Contribution of unvegetated tidal flats to coastal carbon flux

Lin, Wei‐Jen; Wu, Jihua; Lin, Hsing‐Juh

doi:10.1111/gcb.15107

Cited by 32 publications

(26 citation statements)

References 68 publications

(108 reference statements)

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“…Higher temperatures generally stimulate metabolic processes and photosynthesis rates. Lin et al (2020) further indicated that the effects of temperature on the CO 2 fluxes in tidal flats were non-linear, showing a quadratic relationship with an optimal temperature at which the CO 2 fluxes were highest. In this study, the sediment temperatures in summer ranged from 31.2 • C to 40.6 • C, which far exceeded the optimal temperatures (28.7 • C for GPP m , 26.6 • C for NPP; Lin et al, 2020) for primary production.…”

Section: Discussionmentioning

confidence: 95%

“…whenever the sum of NPP and TR was negative, the tidal flat showed heterotrophic conditions; the GPP was then assumed to be zero. Measurements were considered outliers and excluded for further analysis when they fell outside the interquartile range (i.e., between Q1 -1.5 × IQR and Q3 + 1.5 × IQR, where Q1 is the first quartile, Q3 is the third quartile, and IQR is the difference between Q1 and Q3, Lin et al, 2020). At each site in each season, at least 10 random and non-repeating replicates of CO 2 flux measurements were obtained.…”

Section: Carbon Flux Measurementsmentioning

confidence: 99%

“…In subtropical regions, tidal flats act as carbon sinks during emersion (Lee et al, 2011). Lin et al (2020) demonstrated a clear latitudinal gradient in winter from 20 • N to 40 • N in which primary production and respiration in tidal flats during emersion decreased by up to 104% toward higher latitudes, but no clear trend was detected across the latitudinal gradient in summer. It appears that the contribution of NPP from tidal flats to the coastal carbon flux was greater in tropical and subtropical regions than in temperate regions (Lin et al, 2020).…”

Section: Introductionmentioning

confidence: 98%

“…The estimated global area of tidal flats is only 16% of that of seagrass beds but is comparable to that of mangroves and 2.3 times that of salt marshes (Davidson and Finlayson, 2019). Although the daily rate of net primary production (NPP) in tidal flats is at most 20% of that of vegetated coastal habitats, the global NPP of tidal flats (11.04 Tg C yr −1 ), obtained by multiplying the NPP by the global area, might reach approximately 50% of that of salt marshes (Lin et al, 2020). The carbon stock of tidal flats (78.07 Tg C) is nearly four times higher than that of vegetated habitats (20.53 Tg C) along the coast of China (Chen et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…It appears that the contribution of NPP from tidal flats to the coastal carbon flux was greater in tropical and subtropical regions than in temperate regions (Lin et al, 2020). Along the latitudinal gradient, sediment temperature is a main factor that regulates carbon fluxes in tidal flats (Lin et al, 2020). The authors also indicated that sediment features might be more prominent in regulating carbon fluxes in tidal flats at a local scale.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Sediment Characteristics on Carbon Dioxide Fluxes Based on Interacting Factors in Unvegetated Tidal Flats

et al. 2021

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The contribution of unvegetated tidal flats to global net primary production is comparable to that of some vegetated coastal habitats. However, compared to carbon flux regulating factors in vegetated habitats, those in unvegetated tidal flats are not well understood, particularly in terms of their cause-effect relationships. Maximum gross primary production (GPPm), net primary production (NPP) and total respiration (TR) during emersion at noon when the irradiance level was at the saturation level for photosynthesis in nine unvegetated tidal flats across the Taiwan Strait in tropical and subtropical regions were determined in winter and summer from 2011 to 2016 to examine the direct and indirect relationships between sediment characteristics and carbon fluxes by using structural equation models (SEM). Most of the GPPm and NPP values were higher in winter than in summer. Conversely, the TR values were higher in summer than in winter. The NPP values at some sites shifted to negative values in summer, indicating the sites were carbon sources. The values of GPPm, TR and NPP for the tidal flats all increased significantly with increasing sediment mud content. The SEM results showed that the sediment mud content directly increased GPPm or indirectly increased GPPm via a compositional shift in benthic microalgae. The sediment mud content also directly increased TR or indirectly increased TR via increased organic matter content. The contribution of benthic microalgal and macrofaunal biomass to TR was relatively minor. This result suggests that primary production was stimulated mainly by the organic matter content rather than by increased microalgal biomass. With the integrated SEM framework, our results showed mechanistic evidence of how sediment mud content acted as a critical factor regulating carbon fluxes in unvegetated tidal flats.

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Section: Discussionmentioning

confidence: 95%

Section: Carbon Flux Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Sediment Characteristics on Carbon Dioxide Fluxes Based on Interacting Factors in Unvegetated Tidal Flats

et al. 2021

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Going under: The implications of sea‐level rise and reduced light availability on intertidal primary production

Flowers

Needham

Bulmer

et al. 2023

Limnology & Oceanography

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Estuarine intertidal flats are known for high rates of primary production, however, globally these ecosystems are under threat from rising sea‐level and accelerated inputs of terrestrial sediments. These stressors simultaneously alter the duration of submersion/emersion periods and water‐column turbidity impacting seafloor photoperiods. To assess how changes in submergence time and water‐clarity can affect benthic primary production, we derived in situ seasonal photosynthesis‐irradiance (P‐I) curves over 2 yr. These were conducted during submerged and emerged periods in a seagrass meadow (Zostera muelleri) and an unvegetated sandflat (dominated by microphytobenthos). P‐I curves showed strong light responses during submergence in both habitats and seagrass during emergence, but in the exposed sandflat there was little relationship between light availability and photosynthesis. Light‐saturated measures of gross primary production (GPPsat) were 2.1 (submerged) and 4.1 times (emerged) higher in the seagrass than the sandflat habitat. Submerged GPPsat was always higher than emerged GPPsat, but this difference was much more pronounced in the sandflat habitat (2.4 vs. 1.3 times for seagrass). Integrating seasonally averaged P‐I curves for both tidal states into a simple model suggests that increasing submergence time could increase primary production in both habitats. However, reductions in water‐clarity will decrease submerged primary production; an effect that will be exacerbated with sea‐level rise. The sandflat trophic state was more sensitive to these environmental stressors because emerged production could not compensate for reductions during submergence. Collectively, regional management of water‐clarity may be key to providing resilience to intertidal habitats, against the inevitable effects of sea‐level rise.

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Carbon Dioxide Fluxes from Peri-urban Tidal Flats in South China

Chen,

Lee

2024

Estuaries and Coasts

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Coastal ecosystems are recognized as important carbon reservoirs. However, assessments of coastal carbon dioxide (CO2) fluxes often neglect unvegetated tidal flats, particularly in peri-urban areas. This study investigated the gross primary production (GPP), net primary production (NPP), and total respiration (TR) of three tidal flats in Hong Kong, one of the largest cities in South China, during both summer and winter seasons to understand their CO2 fluxes. Results showed that GPP of three tidal flats was significantly higher in winter than in summer. However, no significant seasonal variations in TR were observed among the tidal flats. Structural equation modelling was used to examine the drivers of CO2 fluxes in the three tidal flats. The model showed that temperature and microphytobenthos abundance were identified as positive drivers of GPP, while sediment mud content had a positive effect on TR. The estimated daily NPP of these tidal flats ranged from -0.853 to 0.112 g C m−2 d−1, which is lower than the mean value reported for global vegetated coastal wetlands. Despite some seasonal and spatial variations, those peri-urban tidal flats may be considered as weak CO2 sources rather than CO2 sinks.

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Contribution of unvegetated tidal flats to coastal carbon flux

Cited by 32 publications

References 68 publications

Effects of Sediment Characteristics on Carbon Dioxide Fluxes Based on Interacting Factors in Unvegetated Tidal Flats

Effects of Sediment Characteristics on Carbon Dioxide Fluxes Based on Interacting Factors in Unvegetated Tidal Flats

Going under: The implications of sea‐level rise and reduced light availability on intertidal primary production

Carbon Dioxide Fluxes from Peri-urban Tidal Flats in South China

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