Alaskan Pollock Showing Higher Carbonate Levels In Blood - Likely Response To Ocean Acidification

No matter what you believe about climate change, ocean chemistry doesn't lie. Even toy store chemistry tests will show that the seas are becoming more acidic, and the off-kilter levels can have a scary impact on sea creatures: it dissolves them.

The oceans absorb carbon dioxide from the atmosphere, produced mostly by tailpipes and coal and oil-fired power plants. The CO2 increases acidity (pH) in the ocean which robs it of calcium carbonate, the building block of sea creatures' skeletons and shells. Scientists estimate the ocean is 25 percent more acidic now than it was 300 years ago. Corals, oysters and clams in the wild already show corrosion from the rising acid levels, and tests on king crab have been under way in Kodiak labs for several years. At a seminar last week, reports of potential impacts on pollock, Alaska's largest fish resource, raised eyebrows and more questions.

In tests on one-year old pollock at varying levels of pH, researchers at NOAA Fisheries Newport lab discovered that the fish seemed to compensate for increased levels of carbon dioxide by boosting levels of bicarbonate in their blood

"Bicarbonate is just a buffer - it's like drinking Milk of Magnesia when you have a stomach ache. It buffers the acid in your stomach," explained Jeremy Mathis, a chemical oceanographer at the University of Alaska/Fairbanks. "So the bicarbonate in their blood is just buffering the change of pH. The fish that were treated in the lowest acidity had the highest concentration of bicarbonate in their blood, so it's almost like they overcompensated for the pH effect that they were being exposed to."

The big pollock question is where that bicarbonate comes from. "Fish can take bicarbonate in through their gills from sea water, or they can dissolve bone in order to get bicarbonate in their blood," Mathis said. "If they started dissolving bone that opens up a whole other can of impacts of size, growth and health. "Even if they were absorbing it from sea water, that is energy they are spending on regulating pH that they are not spending on growth and reproduction and foraging," he added. "So either way there was likely an energetic cost to the fish."

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