Professor: As estuary health weakens, greenhouse gases increase

Western Today staff
  • Western Washington University graduate student Katrina Poppe (Mercer Island/San Diego, Calif.) prepares to take a sample along the Snohomish River, testing the estuary's natural ability to lock carbon and help reduce greenhouse gases.
    Western Washington University graduate student Katrina Poppe (Mercer Island/San Diego, Calif.) prepares to take a sample along the Snohomish River, testing the estuary's natural ability to lock carbon and help reduce greenhouse gases.

At a pair of research projects in Snohomish County, Western Washington University Professor of Environmental Science John Rybczyk is looking to find out more about the relationship between river deltas and estuary systems and their ability to lock in carbon.

Carbon is a naturally occurring element found in all living things, and the soft, oxygen-free sediments of estuaries are natural sponges that lock in carbon. When these estuaries and river deltas are drained or impounded, that sediment becomes exposed to oxygen and combines with the newly-freed carbon to form carbon dioxide, perhaps the world’s top cause of global warming, as it enters the atmosphere.

“Coastal wetlands play a huge role in storing carbon,” said Rybczyk, “And as we have developed our coast – for example, by filling in wetlands and river deltas for use in agriculture – we have removed that ability to store carbon. The good news is, the research we are doing shows that we can gain that carbon storage back again by restoring those same wetlands.”

Along the Stillaguamish and Snohomish rivers, Rybczyk and student researchers from Western as well government agencies such as the U.S. Geologic Survey and partnering nonprofits such as The Nature Conservancy and Earth Corps continue to work to see how restoring estuaries can benefit the environment as a whole.

At the mouth of Stillaguamish, Rybczyk is faced with a common issue along Puget Sound; a delta system that has been diked and impounded for more than 100 years for use in agriculture. But as the land has subsided, or sunk, and water levels have risen, many of the fields have become so low they are actually below sea level and are just too low to be farmed any longer. A parcel of this unused farmland at the mouth of the “Stilly” was bought by the Nature Conservancy and the coastal dikes removed or opened to the tides.

Rybczyk and his team have been monitoring these restored sites to see how they are helping reshape the Stilly’s river mouth and how these lands compare to “control” parcels of existing non-diked Stillaguamish estuaries in terms of salinity, vegetation, and the recurrence of key target species such as salmon.

“We got involved along the Stilly about three or four years ago, thanks to some grant funding from The Nature Conservancy. We have set up monitoring stations, watching for the development of channel systems in the reopened areas, the return of vegetation – basically the redevelopment of a healthy nearshore habitat,” he said. “It has been less than a year since the dike removal but it’s amazing how quickly these areas are healing themselves.”

The Snohomish River’s estuary presents a different set of problems in many ways, but with the same endgame in mind: healthy estuaries that help store carbon instead of unlocking it.

“The Snohomish empties into Puget Sound at Everett in a way most of us can easily visualize because we drive by it all the time on the interstate; it’s a highly modified, urbanized estuary with high levels of agriculture use, water treatment facilities, industry, and more – it’s a huge challenge,” he said.

Rybczyk literally dug deep into the Snohomish estuary, tracking carbon counts in natural wetlands that have not been altered; drained former wetlands; and restored wetland areas, similar to those created on the Stillaguamish.

“The wild, unaltered sites store carbon very efficiently,” Rybczyk said. “The unrestored areas only hold a fraction of what they could hold and of what they held when they were functioning wetlands.”

“The great news is that the restored wetlands seem to do a fantastic job, very quickly, of storing carbon once again ­– which points to the win/win situation of a healthier ecosystem and more species paired with the environment’s increased ability to naturally sequester the very compounds which are causing so much environmental degradation worldwide,” he said.

Working alongside Rybczyk on the Snohomish this past summer were graduate student Katrina Poppe (Mercer Island) and undergraduate Nathan Moore (Ilwaco).

“I was attracted to this project because its results could be quite valuable in helping to prioritize coastal habitat restoration or protection projects. Plus there isn't much information out there yet on actual rates of carbon sequestration in these kinds of habitats, especially on the West Coast,” Poppe said. “Our results so far have presented several new questions, so there is a lot of potential future research that could stem from this.”

For more information on Rybczyk’s wetlands research, contact him at 360-650-2081.

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Tuesday, October 29, 2013 - 10:50am