“The intensity, duration, and extent of low-ph events are increasing in one of the most productive and diverse ecosystems on earth”. – Jeremy T. Mathis, Supervisor of Oceanography at NOAA Pacific Marine Environmental Laboratory.
Since the pre-industrial era, human activities have increased atmospheric carbon dioxide (CO2) concentrations by about 40%, to values now greater than 400 ppm. During this rapid loading of the atmosphere, the ocean has absorbed more than 25% of the two Trillion tons of emitted anthropogenic (human-caused) CO2, helping to offset atmospheric warming, but fundamentally changing ocean chemistry. The uptake of CO2 triggers a series of well-understood reactions in the surface ocean called ocean acidification (OA) that has already made the ocean 30% more acidic than in pre-industrial times. During this process, biologically important carbonate minerals are diminished, which makes it more difficult for organisms like mollusks to create and maintain their shells, especially during early life stages.
Impacts in Alaska?
The intensity, duration, and extent of low-pH (high acidity) events are increasing in one of the most productive and diverse ecosystems on Earth. While there have been few comprehensive studies, OA appears to act more strongly on certain species, but lower pH environments can fundamentally alter ecosystem composition toward dominance by non-calcifying organism. Mollusks, such as oysters and clams, appear to be the calcifying group most negatively affected by OA. However, crustaceans such as the red king crab and tanner crab species exhibit negative responses that included slower growth and lower survival rates when they are exposed to high-CO2, lower-pH water.