Pharmaceuticals could be linked to bonefish decline: study

Dive Deeper

What’s happening? Pharmaceuticals may be contributing to the decline in bonefish numbers in south Florida, according to research from Florida International University. Populations of the fish, which is popular with anglers, have fallen by over 50% over four decades. All 93 bonefish sampled tested positive for one or more pharmaceuticals. Of the fish studied, 56% had levels of pharmaceuticals higher than those at which negative impacts could be anticipated. Drugs were also found in bonefish prey, including shrimp, small fish and crabs. Pharmaceuticals enter the water through manufacturing and rainwater run-off and via livestock and human wastewater.

Why does this matter? Studies on the extent and impacts of pharmaceuticals in water bodies have been focused largely on freshwater environments such as rivers rather than the ocean, in which their effects are relatively unknown. However, this study highlights that widespread pharmaceutical marine pollution is an emerging issue already harming marine life in some regions, which needs to be tackled to minimise further impacts on marine ecosystems and coastal fisheries. Wastewater is transported to the sea from a number of sources including run-off from industrial plants or agricultural land, sewage spills, treated wastewater discharges and misfunctioning septic tanks. Traditional sewage treatment plants can often miss pharmaceutical contamination and fail to remove it due to outdated infrastructure and difficulty in identifying the compounds in water. Bonefish are categorised as near threatened by the International Union for the Conservation of Nature and their populations are declining due to several threats including water contamination, habitat loss and fishing. Around 58 different medications were found in the bonefish studied and their prey, including opioids, antidepressants, heart medications and antifungals. One bonefish tested positive for 17 separate pharmaceuticals – eight of these were antidepressants present in levels over 300 times the human therapeutic level. Researchers suggest pharmaceutical contamination can alter fish throughout all stages of their lifecycle. For instance, drugs such as Valium cause fish to be less active and take more risks, which could increase the likelihood of them being eaten by predators and decrease their overall survival rates. Contaminated water can also hinder the endocrine system and reproductive abilities of marine life. These impacts could be permanent due to the way increased exposure can alter brain chemistry in fish. From an economic perspective, impacts can be costly. South Florida’s flats fisheries are an important part its recreational saltwater industry, which has a yearly economic impact of more than $9bn and supports nearly 90,000 jobs. Florida has struggled with wastewater leaks into waterways in recent years – last year, an old phosphate mining facility Piney Point leaked over 200 million gallons of wastewater containing harmful levels of nutrients into Tampa Bay. In terms of solutions, legislation addressing pharmaceutical pollution in the environment is lagging. In the US, pharmaceutical release into the environment is currently unregulated, meaning there are no limits to quantities that can be released. Other existing initiatives place more emphasis on mitigating impacts to freshwater environments. Alongside regulation, proactive measures can improve wastewater infrastructure on a global scale and remove pharmaceuticals before they contaminate waterways, and negate the need for reactive responses after spills or release. Retrofitting treatment plants with advanced techniques could help. Ozonation – adding ozone into water to eliminate remaining contaminants not detected by traditional wastewater treatment – could curb the concentration levels of harmful compounds by as much as 95%. Activated carbon or biochar can also be used to absorb chemicals from polluted waters.

Other efforts to make the substances “greener” during production stages, such as creating pharmaceuticals with faster breakdown abilities when released into the environment, could further act to minimise impacts.


The Guardian

Bonefish & Tarpon Trust