Rising acid levels in oceans threaten shellfish

Rising acidity levels in the ocean, due mainly to increased levels of carbon dioxide from fossil fuels, could pose a major threat to New Jersey’s shellfish industry by the end of the century.

That view comes from scientists with the National Oceanic and Atmospheric Administration, or NOAA, and has drawn serious attention from U.S. Sen. Frank Lautenberg, D-N.J.

Lautenberg said the problem could harm the state’s $121 million-per-year shellfish industry. A NOAA scientist said the problem could affect 500 million people worldwide who rely on the ocean for food. In the U.S. alone, the fish and shellfish industry is worth $4 billion per year. Lautenberg has sponsored a bill to study the problem.

The immediate concern is that certain marine creatures, especially in their juvenile stages, may not be able to form calcium carbonate skeletons and shells if the ocean is too acidic. This includes plankton, shellfish, coral, sea urchins and starfish.

“Ocean acidification is a threat to our marine ecosystem and our economy. The change in ocean chemistry caused by greenhouse gases is corrosive and affects our marine life, food supply and overall ocean health,” Lautenberg said.

The Federal Ocean Acidification Research and Monitoring Act of 2007, or FOARAM, co-sponsored by Lautenberg and Sen. Barbara Boxer, D-Ca., would include $30 million to study the problem. The bill would lead to the formation of a committee and a national plan to address the issue.


Some study and water sampling has been done, according to Dr. Richard Feely, a NOAA oceanographer working on the problem at the Pacific Marine Environmental Laboratory in Seattle.

“I’d rather see $50 million, but $30 million is good. I just met with the Pacific Northwest Fishing industry, and they’re very concerned,” Feely said.

Acidity is measured by a pH test with 1 being very acidic and 14 being very alkaline or basic. Feely said two centuries ago, as the industrial age was beginning, the ocean’s pH was 8.2. It has only dropped to 8.1 so far, but even such a small change may already be affecting sensitive corals and planktons.

“The impacts are probably occurring now. We need to start analyzing. We have nothing right now,” Feely said.

He said water samples show a 30-percent increase in the hydrogen ion content, a measure of acidity, compared with 200 years ago. Computer modeling suggests this could increase by another 150 percent by the end of this century.

Carbon dioxide is considered the main contributor, but nitrogen and sulfur compounds, along with other products of fossil fuel combustion, are adding to the acidity.

Feely said atmospheric carbon dioxide levels are now at 383 parts per million and rising by 1 to 1.5 parts per million each year. In laboratory experiments, a level of 650 parts per million had an impact on some marine life, while at 800 parts the calcium carbonate shells and skeletons corroded.

“Coral reefs show a clear tipping point at 800 parts per million. By the end of the century, we could be close to 800 parts. The next century will be very important. If we continue to release CO2 at the rates we are, we’ll have serious impacts on our marine ecosystem by the end of the century,” Feely said.

For years scientists have said the oceans fight global warming by taking in carbon dioxide. Feely said oceans take in about 2 billion metric tons per year, or 30 percent of the 7 billion metric tons being spewed into the atmosphere.

“The oceans eat CO2. It’s a good thing for global warming. Without it, we’d have 90 parts per million higher levels in the atmosphere. The 383 parts per million we have would be 470 parts. Global temperatures would be half a degree Celsius higher,” Feely said.

The problem is that carbon dioxide converts to carbonic acid in the ocean and makes the water more acidic. That this could cause widespread changes in pH was first a theory in the 1970s. Feely published his first paper on the issue in 1982. The rise of carbon dioxide in the atmosphere has been measured since 1958.

While the economic concern is for marketable species, such as scallops and surf clams, Feely is also worried about marine life at the bottom of the food chain. Experiments show impacts on planktons that have hard skeletons. He said putting them in corrosive waters caused shell erosion within 48 hours. Planktons are a major part of the marine food chain.

Other experiments show some species in coral reefs would live on without their shells, which would form again if the water was returned to a higher pH.

“At 7.6 pH they can’t calicify. They don’t die. The organism survives, but it’s an anemone rather than a coral. We change pH back to 8.1, and it goes back to being a coral,” Feely said.

Computer modeling shows the first fishing area that would be affected is off Alaska, but then problems could spread along the West Coast. Feely said the most acidic water off the East Coast is now at 2,500 meters. One model puts it in the 50-meter depth within a century.

“Even at 2,500 meters, we’re seeing effects of CO2 down there. Fifty meters, that’s on the (Continental) Shelf. We have to avoid that somehow,” Feely said.

Coral reefs are another concern since they are so sensitive and are so full of diversity. Lautenberg termed them “rain forests of the sea” in his Senate testimony for the bill.

On land, lakes hurt by acid rain can be treated with alkaline products in a process known as “liming.” Feely said it can’t be done in a body of water as big as the ocean. The only solution is to emit less carbon dioxide.

“Two billion metric tons go into the oceans each year. That’s .02 pH units a decade, a 6 percent increase in acidity per decade. If we reduce CO2, we can have an impact,” Feely said.

Lautenberg’s bill is slated to be heard in committee later this month. A companion bill is being drafted in the House, but it has not been introduced.
Richard Degener, pressofatlanticcity.com, 3 November 2007. Article.


				
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