NEW BRUNSWICK—Tiny amounts of estrogen have long been linked to changes in fish physiology but now a Canadian study published in the Philosophical Transactions of the Royal Society B (yes, that is what it is called) last Monday has determined that small amounts of estrogen introduced into a lake has led to the near-extinction of the fathead minnow, interfering in the minnow’s ability to reproduce.
The article, ‘Direct and Indirect Responses of a Freshwater Food Web to a Potent Synthetic Oestrogen,’ discussed their findings of endocrine disrupting chemicals in municipal effluents (sewage, waste water, etc).
The experiments were conducted at the Experimental Lakes Area in northwestern Ontario and involved a long term, whole lake experiment using a before and after control impact design to determine the direct and indirect effects of the synthetic estrogen used in birth control pills.
The findings, which provided a clear link between very small amounts of estrogen and the disturbance of reproduction among fish, have pointed to a critical need to revamp municipal sewage treatment plants to deal with the chemicals.
“Our results demonstrate that small-scale studies focussing solely on direct effects are likely to underestimate the true environmental impacts of estrogens in municipal wastewaters and provide further evidence of the value of whole-ecosystem experiments for understanding indirect effects of EDCs and other aquatic stressors,” reads the conclusion of the study’s abstact.
Dr. Michael Paterson works with the Experimental Lakes Area facility and was a co-author of the report and he spoke to The Expositor on Monday following the release of the study’s findings. Dr. Karen Kidd of the University of New Brunswick was the lead researcher on the project that has been ongoing since the late 1990s.
It was in the late 1990s that a study in the United Kingdom had discovered that male trout were developing female characteristics due to estrogen being introduced into their environment.
The first moment that the researchers introduced the chemicals into the water in 2001, the fish began to respond to the exposure, noted Dr. Kidd. “Right away, the male fish started to respond to the estrogen exposure by producing egg yolk proteins and shortly after that they started to develop eggs,” she said.
The result was dramatic as the flathead minnow population plunged to barely one percent of its pre-estrogen numbers.
“It was really unexpected that they would react so quickly and dramatically,” she said. The plunge in population numbers was clearly linked to the introduction of the hormone.
As all ecosystems are, just that, systems, the impact of the food source fish echoed into the minnow’s main predator species, lake trout, which began its own decline due to the loss of its main food supply. On the other end of the food chain, the lake’s insect population, which is the flathead minnow’s own prey, saw a dramatic increase in population.
In a clear message to municipal planners, the removal of the estrogen had an almost immediate impact as well, as once the estrogen was no longer being introduced into the environment the fish populations began to rebound.
Unfortunately, the study does not go into how to remove the estrogens from the water, according to Dr. Paterson, but the study did look into how long it took for the estrogen to disappear from the lakes once the introduction ceased.
“We found that within a year we couldn’t detect it in the lake,” said Dr. Paterson. The researcher could not extrapolate the impact of estrogens into the Great Lakes from the municipal sewage plants operating along the lakes and Georgian Bay. “The concentrations we were working with were a lot less than what you would find in a toxicity study, but a lot more than what you would likely find in a larger body of water.” The study worked with concentrations resembling what might be found just downstream from a sewage treatment plant.
The location of the experiment itself was the subject of considerable controversy when a federal government threat to close the facility was averted by the intervention of the Ontario government and a not for profit which took over official responsibility for the facility in June of this year.
The research station was labeled by the Ontario government at the time as being “the only freshwater research facility of its kind in the world.” That assertion was made because the facility is the only one that provides scientific access to entire lakes. The Ontario government agreed to provide the $2 million a year the federal government wanted to save and the Manitoba government kicked in $900,000 over six years through a not for profit institute focused on sustainable development policy.
“We are very thankful to Premier Wynne and the Manitoba government for their support of this facility,” said Dr. Paterson.
He noted that the facility was able to retain much of its core research staff and has been successful in attracting top scientific personnel. “This is really the only facility of its kind, it is unique in the world,” he said. The Experimental Lakes Area is the only facility where researchers can study the impact of human activity on whole lakes. “Nowhere else in the world can you do that.” That capacity also allows for the study of how lakes recover from the impact of human activities.
The study and its importance for marine communities that depend on fisheries and tourism dollars from the sports fishing industry do appear to validate the two provincial government investments in the facility.
The estrogen study is pretty much wrapped up with the release of this paper, said Dr. Paterson. “That is pretty much consistent with all of our long term studies,” he said.
