Seawater carbonate chemistry and shell growth rate and Vicker hardness of oyster Crassostrea hongkongensis

• Main Authors: Rajan, K, Meng, Yuan, Yu, Ziniu, Roberts, Steven B, Thiyagarajan, Vengatesen
• Format: Dataset
• Language: English
• Published: PANGAEA 2021
• Subjects: Alkalinity; total; standard deviation; Animalia; Aragonite saturation state; Benthic animals; Benthos; Bicarbonate ion; 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; Coast and continental shelf; Containers and aquaria (20-1000 L or < 1 m**2); Crassostrea hongkongensis; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Growth rate; Laboratory experiment; Mollusca; Month; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Other studied parameter or process; Partial pressure of carbon dioxide; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Potentiometric; Potentiometric titration; Registration number of species; Salinity; Ocean acidification
• Online Access: https://doi.pangaea.de/10.1594/PANGAEA.943184; https://doi.org/10.1594/PANGAEA.943184

Biomineralization is one of the key processes that is notably affected in marine calcifiers such as oysters under ocean acidification (OA). Understanding molecular changes in the biomineralization process under OA and its heritability, therefore, is key to developing conservation strategies for protecting ecologically and economically important oyster species. To do this, in this study, we have explicitly chosen the tissue involved in biomineralization (mantle) of an estuarine commercial oyster species, Crassostrea hongkongensis. The primary aim of this study is to understand the influence of DNA methylation over gene expression of mantle tissue under decreased pH 7.4, a proxy of OA, and to extrapolate if these molecular changes can be observed in the product of biomineralization—the shell. We grew early juvenile C. hongkongensis, under decreased pH 7.4 and control pH 8.0 over 4.5 months and studied OA-induced DNA methylation and gene expression patterns along with shell properties such as microstructure, crystal orientation and hardness. The population of oysters used in this study was found to be moderately resilient to OA at the end of the experiment. The expression of key biomineralization-related genes such as carbonic anhydrase and alkaline phosphatase remained unaffected; thus, the mechanical properties of the shell (shell growth rate, hardness and crystal orientation) were also maintained without any significant difference between control and OA conditions with signs of severe dissolution. In addition, this study makes three major conclusions: (1) higher expression of Ca2+ binding/signalling-related genes in the mantle plays a key role in maintaining biomineralization under OA; (2) DNA methylation changes occur in response to OA; however, these methylation changes do not directly control gene expression; and (3) OA would be more of a 'dissolution problem' rather than a 'biomineralization problem' for resilient species that maintain calcification rate with normal shell growth and mechanical properties.