys, and measurements of sediment-water fluxes. A state-of-the-art modeling system, the Semi-implicit Cross-scale Hydroscience Integrated System Model (SCHISM), was applied to the Corsica domain with a high-resolution grid and nutrient loads from the most recent version of the Chesapeake Bay watershed model. The Corsica SCHISM model reproduced observed high-frequency variability in dissolved oxygen, as well as seasonal variability in chlorophyll-a and sediment-water fluxes. Time-series signal analyses using Empirical Model Decomposition and spectral analysis revealed that the diurnal and M2 tide frequencies are the dominant high-frequency modes and physical transport contributes a larger share to dissolved oxygen budgets than biogeochemical processes on an hourly time scale. Heterogeneity and patchiness in dissolved oxygen resulting from phytoplankton distributions and geometry-driven eddies amplify the physical transport effect, and on longer time scales oxygen is controlled more by photosynthesis and respiration. Our simulation demonstrates that interactions among physical and biological dynamics generate complex high-frequency variability in water quality and non-linear reposes to nutrient loading and environmental forcing in shallow water systems.

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Section: Physical Impacts On Do Variabilitymentioning

confidence: 51%

Section: Introductionmentioning

confidence: 99%

Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

et al. 2022

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“…From each cross-spectrum, the phase lag between DOs and irradiance was computed at f = 1/24 hr -1 (Figure 6d). A peak in the phase lag distribution between 3 to 6 hours is consistent with biological production, wherein the highest DOs concentrations occur in the afternoon following peak daily solar irradiance (Sanford et al 1990;Duvall et al, 2022). These findings suggest that surface biological production was higher in 2021 despite lower daily solar irradiance, which may suggest higher nutrient concentrations in 2021.…”

Section: Surface Observationsmentioning

confidence: 52%

“…Given that the relationship between DO and physical forcing is non-stationary over the summertime observational period, this allowed us to compute a distribution of the phase lag at the dominant frequency of correlation. A similar phase lag distribution can be obtained using the magnitude-squared wavelet coherence between DO and 𝑦𝑦 𝑡𝑡 , which provides a localized measure of correlation in the time-frequency domain (Duvall et al, 2022). Linear trends in DO were removed prior to computing 𝑃𝑃(𝑓𝑓).…”

Section: Spectral Analysismentioning

confidence: 99%

“…In other estuaries, highfrequency fluctuations in DO have been examined most often in shallow areas, where dielcycling dynamics are typically dominated by diurnal cycles of daytime net production and nighttime net respiration (D'Avanzo and Kremer 1994;Beck and Bruland 2000;Shen et al, 2008). Diel-cycling DO has also been associated with advection and mixing by tides (Simpson et al, 1990;Breitburg, 1990;Tian et al, 2022), and wind-driven mixing associated with sea-breeze dynamics (Duvall et al, 2022). Determining biophysical processes driving high-frequency fluctuations in DO is fundamental to our understanding of water quality dynamics.…”

Section: Introductionmentioning

confidence: 99%

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High-frequency Dissolved Oxygen Dynamics in an Urban Estuary, the Long Island Sound

Duvall,

Hagy,

Ammerman

et al. 2023

Estuaries and Coasts

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The seasonal occurrence of benthic hypoxia in western Long Island Sound (LIS) has been documented for decades by water quality cruise surveys and fixed mooring buoys. While previous studies have focused on factors modulating bottom dissolved oxygen (DO) at subtidal timescales, here we analyze continuous timeseries data from a moored buoy during summers 2021 and 2022 to examine factors controlling high-frequency fluctuations in surface and bottom DO at diurnal and semidiurnal timescales. Fluctuations in surface DO at diurnal timescales are associated with biological production, while fluctuations in bottom DO near semidiurnal timescales are associated with horizontal advection of DO by tides from the upper East River into western LIS. Results from timeseries analysis are supported by weekly cruise surveys that resolve horizontal and vertical DO gradients in the western narrows. However, inferences regarding the duration of hypoxia during a given summer vary across datasets in part because weekly survey data do not resolve dominant intraseasonal timescales of variability. While prior studies have illustrated the importance of nutrient loading, stratification, and wind in controlling the development of hypoxia, the results presented here demonstrate the role of tidal advection in modulating hypoxia in far western LIS. Despite stronger stratification in 2021, the duration of hypoxia was 11.1 days shorter compared to 2022 in part due to greater advection of DO by tidal currents that intermittently ventilated bottom waters near the buoy. While improvements in water quality have been observed in other areas of LIS, increasing hypoxic area in the western narrows highlights the spatially variable response of DO to nutrient load reductions. Future analysis of hypoxia in LIS should focus on leveraging high-frequency information contained in continuous datasets to improve estimates of hypoxia based on less temporally resolved water quality surveys.

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Influence of Vegetation Coverage on Dissolved Oxygen Concentration in Seagrass Bed in the Seto Inland Sea: Possible Effects on Fish Nursery Function

Shoji

Tomiyama

2023

Estuaries and Coasts

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Effects of Biophysical Processes on Diel-Cycling Hypoxia in a Subtropical Estuary

Cited by 12 publications

References 49 publications

Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

Simulation of high-frequency dissolved oxygen dynamics in a shallow estuary, the Corsica River, Chesapeake Bay

High-frequency Dissolved Oxygen Dynamics in an Urban Estuary, the Long Island Sound

Influence of Vegetation Coverage on Dissolved Oxygen Concentration in Seagrass Bed in the Seto Inland Sea: Possible Effects on Fish Nursery Function

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