Publication Date:
2024-07-22
Description:
Ocean acidification, the assimilation of atmospheric CO2 by the oceans that decreases the pH and CaCO3 saturation state (Omega) of seawater, is projected to have severe adverse consequences for calcifying organisms. While strong evidence suggests calcification by tropical reef-building corals containing algal symbionts (zooxanthellae) will decline over the next century, likely responses of azooxanthellate corals to ocean acidification are less well understood. Because azooxanthellate corals do not obtain photosynthetic energy from symbionts, they provide a system for studying the direct effects of acidification on energy available for calcification. The solitary azooxanthellate orange cup coral Balanophyllia elegans often lives in low-pH, upwelled waters along the California coast. In an 8-month factorial experiment, we measured the effects of three pCO2 treatments (410, 770, and 1220 µatm) and two feeding frequencies (3-day and 21-day intervals) on "planulation" (larval release) by adult B. elegans, and on the survival, skeletal growth, and calcification of newly settled juveniles. Planulation rates were affected by food level but not pCO2. Juvenile mortality was highest under high pCO2 (1220 µatm) and low food (21-day intervals). Feeding rate had a greater impact on calcification of B. elegans than pCO2. While net calcification was positive even at 1220 µatm (~3 times current atmospheric pCO2), overall calcification declined by ~25-45%, and skeletal density declined by ~35-45% as pCO2 increased from 410 to 1220 µatm. Aragonite crystal morphology changed at high pCO2, becoming significantly shorter but not wider at 1220 µatm. We conclude that food abundance is critical for azooxanthellate coral calcification, and that B. elegans may be partially protected from adverse consequences of ocean acidification in habitats with abundant heterotrophic food.
Keywords:
Alkalinity, total; Alkalinity, total, standard deviation; Animalia; Aragonite saturation state; Aragonite saturation state, standard deviation; Balanophyllia elegans; Benthic animals; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (〈20 L); Calcification/Dissolution; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, inorganic, dissolved, standard deviation; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cnidaria; Coulometric titration; Density; Density, standard error; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Identification; Individuals; Laboratory experiment; Laboratory strains; Larvae; Length; Length, standard error; Mass; Mass, standard error; Mortality/Survival; Nitrate; Nitrate, standard deviation; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Other; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH, standard deviation; Phosphate; Phosphate, standard deviation; Potentiometric titration; Proportion; Reproduction; Salinity; Salinity, standard deviation; Silicate; Silicate, standard deviation; Single species; Species; Table; Temperature, water; Temperature, water, standard deviation; Treatment; Volume; Volume, standard error; Width; Width, standard error
Type:
dataset
Format:
text/tab-separated-values, 20615 data points
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