Recent research and testing of the native minnow known as the longnose dace has shown elevated levels of a protein called hepatic vitellogenin. This protein is normally only found in the blood females is used by the females to produce eggs. Up to 44 percent of the male fish tested were showing eggs present in their testes. This will greatly affect their reproductive ability and cause a severe decline in the fish population.
The researchers claim that the fish are being exposed to estrogen or something that looks like estrogen to the fish. The most commonly found pollutants in the rivers were synthetic estrogen (most likely from birth control pill compounds and hormone therapy drugs); bisphenol A which is used in making plastics; and certain types of natural and synthetic steroids which are by-products of agricultural run-off and cattle production.
Further research is to be conducted on the causes of this finding.
Gender-bending fish on the rise in Southern Alberta
By Rose Sanchez
University of Calgary researchers have discovered chemicals present in southern Alberta rivers which are responsible for the feminization of fish.
“What is unique about our study is the huge geographical area we covered,” says co-author Lee Jackson, about the research paper results published in the journal Environmental Toxicology and Chemistry. “We found that chemicals — man-made and naturally-occurring — that have the potential to harm fish were present along approximately 600 kilometres of river.”
An initial study done by an undergraduate student a number of years ago, looked at the effects of chemicals on fish in the Red Deer River.
Researchers expanded on that and focused on two rivers in the South Saskatchewan River Basin, the Red Deer and Oldman rivers.
“We didn’t have any results in mind, we were letting the fish tell us the message,” says Jackson, who is also executive director of Advancing Canadian Wastewater Assets, a research facility that develops and tests new approaches for treating wastewater. It will be located at the City of Calgary’s new Pine Creek Wastewater Treatment Plant.
The message from the fish tested, which were native minnow known as longnose dace, was clear. At 14 of 15 locations, the male dace showed elevated levels of a protein called hepatic vitellogenin, which is normally only found in the blood of females and used by females to produce eggs.
“... it tells us the fish are exposed to estrogen or something that looks like estrogen to the fish,” explains Jackson.
Water from the rivers was analyzed for organic contaminants commonly found in wastewater or rivers impacted by human and agricultural activity. Found in the water were synthetic estrogens, (such as birth control pill compounds and hormone therapy drugs); bisphenol A which is used in making plastics; and certain types of natural and synthetic steroids which are by-products of agricultural run-off and cattle production.
In some sites up to 44 per cent of the male fish had eggs in their testes, effecting their reproductive ability. Fewer male fish able to reproduce means fewer fish born into the population in the future.
“The situation for native fish will likely get worse as the concentration of organic contaminants will become more concentrated as a response to climate change and the increase in human and animal populations,” says Jackson.
Researchers were also surprised by the results downstream of two communities, south of Fort Macleod and Lethbridge.
“Most notably, we saw a significant increase in a specific protein marker for the presence of compounds with estrogen-like activity,” says co-author Hamid Habibi. “Our results showed females make up 85 per cent of the population of longnose dace. In the upstream locations, females comprise 55 per cent of the population.”
Jackson likened the research project to that of peeling away the layers of an onion. Now that researchers have the pattern of fish effected and the contamination, work can be done to learn more detail about the chemicals causing the skewing of sex ratios in river fish populations and ultimately how that may effect human populations.
Also, a student this fall will use the information gathered so far to learn how the fish may be moving between the different sampling sites.
“The ultimate hope is that regional agencies in coming up with new policies will use this document,” says Jackson, about the research paper, which was also co-authored by Ken Jeffries of the University of B.C. and Michael Ikonmou of the Institute of Ocean Sciences.
Researchers will be able to continue further studies when the new research facility linked to the Pine Creek Wastewater Treatment Centre, is operational in two to three years. Different fish will be able to be stocked in experimental streams and the effects of chemicals found in water studied further.
Posted by Danielle Ritter