Seawater carbonate chemistry and ecosystem calcification, community production of coral reef

• Main Authors: DeCarlo, Thomas M, Cohen, Anne L, Wong, George T F, Shiah, Fuh Kwo, Lentz, S J, Davis, Kristen A, Shamberger, K E F, Lohmann, Pat
• Format: Dataset
• Language: English
• Published: PANGAEA 2017
• Subjects: Alkalinity; total; Aragonite saturation state; Benthos; Bicarbonate ion; Calcification/Dissolution; Calcification rate; standard deviation; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; net production; Carbonate ion; Carbonate system computation flag; Carbon dioxide; air-sea; flux; Coast and continental shelf; Density; DEPTH; water; Dongsha_Atoll; Entire community; EXP; Experiment; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Irradiance; Net calcification rate of calcium carbonate; Net community production; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Primary production/Photosynthesis; Rocky-shore community; Salinity; Sampling date; Temperature; Time; Time in hours; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.875891; https://doi.org/10.1594/PANGAEA.875891

Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a two-week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the non-bleaching period was 8.5, significantly elevated above that of the surrounding open ocean (8.0-8.1) as a consequence of daytime NEP (up to 112 mmol C/m**2/h). Diurnal-averaged NEC was 390?+/-?90 mmol CaCO3/m**2/day, higher than any other coral reef studied to date despite comparable calcifier cover (25%) and relatively high fleshy algal cover (19%). Coral bleaching linked to elevated temperatures significantly reduced daytime NEP by 29 mmol C/m**2/h. pH on the reef flat declined by 0.2 units, causing a 40% reduction in NEC in the absence of pH changes in the surrounding open ocean. Our findings highlight the interactive relationship between carbonate chemistry of coral reef ecosystems and ecosystem production and calcification rates, which are in turn impacted by ocean warming. As open-ocean waters bathing coral reefs warm and acidify over the 21st century, the health and composition of reef benthic communities will play a major role in determining on-reef conditions that will in turn dictate the ecosystem response to climate change.