Ocean Acidification May Corrode Animals' Shells by 2030

It's no secret that ocean acidification as a result of climate change is causing calcifiers like mollusks, starfish and corals to struggle. But now new research says that surface waters of the Chukchi and Beaufort seas, in particular, could reach levels of acidity that threaten the ability of animals to build and maintain their shells by 2030, with the Bering Sea reaching this level of acidity by 2044.

"Our research shows that within 15 years, the chemistry of these waters may no longer be saturated with enough calcium carbonate for a number of animals from tiny sea snails to Alaska King crabs to construct and maintain their shells at certain times of the year," Jeremy Mathis, an oceanographer at NOAA's Pacific Marine Environmental Laboratory and the study's lead author, said in a news release. "This change due to ocean acidification would not only affect shell-building animals but could ripple through the marine ecosystem."

From 2011-2012, a team of scientists from the NOAA, as well as the University of Alaska and Woods Hole Oceanographic Institution (WHOI), collected observations on water temperature, salinity and dissolved carbon during two month-long expeditions to the Bering, Chukchi and Beaufort Seas onboard US Coast Guard cutter Healy.

Using this data, they validated a predictive model for the region, which calculates how the amount of calcium and carbonate ions dissolved in seawater - an important indicator of ocean acidification - will change over time.

According to the model, these ion levels will drop below the current range in 2025 for the Beaufort Sea, 2027 for the Chukchi Sea, and 2044 for the Bering Sea.

This is critical because certain marine animals rely on calcium carbonate (eg - aragonite) to build and maintain their shells, which they use for protection. However, if carbonate ion concentrations dip below tolerable levels, their shells may start to dissolve, even early in life. This will not only negatively affect shell-building organisms but also the fish that depend on these types of species for food.

"The Pacific-Arctic region, because of its vulnerability to ocean acidification, gives us an early glimpse of how the global ocean will respond to increased human-caused carbon dioxide emissions, which are being absorbed by our ocean," said Mathis. "Increasing our observations in this area will help us develop the environmental information needed by policy makers and industry to address the growing challenges of ocean acidification."

The findings were published in the journal Oceanography.

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