HOOD CANAL (March 4, 2008) – Deep in the mud of Hood Canal, lives a creature that carries decades of crucial water quality history. The geoduck, with a lifespan of more than 160 years, may be the definitive record-keeper of the canal’s oxygen levels, water quality and their changes over time.
Teasing that information from the largest burrowing clam in the world has never been tried — until now. Yongwen Gao, a researcher for the Makah Tribe with a doctorate in fisheries and ocean sciences, is using a technique known to only a handful of scientists on the West Coast to extract the water quality information.
Previously, Gao has used a similar biochemical analysis technique to gather information about salmon, halibut, and black cod and other species important to the Makah Tribe. By analyzing ratios of carbon and oxygen isotopes found in the fish’s ear bone, Gao is able to determine what the fish has been eating, migration patterns and the distribution of age classes within a particular stock.
A geoduck’s shell can provide similar information and more, using the same technique. As part of a project sponsored by the state Department of Natural Resources, geoduck shells were collected from three sites in Hood Canal that have been closely monitored by the Department of Ecology for the past 16 years. Researchers from the University of Washington determined the approximate age of the clams by counting the growth rings of the shells. Gao then analyzed the shell samples for oxygen and carbon isotopes and other water quality indicators, then compared that information with data collected by DOE.
“The chemical variations in the shells corresponded with the dissolved oxygen levels found by DOE monitoring,” said Gao.
That’s important because it validates the method for use in further probing information that the shells may hold -especially changes in nutrient levels in 160 years. High nutrient levels are the main cause of low oxygen in the canal today. Many thousands of fish have been killed by algae blooms that rob oxygen from the water. The blooms are fueled by increased nutrient levels from fertilizers and leaking septic systems. By analyzing organic carbon and sulphur in shells, it is possible to find the nutrient level changes through the geoduck’s long life history.
To see further into the past, Gao will need to analyze many more shells. Funding for that project is being considered by the Washington State Legislature.
“This shell work is really groundbreaking,” said Todd Palzer, Washington Department of Natural Resources program operations manager. “It’s never been done before. This helps us tie together the health of North and South central Puget Sound.
We hope it will continue in the future as it ties in well with other research that’s being done in Hood Canal and Puget Sound.”
“We are all in this together as co-managers when it comes to understanding the health of our marine resources,” said Russell Svec, Makah fisheries program manager. “We think it’s great that Yongwen is expanding the use of his research with other government agencies.
“Given the dramatic fluctuations in fish species and fish composition relative to ocean environmental change, the Makah Tribe believes that Yongwen’s research is going to be vital to gaining a better understanding of the effects marine environments have on our commercially valuable resources.”
For more information, contact: Dr. Yongwen Gao, Makah research scientist, (360-645-3164, [email protected]; Russell Svec, Makah fisheries program manager, (360) 645-3156; Bob Sizemore Washington Department of Natural Resources program operations manager, (360) 902-1864, ; Debbie Preston, Northwest Indian Fisheries Commission, coastal information officer, (360)374-5501, [email protected]