NOTNicknamed “Gray Ghosts” for their shiny silver scales, remarkable stealth and speed, bonefish can swim up to 40 mph. This species, protected by catch-and-release laws in the United States, is revered by anglers around the world, many of whom visit Florida to seek out the elusive fish.
But evidence points to a steep decline in bonefish numbers in South Florida. Populations have fallen by more than 50% in four decades, researchers estimate.
Dr. Jennifer Rehage, a fish ecologist and associate professor at Florida International University (FIU), has spoken to many anglers about the disappearance of Florida seagrass fish: “They said to me, ‘I sin [bonefish] all my life and I can’t find them. I haven’t seen a bonefish in five years, and that freaks me out.”
Over the past three years, Rehage has conducted a study to find out why, and discovered something that might help explain it: pharmaceuticals.
Of the 93 bonefish she and her team sampled, all tested positive for at least one drug, including heart medications, opioids, antifungals and antidepressants, according to study results, published in february.
In 56% of the fish, the researchers detected pharmaceutical amounts at levels “above which adverse effects are expected,” according to the study. A bonefish sampled in Key West tested positive for 17 pharmaceuticals, including eight antidepressants that were up to 300 times above human therapeutic levels. Exposure to pharmaceuticals in South Florida bonefish was “widespread and concerning,” the study concluded.
The researchers also studied 125 animals preyed upon by bonefish, including shrimp, crabs and small fish. Each contained an average of 11 pharmaceutical contaminants, indicating that the contamination is not limited to bonefish.
While more is known about the potential impacts of pharmaceutical pollution in freshwater, marine impacts have been much less studied. There’s still not enough information to directly link bonefish decline to drugs, but “the possibility of pharmaceuticals being a problem [for fish in the sea] is great and concerning,” says Rehage.
Nearly 5 billion drugs are prescribed each year in the United States alone, and the average American has about 12 prescriptions per year. Pharmaceuticals reach water in a variety of ways, including through manufacturing and rainwater runoff, but human and animal sewage is one of the main causes – especially what humans flush down toilets.
The specific health consequences of pharmaceutical contamination on marine life are not yet fully understood, but there is evidence of multiple negative effects.
“[It] can cause several consequences, mainly on the behavior of fish, but it can also affect their ability to reproduce and their endocrine system,” explains Elena Fabbri, professor in the department of biological, geological and environmental sciences at the University of Bologna in Italy. .
In 2013, scientists from Umeå University in Sweden – which partnered with the FIU for the bonefish study – found that wild perch were less fearful and more antisocial when exposed to anti-anxiety drugs, which could affect feeding and reproduction. A 2016 study from the same university found that salmon exposed to this drug swam faster and exhibited riskier behavior. Exposure of crayfish to antidepressants has been linked to altered behavior, increasing their boldness and the amount of time they spend feeding, potentially making them more vulnerable to predators.
According to Rachel Silverstein, director of the environmental organization Miami Waterkeeper, sewage ends up in the sea in three main ways: sewage spills, discharge of treated sewage into the ocean, and faulty septic systems. These are all major problems in Florida. In 2020, 212 million US gallons (800 million liters) of sewage flowed into Fort Lauderdale’s waterways.
“Although most contaminants are filtered out in wastewater treatment plants, it is very difficult to remove some of these pharmaceuticals from water,” says Silverstein. Additionally, more than half of Miami-Dade County’s septic systems are not properly filtering waste due to rising sea levels, creating an environmental and public health hazard, he said. she.
Silverstein sees the CRF study as “further proof that we need to make urgent changes to modernize our infrastructure in order to continue to live in this region and protect our economic and environmental interests.”
The problem is not limited to Florida. Experts say there is an urgent need to improve wastewater treatment infrastructure globally to eliminate pharmaceuticals before they reach the ocean.
Implementing an additional step in wastewater management called “ozonation” could help, Rehage says. The technique adds ozone to water to help remove contaminants that are often missed by traditional wastewater treatment, including pharmaceuticals and pesticides. But not enough countries are renovating factories to incorporate this step, she says, pointing to Switzerland, Sweden and Germany as among the only countries “that really deal with this issue of pharmaceuticals”.
Improving wastewater management is important, but the pharmaceutical industry itself also has a responsibility to tackle the problem by exploring greener alternatives, says Fabbri. “We cannot ban these substances because we need them, but we could favor or push the pharmaceutical industries to find greener alternatives.” This could include producing drugs that break down faster in the environment.
There are political movements to better understand the impact of drugs on waterways. In 2019, for example, the EU adopted a “strategic plan” to address the risks of pharmaceutical pollution in the environment. But many such initiatives focus more on the impact on freshwater environments.
While other research points to the impact of pharmaceuticals in the ocean, Fabbri says, “We need to continue to publish on this topic to inform regulatory agencies that these regulations are also needed in marine environments.”
For now, researchers say there is a long way to go in the United States. “Control of chemicals entering our environment has always been reactive,” says Aaron Adams, director of science and conservation at the Bonefish & Tarpon Trust, the conservation organization that commissioned the CRF study.
“No legal limits exist for the control of pollution from pharmaceuticals during manufacture, use or disposal,” the report notes.
Nick Castillo, a CRF PhD student and co-author of the study, says standardized measures are needed to assess the effects of drugs on exposed organisms. Currently, he points out, these “outdated” environmental regulations tend to ignore pharmaceuticals “because they are not lethal.”
The study of the impacts of pharmaceuticals in waterways has always had a strong focus on freshwater, says Rehage: “This is one of the first studies to go into coastal marine environments and a wide area to show that pharmaceuticals are everywhere.”