| Summary: | Laboratory experiments reveal calcification rates of crustose coralline algae (CCA) are strongly correlated to seawater aragonite saturation state. Predictions of reduced coral calcification rates, due to ocean acidification, suggest that coral reef communities will undergo ecological phase shifts as calcifying organisms are negatively impacted by changing seawater chemistry. The water chemistry data described here are from discrete water samples collected by the NOAA Coral Reef Ecosystem Program (CREP) to assess the seawater carbonate systems at fixed climate survey sites located in coral reef habitats in the Philippines in 2012, 2013, and 2015. Climate sites were established by CREP to assess multiple features of the coral reef environment (in addition to the data described herein) over time. SCUBA divers collected two discrete water samples from each site; one at the reef and one at the surface directly above the reef. The samples were processed by CREP and sent to NOAA Pacific Marine Environmental Laboratory (PMEL) to be analyzed for total alkalinity (TA) and dissolved inorganic carbon (DIC). From these constituents, alongside temperature, salinity, and depth data, other parameters of the seawater carbonate system can be calculated. Additionally in 2015, conductivity-temperature-depth (CTD) casts were also performed to characterize the spatial structure of the physical and chemical properties of the ocean environment influencing the living coral reef resources observed during climate site surveys. Data are collected by lowering the CTD in a profiling mode from a small boat, resulting in vertical profiles (max 18 meter depth, downcast only) of water column conductivity, temperature, and pressure. Vertical profiles of temperature, salinity, and turbidity resulting from CTD casts provide indicators for local sea water chemistry changes. These water chemistry and CTD data provide a baseline for tracking reef carbonate system changes due to globally increasing levels of atmospheric carbon dioxide. In addition to these discrete samples, water samples were collected as part of CREP's ocean acidification diurnal suite, which also includes vertical profiles from CTD casts, current direction and magnitude from an Acoustic Doppler Current Profiler, and pH from an SeaFET sensor. The data associated with the diurnal suite are documented and archived separately.
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