Posted: March 8, 2012
If you were the most common bait fish, you would be anxious too.
You would hide in dark crannies, avoiding predators. That’s what fathead minnows normally do. But a new study from Baylor University, published 7 March in Environmental Science and Technology, shows that when the rosy-silver fish get a dose of Zoloft, they develop a false sense of security. Instead of ducking for cover when it’s light, they linger in the open, unconcerned.
Drugs like Zoloft and Prozac get into rivers, lakes and streams every time people who take them flush their toilets. The drugs can have bizarre effects on fish behavior. This is not big news: as my classmate Nina Bai reported in 2008, scientists have been documenting how antidepressants impact fish for a while. Other organisms, like shrimp and mussels, are also affected. But each new study is a step toward understanding how different species tolerate different chemicals, and in what concentrations.
For the minnows, it took 3 micrograms per liter of Zoloft to dim their evasive instincts. The concentration of SSRIs in the wastewater described in the study was 3.2 micrograms per liter. Once the drugs have made it into the water, most wastewater treatment plants aren’t equipped to filter them out.
Image credit: Ohio Department of Natural Resources, BK