Calcification rates of crustose coralline algae (CCA) derived from calcification accretion units (CAUs) deployed at coral reef sites in Timor-Leste from 2012-10-15 to 2014-10-09 (NCEI Accession 0170031)

The calcification rate data described here were collected by the NOAA Coral Reef Ecosystem Program (CREP) from calcification accretion units, or CAUs, moored for two years at fixed climate survey sites and located on hard bottom shallow water (< 15 m) habitats in Timor-Leste, in accordance with protocols developed by Price et al. (2012). Five CAUs were deployed at each survey site. Climate sites were established in Timor-Leste by CREP in October 2012 to establish ecological baselines for climate change by measuring multiple features of the coral reef environment (in addition to the data described herein) over time.

CAUs, constructed in-house by CREP, are composed of two 10 x 10 cm flat, square, gray PVC plates, stacked 1 cm apart, and are attached to the benthos by SCUBA divers using stainless steel threaded rods. Deployed on the seafloor for a period of time, calcareous organisms, primarily crustose coralline algae and encrusting corals, recruit to these plates and accrete/calcify carbonate skeletons over time. By measuring the change in weight of the CAUs, the reef carbonate accretion rate can be calculated for that time period, measured in grams per centimeter per year.

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. CAUs are used by CREP to assess the current effects of changes in seawater carbonate chemistry on calcification and accretion rates of calcareous and fleshy algae.

These calcification rate data for Timor-Leste, along with other data collected at the climate survey sites (water temperature and chemistry, invertebrate biodiversity, and benthic cover, all archived separately), serve as a baseline for detecting changes associated with changing seawater chemistry and can be used to help scientists assess and understand how Timor-Leste's coral reefs are responding to ocean acidification.