They’re so effective, in fact, that humans use them as living barometers of pollution. The Washington [State] Department of Fish and Wildlife regularly places mussels raised in controlled, pollution-free environments at 18 set locations around Puget Sound, an inlet of the Pacific Ocean. After two or three months, the mussels get switched out and tested for contaminants. It’s a helpful way to find out what pollutants are in certain waters.
Mussels are the filters of the sea. A single one of the mollusks filters up to two liters (about half a gallon) of water each day to extract microscopic algae and bacteria to eat. Pretty much whatever ends up in the sea eventually ends up in a mussel.
It’s also, it turns out, an effective way to gauge the extent of the US opioid crisis. When scientists from the Puget Sound Institute of the University of Washington-Tacoma tested mussels from three sites near the harbors of greater Seattle, they found traces of oxycodone, a highly-addictive narcotic and one of the most-frequently abused opioids in the US. Scientists believe the chemical ended up in the sound via wastewater-treatment plants processing Seattle’s human sewage.
The concentrations were thousands of times lower than those that would affect humans, research scientist Andy James of the Puget Sound Institute said in a statement, and weren’t in areas where edible mussels are harvested—even in the best of circumstances, no one wants to eat an urban mussel. But it does pose worrying questions about the health of local fish, who are more responsive to opioids. In fact, according to the Puget Sound Institute, studies have shown that, when exposed to opioids, zebrafish will learn to dose themselves, and scientists believe salmon and other fish might respond similarly.
That mussels in Puget Sound are also yet another, very worrying, sign of the extent of the US drug crisis. At this point, research shows, one in five Americans know someone who has been addicted to opioids.