Chemicals in Cootes Paradise are making fish sluggish
Study says fish are burning energy to deal with effluent from treatment plant instead of on feeding, mating
by Mark McNeil, Hamilton Spectator
If you've ever noticed fish looking unusually tuckered out in the waters of Cootes Paradise, a new McMaster study might have an explanation.
It seems effluent from the Dundas Wastewater Treatment Plant could be the cause.
The study published this week in the journal Environmental Science and Technology says wild sunfish downstream from the plant expended 30 per cent of their energy to push back the onslaught of chemicals. That means less stamina for other things like finding food and a mate.
"The main thing we found is that the exposure essentially required the fish to burn a lot more energy," said Graham Scott, senior author of the research paper.
A lot of chemicals — including pharmaceuticals — just pass through the treatment plants into receiving waters. Exposed fish will have the chemicals enter their bodies, "and what we found is that the fish has to burn a lot more energy to cope with the chemicals, just to stay alive."
"Essentially it needs to divert a lot of its finite resources to dealing with the contaminants."
The discovery is interesting because it introduces a new area of concern about effluent from wastewater treatment plants, such as the one in Dundas.
Some chemicals in discharges are known to be highly toxic in high concentrations, or carcinogenic. Others could adversely affect fertility.
But the new study found there are also less noticeable outcomes.
"This is something that is more subtle but it could have a very serious impact to the day to day living of fish," said Scott. "One of the reasons they seem more sluggish when exposed to wastewater effluent is because in a way they are sick. They are burning more energy to cope and they don't have as much energy for other things."
The study comes several weeks after a similar published study by a team of scientists with Environment and Climate Change Canada and McMaster University that looked specifically at the effect of pharmaceuticals from the Dundas plant's effluent.
The researchers found fish had elevated levels of serotonin in their blood plasma and that caused them to be more active and willing to explore than fish kept away from the discharges.
The fish tended to avoid cautionary instincts such as keeping still after being startled, said Sigal Balshine, a professor in the department of psychology, neuroscience and behaviour at McMaster and one of the authors on the papers. Balshine and five other colleagues also worked on Scott's research.
Meanwhile, the City of Hamilton is exploring options for the 1980s-era Dundas treatment facility to mitigate its discharges into Cootes Paradise that among other things have led to algae blooms.
The city previously earmarked about $25 million to upgrade the plant that manages sewage from Dundas and parts of Waterdown. A total rebuild would cost $45 million.
But Scott noted that even a state-of-the-art treatment facility would be generally ineffective at blocking pharmaceuticals such as birth-control medications, antidepressants and beta blockers from passing into receiving waters.
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