To better monitor the ocean chemistry "Citizens Science Program" planned
By LAINE WELCH
June 07, 2010
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 underway 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 '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 producer of oyster spat for most of the west coast. For the past two years, the hatchery has had almost 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 Dr. 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, for example 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% of the diet of Alaska pink salmon. A 10% drop in pteropod production would lead to about a 20% 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. "It is a great partnership."
Bristol Bay is open for kings, salmon fisheries along the Alaska Peninsula and Kodiak get underway this week, and openers will pop up all over the state from here on out.
Alaska's 2010 salmon season should produce a catch of 137 million fish, a 15% decrease from last year, but still the 19th largest since 1900. Fish and Game's projections are usually within 10-20 percent of the actual harvest and it provides an important "ballpark" figure for salmon buyers. Here's a season snapshot from ASMI"s Seafood Market Bulletin:
The anticipated statewide Chinook harvest is 415,000 fish, about 20 percent below the 5-year average. For the big money fish, Alaska sockeye, the catch is pegged at 45 million fish, similar to the past 7 years. Thirty million of those reds are expected to come from Bristol Bay. For chum salmon, the projected catch is 18 million fish, up slightly. The biggest producers are Southeast and Prince William Sound; 60% of Alaska's chum harvest is hatchery fish. Coho catches should top 4 million, similar to past years, although managers caution that coho catches can vary widely. Even more tricky: those hard to predict pinks, which cause most of the ups and downs in Alaska's yearly salmon catch. The 2010 pink harvest is projected at 69 million, down by 30 million from last year, and the second smallest catch in 20 years.
Seafood.com reported last week
that at a pre-season pink salmon auction at a Prince William
Sound sound hatchery, prices more than doubled to 57 cents a
pound, compared to 27 cents last year.
Comedian Rodney Dangerfield was famous for the 'no respect' line, not Don Rickles, as was reported last week.