Human contamination in the aquatic environment is usually evident from oil spills that blacken the water and from plastic waste that floats concentrated in some areas or that ends up reaching the coast, but many of the medicines we consume also end up reaching the The aquatic environment and the current treatment of water through treatment plants is not prepared to filter or neutralize these substances. Drugs like fluoxetine (also known as Prozac) that get into our waterways can embolden fish and alter their behavior. But drug contamination doesn’t end with prescription medication. Illegal drugs, such as methamphetamine, can also accumulate in rivers and streams. New research has examined the extent to which fish exposed to drugs can develop drug dependence.
Pavel Horky’s team, from the Czech University of Biological Sciences in Prague, carried out experiments during which trout of the species Salmo trutta were isolated in a tank of water with a small amount of methamphetamine (the same concentration at which that drug has been found in freshwater rivers) for 8 weeks. After those 8 weeks, Horky and his colleagues transferred the fish to a freshwater tank and checked the animals for withdrawal symptoms (offering them a choice between normal freshwater or freshwater with methamphetamine) every alternate day for 10 days. If the fish had become addicted to the low levels of methamphetamine in the water, they would be feeling the effects of withdrawal and would choose the drug when it became available.
By tracking fish choices, the team clearly saw that trout that had spent 2 months in methamphetamine-contaminated water had become addicted, selecting the water that contained the drug while suffering from withdrawal symptoms for the first 4 days after switching to normal fresh water. On the other hand, the addicted fish were less active than the trout that had never used the drug. Additionally, the researchers found evidence of the drug in fish brains for up to 10 days after methamphetamine withdrawal. It appears that even low drug levels in waterways can affect the animals that reside in them.
Trout of the species Salmo trutta. (Photo: USGS)
The study is titled “Methamphetamine pollution elicits addiction in wild fish.” And it has been published in the academic journal Journal of Experimental Biology. (Source: NCYT from Amazings)