The Alarming Connection Between Salmon Mortality and Car Tires
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Chapter 1: Introduction to the Coho Salmon Crisis
The Coho salmon (Oncorhynchus kisutch) has been migrating from the ocean to freshwater for approximately six million years to spawn. After laying their eggs, they typically die, which is a normal part of their life cycle. However, recent decades have revealed a troubling trend: salmon are dying before they can spawn, a phenomenon known as pre-spawn mortality. While this rate used to hover around 1%, it has surged in some areas to alarming levels of 90%. This decline poses a significant threat to the survival of the Coho salmon, which holds considerable ecological, economic, and cultural importance.
Chapter 2: Identifying the Cause of Pre-Spawn Mortality
The search for the cause of this drastic increase in pre-spawn mortality began after extensive habitat restoration efforts in the Puget Sound region, which had initially boosted Coho populations. Despite the increased numbers, the fish were not thriving, with pre-spawn mortality rates ranging between 40% and 90%. Surveys conducted from 2002 to 2009 revealed that these high mortality rates were predominantly found in urban streams.
Research conducted by Scholz et al. (2011) pinpointed the issue to a mysterious toxic substance present in urban runoff. Typically, rainwater is absorbed by soil; however, in urban areas, it runs off concrete surfaces, carrying various contaminants into nearby streams.
The first video titled "The Deadly, Little-Known Side Effect Of Car Tire Dust" discusses how tire dust contributes to environmental toxicity, specifically affecting salmon habitats.
Section 2.1: Investigating Urban Runoff
Following this initial discovery, scientists began analyzing the chemical compounds present in urban runoff across different locations, focusing on those related to vehicles. In 2018, they linked tire wear particles to the Urban Runoff Mortality Syndrome (URMS), which became a focal point for further investigation.
Recent research has identified the toxic compound responsible for the deaths of Coho salmon: 6PPD-quinone. This substance, derived from the widely used tire additive 6PPD, is intended to protect tires from ozone damage. However, when 6PPD reacts with ozone, it transforms into 6PPD-quinone, a compound significantly more toxic to fish and capable of contaminating aquatic environments.
Chapter 3: Natural Solutions and Green Infrastructure
Given that changes to tire composition are unlikely in the near future—due to regulatory allowances and a lack of viable alternatives—scientists are exploring natural solutions. Remarkably, studies have shown that filtering urban runoff through sand and compost prevents the toxic compounds from reaching salmon habitats, demonstrating the potential of green infrastructure.
The second video titled "Worn tires contribute to chemical that kills Coho salmon" delves deeper into the environmental challenges posed by tire wear and its impact on aquatic life.
Section 3.1: The Broader Implications
This narrative underscores our interconnectedness with the natural world. Human activity significantly influences the environment, a reality that has led to the designation of this era as the Anthropocene. While individuals may feel powerless to change the composition of car tires or their manufacturing processes, there are still choices within our control.
For instance, consider your daily decisions: what meals you prepare, your consumption habits, or your mode of transportation. While we can't change everything, every action has consequences, and we can choose how we engage with the world around us.