Ocean Acidity Level Means Trouble for Sea Life

Parts of the world’s oceans appear to be acidifying far faster than scientists have expected. The culprit: rising levels of carbon dioxide in the atmosphere pumped into the air from cars, power plants, and industries. Measured on a 1 to 10 scale, the lower the pH, the more acidic the water. A slight dip in pH as small as .1 can be a deadly consequence for some sea life. As emissions increased over the last 50 years, the atmosphere and ocean waters have picked up higher levels of carbon dioxide.

Burke Hales, an associate professor of chemical oceanography at Oregon State University, has been studying the increased presence of the gas caused in the ocean, which has created more acidic water. Hales' research shows that by the end of the 21st century pH levels could lower by .3 to .5 in the ocean, a 150 percent change from normal levels. "It absolutely is a sign of the times," said Hales. "We know very, very well how much carbon dioxide gets omitted because of how much of a role oil plays in the economy."

Acidic water makes it difficult, if not impossible, for young shellfish, corals and other animals to grow life-sustaining structures, like shells. The Whiskey Creek Shellfish Hatchery in Netarts along the Oregon coast in Tillamook County has reported on testing that revealed multiple factors, including more acidic waters, have contributed to deaths among shellfish larvae.

Like any gas, carbon dioxide dissolves in water. The increasing levels of carbon dioxide emitted into the atmosphere are absorbed by the ocean but unlike other gases, it reacts and lowers the pH of the water. When there is more gas, water reaches higher acidity levels. A group of researchers, led by Richard Feely, an oceanographer at the National Oceanic and Atmospheric Administration, spent part of 2007 examining rising acidity levels on West Coast shores. The scientists compared the total amount of carbon dioxide against the total amount of other gases on the shore and have found that today, for every million molecules of other gases; there are 390 molecules of carbon dioxide, significantly higher than before the industrial revolution, when it was 280. Measurements taken last year along the west coast measured 315 which is enough to make water corrosive to some sea creatures' shells.

Feely co-authored a paper documenting the effects of acidification. These changes in the ocean's waters already seem to be impacting certain ocean creatures, preventing organisms like coral reefs and shellfish, such as oysters, from fully developing shells. Alan Barton at the Whiskey Creek Shellfish Hatchery said a combination of factors have led to the deaths of the hatchery's larvae. The hatchery, one of the main suppliers of oyster larvae in the nation, produces about 10 billion each year. A couple of months ago, production went down to about 20 percent of normal levels. "The industry is in huge shock that we haven't been able to produce," said Cudd, co-owner of the hatchery. Oyster larvae grow aragonite shells about 24 hours after they are hatched. Barton is testing to see whether the more acidic water is preventing the shells from growing, thus killing the baby oysters. Research points toward lower pH in the ocean as a primary cause of death. If more acidic oceans are killing the sea creatures, the impact on the sea-life industries is obvious and if the hatchery staff can't figure out what is killing the oyster larvae soon, operations may have to shut down.

On Tatoosh Island, off the northwest tip of Washington State’s Olympic Peninsula, researchers have found acidification trends running some 10 times faster than projected. The University of Chicago’s Timothy Wootton led a team that analyzed more than 24,500 water samples gathered over eight years. They found wide swings in carbonate levels during the year. As acidification increased, they found, larger shell-forming creatures such as mussels and barnacles lost ground to smaller ones and nonshell types of algae. As acidification changes the mix of marine life in coastal areas, it could eliminate species important to commercial fisheries and increase the population of animals that prefer acidic water causing yet another unknown impact on any variety of sea life. It is still not clear whether the oyster larvae in particular will be able to adapt to more acidic waters or if any will be able to evolve without soluble shells. What is clear, is that the oceans are more acidic than ever because of the rise in human carbon dioxide omissions and amazingly there are still people out there who will try to argue this point.

Summarized from the articles "Ocean Acidity Level Means Trouble for Sea Life" by David Holley for the Observer and "World’s Oceans Turning Acidic Faster Than Expected" by Peter Spotts for the Christian Science Monitor.