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NOAA acidification study

31 Jul 2013
The Pacific Clam is under threat from rising acidity along with oysters, scallops and crabs

The Pacific Clam is under threat from rising acidity along with oysters, scallops and crabs

The US National Oceanic and Atmospheric Administration (NOAA) is conducting a survey of the Pacific Ocean to determine how bad the problem of acidification is for the shellfish industry.

Ocean acidification is caused by increased levels of CO2 in the atmosphere which is then absorbed by the ocean water to become carbonic acid.

NOAA’s Pacific Environmental Marine Laboratory (PMEL) says that there is already evidence of pitting and weakening of snail shells – a sure sign of increasing acid content.

The stronger the acid, the more difficult it is for shellfish such as oysters, clams, scallops and crabs to create their protective shells creating an obvious threat to the shellfish industry.

Dr Richard Feely, NOAA/PMEL senior scientist, said to World Fishing & Aquaculture: “The west coast of America is a vulnerable area for acidification. Every year from April to September the problem gets particularly bad due to natural upwellings."

The shellfish industry in the US is worth half a billion dollars so acidification is a really big issue for the US, but also globally. Dr Feely says that it's a problem affecting East Africa, South America and Portugal too.

For this reason, Dr Feely and a team of scientists will set off on a month long voyage on the NOAA ship Fairweather this week to monitor the problem. Starting in Seattle, the scientists will travel down to an area just off the coast of Mexico and will use the tiny snail terrapod to monitor ocean acidity along the way.

The terrapod will be used to determine how far the effects of acidification permeate through the food chain because they are the primary food source for young salmon.

Biologists onboard will also examine algal blooms which thrive in highly acidic conditions. Algal blooms also produce more toxins in acidic conditions, which Dr Feely calls a "double whammy" which exacerbates the problem.

The results from the voyage will be compared to Dr Feely's first benchmark study completed in 2007 to see how much acid levels have risen.

Dr Feely was alerted to the problem back in 2006 when he was investigating why oyster hatcheries along the Washington State coast started to experience 80 to 100% die-offs, a major problem because they supply all of the oyster seed for US fisheries.

The problem was initially thought to be down to bacteria but after the pH of the water in the hatchery tanks was measured, scientists discovered extremely high acid levels. After this problem was brought under control, survival rates went up from 20 to 80% in a year, saving the industry well over $35m.

The new research will be used to advise shellfish growers on how to change the chemistry of a controlled environment such as in an aquaculture tank. It will also be used to help growers identify new open-ocean areas to do business in where acid levels are lower.

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The Pacific Clam is under threat from rising acidity along with oysters, scallops and crabs

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