Chemical in lakes harm fish

[Lee Borgersen]

 
    Chemical traces in lakes could harm fish


 Tiny amounts of chemicals in Minnesota lakes might be having a big effect on some fish populations, according to two new studies by Minnesota researchers.

From the time they hatch, baby fathead minnows have limited chances of survival. Odds are good that they will be eaten by larger fish. But when exposed to drugs, their chances of surviving are worse, said Heiko Schoenfuss, a professor of toxicology at St. Cloud State University.
Graduate student Daniel Rearick, who works with Schoenfuss, exposed fathead minnows to pharmaceuticals and estrogen at the same levels documented in Minnesota lakes and compared them with other fish that were not exposed.

“What he found, which is really quite striking, is that fish that were exposed were slower to respond, swam away more slowly than their control counterparts, and as a result of that were more likely be eaten by a predator,” Schoenfuss said.

The researchers marked the fish so they could tell them apart. The graduate student then put all the fish into a tank with a predator, a sunfish.
Their results indicate a lower survival rate for the fathead minnows exposed to chemicals. That’s an important finding because fathead minnows are a big source of food for predatory sport fish like walleye.

The chemicals could have the same effect on other species said Schoenfuss, who is coordinating his research with U.S. Geological Survey scientist Richard Kiesling.
Kiesling, who has been examining how exposure to endocrine disrupting chemicals affects fish reproduction, studied fathead minnows and bluegills. He found exposed fish spawned later and produced fewer eggs than fish not exposed to the chemicals.
Add that conclusion to the finding that exposed young fish are more likely to be eaten and the impact is significant, Kiesling said.
“In an environment where there’s such heavy predation those small differences might be enough make a different in population level responses,” he said.
In other words it could cause fish populations to drop dramatically. That’s what happened a few years ago, when Canadian researchers exposed an entire lake to endocrine disrupting chemicals. The fathead minnow population crashed.
The Canadian scientists weren’t sure what caused it.
But the two new studies in Minnesota might help explain why. If fish produce fewer young, and those young are more likely to be eaten, the population will shrink.
However, although researchers appear to have several puzzle pieces that look like they fit together, they still haven’t been snapped into place.
Scientists have known for some time that exposure to endocrine disrupting chemicals causes adult male fish to develop more pronounced feminine characteristics. Other scientific studies around the world found exposure to traces of endocrine disrupting chemicals can cause fish to become more aggressive.
Monitoring shows found endocrine disrupting compounds are common in Minnesota rivers and lakes. Most likely come from wastewater treatment plants along rivers, or septic systems near lakes.
Schoenfuss, the St. Cloud professor, said the latest studies show Minnesota lakes are at risk from pharmaceutical and estrogen compounds.
“Even these very minute concentrations of compounds can have a pretty profound effect on aquatic environments,” he said. “So just because a lake looks nice and there’s still fish in there doesn’t necessarily mean this lake is not susceptible to the effects of endocrine disruption.”
How big is the risk? Kiesling, a hydrologist and water quality specialist, is trying to answer that question. He’s studying Minnesota lakes, trying to determine how much chemical bluegills absorb and how it affects spawning behavior. He hopes to follow fish populations in a lake for several years.
But Kiesling said he believes scientists now have a critical mass of research and there’s enough scientific evidence to consider action to protect lakes.
“There’s that old saying, ‘well, we have to study it more before we move forward,’” he said. “We know that aquatic resources, biotic resources are being affected by these compounds. We certainly have enough information about a number of these chemicals to evaluate if we should move forward with regulatory efforts.”
Taking action to safeguard Minnesota lakes is up to regulators and lawmakers, Kiesling said. Meanwhile, scientists will keep trying to define the risk to aquatic life.
Kiesling and Schoenfuss both plan to publish results of their studies later this year.  Article written by Dan Gunderson of Minnesota Public Radio News

[Lee Borgersen]

  Another fish study about fish being stoned

Study: Fish in drug-tainted water suffer reaction.
February 14, 2013


BOSTON (AP) — What happens to fish that swim in waters tainted by traces of drugs that people take? When it's an anti-anxiety drug, they become hyper, anti-social and aggressive, a study found. They even get the munchies. It may sound funny, but it could threaten the fish population and upset the delicate dynamics of the marine environment, scientists say.

The findings, published online Thursday in the journal Science, add to the mounting evidence that traces of medicines in rivers and streams can alter the biology and behavior of fish and other marine animals.

"I think people are starting to understand that pharmaceuticals are environmental contaminants," said Dana Kolpin, a researcher for the U.S. Geological Survey who is familiar with the study.

Calling their results alarming, the Swedish researchers who did the study suspect the little drugged fish could become easier targets for bigger fish because they are more likely to venture alone into unfamiliar places.

"We know that in a predator-prey relation, increased boldness and activity combined with decreased sociality ... means you're going to be somebody's lunch quite soon, " said Gregory Moller, a toxicologist at the University of Idaho and Washington State University. "It removes the natural balance."

The study adds to the worldwide body of research on the effects of pharmaceuticals in extremely low concentrations measured in parts per billion. Such drugs have turned up in samples taken from waterways in Europe, the U.S. and elsewhere over the past decade.

They come mostly from humans and farm animals; the drugs pass through their bodies in unmetabolized form. These drug traces are then piped to water treatment plants, which are not designed to remove them from the cleaned water that flows back into streams and rivers.

The Associated Press first reported in 2008 that the drinking water of at least 51 million Americans carries low concentrations of many common drugs. The findings were based on questionnaires sent to water utilities, which reported the presence of antibiotics, sedatives, sex hormones and other drugs.

The news reports led to congressional hearings and legislation, more water testing and more public disclosure. To this day, though, there are no mandatory U.S. limits on pharmaceuticals in waterways.

The research team at Sweden's Umea University used minute concentrations of 2 parts per billion of the anti-anxiety drug oxazepam, similar to concentrations found in real waters. The drug belongs to a widely used class of medicines known as benzodiazepines that includes Valium and Librium.

The team put young wild European perch into an aquarium, exposed them to these highly diluted drugs and then carefully measured feeding, schooling, movement and hiding behavior. They found that drug-exposed fish moved more, fed more aggressively, hid less and tended to school less than unexposed fish. On average, the drugged fish were more than twice as active as the others, researcher Micael Jonsson said. The effects were more pronounced at higher drug concentrations.

"Our first thought is, this is like a person diagnosed with ADHD," said Jonsson, referring to attention deficit-hyperactivity disorder. "They become asocial and more active than they should be."

Most previous research on trace drugs and marine life has focused on biological changes, such as male fish that take on female characteristics. However, a 2009 study found that tiny concentrations of antidepressants made fathead minnows more vulnerable to predators.

It is not clear exactly how long-term drug exposure, beyond the seven days in this study, would affect real fish in real rivers and streams. The Swedish researchers argue that the drug-induced changes could jeopardize populations of this sport and commercial fish, which lives in both fresh and brackish water.

Water toxins specialist Anne McElroy of Stony Brook University in New York agreed: "These lower chronic exposures that may alter things like animals' mating behavior or its ability to catch food or its ability to avoid being eaten — over time, that could really affect a population."

Another possibility, the researchers said, is that more aggressive feeding by the perch on zooplankton could reduce the numbers of these tiny creatures. Since zooplankton feed on algae, a drop in their numbers could allow algae to grow unchecked. That, in turn, could choke other marine life.

The Swedish team said it is highly unlikely people would be harmed by eating such drug-exposed fish. Jonsson said a person would have to eat 4 tons of perch to consume the equivalent of a single pill.

Researchers said more work is needed to develop better ways of removing drugs from water at treatment plants. They also said unused drugs should be brought to take-back programs where they exist, instead of being flushed down the toilet. And they called for drug companies to work on new "greener" drugs that degrade more easily.

Sandoz, one of three companies approved to sell oxazepam in the U.S., "shares society's desire to protect the environment and takes steps to minimize the environmental impact of its products over their life cycle," spokeswoman Julie Masow said in an emailed statement. She provided no details.