© AlamyThe effect of the drug on European perch (above) was similar to its effect on people, with potential evolutionary and ecological impacts.
Normally shy perch became bolder and more independent when exposed to a drug called oxazepam for treating anxietyDrugs to treat anxiety in people may alter the behaviour of fish when the chemicals are flushed into rivers, according to scientists. Swedish researchers found that European perch exposed to tiny concentrations of a drug became less sociable, ate more and became more adventurous - all changes in behaviour that could have unexpected ecological impacts on fish populations.
When scientists at Umeå University in Sweden screened rivers for pharmaceuticals they found that a drug for treating anxiety, called
oxazepam, was accumulating in fish. Many drugs and other synthetic chemicals used by humans in everything from pesticides to cosmetics can
pass through waste water treatment and end up in wildlife, potentially accumulating to toxic levels.
But until now scientists had never studied the behavioural impacts of small quantities of contaminants. Tomas Brodin led a team that mimicked in the lab the concentrations of oxazepam found in the wild - around a microgram per kilogram of fish body weight - and watched for changes in how bold, sociable and active the fish were.
"Normally, perch are shy and hunt in schools," said Brodin. "This is a known strategy for survival and growth. But those who swim in oxazepam became considerably bolder."
Comment: Note the falls appear to concentrate over populated areas. While this could be explained by saying that naturally more meteorites will be found in areas where there are more people, we have to wonder if masses of people can act as some sort of 'attractor' for these things...
To find out more, check out Comets and the Horns of Moses.