Treading Water: Tire Wear Particle Leachate Recreates an Urban Runoff Mortality Syndrome in Coho but Not Chum Salmon

Tire tread wear particles (TWP) are increasingly recognized as a global pollutant of surface waters, but their impact on biota in receiving waters is rarely addressed. In the developed U.S. Pacific Northwest, acute mortality of adult coho salmon (Oncorhynchus kisutch) follows rain events and is correlated with roadway density. Roadway runoff experimentally triggers behavioral symptoms and associated changes in blood indicative of cardiorespiratory distress prior to death. Closely related chum salmon (O. keta) lack an equivalent response. Acute mortality of juvenile coho was recently experimentally linked to a transformation product of a tire-derived chemical. We evaluated whether TWP leachate is sufficient to trigger the acute mortality syndrome in adult coho salmon. We characterized the acute response of adult coho and chum salmon to TWP leachate (survival, behavior, blood physiology) and compared it with that caused by roadway runoff. TWP leachate was acutely lethal to coho at concentrations similar to roadway runoff, with the same behaviors and blood parameters impacted. As with runoff, chum salmon appeared insensitive to TWP leachate at concentrations lethal to coho. Our results confirm that environmentally relevant TWP exposures cause acute mortalities of a keystone aquatic species.

Automated summary

The study reveals that tire tread wear particles (TWP) in the developed U.S. Pacific Northwest cause acute mortality of adult coho salmon, with closely related chum salmon showing a different response. Adult coho salmon exhibit acute lethal responses to TWP leachate similar to roadway runoff, displaying similar behaviors and blood changes. These findings confirm that environmentally relevant TWP exposures lead to acute mortalities in a key aquatic species.