The endangered coho salmon. Source: baynature.org.
It is no secret that various species of fish are at high risk of habitat loss and endangerment due to human activities such as overfishing and water pollution. It may come as a surprise, however, that something as unsuspecting as car tires could be the cause of a massive death rate in salmon on the West Coast of the United States.
Coho salmon, which grow to around two feet in length and journey every year between the ocean and the streams and rivers of Washington State, have been found to die at alarmingly high rates when returning back from the ocean. At certain sites, scientists recorded death rates of around 40 to 90 percent for returning salmon, before the fish have the chance to reproduce. Now, researchers have found a likely answer to the mystery surrounding these deaths: car tires. When it rains, rainwater carries fragments of old tires down to the streams and rivers inhabited by the coho salmon. These tires contain a chemical antioxidant called 6PPD, which is used in tires around the world to increase their durability. However, as the old tires start to wear down, the 6PPD reacts with ozone in the atmosphere, forming another chemical called 6PPD-quinone. This very toxic chemical has been observed across the West Coast in roadway runoff, which then pollutes the urban waterways used by coho salmon to return from the ocean. The lead investigator of this study, Edward Kolodziej, stated, “We believe that 6PPD-quinone is the primary causal toxicant for these observations of coho salmon mortality in the field. It's exciting to start to understand what is happening because that starts to allow us to manage these problems more effectively.” Indeed, it is good news that the problem has been identified, both for the salmon and their surrounding ecosystem. Coho salmon make up one of the five Pacific Northwest salmon species and are a critical part of the food chain. According to Kolodziej, the presence of healthy coho salmon is a key indicator of a thriving ecosystem.
Evidently, these coho salmon death rates cannot continue. A change must be made in the production of car tires in order to prevent further coho salmon massacres. Steps must be taken to identify a more environmentally-friendly chemical for tires—one that will maintain the durability of tires without being harmful to such a vital species of our ecosystem.
Comentários