Sensitivity of marine invertebrates to acidification of seawater by an atmosphere enriched with CO2

Ocean acidification, a consequence of increasing atmospheric CO2, results from oceans absorbing about one-third of CO2 emissions, leading to a decrease in pH. This phenomenon can cause sublethal or lethal damage to marine organisms some of which are crucial for coastal ecosystems and human economies. Understanding how to reproduce acidified seawater in a laboratory is essential for assessing potential impacts. Our protocol uses a CO2-enriched atmosphere to determine the pH tolerance of Mysidopsis juniae, exposed at pH 6.8 and 7.0, and larvae of Arbacia lixula, exposed at pH 7.2. M. juniae showed lethal responses at pH 6.8 ± 0.3, while A. lixula exhibited delayed larval development as a sublethal reaction at pH 7.2 ± 0.3. However, these pH levels are extreme and cannot be predicted for future oceanic conditions. Other studies have indicated negative sublethal effects on similar organisms at higher pH levels than those observed in this study. Continued experiments are necessary to prepare for and inform about the dangers of ocean acidification, and also to develop other types of studies.