Environ. Sci. Technol. http://doi.org/jgz (2012)

Coastal oceans are experiencing increased pressure from climate change and anthropogenic influence, such as nutrient increases from run-off. Ocean acidification is of growing concern as atmospheric carbon dioxide increases, and excess nutrients fuel large algal blooms that deplete oxygen in subsurface waters and release CO2 on decay.

How these two CO2 sources affect coastal water acidity was investigated by William Sunda, National Oceanic and Atmospheric Administration, North Carolina, USA and Wei-Jun Cai, University of Georgia, USA. A biogeochemical model predicted the decrease in coastal water pH from organic matter decay to be up to 1.1 units, with the greatest effects at low salinity and temperature. Complex interactions with rising atmospheric CO2 result in the combined effects being more than additive in seawater at intermediate to higher temperatures. These interactions have important biological and food security implications as the coastal ocean supports most of the global fin fish and shellfish production.