Seawater carbonate chemistry and microbioerosion of coral skeletons

• Main Authors: Reyes-Nivia, Catalina, Diaz-Pulido, Guillermo, Kline, David I, Hoegh-Guldberg, Ove, Dove, Sophie
• Format: Dataset
• Language: English
• Published: PANGAEA 2013
• Subjects: Abundance; standard error; Alkalinity; total; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Biomass; Bottles or small containers/Aquaria (<20 L); Buoyant weighing technique according to Davies (1989); Calcification/Dissolution; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon; inorganic; dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cnidaria; Coast and continental shelf; Dissolution/calcification; Dissolution rate of calcium carbonate; Distance; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Great_Barrier_Reef; Great Barrier Reef; Australia; Hyella sp.; Identification; Irradiance; Isopora cuneata; Laboratory experiment; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.830261; https://doi.org/10.1594/PANGAEA.830261

Biological mediation of carbonate dissolution represents a fundamental component of the destructive forces acting on coral reef ecosystems. Whereas ocean acidification can increase dissolution of carbonate substrates, the combined impact of ocean acidification and warming on the microbioerosion of coral skeletons remains unknown. Here, we exposed skeletons of the reef-building corals, Porites cylindrica and Isopora cuneata, to present-day (Control: 400 µatm - 24 °C) and future pCO2-temperature scenarios projected for the end of the century (Medium: +230 µatm - +2 °C; High: +610 µatm - +4 °C). Skeletons were also subjected to permanent darkness with initial sodium hypochlorite incubation, and natural light without sodium hypochlorite incubation to isolate the environmental effect of acidic seawater (i.e., Omega aragonite <1) from the biological effect of photosynthetic microborers. Our results indicated that skeletal dissolution is predominantly driven by photosynthetic microborers, as samples held in the dark did not decalcify. In contrast, dissolution of skeletons exposed to light increased under elevated pCO2-temperature scenarios, with P. cylindrica experiencing higher dissolution rates per month (89%) than I. cuneata (46%) in the high treatment relative to control. The effects of future pCO2-temperature scenarios on the structure of endolithic communities were only identified in P. cylindrica and were mostly associated with a higher abundance of the green algae Ostreobium spp. Enhanced skeletal dissolution was also associated with increased endolithic biomass and respiration under elevated pCO2-temperature scenarios. Our results suggest that future projections of ocean acidification and warming will lead to increased rates of microbioerosion. However, the magnitude of bioerosion responses may depend on the structural properties of coral skeletons, with a range of implications for reef carbonate losses under warmer and more acidic oceans.