How Depression Medication Is Polluting the Ocean and Altering the Behaviors of Sea Creatures

It’s well known that much of our unused and discarded pharmaceutical drug supply ends up in the ocean, and it turns out the chemicals in these drugs are affecting ocean inhabitants in some distressing ways.

A study from researchers at Portland State University finds shore crabs exhibit more risky behaviors when exposed to Prozac, the most commonly prescribed antidepressant. The drugs, it seems, makes crabs more defiant toward other animals that may prey upon them. As a result, they’re more likely to be caught by their predators.

For the study, published in Ecology and Evolution, the researcher put the crabs in water with low levels of fluoxetine, which is the active chemical in Prozac. With exposure to the drug, the crabs were more likely to engage in “foraging behavior.” The animals also appeared to care less about the potential for predators. Most surprisingly, they were more active during the day, which is when crabs tend to hide to protect themselves.

“Fluoxetine is one of the most widely used antidepressants in the world and a large amount of research has documented its occurrence in aquatic and marine environments,” write the researchers. “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 researchers also noticed some other distressing effects of the drug chemical. The crabs exposed to fluoxetine interacted differently with members of their own species. The drug-exposed crabs were more likely to pick fights with each other and end up dead in the process. 

At least half of all medications we bring into our homes aren’t used. These drugs are simply thrown out in the trash. As a result, the chemicals in many pharmaceutical products end up polluting the ocean and other natural bodies of water. Some people don’t know better and simply flush unused and expired drugs down the toilet. Drug chemicals also end up in the water because so much of the chemicals in the drugs are excreted through human urine and stool.

Endless studies have identified trace pharmaceutical drugs in just about every body of water that’s nearby or used by humans. In addition to antidepressants, studies have found waters are contaminated with antibiotics, blood thinners, heart medications (ACE inhibitors, calcium-channel blockers, digoxin), hormones (estrogen, progesterone, testosterone) and even opioid painkillers.

Join the Discussion