 — in waterways seem to have adverse effects on fish behavior.)
Residues of some drugs — including the antidepressant Prozac (fluoxetine) — in waterways seem to have adverse effects on fish behavior.
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Scientists have known for years that human medications, from anti-inflammatories to the hormones in birth-control pills, are ending up in waterways and affecting fish and other aquatic organisms. But researchers are only beginning to compile the many effects that those drugs seem to be having. And it isn't good news for the fish.
One such drug, fluoxetine, is the active ingredient in the antidepressant Prozac. Like some other pharmaceuticals, fluoxetine is excreted in the urine of people taking it, and reaches lakes and waterways through sewage-treatment plants that are unequipped to remove it.
To investigate the effects of fluoxetine, researchers have turned to a common US freshwater fish species called the fathead minnow (Pimephales promelas). Normally, fathead minnows show a complex mating behavior, with males building the nests that females visit to lay their eggs. Once the eggs are laid and fertilized, the males tend to them by cleaning away any fungus or dead eggs.
But when fluoxetine is added to the water, all of this changes, said Rebecca Klaper, an ecologist at the University of Wisconsin-Milwaukee's Great Lakes Water Institute. Klaper presented her results this week at the 2012 meeting of the North American division of the Society of Environmental Toxicology and Chemistry in Long Beach, California.
Female fathead minnows seem to be unaffected by the chemical, but at concentrations of fluoxetine that are roughly comparable to the highest levels documented in fresh water, male minnows start to spend more time building their nests. When the dose is increased tenfold, the males "become obsessive, to the point they're ignoring the females", Klaper said.
When fluoxetine concentrations are increased yet again, fathead reproduction completely halts. "The males start killing the females," she said. Klaper also noted that if females are introduced a month after males are exposed to the chemical, the males no longer show this aggressive behavior, but the females still don't lay any eggs. "Something happens in that time," she said.
Easy prey
Reproductive behavior isn't the only thing that can be affected by trace pharmaceuticals. At the same symposium, Dan Rearick, an aquatic toxicologist from St Cloud State University in Minnesota, reported that a chemical found in birth-control pills, 17-β-estradiol, reduced the ability of fathead minnow larvae to elude predators.
After exposing the larvae to estradiol, Rearick then subjected them to sudden vibrations, similar to those produced by approaching predators. Using high-speed videos, he measured how long it took the minnows to curve their bodies into a C shape — an escape behavior known as a C-start. "They are preparing to dart away," he explained. He found that, even at environmental levels of estradiol (20 or 100 nanograms per liter), the minnows' reaction time was significantly slowed compared to control larvae that had not been exposed to estradiol.
In a second experiment, he raised hundreds of estradiol-exposed and control larvae, and repeatedly put ten larvae from both groups together in a tank with a predator, a bluegill sunfish (Lepomis macrochirus). When half of the larvae in each experiment had been eaten, Rearick looked at which types of larvae were left.
The result agreed with the C-start experiments: of the surviving fish, only about 45% were from the estradiol-exposed group, with the majority of survivors coming from the control group (55%).
Population crash
That difference might not sound like much, but using a multi-generation population biology model, Rearick found that it would be enough to produce a rapid population crash in the estradiol-exposed fish. Even if the fish weren't as badly affected, there would still be a slow, steady decline, he found. "There is probably a need for concern," he said.
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14 Comments
Add CommentTreatments plants near large cities usually have the means to oxidize these compounds but not the ones in rural areas where settling and aeration are about the only treatment.
Reply | Report Abuse | Link to thisIt's not always correct, though. The community of Goleta, sandwiched between Santa Barbara and UCSB mostly, uses settling only on two-thirds of the sewage which is then flushed in the ocean where it normally gets carried by currents to the beaches near Santa Barbara.
Why is there one in every thread? Do you guys just hate science that much? You have no reason whatsoever to think that these people are anything but honest except your own bigotry.
Reply | Report Abuse | Link to thisIts an interesting question, what are the effects of pharmaceuticals on the environment. Would you rather we just assume arrogantly that "it sounds like a crock" and not even bother to ask the question? Would that be less inconvenient to you maybe? Got news for you, the world doesn't exist to just be what you think it is, and if nobody bothered to actually ask questions and seek answers we'd still be living in caves. Would you like that better?
What chemicals make fish Salmon?
Reply | Report Abuse | Link to this'When fluoxetine concentrations are increased yet again, fathead reproduction completely halts. "The males start killing the females," she said.'
Reply | Report Abuse | Link to thisSo Prozac is the Screwfly Solution for fathead minnows. http://en.wikipedia.org/wiki/Screwfly_Solution
The use of the bioassay in the second part, the bluegill, was an excellent idea and worthy of acclaim. I forgot to mention this in my first post, but reactionary elements reminded me that this approach is important since it verifies the conclusions of the first experiment.
Reply | Report Abuse | Link to thisFathead minnows are the link between plankton and predators so if their population crashes then so will bass, bluegill, and pike. Oh, and crappie, I've always liked this particular fish.
Prozac does screw with one's reproductive ability. That's probably why my wife got a mor productive boyfriend while I became "extinct" to her. Ya, and if I was to take 10x the amount or even 2 or 3x it, I'd get manic and obsessive. My god, then they gave the fish even more still and the really flipped out and killed the poor females. I thought by taking "fish oil" supplaments, people become less depressed &/or hyperactive,ect. Maybe it's partly because they are already getting a little medicine along with omega-3's to facilitate your thinking. It may not be a fully natural solution to depression after all(mostly kidding now), just mostly.
Reply | Report Abuse | Link to thisLoaves and fishes. You "scientists" are agents of Sat*n. You destroy all His good works for your lies and wicked deceit.
Reply | Report Abuse | Link to thisI wonder if scientists have a few beers and then go to "spiritual" sites, then leave crank comments? There's one below that claims scientists are agents of Saturday afternoon, what have they got against Saturday afternoon?
Reply | Report Abuse | Link to thisLOL, I don't know Charles, most of human behavior is a mystery to me. I suspect the majority of these people cannot even explain what they were thinking about their own behavior when they did things...
Reply | Report Abuse | Link to thisMaybe we all just need to drink more water from Rome. I hear that has cannabinoids too, and surely some people need to mellow out! ;)
Ha, go figure! Anitdepressants make fish dull, and contraceptives do what they do in fish too!
Reply | Report Abuse | Link to thisWow, I'm still marvelling over it.
Since in more and more places recycled effluent is added to the domestic water supply, this is quite worrying for people as well. How pure can they make the recycled water?
Reply | Report Abuse | Link to thisThat is not true, because endocrine disruptor (hormones, drugs, pharmaceuticals) cannot be degraded in conventional wastewater plants. However, advanced oxidation processes like Fenton, wet and oxidation, ozone, etc. are considered highly efficient do deal with disruptors
Reply | Report Abuse | Link to thisAdvanced waste water treatment plants that produce drinkable water through reverse osmosis, UV lights and other methods produce water that is so pure it would kill you to drink it due to the ion imbalance it would cause and the osmosis gradient. The water is so pure and good at dissolving stuff that they need to harden it before they can even pipe it anywhere or else the pipes get worn out quickly. The regular waste water treatment plants give no where near this level of attention to the water and this is the water that is being released into dams and rivers and (hopefully) go no where near our drinking water. I hope this sheds some light on your concern.
Reply | Report Abuse | Link to thisSeriously though, the effects of estradiol are downplayed and barely mentioned in this article. Sci Am needs to do a round-up of these scary findings even if it might offend some people.
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