(CNN) – Brown trout can become addicted to methamphetamine when this illegal drug accumulates in waterways, according to new research.
A group of researchers led by Pavel Horky, a Behavioral Ecology professional at the Czech University of Life Sciences in Prague, set out to study whether illicit drugs found in water bodies alter the behavior of fish, according to the study published Tuesday.
The team put 40 common trout in a tank of water with the same levels of methamphetamine that have been found in freshwater rivers. They stayed there for a period of eight weeks and then transferred to a clean tank.
The researchers then checked, every two days, whether the trout suffered from methamphetamine withdrawal syndrome by giving them the option to choose between water that contained the drug and water that did not. 40 more trout were used as a control group.
Trout with methamphetamine withdrawal syndrome
Trout that had spent eight weeks in water containing methamphetamine selected in water containing the drug for four days after being transferred to fresh water.
This indicates that they suffered from withdrawal symptoms, because they sought out the drug when it was available, according to the researchers.
The team found that the addicted fish were less active than those that had never been exposed to methamphetamine. They also found traces of the drug in their brains for up to 10 days after exposure.
The researchers concluded that even low levels of illicit drugs in bodies of water can affect the animals that live in them.
Drugs excreted by users travel through sewage systems and into wastewater treatment plants, which are not designed to treat this type of contamination, according to the study.
“Fish are sensitive to the adverse effects of many neurologically active drugs, from alcohol to cocaine, and can develop drug addiction related to the dopamine reward circuit in a similar way to humans,” Horky told CNN. via email.
Horky expressed concern that this drug addiction could lead to fish spending more time near treated water discharge sites, which are unhealthy for them.
“Such effects could change the functioning of entire ecosystems, as the adverse consequences are significant at both the individual and population levels,” he said.
Drug cravings may turn out to be more powerful than natural rewards such as foraging and mating, he added.
The researchers then euthanized the fish and analyzed their brain tissues.
Less visible pollution
The study reveals how humans pollute the natural environment beyond the most visible cases such as oil spills and plastic waste disposal.
Horky said the research findings also have implications for the effects on aquatic life of prescription drugs like fluoxetine, commonly known as Prozac.
“Current research from teams around the world clearly shows the adverse impact on ecosystems, which in turn can influence humans,” he said.
The study was published in the journal Journal of Experimental Biology.
It is not the first time that aquatic life has felt the effect of drug use by humans.
In May 2019, UK researchers said they had found traces of illicit drugs, pharmaceuticals and pesticides in samples of freshwater shrimp.
On the other hand, in May 2018, scientists working in the Puget Strait, an inlet of the Pacific Ocean located along the northwest coast of Washington state in the United States, they said mussels in the area had tested positive for oxycodone, a prescription opioid.