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Buffer Capacity, Ecosystem Feedbacks, and Seawater Chemistry under Global Change
Hawai'i Institute of Marine Biology, Department of Oceanography, University of Hawai'i at Mānoa, P.O. Box 1346, Kāne'ohe, HI 96744, USA
Deceased on 18 February 2013.
* Author to whom correspondence should be addressed.
Received: 19 June 2013; in revised form: 26 July 2013 / Accepted: 19 August 2013 / Published: 6 September 2013
Abstract: Ocean acidification (OA) results in reduced seawater pH and aragonite saturation state (Ωarag), but also reduced seawater buffer capacity. As buffer capacity decreases, diel variation in seawater chemistry increases. However, a variety of ecosystem feedbacks can modulate changes in both average seawater chemistry and diel seawater chemistry variation. Here we model these effects for a coastal, reef flat ecosystem. We show that an increase in offshore pCO2 and temperature (to 900 µatm and + 3 °C) can increase diel pH variation by as much as a factor of 2.5 and can increase diel pCO2 variation by a factor of 4.6, depending on ecosystem feedbacks and seawater residence time. Importantly, these effects are different between day and night. With increasing seawater residence time and increasing feedback intensity, daytime seawater chemistry becomes more similar to present-day conditions while nighttime seawater chemistry becomes less similar to present-day conditions. Recent studies suggest that carbonate chemistry variation itself, independent of the average chemistry conditions, can have important effects on marine organisms and ecosystem processes. Better constraining ecosystem feedbacks under global change will improve projections of coastal water chemistry, but this study shows the importance of considering changes in both average carbonate chemistry and diel chemistry variation for organisms and ecosystems.
Keywords: ocean acidification; climate change; coral reef; ecosystem modeling; calcification; aragonite saturation; carbonate; pH
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Cite This Article
MDPI and ACS Style
Jury, C.P.; Thomas, F.I.; Atkinson, M.J.; Toonen, R.J. Buffer Capacity, Ecosystem Feedbacks, and Seawater Chemistry under Global Change. Water 2013, 5, 1303-1325.
Jury CP, Thomas FI, Atkinson MJ, Toonen RJ. Buffer Capacity, Ecosystem Feedbacks, and Seawater Chemistry under Global Change. Water. 2013; 5(3):1303-1325.
Jury, Christopher P.; Thomas, Florence I.; Atkinson, Marlin J.; Toonen, Robert J. 2013. "Buffer Capacity, Ecosystem Feedbacks, and Seawater Chemistry under Global Change." Water 5, no. 3: 1303-1325.