Surface water samples (0-3m, n=195) for salinity, nutrients, total alkalinity (TA), and dissolved inorganic carbon (DIC) were collected from reef sites throughout the Palauan archipelago at multiple time points between sunrise and sunset on September 19-24, 2011; March 28-April 7, 2012; December 7-9, 2012; and November 1-15, 2013 (detailed water sampling procedure in Shamberger et al. (2014)). Sampling was performed from small boats taken out daily from the Palau International Coral Reef Center (PICRC).
\nIn situ temperature was measured in 2011 with TidbiT v2 water temperature data loggers produced by Onset with a manufacturer stated accuracy of 0.2 degrees C, in 2012 with a RBR XR-620 CTD with a manufacturer stated temperature accuracy of +/-0.002 degrees C, and in 2013 with a Sontek Castaway CTD with a manufacturer stated temperature accuracy of +/-0.05 degrees C. Surface water (0-3 m) samples were collected multiple times a day between sunrise and sunset and on 3-9 separate days for each site from a Niskin bottle into 300 ml glass bottles (TA/DIC) and 125 ml glass bottles (salinity). Approximately 5 ml were removed from each bottle to allow headspace for expansion and each TA/DIC sample was poisoned with 50 ul saturated mercuric chloride solution immediately after collection to inhibit biological activity and then sealed with screw tops and tape.
\nTA and DIC analyses were performed using a Versatile Instrument for the Determination of Total inorganic carbon and titration Alkalinity (VINDTA, Marianda Analytics and Data), which uses open cell potentiometric (TA) and coulometric (DIC) titrations, and standardized using certified reference materials obtained from Andrew Dickson (Scripps Institution of Oceanography; Dickson 2001, Dickson et al. 2007). Analysis of replicate samples (n=13) showed a mean precision of ~2 umol/kg for TA and ~1 umol/kg for DIC.
Seawater carbonate chemistry is reported from samples collected at 13 different coral reef sites in Palau from September 2011 to November 2013.
\nFor more information, see main article and supporting information (including figures and tables) from:
\nBarkley, H.C., A.L. Cohen, Y. Golbuu, V.R. Starczak, T.M. DeCarlo, K.E.F. Shamberger. 2015. Changes in coral reef communities across a natural gradient in seawater pH. Science Advances, 1, e1500328. doi:10.1126/sciadv.1500328
DeCarlo, T.M., A.L. Cohen, H.C. Barkley, Q. Cobban, C. Young, C., K.E.F. Shamberger, R.E. Brainard, Y. Golbuu. 2015. Coral macrobioerosion is accelerated by ocean acidification and nutrients. Geology, 43, 7-10. doi:10.1130/G36147.1
\nShamberger, K. E. F., A. L. Cohen, Y. Golbuu, D. C. McCorkle, S. J. Lentz, and H. C. Barkley. 2014. Diverse coral communities in naturally acidified waters of a Western Pacific Reef, Geophys. Res. Lett., 41. DOI: 10.1002/2013GL058489.
The full seawater CO2 system was calculated using salinity, temperature, TA, and DIC data using an Excel Workbook Visual Basic for Applications translation of the original CO2SYS program (Lewis and Wallace, 1998) by Pelletier, Lewis, and Wallace at the Washington State Department of Ecology, Olympia, WA. The CO2SYS program was run with carbonate constants from Mehrbach et al. (1973) refit by Dickson and Millero (1987).
\nSee the supplementary information from Shamberger et al. (2014) for more information (DOI: 10.1002/2013GL058489).
\nBCO-DMO Processing Notes:
\n- Modified parameter names to conform with BCO-DMO naming conventions.
\n- Separated date/time field into separate columns.
\n- Replaced blanks (missing data) with 'nd' to indicate 'no data'.