Pollutants in water making fish work harder just to stay alive, study suggests

A new study has found pharmaceuticals and other contaminants are forcing Hamilton's fish to work harder to survive.

A team of researchers from McMaster University have found that when exposed to elevated levels of pollutants inwater, fish are burning more energy that would otherwise go towards vital functions, ultimately making them more vulnerable.

"The evidence is mounting that these sorts of chemicals are having impacts on the natural environment," said Graham Scott, a biologist atMcMaster University and senior author of the paper that was published in the journalEnvironmental Science and Technology onJan. 16.

Field research for the studywas conducted over a three-week periodin 2016, when researchers put wild sunfish in cages at different points downstream from the Dundas Wastewater Treatment Plant,before bringing them back to the lab to be observed.

"Specifically we were interestedin working in the DundasWastewater Treatment Plant because it's so close to Cootes Paradise marsh, which is of course an important natural environment," said Scott.

Once in the lab, they compared the metabolism of the fish exposed to the wastewater to the fishheld in unpolluted water.

Researchers measured how much oxygen the fish were consuming to get an indication of what theirmetabolism was.

Ourwastewater treatment plants are definitely having impacts on the fish that live close by and many wastewater treatment plants release their effluent into water.- Graham Scott,biologist, McMasterUniversity

Scott says the fish exposed to contaminants required more oxygen, meaning they require more nutrients just to stay alive.

According to Scott, the fish had to work at least 30 per cent harder to survive.

"It means they won't have as much energy available to support the other important things that a fish needs to do like move around and interact with other fish whether it be for defending territories or for finding mates," said Scott.

"It might not have as much available to get away from predators, to do all the things that a fish needs to do tobe a healthy, happy fish in the wild."

Scott says we need to think about how wastewater treatment plantsare going to workin the future, because a natural environment like Cootes Paradise is important to both many different animals and people.

"The most important impact is that it suggests that our wastewater treatment plants are definitely having impacts on the fish that live close by and many wastewater treatment plants release their effluent into water that are natural environments," said Scott.