A pump collects water for sampling from a tidal pool on the California coast. Photo by Carnegie Science Foundation

WASHINGTON, March 18 (UPI) -- Ocean acidification is a growing threat in both the Atlantic and Pacific. New research along the California coast suggests the phenomenon is particularly problematic at night.

As the ocean takes up more carbon dioxide, the water becomes more acidic, making it difficult for mollusks like mussels and oysters to build their calcium carbonate shells.


Scientists monitoring tidal pools in California found ocean acidification exacerbates natural chemical changes that happen overnight.

During the day, photosynthesis limits the levels of CO2 in tidal pools, but at night, the respiration of plants and animals boosts CO2 levels. During low tides at night, tidal pools often became corrosive to shells and exoskeletons made of calcium carbonate.

Researchers published their findings in the journal Scientific Reports.

"Unless carbon dioxide emissions are rapidly curtailed, we expect ocean acidification to continue to lower the pH of seawater," lead study author Lester Kwiatkowski, a researcher at the Carnegie Science Foundation, said in a news release. "This work highlights that even in today's temperate coastal oceans, calcifying species, such as mussels and coralline algae, can dissolve during the night due to the more-acidic conditions caused by community respiration."

"If what we see happening along California's coast today is indicative of what will continue in the coming decades, by the year 2050 there will likely be twice as much nighttime dissolution as there is today," co-author Ken Caldera added. "Nobody really knows how our coastal ecosystems will respond to these corrosive waters, but it certainly won't be well."