Too many drugs for the fish
Clemson research explores possible negative effects of pharmaceuticals in the water system.
Tuesday, November 3, 2009 - 17:30
HAPPY PILLS: Fish have plenty to be depressed about with poor water quality, but antidepressants won't help the situation. (Photo: Kristen Gaworecki)
As the bouncing rock moves across the television screen and the voice-over lists the possible side-effects of an anti-depressant drug, she never mentions "changing behavior in fishes."
At the Institute of Environmental Toxicology, lab fellow Dr. Kristen Gaworecki and PhD student Joe Bisesi have been investigating the environmental effects of antidepressants. Their studies are examining changes in behavior due to exposure to fluoxetine (Prozac) and venlafaxine (Effexor) on hybrid striped bass.
Pharmaceuticals pass through our bodies and are flushed through wastewater treatment facilities, ending up in lakes and river systems, and consequently affecting aquatic organisms and ecosystems. Some of the drugs that have been detected in surface waters include antibiotics, birth control hormones and antidepressants.
In humans, fluoxetine works to boost mood by blocking the reuptake of serotonin. Serotonin is a neurotransmitter that influences many functions including sleep, appetite, memory and learning.
Just because the mood-boosting effects of fluoxetine are beneficial to the humans to whom they are prescribed, does not mean that they are beneficial to aquatic organisms that encounter them second-hand.
"I don't think there would be any sort of benefit for these fish," said Bisesi.
Gaworecki's study saw that it took fish exposed to the drug longer to capture prey than fish in a clean water environment. After the behavioral assay, Gaworecki examined the brains of the fish to find a correlation of the amount of serotonin with the time it took to capture their dinner.
Gaworecki saw effects in the fish at fluoxetine concentrations as low as 40 µg/L. She also tested concentrations from 0.1-10 µg/L, but saw no change in behavior in the fish.
Bisesi picked up the research where Gaworecki left off, observing fish exposed to fluoxetine concentrations between 0 and 40 µg/L at 10 µg/L increments. He only saw slower prey capture in the fish that were in 40 µg/L of the drug, indicating that level may be the threshold for these fish.
Fish may not be in danger of starving to death yet. "About the highest levels I've seen measured in the environment are around 100 ng/L," Bisesi said. That's 0.25 percent of the levels that affected the fish in their experiments.
Even though the concentrations where negative effects were seen are much higher than what is seen in the environment, this information can be useful in making policies and setting water quality standards. "It's important to know where that line is, so we know we aren't going to have any negative effects in the environment," Bisesi said.
Bisesi will continue to work on this project. His agenda includes analyzing the brains of the fish he exposed to different levels of fluoxetine. The next step is to go through the same steps to examine the effects of venlafaxine (Effexor) on the same species of fish.
Also on MNN: Birth control pill endangers fish populations
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