Fish are in danger of becoming addicted to methamphetamine when traces of the drug enter our rivers, a new study warns.
Researchers in the Czech Republic performed lab experiments with the brown trout (Salmo trutta) in waters contaminated with the illegal drug.
After immersion in the meth-contaminated waters, the team found the fish became less active, but also displayed disturbing levels of dependence.
Meth – which comes in several different forms including tablets, powder and crystals – enters our waterways directly from the drug user in their home.
The research has been conducted by experts at the Czech University of Life Sciences Prague in the Czech Republic.
‘Methamphetamines, as well as other contaminants of emerging concern, are similarly introduced to surface waters through discharge from wastewater treatment plants,’ said study author Pavel Horký.
‘Users of these substances excrete them into the sewage collection systems, then the substances enter the wastewater treatment plants that were not designed to treat such contamination.
‘Finally, contaminants enter the freshwater ecosystems at relatively low, but detectable and biologically efficient levels.’
Drug addiction could potentially drive fish to congregate near unhealthy water treatment discharges ‘in search of a fix’.
While meth is illegal, prescribed drugs such as fluoxetine – also known as Prozac – can ’embolden’ fish and alter their behaviour when in our waterways, studies show.
‘Whether illicit drugs alter fish behaviour at levels increasingly observed in surface water bodies was unclear,’ Horký said.
For their study, the researchers isolated brown trout in a water tank for two months laced with one microgram (μg) of methamphetamine – a level of meth that has previously been found in freshwater rivers.
They then transferred the fish to a freshwater tank, but offered them a choice between freshwater or water containing methamphetamine every alternate day for 10 days.
The researchers thought that if the fish had become addicted to the low levels of meth in their water, they would be feeling the effects of withdrawal and would seek the drug when it was available.
For the first four days, fish that had been in the drug-laced tank for two months were more likely to choose to return to a meth-laced tank than fish who had not had the long exposure to meth, the team found.
During that time, the fish with long term drug exposure were less active than the control fish, and researchers found evidence of the drug in their brains 10 days after significant exposure.
From the results, it seems that even low levels of illicit drugs in our waterways can badly impact the animals that reside there.
The study has been published in the Journal of Experimental Biology.