Distribution of the fugacity of carbon dioxide in the surface seawater of the Great Barrier Reef

Kawahata, Hodaka; Suzuki, Atsushi; Ayukai, Tenshi; Goto, Koichi

doi:10.1016/s0304-4203(00)00085-2

Cited by 34 publications

(40 citation statements)

References 36 publications

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“…Hourly X arag shown are the average values from the *1.5-h incubation period. Seasonal average X arag were determined from monthly water sampling by the Bermuda Ocean Acidification and Coral Reef Investigation (BEACON) project TA:DIC property-property plots and lack of a spatial gradient in X arag across the platform To understand why we are not seeing gradients in X arag across the platform, which is a common feature of many reefs (Kawahata et al 1997(Kawahata et al , 2000Suzuki and Kawahata 2003;Watanabe et al 2006;Albright et al 2013), we turn to the plot of salinity-normalized TA versus DIC, which shows data points from the 50 station platform-wide surveys conducted in March and September 2012 (Fig. 10).…”

Section: Controlling Factors Of Seasonal Coral Calcification In Bermudamentioning

confidence: 99%

Multiple driving factors explain spatial and temporal variability in coral calcification rates on the Bermuda platform

2014

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Experimental studies have shown that coral calcification rates are dependent on light, nutrients, food availability, temperature, and seawater aragonite saturation (X arag ), but the relative importance of each parameter in natural settings remains uncertain. In this study, we applied Calcein fluorescent dyes as time indicators within the skeleton of coral colonies (n = 3) of Porites astreoides and Diploria strigosa at three study sites distributed across the northern Bermuda coral reef platform. We evaluated the correlation between seasonal average growth rates based on coral density and extension rates with average temperature, light, and seawater X arag in an effort to decipher the relative importance of each parameter. The results show significant seasonal differences among coral calcification rates ranging from summer maximums of 243 ± 58 and 274 ± 57 mmol CaCO 3 m -2 d -1 to winter minimums of 135 ± 39 and 101 ± 34 mmol CaCO 3 m -2 d -1 for P. astreoides and D. strigosa, respectively. We also placed small coral colonies (n = 10) in transparent chambers and measured the instantaneous rate of calcification under light and dark treatments at the same study sites. The results showed that the skeletal growth of D. strigosa and P. astreoides, whether hourly or seasonal, was highly sensitive to X arag . We believe this high sensitivity, however, is misleading, due to covariance between light and X arag , with the former being the strongest driver of calcification variability. For the seasonal data, we assessed the impact that the observed seasonal differences in temperature (4.0°C), light (5.1 mol photons m -2 d -1 ), and X arag (0.16 units) would have on coral growth rates based on established relationships derived from laboratory studies and found that they could account for approximately 44, 52, and 5 %, respectively, of the observed seasonal change of 81 ± 14 mmol CaCO 3 m -2 d -1 . Using short-term light and dark incubations, we show how the covariance of light and X arag can lead to the false conclusion that calcification is more sensitive to X arag than it really is.

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Section: Controlling Factors Of Seasonal Coral Calcification In Bermudamentioning

confidence: 99%

Multiple driving factors explain spatial and temporal variability in coral calcification rates on the Bermuda platform

2014

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“…Air-sea CO 2 flux values may be used to differentiate coral reefs that act as either sinks or sources of atmospheric CO 2 [6][7][8][9][10][11][12][13][14][15][16][17][18]. Positive values typically characterize coral reefs as a source of atmospheric CO 2 , whilst negative values may [20].…”

Section: Coral Reefs Of the Scs Act As Sources Of Atmospheric Comentioning

confidence: 99%

“…In recent years, several studies have examined the role of coral reefs and their contribution to atmospheric CO 2 by measuring seawater pCO 2 and atmospheric pCO 2 in coral reefs [6][7][8][9][10][11]. They indicate that although coral reefs are mostly net sources [7][8][9][10][11][12][13][14][15][16] of atmospheric CO 2 , they may also act as sinks [6,17,18] for atmospheric CO 2 . Suzuki et al [6] suggested that the contribution of coral reefs to atmospheric CO 2 is largely dependent on their topographic and oceanographic settings.…”

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confidence: 99%

Coral reef ecosystems in the South China Sea as a source of atmospheric CO2 in summer

Yan

Qiu

et al. 2011

Chin. Sci. Bull.

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during the summers of 2008 and 2009 revealed that both air and surface seawater partial pressures of CO 2 (pCO 2 ) showed regular diurnal cycles. Minimum values occurred in the evening and maximum values in the morning. Air pCO 2 in each of the three study areas showed small diurnal variations, while large diurnal variations were observed in seawater pCO 2 . The diurnal variation amplitude of seawater pCO 2 was ~70 μmol mol -1 at the Yongshu Reef lagoon, 420-619 μmol mol -1 on the Yongxing Island reef flat, and 264-579 μmol mol -1 on the reef flat of the Luhuitou Fringing Reef, and 324-492 μmol mol -1 in an adjacent area just outside of this fringing reef. With respect to spatial relations, there were large differences in air-sea CO 2 flux across the South China Sea (e.g. ~0.4 mmol CO 2 m -2 d -1 at Yongshu Reef, ~4.7 mmol CO 2 m -2 d -1 at Yongxing Island, and ~9.8 mmol CO 2 m -2 d -1 at Luhuitou Fringing Reef). However, these positive values suggest that coral reef ecosystems of the SCS may be a net source of CO 2 to the atmosphere. Additional analyses indicated that diurnal variations of surface seawater pCO 2 in the shallow water reef flat are controlled mainly by biological metabolic processes, while those of deeper water lagoons and outer reef areas are regulated by both biological metabolism and hydrodynamic factors. Unlike the open ocean, inorganic metabolism plays a significant role in influencing seawater pCO 2 variations in coral reef ecosystems. coral reefs, pCO 2 , carbon cycle, summer, South China Sea Citation:

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“…Some restricted lagoons, for example, may experience significant dissolution between tidal flushings. Observations within the Great Barrier Reef lagoon revealed that lagoon waters reflected a strong calcification signal relative to the open ocean waters adjacent to the lagoon; that is, higher levels of pCO 2 , lower alkalinity, and thus a lower saturation state [Kawahata et al, 2000]. However, any dissolution acting to balance the carbonate system was not enough to maintain alkalinity above that of the open ocean waters.…”

Section: Natural Variability Of the Carbonate System On Coral Reefsmentioning

confidence: 99%

Coral reefs and changing seawater carbonate chemistry

Kleypas¹,

Langdon²

2006

Coral Reefs and Climate Change: Science and Management

151

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Seawater carbonate chemistry of the mixed layer of the oceans is changing rapidly in response to increases in atmospheric CO 2 . The formation and dissolution of calcium carbonate is now known to be strongly affected by these changes, but many questions remain about other controls on biocalcification and inorganic cementation that confound our attempts to make accurate predictions about the effects on both coral reef organisms and reefs themselves. This chapter overviews the current knowledge of the relationship between seawater carbonate chemistry and coral reef calcification, identifies the hurdles in our understanding of the two, and presents a strategy for overcoming those hurdles.

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Distribution of the fugacity of carbon dioxide in the surface seawater of the Great Barrier Reef

Cited by 34 publications

References 36 publications

Multiple driving factors explain spatial and temporal variability in coral calcification rates on the Bermuda platform

Multiple driving factors explain spatial and temporal variability in coral calcification rates on the Bermuda platform

Coral reef ecosystems in the South China Sea as a source of atmospheric CO2 in summer

Coral reefs and changing seawater carbonate chemistry

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