Net uptake of atmospheric
 <scp>CO</scp>
 2
 by coastal submerged aquatic vegetation

Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

doi:10.1111/gcb.12543

Cited by 110 publications

(94 citation statements)

References 59 publications

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“…The f CO 2 variations in the lagoon, which are among the parameters that regulate air-water CO 2 fluxes, have been confirmed to be related to mixing of lagoon water with freshwater coming from rivers and with biological processes such as photosynthesis (Tokoro et al, 2014). Given that the former and latter phenomena are caused by the semi-diurnal tidal cycle and diel changes of irradiance, respectively, the peaks in the power spectrum are consistent with the results of Tokoro et al (2014). This consistency is a good demonstration of the utility of the PP2.…”

Section: Discussionmentioning

confidence: 94%

“…Freshwater flows into the western basin through several rivers that run through the surrounding grass farms, and seawater is exchanged through the lagoon mouth, which opens to the Okhotsk Sea. A previous study has found that the air-water CO 2 flux in the lagoon is affected by changes of salinity caused by the inflow of river water and tides as well as by changes of dissolved inorganic carbon resulting from biological processes such as photosynthesis (Tokoro et al, 2014). The measurement platform was built at the same site used in that previous study (43 • 19.775 ′ N, 145 • 15.463 ′ E); the effects of photosynthesis and changes in salinity are most notable at this location in the lagoon (Tokoro et al, 2014).…”

Section: Field Measurementsmentioning

confidence: 99%

“…Several previous studies, after taking into account carbon inputs from land, have concluded that shallow aquatic ecosystems are sources of atmospheric CO 2 (e.g., Gazeau et al, 2005;Borges et al, 2006;Chen et al, 2013). In contrast, some autotrophic, shallow aquatic ecosystems have been reported to be net sinks for atmospheric CO 2 (e.g., Schindler et al, 1997;Tokoro et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Tokoro

Kuwae

2018

Front. Mar. Sci.

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The capture of carbon by aquatic ecosystems and its sequestration in sediments has been studied as a potential method for mitigating the adverse effects of climate change. However, the evaluation of in situ atmospheric CO 2 fluxes is challenging because of the difficulty in making continuous measurements over areas and for periods of time that are environmentally relevant. The eddy covariance method for estimating atmospheric CO 2 fluxes is the most promising approach to address this concern. However, methods to process the data obtained from eddy covariance measurements are still being developed, and the estimated air-water CO 2 fluxes have large uncertainties and differ from those obtained using conventional methods. In this study, we improved the post-processing procedure for the eddy covariance method to reduce the uncertainty in the measured air-water CO 2 fluxes. Our procedure efficiently removes low-quality fluxes using a combination of filtering methods based on the received signal strength indicator of the eddy covariance sensor, the normalized standard deviation of atmospheric CO 2 and water vapor concentrations, and a high-pass filter. The improved eddy covariance fluxes revealed diurnal and semi-diurnal cycles and a significant relationship with water fCO 2 , patterns that were not observed from the results before filtering. Although there were still differences with indirect conventional measurements like the bulk formula method, the methods used in this study should improve the accuracy of carbon flow estimates at sites with complex terrains like coastal areas.

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Section: Discussionmentioning

confidence: 94%

Section: Field Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Tokoro

Kuwae

2018

Front. Mar. Sci.

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“…The net ecosystem production of seagrass meadows is a key factor determining whether they are sinks or sources of C air (Maher and Eyre, 2012;Tokoro et al, 2014;Watanabe and Kuwae, 2015). Previously, however, such an exchange of CO 2 has been thought to occur only via the air-water interface with subsequent exchange with seagrasses as DIC.…”

Section: Resultsmentioning

confidence: 99%

Radiocarbon isotopic evidence for assimilation of atmospheric CO2 by the seagrass Zostera marina

Watanabe

Kuwae

2015

Biogeosciences

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Abstract. Submerged aquatic vegetation takes up watercolumn dissolved inorganic carbon (DIC) as a carbon source across its thin cuticle layer. It is expected that marine macrophytes also use atmospheric CO 2 when exposed to air during low tide, although assimilation of atmospheric CO 2 has never been quantitatively evaluated. Using the radiocarbon isotopic signatures ( 14 C) of the seagrass Zostera marina, DIC and particulate organic carbon (POC), we show quantitatively that Z. marina takes up and assimilates atmospheric modern CO 2 in a shallow coastal ecosystem. The 14 C values of the seagrass (−40 to −10 ‰) were significantly higher than those of aquatic DIC (−46 to −18 ‰), indicating that the seagrass uses a 14 C-rich carbon source (atmospheric CO 2 , +17 ‰). A carbon-source mixing model indicated that the seagrass assimilated 0-40 % (mean, 17 %) of its inorganic carbon as atmospheric CO 2 . CO 2 exchange between the air and the seagrass might be enhanced by the presence of a very thin film of water over the air-exposed leaves during low tide. Our radiocarbon isotope analysis, showing assimilation of atmospheric modern CO 2 as an inorganic carbon source, improves our understanding of the role of seagrass meadows in coastal carbon dynamics.

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“…Lake Furen is approximately 1-m deep, with the exception of water routes that cause it to deepen towards the main channel (maximum depth: 11 m). Seagrasses (Zostera marina L.) fill approximately 67% of the lake area, and their aboveground biomass ranges seasonally between 16 and 318 g dry weight m −2 (Tokoro et al 2014). The lake freezes from December to March.…”

Section: Field Samplingmentioning

confidence: 99%

Spatial variability in an estuarine phytoplankton and suspended microphytobenthos community

Tsuji

Montani

2017

Plankton Benthos Res

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Estuarine material circulation depends on the presence of both phytoplankton and suspended microphytobenthos in the water column. However, the spatial distribution of suspended microphytobenthos and phytoplankton in estuaries is poorly understood. In this study, the abundance of suspended microphytobenthos and phytoplankton in the water column was determined along the salinity gradient in Lake Furen, Japan, from April to October 2015. Throughout the study period, surface and bottom salinity changed horizontally from <10 to >30. Phytoplankton was the main contributor to spatial increases in total cell abundance in mesohaline water as a result of the lake s hydrographic characteristics and water quality. The suspended microphytobenthos cell abundance in the surface and bottom water decreased with increasing salinity and was affected by the depth gradient. Suspended microphytobenthos cell abundances increased with depth (∼10 and 20% of total cell abundance in the surface and bottom water, respectively), which indicated that they were derived from microphytobenthos on the seafloor. The dominant suspended microphytobenthos taxa (Cocconeis spp. and Melosira varians) were mainly distributed in oligo-and mesohaline water, with peaks in mesohaline bottom water. In contrast, the dominant phytoplankton taxa (Skeletonema spp., Heterocapsa triquetra, and Prorocentrum spp.) were abundant at different salinity levels. The spatial distribution of dominant benthic and planktonic species in the water column was influenced by their tolerance to salinity. Our results suggest that suspended microphytobenthos contribute to microalgal communities in estuaries, especially those in bottom waters. Quantification of phytoplankton and suspended microphytobenthos will allow a better understanding of the effects of their spatial distribution on estuarine material circulation.

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Net uptake of atmospheric CO ₂ by coastal submerged aquatic vegetation

Cited by 110 publications

References 59 publications

Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Radiocarbon isotopic evidence for assimilation of atmospheric CO<sub>2</sub> by the seagrass <i>Zostera marina</i>

Spatial variability in an estuarine phytoplankton and suspended microphytobenthos community

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Net uptake of atmospheric CO 2 by coastal submerged aquatic vegetation

Cited by 110 publications

References 59 publications

Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Improved Post-processing of Eddy-Covariance Data to Quantify Atmosphere–Aquatic Ecosystem CO2 Exchanges

Radiocarbon isotopic evidence for assimilation of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; by the seagrass &lt;i&gt;Zostera marina&lt;/i&gt;

Spatial variability in an estuarine phytoplankton and suspended microphytobenthos community

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Product

Resources

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Net uptake of atmospheric CO ₂ by coastal submerged aquatic vegetation

Radiocarbon isotopic evidence for assimilation of atmospheric CO<sub>2</sub> by the seagrass <i>Zostera marina</i>