Friday, August 1, 2014

Good morning,

Up and down the Pacific Coast, from California to British Columbia to Alaska, shellfish farms experienced a decline in production numbers: Something was happening to their larvae at the formative stage of life when they build their shells. No one in the industry knew why.

Scientists testing the water up and down the Pacific Coast found evidence of the same steep decline in pH. Studies have found more acidic water in Alaska is stunting the growth of red king crabs and tanner crabs. Plummeting pH levels across the Eastern Seaboard have been impacting the shellfish industry for decades.

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The economic impacts of rising acidity can be devastating. At its peak in 1952, U.S. producers harvested 72 million pounds of eastern oysters, according to data collected by the National Marine Fisheries Service. In 2012, the last year for which data is available, farmers hauled in just 23.8 million pounds. Producers haven't harvested more than 30 million pounds since 1996.

Acidification happens as a result of increased carbon in the atmosphere. The top layer of the world's oceans, perhaps the first 100 meters, absorb the elements in the atmosphere. The more carbon, the more acidic the water becomes. Currents take that layer of surface water and plunge it into the depths of the Pacific; decades later, the water is forced back to the surface as it reaches the West Coast, a process scientists call upwelling.

The impacts go far beyond oysters and crabs. In a paper published in April in the Proceedings of the Royal Society B, a team of scientists from the National Oceanic and Atmospheric Administration said it had found evidence that acidification is dissolving the shells of pteropods, tiny free-swimming marine snails, off the West Coast. Pteropods are a staple food source for salmon, mackerel and herring. When one food source disappears, the impact is felt up and down the food chain; fishing industries based on the West Coast could see their stocks move away, in search of food.

What scares scientists the most about the increasingly acidic oceans is that there is no obvious solution. Acidity can be mitigated in some localized areas by spreading crushed up shells, and fields of sea grass can take some carbon out of the ocean. But those are localized solutions. Even if man flipped a switch and turned off every carbon-emitting machine on earth, the higher-carbon water moving toward the Pacific Coast would mean oceans will continue the march toward acidity for the next century, at least.