Drug contamination in water puts salmon in more risk

“Invisible, Not Mind” is a method of handling things that are washed away in the toilet frequently. But from anxiety drugs to antibiotics, the medications we take don’t simply go away after we leave our bodies. Many are not completely removed by wastewater treatment systems, but end up in rivers, lakes, and streams where they can affect and affect wildlife in unexpected ways.

Our new study investigated how sedatives commonly prescribed for sleep and anxiety disorders, called clobazam, affect the movement of young Atlantic salmon (salmosalah) from the Dal River in central Sweden to the Baltic Sea.

Our findings suggest that even small traces of drugs within the environment can alter animal behavior in ways that can shape survival and success in the wild.

Recent global studies of rivers around the world have found that drugs contaminate waterways on all continents. These substances enter the aquatic ecosystem through daily use, as the active compounds not only pass through our bodies and through sewage systems, but are caused by inappropriate disposal and industrial wastewater.

To date, almost 1,000 different active drugs have been detected in environments around the world.

Of particular concern is the fact that many biological targets of these drugs are also present in a variety of other species, including receptors in the human brain. This means that wild animals can also be affected.

In fact, research over the past decades has demonstrated that pharmaceutical contaminants can disrupt a wide range of animals’ characteristics, including physiology, development, and reproduction.

Wild drug contamination

Although the behavioral effects of pharmaceutical contaminants are paid relatively little attention, clinical testing shows that a variety of these contaminants can alter brain function and behavior in fish and other animals. This is a major source of concern given that all survival-critical behaviors, including predator avoidance, food foraging, and social interactions, can be confusing.

Although lab-based research has provided useful insights, experimental conditions rarely reflect the complexity of nature. The environment is dynamic and difficult to predict, and animals often behave differently from controlled settings. That is why we set out to test the effectiveness of drug exposure in the wild.

As part of a large-scale field study in Central Sweden, we also attached an implant that slowly released clobazam (a common drug contaminant) and a miniature tracking transmitter to larvae Atlantic salmon on sea-side migration via DAL.

It was found that Crobazam increased the success of travelling from this river to the sea. This is because crobazam-treated salmon reached the Baltic Sea compared to untreated fish. Salmon exposed to these crobazams took less time to pass through two major hydroelectric dams, which often slow or block salmon movements.

To better understand these changes, we followed a laboratory experiment that revealed that clobazams moved with groups of fish when faced with predators, that is, changed what scientists call shallow water behavior.

This suggests that changes in migration observed in the wild may be attributed to drug-induced changes in social dynamics and risk-taking behavior.

What does this mean for wildlife?

Our study was one of the first to show that drug contamination can affect not only laboratory behavior but also animal outcomes in the natural environment.

While increasing success in mobility may sound like a positive effect at first, the destruction of natural behavior can have ripple effects across ecosystems.

Even seemingly beneficial changes to animal behavior can be sacrificed, like faster passage through a barrier. For example, changes in timing of movement can result in fish reaching the ocean if conditions are not ideal or exposed to new predators or risks. Over time, these subtle changes can affect the dynamics of the entire population and threaten the balance of the ecosystem.

Medicines are essential to keeping people and animals healthy. However, the accumulation of these drugs in rivers and lakes requires a smarter approach to keeping the waterways clean.

Part of the solution is upgrades to wastewater treatment plants. Several advanced methods such as ozonation, which involves frothing ozone gas through wastewater to decompose contaminants, are effective in removing pharmaceuticals. However, such advanced treatment systems are often more expensive than they are out of reach of many local installations.

Another promising measure is green chemistry. It is a drug designed to decompose more easily in the environment and reduce toxicity even after use. Our team has recently highlighted this as an important step to reducing pharmaceutical contamination in the environment.

Stronger regulations and better drug processing practices can also help prevent drugs from ending in the waterway in the first place.

There is no single modification, but by advancing and integrating science, technology and policies, it can help protect wildlife from the unintended effects of drug contamination.

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