Antidepressants Washed Into The Ocean Are Making Crabs Behave Very Strangely


Tom Hale

Senior Journalist

clockOct 23 2017, 13:08 UTC

The oceans are not happy. Kelly vanDellen/Shutterstock

The US is consuming more antidepressants than ever before. In turn, this means that the world’s marine life is also taking more antidepressants than ever before.

While many of these chemicals are broken down by the liver, traces of these pharmaceuticals are pumped out in our pee and end up being flushed into our water supplies, sewage systems, and oceans. So, given this rising trend, a new study published in the journal Ecology and Evolution wanted to find out how fluoxetine, the active ingredient in the selective serotonin reuptake inhibitor (SSRI), Prozac, affected the behavior of Oregon shore crabs within a laboratory setting. 


They found out the fluoxetine-exposed crabs were more daring, more aggressive, and more prone to taking clumsy risks. The crabs were shown to increase their foraging behavior, particularly during the time of day when they normally stay hidden. In the wild, this would dramatically increase the risk of being snapped up by a predator. They also found that these crustaceans became more aggressive to their fellow crabs, often getting killed as a result of intense pinching.

"The changes we observed in their behaviors may mean that crabs living in harbors and estuaries contaminated with fluoxetine are at greater risk of predation and mortality," researcher Elise Granek, a professor in PSU's Department of Environmental Sciences and Management said in a statement.

Even though this experiment was carried out in a lab, not the "real world," the researchers attempted to simulate realistic concentrations of fluoxetine in the tank’s water.

This is not the first piece of research to highlight the effect of antidepressants in coastal waters on sea-life behavior. A 2010 study found that fluoxetine also made shrimps engage in more risky behavior and, as a result, can diminish their population numbers and disrupt food chains. All kinds of chemicals from prescription drugs and over-the-counter medications end up in our waterways, not just antidepressants. Of course, none of this means you should stop taking any medication without a doctor’s advice. However, it is certainly an issue for both environmental scientists and pharmaceutical developers to consider.


"With growing human populations in coastal zones, increasing use of antidepressants like fluoxetine is expected, suggesting higher future concentrations in the marine environment. Our results demonstrate how pharmaceuticals affect species behaviors and their interactions," the study concludes.

  • tag
  • marine life,

  • depression,

  • ssri,

  • drug,

  • crab,

  • anti depressants,

  • pharmaceutical,

  • sea life,

  • shore crabs