2014-08-24. What's Killing the Bay Area's Oysters?

posted Aug 31, 2014, 1:18 PM by Alan Gould

For GSS Climate Change chapter 8 and Losing Biodiversity chapter 7. Excerpt: Signifiers of the good life, local bivalves may be harbingers of another phenomenon: species extinction. ...roughly 7 million oysters ... the five oyster farms on Tomales Bay sell each year to local restaurants and bars. ...Though Hog Island’s inventory had restabilized by 2013, ...We just couldn’t supply the product. It was painful—and still is because we’re not over it. The culprit? Ocean acidification—climate change’s caustic cousin—caused by rising carbon dioxide emissions. ...In 2005, the National Oceanic and Atmospheric Administration began reporting that hatcheries throughout the West Coast were seeing steep declines in production, putting the $84 million industry in jeopardy. Hatchery staff and scientists scrambled to pinpoint the cause, .... It wasn’t until a year later that [Alan] Barton [or Whiskey Creek shellfish hatchery in Tillamook, Oregon] solved the mystery that had stumped scientists. On an ordinary summer day that was marred by a particularly bad die-off, he decided to test the pH levels in the tanks. ...Lo and behold, the pH level of the water was drastically lower (read: more corrosive) than usual. ...because the acidification is exacerbated by carbon dioxide emissions, every year it gets a little worse. ...These days, we release roughly 70 million tons per day—and the oceans soak up nearly a third of that. The result? On average, the sea is 30 percent more acidic than it was 200 years ago. And in the last decade, it began passing the point where young oysters can survive. It’s not necessarily the acidity that causes problems for the oysters, but rather the concomitant lack of carbonate ions in the water. Shellfish use these free-floating ions to build their shells. When seawater absorbs carbon dioxide, the number of carbonate ions available for the shellfish is reduced. “A baby oyster is trying to eat, grow, move around, and make a shell. So if it spends more energy trying to make a shell, then something else in that equation is going to suffer,” says Tessa Hill, a scientist with UC Davis who studies the impacts of rising carbon dioxide levels on native shellfish. “I say it’s like balancing your checkbook—you can’t spend a lot of energy on one thing without cutting back in some other category.” http://modernluxury.com/san-francisco/story/whats-killing-the-bay-areas-oysters. By Jacoba Charles, San Francisco Magazine.

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