Male fish being feminized in Okanagan wastewater

Estrogenic compounds in treated effluent discharged from local treatment plants is feminizing male fish.

Scientists from UBCO who have been studying the impacts of estrogenic compounds in wastewater from sewage treatment plants in the Okanagan have found that male goldfish in a treated effluent reservoir are becoming feminized.

Biologist Bruce Mathieson has been collecting fish and water samples from Vernon’s MacKay Reservoir the past two years, as well as fish and water samples from a similar-sized pond just a few kilometres away—one fed by natural runoff and rainwater.

The reservoir holds treated effluent from the Vernon Water Reclamation Centre, a wastewater treatment plant, prior to it being used to irrigate grazing lands and golf courses south of Vernon.

Mathieson detected the changes in the male fish using molecular biology to study genes in the fish that are estrogen-dependent.

“I expected females to have a higher expression of these bio-markers for estrogen, but in MacKay Reservoir the males also have those bio-markers.

“Those altered genes are of concern. It’s hard to predict what other changes are being made,” he commented.

It’s the type of alteration that is typical of endocrine disruption, he explained.

Endocrine disruptors such as estrogenic compounds can mimic female hormones in male fish, he said. In fact, it has been known to result in male fish that produce both sperm and eggs, he said.

Estrogenic compounds can act at very low concentrations, he noted.

However, the expectation is that they will break down over time.

Limnologist Jeff Curtis at UBCO has been working for several years on an investigation of receiving waters for the Okanagan’s wastewater treatment plants for chemicals which are not removed during treatment, but which can have an impact on aquatic life in very low concentrations, such as estrogenic compounds.

He says he has found that luckily the loss rates of estrogen are fairly quick, through degradation or adsorption in the waters where they are released. That includes Okanagan Lake for Kelowna’s treatment plant, MacKay Reservoir for Vernon’s and the Okanagan River for Penticton’s.

However, because of the volume of water in Okanagan Lake there’s less impact immediately in that body of water.

He is concerned that there will be an emerging contaminant that doesn’t lose its effectiveness over time, and which eludes current treatment technology. Because the turnover rate for water in the big lake is 60 years, such a compound could accumulate there over time.

The reservoir is a good place to look, so he intends to screen for compounds from pharmaceuticals and personal care products in the treated effluent, where the levels would be higher and easier to detect.

Mathieson says they have also noticed that the goldfish in the MacKay Reservoir are 10 times larger than those in the ‘control’ pond, but he doesn’t know whether that’s because they’re older age classes, but he’ll be looking into that over the winter. Or, they could be getting more nutrients than the fish in the control pond, or there could even be a bird taking all the smaller fish from the reservoir.

All of his work is preliminary at this stage, with more data needed to answer questions and fill in the gaps, he emphasized.

Since it’s impossible to remove everything from treatment plant effluent, it’s important to figure out what compounds and chemicals are the important ones to target, he noted.

He would like to expand his analysis to include pharmaceuticals and personal care products, and he’d like to do more sampling in the colder months to see what differences there are then.



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