Seawater carbonate chemistry, calcification and shell size of hard clam Mercenaria mercenaria during experiments, 2011

• Main Authors: Waldbusser, George G, Bergschneider, Heather, Green, Mark A
• Format: Dataset
• Language: English
• Published: PANGAEA 2010
• Subjects: Alkalinity; total; Alkalinity anomaly technique (Smith and Key; 1975); Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; Bottles or small containers/Aquaria (<20 L); Calcification/Dissolution; Calcification rate; standard deviation; Calcification rate of calcium carbonate; 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; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Identification; Laboratory experiment; Laboratory strains; Measured; Mercenaria mercenaria; shell size; Mollusca; North Atlantic; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; pH meter (Thermo Fisher Scientific); Salinity; Single species; Species; Temperature; water; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.771576; https://doi.org/10.1594/PANGAEA.771576

Increasing atmospheric carbon dioxide threatens to decrease pH in the world's oceans. Coastal and estuarine calcifying organisms of significant ecological and economical importance are at risk; however, several biogeochemical processes drive pH in these habitats. In particular, coastal and estuarine sediments are frequently undersaturated with respect to calcium carbonate due to high rates of organic matter remineralization, even when overlying waters are saturated. As a result, the post-larval stages of infaunal marine bivalves must be able to deposit new shell material in conditions that are corrosive to shell. We measured calcification rates on the hard clam, Mercenaria spp.,in 5 post-larval size classes (0.39, 0.56, 0.78, 0.98, and 2.90 mm shell height) using the alkalinity anomaly method. Acidity of experimental water was controlled by bubbling with air-CO2 blends to obtain pH values of 8.02, 7.64, and 7.41, corresponding to pCO2 values of 424, 1120, and 1950 µatm. These pH values are typical of those found in many near-shore terrigenous marine sediments. Our results show that calcification rate decreased with lower pH in all 5 size classes measured. We also found a significant effect of size on calcification rate, with the smaller post-larval sizes unable to overcome dissolution pressure. Increased calcification rate with size allowed the larger sizes to overcome dissolution pressure and deposit new shell material under corrosive conditions. Size dependency of pH effects on calcification is likely due to organogenesis and developmental shifts in shell mineralogy occurring through the post-larval stage. Furthermore, we found significantly different calcification rates between the 2 sources of hard clams we used for these experiments, most likely due to genotypic differences. Our findings confirm the susceptibility of the early life stages of this important bivalve to decreasing pH and reveal mechanisms behind the increased mortality in post-larval juvenile hard clams related to dissolution pressure, that ...