Copper use has more than doubled in the United States over the past three decades, according to a 2012 report from the Copper Development Association.
Copper and other metal contaminants are a factor in the poor survival of the West Coast’s coho salmon, which are endangered or threatened in most of the region, Scholz said.
Young coho salmon exposed to low levels of copper did not evade predators – cutthroat trout – nearly as well as unexposed salmon, according to a lab study by Scholz and colleagues.
This is concerning, Scholz said, because they are listed as endangered or threatened throughout most of the Northwest United States.
The problem is “likely to be widespread in many freshwater aquatic habitats,” according to a NOAA report. The report said that increases in salmon response time to smells came within 10 minutes of exposure in some cases.
Adding to the concern, Tierney found that zebrafish hung out where the herbicides entered their water, instead of avoiding it. The fish seemed to think that there was more food where the chemicals were because of excessive nutrients and bacteria.
Pyle said one way to mitigate the problem is cleaning up contamination near spawning sites, as embryos are sensitive to the metals. Pyle said hatching in clean water, even if the fish ends up in dirty water, bolsters the chance it will maintain its sense of smell.
“You and I can communicate and learn about our environment from seeing and listening,” Pyle said. “But when you’re living in water, you get a lot better info from molecules dissolved in your immediate surroundings. It’s crucial for them.”
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.