American Association for the Advancement of Science

Something fishy going on... Antidepressants contaminating rivers make perch antisocial

 

Science Editor, Boston

Drugs used to treat anxiety and depression are contaminating rivers and streams where they are building up in concentrations that can affect the behaviour of wild freshwater fish, scientists have found.

Significant amounts of a benzodiazepine drug called Oxazepam, which is widely used to treat anxiety, are being flushed into rivers from sewage works. The concentrations are too low to be considered a health risk to humans but a study has shown they can still affect fish.

Benzodiazepines, such as Valium, are one of the most widely prescribed groups of drugs. They can be excreted from the body intact and persist in the treated effluent water released from sewage works into rivers, scientists said.

A study carried out in Sweden found that the relatively low concentrations of benzodiazepines commonly found in rivers throughout Europe, including Britain, can significantly affect the behaviour of the European perch.

The scientists found that perch exposed to extremely small concentrations of Oxazepam, as low as a fraction of a microgram per litre of water, were less sociable, bolder and ate faster than fish that were not exposed to the drug.

The scientists believe the subtle behavioral changes seen under experimental conditions indicate how the wider freshwater ecology could be affected by this kind of hidden environmental pollution.

They said that pharmaceutical compounds released into the aquatic environment might pose a greater problem than hitherto realised and that more should be done to degrade the chemicals before being released in the treated effluent water from sewage works.

“The solution to this problem isn't to stop medicating people who are ill but to try to develop sewage-treatment plants that can capture environmentally hazardous drugs,” said Jerker Fick of Umeå University in Sweden, who was part of the team.

“These drugs are not toxic or harmful in small doses, and are used to treat patients for therapeutic reasons. So there has not been that much research into what it does when it gets into our waterways,” Dr Fick said.

A survey of the River Fyris in Sweden, which receives wastewater effluent from the city of Uppsala, found concentrations of oxazepam of around 0.58 micrograms per litre. “These concentrations are comparable to hose of benzodiazepines reported in other European and American waters,” the scientists report in the journal Science.

It was one of 21 pharmaceuticals found in the water sampled by the researchers that have a similar effect to Oxazepam, the scientists said.

Tomas Brodin of Umea, the lead author of the study, told the American Association for the Advancement of Science meeting in Boston that when wild perch were exposed to similar concentrations they exhibited subtle but distinct changes to their natural behaviour.

“Perch that were exposed to Oxazepam lost interest in hanging out with the group, and some even stayed as far away from the group as possible,” Dr  Brodin said.

“While alone, fish that were exposed to Oxazepam dared to leave safe refuge and enter novel, potentially dangerous areas. In contrast, unexposed fish stayed hidden in their refuge. The exposed fish seemed much less stressed and scared, behaving calmer and bolder,” he said.

Fish exposed to the drug ate faster than non-exposed fish. This could affect the wider ecology because more voracious perch would eat more of the zooplankton that might otherwise prevent algal blooms, Dr Fick said.

'We found distinct behavioural changes in the perch, even at low levels of exposure. The changes can be seen as both beneficial or detrimental depending on the ecology,“ he said.

”The fish became bolder and fed faster, which is a good thing if there are no predators around, but could be risky if there are,“ be added.

”It could also have a knock-on effect on the surrounding environment. If the fish eat more zooplankton, then there is less in the water. Zooplankton eat algae, so without them there could be algae blooms.“

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Business Analyst - 12 Month FTC - Entry Level

£23000 - £27000 per annum: Recruitment Genius: A Business Analyst is required ...

Recruitment Genius: Chefs - All Levels

£16000 - £23000 per annum: Recruitment Genius: To succeed, you will need to ha...

Recruitment Genius: Maintenance Engineer

£8 per hour: Recruitment Genius: This is an opportunity to join an award winni...

Recruitment Genius: Telesales Executive & Customer Service - Call Centre Jobs!

£7 - £9 per hour: Recruitment Genius: Are you outgoing? Do you want to work in...

Day In a Page

Isis in Syria: Influential tribal leaders hold secret talks with Western powers and Gulf states over possibility of mobilising against militants

Tribal gathering

Influential clans in Syria have held secret talks with Western powers and Gulf states over the possibility of mobilising against Isis. But they are determined not to be pitted against each other
Gaza, a year on from Operation Protective Edge: A growing population and a compromised and depleted aquifer leaves water in scarce supply for Palestinians

Gaza, a year on from Operation Protective Edge

A growing population and a compromised and depleted aquifer leaves water in scarce supply for Palestinians
Dozens of politicians, bureaucrats and businessmen linked to Indian bribery scandal die mysteriously

Illnesses, car crashes and suicides

Dozens of politicians, bureaucrats and businessmen linked to Indian bribery scandal die mysteriously
Srebrenica 20 years after the genocide: Why the survivors need closure

Bosnia's genocide, 20 years on

No-one is admitting where the bodies are buried - literally and metaphorically
How Comic-Con can make or break a movie: From Batman vs Superman to Star Wars: Episode VII

Power of the geek Gods

Each year at Comic-Con in San Diego, Hollywood bosses nervously present blockbusters to the hallowed crowd. It can make or break a movie
What do strawberries and cream have to do with tennis?

Perfect match

What do strawberries and cream have to do with tennis?
10 best trays

Get carried away with 10 best trays

Serve with ceremony on a tray chic carrier
Wimbledon 2015: Team Murray firing on all cylinders for SW19 title assault

Team Murray firing on all cylinders for title assault

Coaches Amélie Mauresmo and Jonas Bjorkman aiming to make Scot Wimbledon champion again
Wimbledon 2015: Nick Bollettieri - Vasek Pospisil must ignore tiredness and tell himself: I'm in the quarter-final, baby!

Nick Bollettieri's Wimbledon Files

Vasek Pospisil must ignore tiredness and tell himself: I'm in the quarter-final, baby!
Ashes 2015: Angus Fraser's top 10 moments from previous series'

Angus Fraser's top 10 Ashes moments

He played in five series against Australia and covered more as a newspaper correspondent. From Waugh to Warne and Hick to Headley, here are his highlights
Greece debt crisis: EU 'family' needs to forgive rather than punish an impoverished state

EU 'family' needs to forgive rather than punish an impoverished state

An outbreak of malaria in Greece four years ago helps us understand the crisis, says Robert Fisk
Gaza, a year on from Operation Protective Edge: The traumatised kibbutz on Israel's front line, still recovering from last summer's war with Hamas

Gaza, a year on from Operation Protective Edge

The traumatised kibbutz on Israel's front line, still recovering from last summer's war with Hamas
How to survive electrical storms: What are the chances of being hit by lightning?

Heavy weather

What are the chances of being hit by lightning?
World Bodypainting Festival 2015: Bizarre and brilliant photos celebrate 'the body as art'

World Bodypainting Festival 2015

Bizarre and brilliant photos celebrate 'the body as art'
alt-j: A private jet, a Mercury Prize and Latitude headliners

Don't call us nerds

Craig Mclean meets alt-j - the math-folk act who are flying high