Drugs From Sewage Can Cause Addiction In Some Trout Species
Ecologists have found out that the concentration of methamphetamine and similar drugs in the sewage of cities is enough to cause a full-fledged dependence in some trout species. The results of their study are available in the Journal of Experimental Biology.
In the sewage of some large American cities, the concentration of amphetamine and other drugs reaches quite large indicators. In a new study, Tomas Randak, a professor at the University of Southern Bohemia, and his colleagues decided to learn whether narcotic substances that enter lakes and rivers together with sewage can cause full-fledged dependence in their inhabitants.
To answer this question, scientists measured the typical concentration of methamphetamine and its derivatives in rivers and lakes near major European cities. The researchers then filled the laboratory aquariums with water with a comparable concentration of drugs. There, scientists released several dozen individuals of trout-trout-a commercial fish from the salmon family, which is often used in laboratory experiments.
The fish lived in these aquariums for about eight weeks. After that, the ecologists tracked how the trout behaves when the concentration of the drug in the water changes. They also analyzed how the behavior of the fish differed in different life situations. In addition, ecologists have studied the chemical composition and structure of the brain of fish that lived both in polluted aquariums and in clean water.
It turned out that even those minimal concentrations of methamphetamine that the trout were dealing with were quite enough to cause them to become addicted. Scientists tracked this by the fact that the trout preferred to swim across the part of the aquarium with the highest concentration of drugs. In addition, after the scientists cleaned the aquarium of methamphetamine, the fish did not move much and suffered from other consequences of withdrawal. Individuals from the control group who lived in aquariums with clean water behaved completely differently.
All changes in the behavior of fish after the acquisition of addiction and withdrawal were accompanied by characteristic increases and decreases in the concentration of narcotic substances in their brain, as well as changes in the level of activity of the nervous system and the nature of metabolism in its tissues.
Such results, according to Randak and his colleagues, say that drug leaks can already have a strong impact on freshwater ecosystems and fish behavior. That can negatively affect their survival, which should be taken into account when assessing the stability of river and lake flora and fauna, the scientists concluded.