Eddy correlation measurements of oxygen fluxes in permeable sediments exposed to varying current flow and light

Berg, Peter; Long, Matthew H.; Huettel, Markus; Rheuban, Jennie E.; McGlathery, Karen J.; Howarth, Robert W.; Foreman, K.; Giblin, Anne E.; Marino, Roxanne

doi:10.4319/lo.2013.58.4.1329

Cited by 98 publications

(112 citation statements)

References 44 publications

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“…6d). Fundamental differences between the two flux methods, especially when applied to permeable sandy sediments, may explain this disagreement (Glud, 2008;Reimers et al, 2012;Berg et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

et al. 2015

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Abstract. Extracting benthic oxygen fluxes from eddy covariance time series measured in the presence of surface gravity waves requires careful consideration of the temporal alignment of the vertical velocity and the oxygen concentration. Using a model based on linear wave theory and measured eddy covariance data, we show that a substantial error in flux can arise if these two variables are not aligned correctly in time. We refer to this error in flux as the time lag bias. In one example, produced with the wave model, we found that an offset of 0.25 s between the oxygen and the velocity data produced a 2-fold overestimation of the flux. In another example, relying on nighttime data measured over a seagrass meadow, a similar offset reversed the flux from an uptake of −50 mmol m −2 d −1 to a release of 40 mmol m −2 d −1 . The bias is most acute for data measured at shallow-water sites with short-period waves and low current velocities. At moderate or higher current velocities (> 5-10 cm s −1 ), the bias is usually insignificant. The widely used traditional time shift correction for data measured in unidirectional flows, where the maximum numerical flux is sought, should not be applied in the presence of waves because it tends to maximize the time lag bias or give unrealistic flux estimates. Based on wave model predictions and measured data, we propose a new time lag correction that minimizes the time lag bias. The correction requires that the time series of both vertical velocity and oxygen concentration contain a clear periodic wave signal. Because wave motions are often evident in eddy covariance data measured at shallow-water sites, we encourage more work on identifying new time lag corrections.

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Section: Discussionmentioning

confidence: 99%

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

et al. 2015

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“…Spectral analysis was applied to selected data sequences to validate this assumption. Abnormalities in the EC data record, usually caused by debris colliding with or attaching to the O 2 sensor, were then removed as described by Lorrai et al (2010), Hume et al (2011) and Berg et al (2013). In total *18 % of the data were discarded by this procedure.…”

Section: Eddy Covariance Measurementsmentioning

confidence: 99%

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

et al. 2016

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Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a *65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated by the brittle star A. filiformis. The numerous burrows were intensively irrigated enhancing the benthic in situ O 2 uptake by *50 %, and inducing highly variable redox conditions and O 2 distribution in the surface sediment as also documented by complementary laboratory-based planar optode measurements. The average benthic O 2 exchange as derived by chamber incubations and the eddy covariance approach were similar (14.9 ± 2.5 and 13.1 ± 9.0 mmol m -2 day -1 ) providing confidence in the two measuring approaches. Moreover, the non-invasive eddy approach revealed a flow-dependent benthic O 2 flux that was partly ascribed to enhanced ventilation of infauna burrows during periods of elevated flow rates. The ratio in exchange rates of RCO 2 and O 2 was close to unity, confirming that the O 2 uptake was a good proxy for the benthic carbon mineralization in this setting. The infauna activity resulted in highly dynamic redox conditions that presumably facilitated an efficient degradation of both terrestrial and marine-derived organic material. The complex O 2 dynamics of the burrow environment also concurrently stimulated nitrification and coupled denitrification rates making the sediment an efficient sink for bioavailable nitrogen. Furthermore, bioturbation mediated a high efflux of dissolved phosphorus and silicate. The study documents a high spatial and temporal variation in benthic solute exchange with important implications for benthic turnover of organic carbon and nutrients. However, more long-term in situ investigations with like approaches are required to fully understand how environmental events and spatio-temporal variations interrelate to the overall biogeochemical functioning of coastal sediments.

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“…Compared to flux chamber methods, it can be deployed so that it does not alter the local hydrodynamics or ambient light (Berg et al 2003). Additionally, O 2 fluxes can usually be extracted from 15 min of data, allowing for high-resolution flux records that typically cannot be obtained with other methods (Lorrai et al 2010).…”

mentioning

confidence: 99%

“…Additionally, O 2 fluxes can usually be extracted from 15 min of data, allowing for high-resolution flux records that typically cannot be obtained with other methods (Lorrai et al 2010). Finally, the seafloor area contributing to the measured flux covers many square meters and can integrate over most heterogeneous environments (Berg et al 2007;Rheuban and Berg 2013). The eddy correlation technique has been used successfully in a number of environments where it is difficult to apply traditional flux methods, including seagrass meadows, permeable sediments, and coral reefs (Hume et al 2011, Long et al 2013.…”

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confidence: 99%

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Ecosystem metabolism along a colonization gradient of eelgrass (Zostera marina) measured by eddy correlation

Rheuban

Berg

McGlathery

2014

Limnology & Oceanography

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The Virginia coastal bays experienced local extinction of eelgrass (Zostera marina) during the early 1930s, and restoration beginning in 2001 has generated an ecosystem state change from bare to vegetated sediments. Oxygen fluxes were measured seasonally using the eddy correlation technique at three sites representing different stages of seagrass colonization: unvegetated (bare), 5 yr, and 11 yr since seeding. Derived seasonal ecosystem respiration (R) and gross primary production (GPP) increased up to 10-fold and 25-fold, respectively, with meadow age. Although hourly oxygen (O 2 ) fluxes were highly correlated with light at the vegetated sites, no identifiable trends with light were observed at the bare site. The light compensation point where O 2 production and respiration are in balance increased from 46 mmol photons m 22 s 21 to 257 mmol photons m 22 s 21 and 63 mmol photons m 22 s 21 to 472 mmol photons m 22 s 21 at the 5 yr and 11 yr seagrass sites, respectively, with increasing seasonal temperatures from 12.3uC to 27.9uC and 9.3uC to 30.5uC, respectively. This suggests that more light, and thus more O 2 production, is required to offset increasing respiration with both temperature and meadow age. Photosynthesisirradiance curves generated from hourly O 2 fluxes throughout the seasons were used to estimate annual net ecosystem metabolism (NEM). Annual NEM rates at the bare, 5 yr, and 11 yr sites were 27.6, 8.6, and 27.0 mol O 2 m 22 yr 21 , respectively. Although the system went through a period of net autotrophy during early stages of colonization, the ecosystem state change from unvegetated sediments to dense seagrass meadows changed the magnitude of both GPP and R, but not the overall metabolic balance of the system.

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Eddy correlation measurements of oxygen fluxes in permeable sediments exposed to varying current flow and light

Cited by 98 publications

References 44 publications

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

Technical note: Time lag correction of aquatic eddy covariance data measured in the presence of waves

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

Ecosystem metabolism along a colonization gradient of eelgrass (Zostera marina) measured by eddy correlation

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