As human waste makes its way into the sea, fish off the coast of Florida are testing positive for a variety of drugs.
Since 2018, researchers from Florida International University and the Bonefish and Tarpon Trust, a Miami-based nonprofit dedicated to bonefish and tarpon conservation, have been studying the two varieties of fish that can be found in Biscayne Bay and the Florida Keys.
They took blood and tissue samples from 93 bonefish and tarpons in the area and found that each used an average of seven pharmaceuticals, including antidepressants, blood pressure medication, prostate treatment pills, antibiotics and painkillers.
The study found that one fish even had a total of 17 different drugs in its tissues, and researchers found pharmaceuticals in bonefish prey, including crabs and shrimp.
These drugs can affect all aspects of fish life, including their feeding habits, sociability and migratory behavior, threatening the already dwindling bonefish population in the region.
“These findings are truly alarming,” Jennifer Rehaga, a coastal and fish ecologist and associate professor at the university, said in a statement.
“Pharmaceuticals are an invisible threat, unlike algae blooms or murky waters,” she explained.
“Yet these results tell us that they pose a formidable threat to our fisheries and underscore the urgent need to address our long-standing wastewater treatment infrastructure issues.”
The researchers found that exposing both individual fish and their social groups – called “shoals” – to different levels of fluoxetine had no apparent effect on the solitary fish.
But as a group, the study published in the journal Biology Letters in 2019 found that mosquitoes relaxed their hunting behavior and ate less food overall when exposed to high levels of the drug – which remains active even at low dose and can be permanently released.
Meanwhile, the Florida International University study reports that nearly 5 billion prescriptions are filed each year in the United States – IQVIA reporting that in 2020, a total of 6.3 billion prescriptions were dispensed .
Yet there are still no environmental regulations for the disposal of pharmaceuticals – which can be released through urine and end up in freshwater bodies like lakes and rivers, as treatment systems water cannot completely filter out traces of the drug.