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Washington State University

Wear and Tear on the Environment: Stormwater biofiltration increases coho salmon hatchling survival

Posted by rdsayler | August 24, 2023
Coho salmon hatching from eggs
[Coho salmon hatching from eggs. Source: U.S. Fish and Wildlife Service.]


What happens to your tires after driving thousands of miles? Obviously, they eventually wear down and have to be replaced with new tires. But what happens to the physical materials (i.e., tire tread) and chemicals that originally composed the tire?

As tires abrade and wear away during driving and friction and contact with roads, various potentially toxic compounds and chemicals are vaporized or otherwise dispersed in the air and soil and end up in streets, ditches, and water drainage channels where they may wash into creeks, streams, and rivers. The resulting effects on aquatic life, such as salmon, are now being better understood through the research of Dr. Jenifer McIntyre who studies toxic impacts of urban runoff in the WSU School of the Environment.

Jenifer McIntyre.In a recent study, Dr. McIntyre and her colleagues in the Northwest Fisheries Science Center and the U.S. Fish and Wildlife Service, noted that juvenile and adult coho salmon may die from even brief (<24h) exposure to roadway runoff but effects on young, hatching coho salmon (called alevins) are less well known, including how to mitigate and reduce effects of urban runoff.

They then conducted experiments on coho salmon eggs and discovered that while many (>90%) of coho embryos were able to survive when exposed to intermittent road runoff, the alevin (newly hatched) experienced high (87%) mortality.

However, when stormwater runoff was treated using green infrastructure (bioretention filtration – runoff filtered through layers of sand, compost, gravel, wood mulch, etc.) it removed many of the toxins and essentially prevented mortality at the alevin stage. The study is important by demonstrating that relatively simple and inexpensive management strategies to treat stormwater runoff may improve survival of salmon and other important aquatic life in rivers and streams.

See: WSU Insider (with YouTube) – Stormwater biofiltration increases coho salmon hatchling survival

Also see: CBS Bay Area (with video) – Tire additive could push California salmon to extinction, study says

Publication: Science of the Total Environment

See more stories @ SoE Science News