Ocean acidification impacts mussel control on biomineralisation

Ocean acidification is altering the oceanic carbonate saturation state and threatening the survival of marine calcifying organisms. Production of their calcium carbonate exoskeletons is dependent not only on the environmental seawater carbonate chemistry but also the ability to produce biominerals through proteins. We present shell growth and structural responses by the economically important marine calcifier Mytilus edulis to ocean acidification scenarios (380, 550, 750, 1000 µatm pCO2). After six months of incubation at 750 µatm pCO2, reduced carbonic anhydrase protein activity and shell growth occurs in M. edulis. Beyond that, at 1000 µatm pCO2, biomineralisation continued but with compensated metabolism of proteins and increased calcite growth. Mussel growth occurs at a cost to the structural integrity of the shell due to structural disorientation of calcite crystals. This loss of structural integrity could impact mussel shell strength and reduce protection from predators and changing environments.

海洋酸化（Ocean acidification）正改变海洋碳酸盐饱和状态（oceanic carbonate saturation state），并威胁海洋钙化生物（marine calcifying organisms）的生存。该类生物的碳酸钙外骨骼（calcium carbonate exoskeletons）形成，不仅依赖于环境中的海水碳酸盐化学（seawater carbonate chemistry）条件，还依赖于通过蛋白质合成生物矿质（biominerals）的能力。本数据集展示了具有经济价值的海洋钙化生物紫贻贝（Mytilus edulis）在4种海洋酸化场景（380、550、750、1000 µatm pCO2）下的壳体生长与结构响应特征。在750 µatm pCO2环境中孵育6个月后，紫贻贝的碳酸酐酶（carbonic anhydrase）蛋白活性与壳体生长速率均出现显著下降。当pCO2升至1000 µatm时，生物矿化作用（biomineralisation）仍可继续进行，但蛋白质代谢出现代偿性变化，且方解石（calcite）生长量有所增加。由于方解石晶体（calcite crystals）的结构取向发生紊乱，贻贝的生长会以壳体结构完整性受损为代价。这种结构完整性的丧失可能会削弱贻贝壳体的强度，进而降低其抵御捕食者以及适应环境变化的能力。