Mussels were transplanted via cages in 18 locations around Puget Sound, including this one at Appletree Cove. They were then collected and tissues were sampled for 200 contaminants. Photo by David Toth, volunteer for the Washington Department of Fish and Wildlife
“Salish Sea Model allows researchers to decipher trends in toxics data
“With the help of a diagnostic tool called the Salish Sea Model, researchers found that toxic contaminant hotspots in the Puget Sound are tied to localized lack of water circulation and cumulative effects from multiple sources.
“Pharmaceuticals such as opioids and the chemotherapy drug melphalan—along with a suite of 62 other contaminants—were detected by a team of researchers from the University of Washington (UW), Washington State Department of Fish and Wildlife (WDFW), and PNNL.
“Contaminant concentrations varied by location, suggesting toxics tend to concentrate in certain enclosed waterbodies that receive wastewater from various outfalls, but undergo little flushing.
“Environmental contaminants are a global problem. Some toxic chemicals are unregulated, and their environmental effects are not well understood. But pharmaceuticals, flame retardants, detergents, some industrial chemicals, and even fragrances from soap or lotion are what researchers call ”contaminants of emerging concern.”
“The 99 wastewater outfalls that discharge into the Puget Sound are regularly tested and treated to protect human health and marine life. Despite this process, the research team found concentrations in mussels that were potentially concerning in some localized areas.
“There is a regulatory system in place already to manage pollutants from outfalls. But these data show there is still a suite of chemicals that are entering our surface waters that could bioaccumulate if they are not flushed away efficiently,” said PNNLscientist Tarang Khangaonkar, who is supporting UW and WDFW efforts with the Salish Sea Model.
“Contaminants follow a pattern similar to leaves caught in a river eddy—they are transported to wherever water takes them and accumulate in regions with poor circulation. Runoff from parking lots and wastewater pipes all funnel contaminants into the Puget Sound. From there, toxics ride the current and are mixed, churned, and diluted by the pulsing tides. Manmade structures, such as ship canals, can restrict tidal pulses and cause water to stagnate. Contaminants settle out, accumulate, and can show up in marine animals that live there.
Mussels Sounding an Early Warning
Bay mussels are an indicator species and were used by researchers to determine what contaminants are in the water around Puget Sound. Photo provided by the Washington Department of Fish and Wildlife
”Mussels are a canary in the coal mine—an indicator species—that help scientists better understand environmental issues. As filter feeders, mussels consume food from the surrounding water and can accumulate contaminants in their tissue. This accumulation helps researchers understand what contaminants are in the water. This makes mussels a great study subject in the search for toxic contaminants.
“The UW and WDFW research team examined mussels from 18 rural and urban sites around the Puget Sound—spanning from Port Townsend, inland to Everett, south to Olympia—to evaluate whether urban mussels had more contaminants than rural mussels. If contaminants were present, the researchers wanted to determine the source of the toxics. In other words, were contaminants coming from wastewater outfalls or from urban runoff?
“Although this study was limited in scope, they found that mussels near urban areas did not necessarily contain more contaminants in their tissues…”
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