Publication Date:
2013-11-09
Description:
An array of MAPCO 2 buoys, CRIMP-2, Ala Wai, and Kilo Nalu, deployed in the coastal waters of Hawaii, have produced multi-year high temporal resolution CO 2 records in three different coral reef environments off the island of Oahu, Hawaii. This study, which includes data from June 2008 to December 2011, is part of an integrated effort to understand the factors that influence the dynamics of CO 2 –carbonic acid system parameters in waters surrounding Pacific high-island coral reef ecosystems and subject to differing natural and anthropogenic stresses. The MAPCO 2 buoys are located on the Kaneohe Bay backreef, and fringing reef sites on the south shore of Oahu, Hawaii. The buoys measure CO 2 and O 2 in seawater and in the atmosphere at 3-h intervals, as well as other physical and biogeochemical parameters (conductivity, temperature, depth, chlorophyll- a , and turbidity). The buoy records, combined with data from synoptic spatial sampling, have allowed us to examine the interplay between biological cycles of productivity/respiration and calcification/dissolution and biogeochemical and physical forcings on hourly to inter-annual time scales. Air–sea CO 2 gas exchange was also calculated to determine whether the locations were sources or sinks of CO 2 over seasonal, annual, and interannual time periods. Net annualized fluxes for CRIMP-2, Ala Wai, and Kilo Nalu over the entire study period were 1.15, 0.045, and −0.0056 mol C m −2 year −1 , respectively, where positive values indicate a source or a CO 2 flux from the water to the atmosphere, and negative values indicate a sink or flux of CO 2 from the atmosphere into the water. These values are of similar magnitude to previous estimates in Kaneohe Bay as well as those reported from other tropical reef environments. Total alkalinity (A T ) was measured in conjunction with pCO 2 , and the carbonic acid system was calculated to compare with other reef systems and open ocean values around Hawaii. These findings emphasize the need for high-resolution data of multiple parameters when attempting to characterize the carbonic acid system in locations of highly variable physical, chemical, and biological parameters (e.g., coastal systems and reefs).
Print ISSN:
1380-6165
Electronic ISSN:
1573-1421
Topics:
Chemistry and Pharmacology
,
Geosciences
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