Pacific coast turning more acidic( CORVALLIS Ore. An international tea...)

CORVALLIS, Ore. An international team of scientists surveying the waters of the continental shelf off the West Coast of North America has discovered for the first time high levels of acidified ocean water within 20 miles of the shoreline, raising concern for marine ecosystems from Canada to Mexico.

Researchers aboard the Wecoma, an Oregon State University research vessel, also discovered that this corrosive, acidified water that is being upwelled seasonally from the deeper ocean is probably 50 years old, suggesting that future ocean acidification levels will increase since atmospheric levels of carbon dioxide have increased rapidly over the past half century.

Results of the study were published this week in Science Express.

When the upwelled water was last at the surface, it was exposed to an atmosphere with much lower CO₂ (carbon dioxide) levels than todays, pointed out Burke Hales, an associate professor in the College of Oceanic and Atmospheric Sciences at Oregon State University and an author on the Science study. The water that will upwell off the coast in future years already is making its undersea trek toward us, with ever-increasing levels of carbon dioxide and acidity.

The coastal ocean acidification train has left the station, Hales added, and there not much we can do to derail it.

Scientists have become increasingly concerned about ocean acidification in recent years, as the worlds oceans absorb growing levels of carbon dioxide from the atmosphere. When that CO₂ mixes into the ocean water, it forms carbonic acid that has a corrosive effect on aragonite the calcium carbonate mineral that forms the shells of many marine creatures.

Certain species of phytoplankton and zooplankton, which are critical to the marine food web, may also be susceptible, the scientists point out, although other species of open-ocean phytoplankton have calcite shells that are not as sensitive.