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Eyre, BD, Cyronak T, Drupp P, DeCarlo EH, Sachs JP, Andersson AJ.  2018.  Coral reefs will transition to net dissolving before end of century. Science. 359:908-911.   10.1126/science.aao1118   AbstractWebsite

Ocean acidification refers to the lowering of the ocean's pH due to the uptake of anthropogenic CO2 from the atmosphere. Coral reef calcification is expected to decrease as the oceans become more acidic. Dissolving calciumcarbonate (CaCO3) sands could greatly exacerbate reef loss associated with reduced calcification but is presently poorly constrained. Here we show that CaCO3 dissolution in reef sediments across five globally distributed sites is negatively correlated with the aragonite saturation state (War) of overlying seawater and that CaCO3 sediment dissolution is 10-fold more sensitive to ocean acidification than coral calcification. Consequently, reef sediments globally will transition from net precipitation to net dissolution when seawater War reaches 2.92 +/- 0.16 (expected circa 2050 CE). Notably, some reefs are already experiencing net sediment dissolution.

Zablocki, JA, Andersson AJ, Bates NR.  2011.  Diel Aquatic CO(2) System Dynamics of a Bermudian Mangrove Environment. Aquatic Geochemistry. 17:841-859.   10.1007/s10498-011-9142-3   AbstractWebsite

Mangrove ecosystems play an important, but understudied, role in the cycling of carbon in tropical and subtropical coastal ocean environments. In the present study, we examined the diel dynamics of seawater carbon dioxide (CO(2)) and dissolved oxygen (DO) for a mangrove-dominated marine ecosystem (Mangrove Bay) and an adjacent intracoastal waterway (Ferry Reach) on the island of Bermuda. Spatial and temporal trends in seawater carbonate chemistry and associated variables were assessed from direct measurements of dissolved inorganic carbon, total alkalinity, dissolved oxygen (DO), temperature, and salinity. Diel pCO(2) variability was interpolated across hourly wind speed measurements to determine variability in daily CO(2) fluxes for the month of October 2007 in Bermuda. From these observations, we estimated rates of net sea to air CO(2) exchange for these two coastal ecosystems at 59.8 +/- 17.3 in Mangrove Bay and 5.5 +/- 1.3 mmol m(-2) d(-1) in Ferry Reach. These results highlight the potential for large differences in carbonate system functioning and sea-air CO(2) flux in adjacent coastal environments. In addition, observation of large diel variability in CO(2) system parameters (e.g., mean pCO(2): 390-2,841 mu atm; mean pH(T): 8.05-7.34) underscores the need for careful consideration of diel cycles in long-term sampling regimes and flux estimates.

Kuffner, IB, Andersson AJ, Jokiel PL, Rodgers KS, Mackenzie FT.  2008.  Decreased abundance of crustose coralline algae due to ocean acidification. Nature Geoscience. 1:114-117.   10.1038/ngeo100   AbstractWebsite

Owing to anthropogenic emissions, atmospheric concentrations of carbon dioxide could almost double between 2006 and 2100 according to business- as- usual carbon dioxide emission scenarios(1). Because the ocean absorbs carbon dioxide from the atmosphere(2-4), increasing atmospheric carbon dioxide concentrations will lead to increasing dissolved inorganic carbon and carbon dioxide in surface ocean waters, and hence acidification and lower carbonate saturation states(2,5). As a consequence, it has been suggested that marine calcifying organisms, for example corals, coralline algae, molluscs and foraminifera, will have difficulties producing their skeletons and shells at current rates(6,7), with potentially severe implications for marine ecosystems, including coral reefs(6,8 - 11). Here we report a seven-week experiment exploring the effects of ocean acidification on crustose coralline algae, a cosmopolitan group of calcifying algae that is ecologically important in most shallow-water habitats(12-14). Six outdoor mesocosms were continuously supplied with sea water from the adjacent reef and manipulated to simulate conditions of either ambient or elevated seawater carbon dioxide concentrations. The recruitment rate and growth of crustose coralline algae were severely inhibited in the elevated carbon dioxide mesocosms. Our findings suggest that ocean acidification due to human activities could cause significant change to benthic community structure in shallow-warm-water carbonate ecosystems.