Puget Sound — Washington’s inland sea — is a mysterious place. It’s the southern-most fjord in the lower 48 states. It’s fed by rivers that create shallow, mucky tideflats. In other spots it plunges more than 900 feet deep, giving it oceanic traits, but it doesn’t flow freely in and out of the Pacific Ocean. The main entrance and exit into the Sound is relatively narrow and shallow, creating a sort of bathtub that curtails the exchange of seawater and wildlife.
The Sound is facing serious challenges. The beloved local orcas are in alarming decline, the human population and its polluting cars, roadways and buildings is growing, and the damaging effects of climate change loom large.
But scientists are employing a sophisticated computer modeling tool to unravel some of the Puget Sound’s complex puzzles and trigger actions that can help safeguard the iconic Northwest waterway.
“We now are in a position where you can address some really important questions in Puget Sound,” said Joel Baker, director of the University of Washington’s Puget Sound Institute.
One of the more surprising and hopeful results comes from a recently published study on climate change. It predicts that the Sound could in many ways fare a bit better than the Pacific Ocean when considering the damaging effects of a warmer world.
The Salish Sea Model was built by scientists at the Seattle office of the Pacific Northwest National Laboratory (PNNL), part of the U.S. Department of Energy. PNNL program manager Tarang Khangaonkar launched the project in 2008 in partnership with the state Department of Ecology. Their goal was to create a model that’s widely useful and built in a collaborative, transparent process.
Scientists can use the model to test theories about how chemicals and creatures move through Puget Sound, tweaking different inputs to understand past and future events. The model has been used to find conditions favorable for native sixgill sharks, guide restoration in the Stillaguamish River delta, and study oyster reproduction.
Initial work started with a broad riddle. In recent decades, people have observed regularly occurring fish die-offs in Puget Sound. When an event strikes, dead fish litter the beaches, crabs and normally solitary rockfish cluster near shore, and scuba divers report “panting” wolf eels trying to capture enough air with their gills. Scientists knew the cause of death — the level of oxygen in the water was dropping to lethal levels — but the pattern of places experiencing “hypoxia,” or low oxygen, was puzzling.
When scientists tried to understand why some areas were harder hit with the dead zones, Khangaonkar said, “nobody could figure out why.”
Searching for the cause of suffocation
The model encompasses what’s known as the Salish Sea, which spans Puget Sound, the San Juan Islands, a strait running to the northwest tip of Washington and the waters off the east side of Vancouver Island. The researchers also included a stretch of offshore water that extends south along the Washington Coast, past the mouth of the Columbia River.
Early runs of the model could create low-oxygen conditions, but the hypoxia was everywhere, not just the observed hot spots in Hood Canal and other specific inlets and coves. The model included layers of data from multiple sources to create the tides, currents, weather, underwater geographic features, shorelines, water temperature, pH, and salinity. Ecology provided data on nutrients that flowed into Puget Sound from 99 sewage treatment plants, industrial outfalls and other points, plus 161 streams emptying into the sea.
But even with all of that information, the Salish Sea Model couldn’t recreate past conditions of hypoxia. Then researchers added data on the muddy, sandy bottom of Puget Sound. The model worked, revealing a key driver of hypoxia.
“Unless you take into account everything,” Khangaonkar said, “it’s not possible to guess at the reason.”
The scientists figured out that algae were reproducing in great blooms that eventually died, sank, and rotted in the sediment at the bottom of the sea. The decaying plants pulled oxygen out of the water. The result wasn’t necessarily intuitive at first. While alive, the algae released oxygen, as plants do, so they weren’t an obvious culprit for hypoxia.
That conclusion “led to quite a bit of debate,” Khangaonkar said.
But it also helped researchers think more strategically about which pollution sources need to be curbed to prevent them from essentially fertilizing the algae with nutrients. That includes sewage treatment plants, leaking shoreline septic systems, and lawn chemicals. The model highlighted the fact that Puget Sound is not well flushed by water from the ocean, trapping and recycling pollutants in the inland sea.
Officials with Ecology are using these results to update pollution regulations based on scientific research.
“This model is not a black box,” said Cristiana Figueroa-Kaminsky, a pollution and modeling manager for Ecology.
It’s based on open-source code with input from numerous agencies and academic institutions, she said.
The UW’s Baker agreed that it’s a robust model, and added that the university also has the LiveOcean model that can make limited forecasts addressing different issues in the Sound and Pacific.
“They’re as good as any models in the world,” Baker said.
‘Without the numbers you fear’
With the success of the oxygen-level work, Khangaonkar and his team were ready to tackle a bigger question: What will happen to Puget Sound as the planet keeps warming?
The researchers decided to gaze decades ahead to 2095. They added information from a national model and ran the simulation using a trajectory that assumes humankind follows a worst-case scenario path and does little to reduce global warming pollution.
Again, the model generated some surprising predictions.
Puget Sound’s water conditions are greatly impacted by the melting snowpack of surrounding mountains. That water flows from rivers, flushing the inland sea. Warmer weather is shrinking the annual snowpack and reducing its spring and summer runoff. Experts feared that the circulation of the Sound will be disrupted.
“If in the future the flushing strength were to go down, it would lead to catastrophic failure of our ecosystem,” Khangaonkar said.
Because Puget Sound is a relatively small body of water, one might expect it would fare worse than the Pacific Ocean. But the model, pulling together effects of sea level rise, changes in salinity and other factors, predicted a future where the water in Puget Sound’s deep basins would continue circulating, churning the water. That would keep it cooler, less acidic and more oxygenated than the Pacific.
“Climate change brings in a lot of counterintuitive findings,” Baker said. Flooding, however, is another concern.
“Without the numbers you fear… what is it going do to us?” he said. The model gives a glimpse. “Rather than speculate, you can just run it out and get the answer.”
Solving a toxic riddle
For roughly two decades, scientists Jim West and Sandie O’Neill have been sampling Puget Sound wildlife, tracking the amount of pollution they carry. A main focus has been PCBs, a family of long-lasting industrial chemicals banned 40 years ago. Since then, millions of dollars have been spent scrubbing them from Puget Sound.
And yet they’re still here.
PCBs, or polychlorinated biphenyls, show up in resident wildlife, including Pacific herring, Chinook salmon, harbor seals and orcas. What’s particularly weird about the PCBs is that their levels are holding steady or even increasing in some marine creatures, while other pollutants are declining. Although the concentrations of the PCBs in the sediment and water are so low they’re sometimes undetectable, they’re much higher in the fish, seals and whales. The math doesn’t add up.
“Something is happening where the PCBs are getting into the environment and an awful lot of them are ending up in the pelagic [or marine] food web,” said O’Neill, who works with West at the Washington Department of Fish and Wildlife.
The chemicals can disrupt the growth of Chinook salmon, the local orcas’ favorite food, and are believed to threaten the killer whales directly by harming their immune systems and ability to reproduce.
One of the main theories of how toxics get into the marine food web is that chemicals settle into the sediment, get consumed by microscopic organisms, and move their way up the food chain.
But it seems that something else is happening in Puget Sound.
It appears that upland sources of PCBs found in sources such as industrial caulk, electrical transformers, and contaminated soils are still being washed into the sea. West and O’Neill suspect that some of the PCBs are getting sucked into the food chain straight from the water before they even settle into the mud.
There are a couple of ways the PCBs could move from the open water into marine life. The chemicals are lipophilic, meaning they love to stick to fats, which includes the outside of bacteria and algae. The PCBs can also get sucked up by microscopic zooplankton floating in the water column.
As those tiny organisms are eaten by small fish that are eaten by bigger fish that are eaten by marine mammals, the PCBs move through the food chain to larger predators. Their levels build as the toxics are stored in body fat, and mothers can pass PCBs to their babies through their milk. When the animals die and decay, the PCBs are recycled back into the food chain via smaller creatures.
While the hypothesis makes sense, scientists need more data to prove it. They’re eager to pinpoint the pollution sources and pathways of movement in order to close the PCB tap. And for local orcas, whose population has sunk from highs in the 200s to just 73 animals, time is running out.
When Khangaonkar suggested a collaboration, West and O’Neill jumped at the chance. They now have results for the first phase of their research, which included work with UW scientists, and are starting another study correlating the model with pollutants in plankton.
The Salish Sea Model has the potential to “inform us about where the PCBs are coming into the food web, then you can do something about them,” O’Neill said. It could identify hot spots for cleanup that could most benefit marine life. “You can’t clean up the whole of the Puget Sound basin,” she added. “It’s too much.”
It’s just the kind of project that Khangaonkar gets excited about.
“We have developed this [model] for everybody to be able to use,” he said. “And when folks are interested in using it, there is a strong commitment to actually work with them and make it happen.”Editor's Note: Funding for GeekWire's Impact Series is provided by the Singh Family Foundation in support of public service journalism. GeekWire editors and reporters operate independently and maintain full editorial control over the content.