European perch. Photo courtesy of Wikimedia Commons.
A study released on Friday revealed that young fish live longer after being exposed to anti-anxiety medicine concentrated in sewage runoffs.
Past studies on the consequences of other compounds found in streams and waterways such as caffeine, estrogen, and diabetes medicine showed that they were potentially altering the reproductive systems of fish living in the affected areas.
Scientists tested to see if the exposure to Oxazepam, an anti-anxiety and insomnia medication, was impacting the survival rate among Eurasian perch. They tested adult and embryos of the species by exposing them to several levels the sedative. The result concluded that both groups had a significantly higher survival rate than the studies non-exposed control group.
The therapeutic effect of the drug also caused a noticeable change in the species’ behavior. For example, the perch were believed to be less anxious and more comfortable in a predator-free environment, causing them to travel and search for food away from their pack. The change in their behavior led to a higher feeding rate than the unexposed fish.
Researchers are concerned about the shift in behavior and increased longevity of the exposed fish. Baby Eurasian perch typically have a 92 percent mortality rate at hatching but the change in survival rate might potentially alter the the ecosystem.
Tomas Bodin, one of the co-authors of the study, explained, “A therapeutic effect leading to increased survival of one species may generate a proportional increase in mortality of that species’ prey, which may have cascading ecological consequences that need consideration.”
The study has opened a conversation among the research community to take a further look into the long-term effects on fish and wildlife exposed to other human compounds.
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