There have long been concerns that prescription drugs, everything from Prozac to antibiotics are making their ways into waterways where they can be absorbed by fish, and of course illegal drugs are also a part of the chemical cocktail fish encounter in their environment. Not only the fish exposed to these drugs, but they seem to become addicted to them. A new controlled study of 120 juvenile brown trout in the Czech Republic found that fish exhibited addictive behavior towards the drug methamphetamine.
In the study, which was published in The Journal of Experimental Biology, all the of fish were bred in captivity. Half were then put into a clean water tank, and half were placed into a tank laced with one microgram per liter of crystal meth, which is similar to the concentration found in freshwater rivers in Europe. In fact, in some areas the concentration is up to 25 times more.
After a period of eight weeks, the fish in the drug-laced water were introduced to the drug-free tank for four days. All the fish were then given the option to swim in the drug-filled waters. The fish from the control group spent 41.5% of their time in the meth tank, while the fish who had previously been in that tank spent 50.5% of their time there. They also exhibited signs of less activity overall.
The scientists also examined the brains of both the drug-exposed fish, and the non-drug exposed fish, and found that only the fish who had spent two months in the methamphetamine waters had meth present in their brain tissue. In fact, every one of the 60 fish in that group had traces of meth in their brains.
Why do drugs get into waterways?
In short, drugs find their way into natural waters because sewage treatment centers do not filter them out.
What are the effects of drug addiction in fish on the ecological system?
Dr Pavel Horký, co-author of the study thinks that fish exposed to meth may feel the need to linger near water treatment discharges that are heavy in their drug. “Such unnatural attraction to one area together with documented changes in behaviour could result in unexpected ecological consequences influencing whole ecosystems,” he said
“The elicitation of drug addiction in wild fish could represent another example of unexpected evolutionary selection pressure for species living in urban environments along with ecological side effects of human societal problems within aquatic ecosystems.”
Photo via Eva Elijas
