Our Antidepressants Are Making the Ocean Sad

A new study shows how traces of prozac found in waterways are starting to affect sealife.
That's the ocean. Via Shutterstock

Here's some depressing news: all that Prozac we're taking could be putting the ocean at risk. A new study from Portland State University examines how shore crabs can exhibit "risky behaviour" after being exposed to SSRIs (selective serotonin reuptake inhibitors), the most common type of antidepressants.

Given the all-time-high popularity of SSRI drugs, environmental science researchers were interested to know how Prozac in particular might have an impact on sea life. They exposed a sample of Oregon shore crabs to the active ingredient of Prozac, fluoxetine, within the laboratory.


Their research, published in the journal Ecology and Evolution, notes that the fluoxetine-exposed crabs behaved rather oddly. The normally risk-averse crustaceans became gutsier, unusually coming out of hiding and foraging during the day, and "showing less concern for predators than they normally would". They also became more violent, fighting with other crabs of their own species and sometimes getting killed in the process.

"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," said researcher Elise Granek, a professor in PSU's department of Environmental Science and Management, in a media release accompanying the research.

As with many pharmaceuticals, traces of antidepressants make their way into the ocean via sewerage and waste disposal, and are also discharged from drug factories and hospitals. Unlike other ocean pollutants, human and animal pharmaceuticals are specifically designed to have physiological impacts—and can therefore potentially have much more sinister effects on marine life. So scientists have been concerned about the potential environmental impact of pharmaceuticals being flushed into waterways for some time.

In 2010, a similar study found that shrimp exposed to antidepressants also exhibited "riskier" behaviours that made them more vulnerable to prey. In 2014, a UK-based study found that fluoxetine caused native seabirds to eat less food, and another study from Ontario found that the contraceptive pill killed small fish at the bottom of the food chain in local lakes—disrupting entire ecosystems.

You shouldn't stop taking your meds out of concern for the crabs, but anyone worried about marine ecosystems might want to think twice before taking any of those slightly more optional drugs. Studies have shown that traces of cocaine, ecstasy and methamphetamines might also negatively affect the health of marine life.

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