A forthcoming report in the journal Science finds that wild European perch exposed to the popular anxiety medication Oxazepam tend to be antisocial, wander away from the safety of their group, and devour food more quickly than peers, "all behaviors that could have profound ecological consequences."
Further research is needed to determine whether oxazepam and similar drugs are actually causing fish to change their behavior in the wild. If so, profound ecological effects could result, the authors say. For example, fish relieved of their normal stressors—say, of being eaten—could wipe out the population of algae-eating water fleas, which could lead to an algal bloom. On the flip side, anxiety-free fish are likely to be much more vulnerable to predators, Brodin says, suggesting that the overall effect will likely depend on whether perch are the top predator in their environment.All of this indicates a growing need for updated water filtration and treatment systems with the ability to capture and contain pharmaceuticals released by humans into the water system. Drugs "don't mysteriously go away after we excrete them," says Jerker Fick, a toxicologist at Umeå University in Sweden and co-author of the new study.