Our Antidepressants Are Becoming a Big Problem For Fish in Niagara

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http://www.sciencealert.com/antidepressant-chemicals-are-changing-the-brains-of-great-lakes-fish

Our increased use of antidepressants is having a knock-on effect on nature: scientists have found evidence of these drugs in the brain tissue of 10 different species of fish in the Great Lakes region.

Not only does it threaten the biodiversity of the lakes, the researchers say, it can also cause harmful changes to the behaviour of the fish.

The international team of researchers says there's no danger to humans from eating these fish, but that more needs to be done to get these antidepressant chemicals out of our wastewater before they have a chance to damage marine life beyond repair.

"These active ingredients from antidepressants, which are coming out from wastewater treatment plants, are accumulating in fish brains," says lead researcher Diana Aga from the University of Buffalo. "It is a threat to biodiversity, and we should be very concerned."

"These drugs could affect fish behaviour. We didn't look at behaviour in our study, but other research teams have shown that antidepressants can affect the feeding behaviour of fish or their survival instincts."

That previous research suggests, for example, that some fish become less aware of predators when hit with antidepressant chemicals, although the reaction to the drugs varies between species.

The team looked at ten different species of fish in the Niagara River, a crucial channel connecting Lake Erie to Lake Ontario.

In all of the species – smallmouth bass, largemouth bass, rudd, rock bass, white bass, white perch, walleye, bowfin, steelhead, and yellow perch – they found evidence of antidepressants.

The highest concentration of drugs was found in a rock bass: 400 nanograms of norsertraline per gram of brain tissue. Norsertraline is produced in the body by sertraline, the active ingredient in Zoloft.

These chemical levels aren't as high as the ones artificially generated in marine species for related research, but they're still very worrying for scientists.

What's more, the concentrations of drugs in the brains of the fish were significantly higher than the concentrations in the river water, suggesting the fish are picking up more and more of the chemicals over time.

For the researchers, it's important that wastewater plants do more to filter out chemicals like those from antidepressants, which appear in the urine of the people taking them.

These plants generally concentrate on killing bacteria and removing solids and faeces, but need to address drugs that are often being ignored, says the team behind the study.

"These plants are focused on removing nitrogen, phosphorus, and dissolved organic carbon but there are so many other chemicals that are not prioritised that impact our environment," says Aga.