'Citizens science' tests state's water

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 1-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," said 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 'nother 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." Results of the pollock bone tests should be ready in August.

Shellfish growers are seeing firsthand what increased acidity can do to their oyster crops. The Whiskey Creek Hatchery in Oregon is a major West Coast producer of oyster spat. For the past two years, the hatchery has had almost a complete loss of 10 billion oyster larvae due to acidic water flowing through the holding tanks, depending on the direction of the wind.

"The workers go in one day and the tanks are completely empty. The tiny oysters are completely dissolved," said Alan Parks of the Alaska Marine Conservation Council. "Now they shut down the water intakes depending on the wind."

Mathis and Bob Foy at NOAA's Kodiak Near Island lab believe some of the first casualties of increased ocean acid will be the tiny planktonic mollusks at the bottom of the food chain. Pteropods, a key food source for salmon, show signs of damage and dissolution within 48 hours of being exposed to high acidity.

"Pteropods make up 50 percent of the diet of Alaska pink salmon. A 10 percent drop in pteropod production would lead to about a 20 percent drop in salmon body weight," Foy said.

Water samples from the Gulf of Alaska and the Chukchi and Bering seas show acid levels are increasing more quickly and more severely than previously thought.

To better monitor the ocean chemistry, Mathis plans to launch a "Citizens Science Program" this fall in which Bering Sea crabbers will collect water samples in pre-treated, standardized bottles and send them to his lab for analysis. He hopes to expand the program to where fishermen each year collect thousands of samples from Southeast to Nome.

"People want to do something and this gives them a real sense of connection and ownership," Mathis said.

Laine Welch is a Kodiak-based fisheries journalist. Her Fish Radio programs can be heard on stations around the state. Her information column appears every other Sunday. This material is protected by copyright. For information on reprinting or placing on your website or newsletter, contact msfish@alaska.com.