Scientists Solve Mystery of Mass Coho Salmon Deaths. The Killer? A Chemical from Car Tires
t-3 writes:
https://www.latimes.com/california/story/2020-12-03/coho-salmon-tire-chemical
When officials in Seattle spent millions of dollars restoring the creeks along Puget Sound - tending to the vegetation, making the stream beds less muddy, building better homes for fish - they were thrilled to see coho salmon[*] reappear.
But when it rained, more than half, sometimes all, of the coho in a creek would suffer a sudden death.
These mysterious die-offs - an alarming phenomenon that has been reported from Northern California to British Columbia - have stumped biologists and toxicologists for decades. Numerous tests ruled out pesticides, disease and other possible causes, such as hot temperatures and low dissolved oxygen.
Now, after 20 years of investigation, researchers in Washington state, San Francisco and Los Angeles say they have found the culprit: a very poisonous yet little-known chemical related to a preservative used in car tires.
[...] The chemical is just one of a vast number of contaminants that washes off roads whenever it rains. This giant soup of pollutants, which includes trillions of microplastics, rushes down drains and into creeks and ultimately into the sea.
"We pretty much figured out that anywhere there's a road and people are driving their car, little bits of tire end up coming off your tire and end up in the stormwater that flows off that road," said Ed Kolodziej, an environmental engineer and chemist at the University of Washington (Tacoma/Seattle), whose lab led a study that was published Thursday in the journal Science. "We were able to get all the way down to this one highly toxic chemical - something that kills large fish quickly and we think is probably found on every single busy road in the world."
[*] Coho salmon.
Journal Reference:
Zhenyu Tian, Haoqi Zhao, Katherine T. Peter, et al. A ubiquitous tire rubber-derived chemical induces acute mortality in coho salmon [$], Science (DOI: 10.1126/science.abd6951)
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