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Cyronak, T, Andersson AJ, Langdon C, Albright R, Bates NR, Caldeira K, Carlton R, Corredor JE, Dunbar RB, Enochs I, Erez J, Eyre BD, Gattuso JP, Gledhill D, Kayanne H, Kline DI, Koweek DA, Lantz C, Lazar B, Manzello D, McMahon A, Melendez M, Page HN, Santos IR, Schulz KG, Shaw E, Silverman J, Suzuki A, Teneva L, Watanabe A, Yamamoto S.  2018.  Taking the metabolic pulse of the world's coral reefs. Plos One. 13   10.1371/journal.pone.0190872   AbstractWebsite

Worldwide, coral reef ecosystems are experiencing increasing pressure from a variety of anthropogenic perturbations including ocean warming and acidification, increased sedimentation, eutrophication, and overfishing, which could shift reefs to a condition of net calcium carbonate (CaCO3) dissolution and erosion. Herein, we determine the net calcification potential and the relative balance of net organic carbon metabolism (net community production; NCP) and net inorganic carbon metabolism (net community calcification; NCC) within 23 coral reef locations across the globe. In light of these results, we consider the suitability of using these two metrics developed from total alkalinity (TA) and dissolved inorganic carbon (DIC) measurements collected on different spatiotemporal scales to monitor coral reef biogeochemistry under anthropogenic change. All reefs in this study were net calcifying for the majority of observations as inferred from alkalinity depletion relative to offshore, although occasional observations of net dissolution occurred at most locations. However, reefs with lower net calcification potential (i.e., lower TA depletion) could shift towards net dissolution sooner than reefs with a higher potential. The percent influence of organic carbon fluxes on total changes in dissolved inorganic carbon (DIC) (i.e., NCP compared to the sum of NCP and NCC) ranged from 32% to 88% and reflected inherent biogeochemical differences between reefs. Reefs with the largest relative percentage of NCP experienced the largest variability in seawater pH for a given change in DIC, which is directly related to the reefs ability to elevate or suppress local pH relative to the open ocean. This work highlights the value of measuring coral reef carbonate chemistry when evaluating their susceptibility to ongoing global environmental change and offers a baseline from which to guide future conservation efforts aimed at preserving these valuable ecosystems.

Andersson, AJ, Mackenzie FT.  2011.  Technical comment on Kroeker et al. (2010) Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms. Ecology Letters, 13, 1419–1434. Ecology Letters. 14:E1-E2.: Blackwell Publishing Ltd   10.1111/j.1461-0248.2011.01646.x   AbstractWebsite

Meta-analysis of experimental results has been interpreted to imply that the calcification response of organisms depositing high Mg-calcite is more resilient to ocean acidification than organisms depositing aragonite/calcite. This conclusion might be biased by inadequate recognition and categorisation of high Mg-calcite according to mineral solubility.

Paulsen, ML, Andersson AJ, Aluwihare L, Cyronak T, D'Angelo S, Davidson C, Elwany H, Giddings SN, Page HN, Porrachia M, Schroeter S.  2018.  Temporal changes in seawater carbonate chemistry and carbon export from a Southern California estuary. Estuaries and Coasts. 41:1050-1068.   10.1007/s12237-017-0345-8   AbstractWebsite

Estuaries are important subcomponents of the coastal ocean, but knowledge about the temporal and spatial variability of their carbonate chemistry, as well as their contribution to coastal and global carbon fluxes, are limited. In the present study, we measured the temporal and spatial variability of biogeochemical parameters in a saltmarsh estuary in Southern California, the San Dieguito Lagoon (SDL). We also estimated the flux of dissolved inorganic carbon (DIC) and total organic carbon (TOC) to the adjacent coastal ocean over diel and seasonal timescales. The combined net flux of DIC and TOC (FDIC + TOC) to the ocean during outgoing tides ranged from - 1.8 +/- 0.5 x 10(3) to 9.5 +/- 0.7 x 10(3) mol C h(-1) during baseline conditions. Based on these fluxes, a rough estimate of the net annual export of DIC and TOC totaled 10 +/- 4 x 10(6) mol C year(-1). Following a major rain event (36 mm rain in 3 days), FDIC + TOC increased and reached values as high as 29.0 +/- 0.7 x 10(3) mol C h(-1). Assuming a hypothetical scenario of three similar storm events in a year, our annual net flux estimate more than doubled to 25 +/- 4 x 10(6) mol C year(-1). These findings highlight the importance of assessing coastal carbon fluxes on different timescales and incorporating event scale variations in these assessments. Furthermore, for most of the observations elevated levels of total alkalinity (TA) and pH were observed at the estuary mouth relative to the coastal ocean. This suggests that SDL partly buffers against acidification of adjacent coastal surface waters, although the spatial extent of this buffering is likely small.

Smith, SR, Sarkis S, Murdoch TJT, Weil EA, Croquer A, Bates NR, Johnson RJ, de Putron S, Andersson AJ.  2013.  Threats to coral reefs of Bermuda. Coral reefs of the United Kingdom overseas territories, Coral Reefs of the World. Vol. 4( Sheppard CRC, Ed.)., Dordrecht: Springer Science + Business Media   10.1007/978-94-007-5965-7_13