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Published: 2020-08-31

Anxiolytics in lakes gives calming news

NEWS A new thesis from Umeå University shows that pharmaceuticals are more persistent in the environment than previously believed. However, a unique study of a drugged lake gives calming news to those who feared that fish will adopt risky behaviour due to anxiolytic pharmaceuticals.

Text: Ingrid Söderbergh

Traces of pharmaceuticals in waterways is a well-known environmental issue. An increased use of pharmaceuticals as a result of an aging and growing population leads to increased discharge of pharmaceuticals into lakes and waterways via sewage treatment plants. Antibiotics in waters are believed to increase the risk of microbial resistance to antibiotics, and certain pharmaceuticals such as antihistamines and anxiolytics have shown to alter the behaviour of aquatic organisms.

Johan Fahlman’s thesis shows that pharmaceuticals can be surprisingly persistent in northern environments.

“Antibiotics, antihistamines and anxiolytics believed to dissipate quickly in the environment can stay in their active form for months and even years in cold and ice-covered waters”, says Johan Fahlman.

His studies show that the tests used to assess how long pharmaceuticals can affect animal life in waterways misses important processes that causes the dissipation of pharmaceuticals to slow down in natural ecosystems compared to the laboratory environments normally used by scientists.

“There are complex processes controlling the dissipation of pharmaceuticals in the environment that we are yet to recreate in laboratory environments”, says Johan Fahlman.

Earlier studies have shown that low concentrations of anxiolytic pharmaceuticals make perch bolder in laboratory environments and willing to take life-threatening risks, something which have had scientists worried that perch would become easier prey for predatory fish. However, this thesis provides calming news.

Johan Fahlman performed a unique study in collaboration with other researchers where perch in an entire lake were exposed to anxiolytics, the expected behavioural effects remained absent. As the researchers were able to follow the behavioural of every fish in a lake simultaneously, they were able to observe that perch as a collective were not affected in the same way as individual fish studied in laboratory environments.

Social distancing between perch is a more influential factor on perch behaviour than low levels of anxiolytic pharmaceuticals.

“We believe that the presence of the shoal makes the fish as calm and brave as possible, which causes the effects of the anxiolytic pharmaceutical to weaken if the fish are living in groups”, says Johan Fahlman.

Read the whole thesis

Press photos


About the dissertation:

On Friday the 11 September Johan Fahlman, Department of Ecology and Environmental Sciences at Umeå university, defends his thesis entitled: The fate and effect of pharmaceuticals in boreal surface waters.

The dissertation takes place digitally at 10.00
Faculty opponent is Fredrik Jutfelt, Norges teknisk-naturvetenskapliga universitet, Trondheim
Supervisor is Jonatan Klaminder