Nighttime dissolution in a temperate coastal ocean ecosystem increases under acidification@en

Anthropogenic emissions of carbon dioxide (CO2) are causing ocean acidification, lowering seawater aragonite (CaCO3) saturation state (Omega arag), with potentially substantial impacts on marine ecosystems over the 21st Century. Calcifying organisms have exhibited reduced calcification under lower saturation state conditions in aquaria. However, the in situ sensitivity of calcifying ecosystems to future ocean acidification remains unknown. Here we assess the community level sensitivity of calcification to local CO2-induced acidification caused by natural respiration in an unperturbed, biodiverse, temperate intertidal ecosystem. We find that on hourly timescales nighttime community calcification is strongly influenced by Omega arag, with greater net calcium carbonate dissolution under more acidic conditions. Daytime calcification however, is not detectably affected by Omega arag. If the short-term sensitivity of community calcification to Omega arag is representative of the long-term sensitivity to ocean acidification, nighttime dissolution in these intertidal ecosystems could more than double by 2050, with significant ecological and economic consequences.人为二氧化碳（CO₂）排放正在引发海洋酸化（ocean acidification），降低海水文石（aragonite，CaCO₃）饱和状态（Omega arag），并可能在21世纪对海洋生态系统造成显著影响。钙化生物（calcifying organisms）在水族箱的低饱和状态环境中，已表现出钙化作用减弱的现象。然而，钙化生态系统（calcifying ecosystems）对未来海洋酸化的原位（in situ）敏感性仍未明确。本研究针对一处未受干扰、物种丰富的温带潮间带生态系统，评估了钙化作用对自然呼吸作用引发的局地CO₂酸化的群落级敏感性。研究发现，在小时尺度下，夜间群落钙化作用显著受Omega arag影响，酸性更强的环境中净碳酸钙（calcium carbonate）溶解量更高。但日间钙化作用未表现出可检测到的Omega arag相关性影响。若群落钙化作用对Omega arag的短期敏感性可代表其对海洋酸化的长期敏感性，则到2050年，此类潮间带生态系统的夜间溶解量将翻倍以上，进而引发显著的生态与经济后果。