Latitudinal Trends and Drivers in the CO2–Carbonic Acid System of Papahānaumokuākea Marine National Monument

Coral reefs in the northern atolls of Papahānaumokuākea Marine National Monument (PMNM) are particularly vulnerable to climate change and ocean acidification, according to a study analyzing latitudinal trends in marine carbon chemistry. Researchers found that surface seawater pH and CO₂ levels vary three times more near reefs than in open ocean waters, with this variability detectable up to 50 km away from the nearest coral ecosystems. The findings suggest that coral reef metabolism significantly influences local carbon chemistry, while environmental factors like temperature, wind speed, and water residence time further shape these conditions. The study also identified a net calcification process creating an alkalinity sink across PMNM waters, highlighting the complex interplay between biological and physical drivers in this remote yet ecologically critical region.

Kealoha, A. K., Kahng, S. E., Mackenzie, F. T., Alin, S. R., Kosaki, R. K., Brainard, R. E., & Winn, C. D. (2015). Latitudinal Trends and Drivers in the CO2–Carbonic Acid System of Papahānaumokuākea Marine National Monument. Aquatic Geochemistry, 21(6), 535–553. https://doi.org/10.1007/s10498-015-9273-z