Pharmaceutical contamination affects salmon movement behavior

Every spring, youth Atlantic salmon leaves the freshwater house and starts a dangerous trip to the sea. – Avoid predators, explore the dam, and survive by relying on detailed instincts. But new research, publication scienceEven trivial human drugs in the river suggest that this ancient migration rules can be quietly rewritten.

The international researcher’s team, led by the Swedish Agricultural Sciences College, tracked salmon in the Swedish lecture, and found that exposure to anti -pyeong drug chlobadam promotes migration success. The drug helped the fish to explore the dam faster, but changed social behavior in a potentially dangerous way.

Lecture

Rivers, lakes and streams are quietly accumulating pharmaceutical cocktails. – Chemical residues of modern medicine. more 900 other active constraints It is now detected in the freshwater ecosystem worldwide and is expected to increase the concentration.

This drug enters the environment through various paths. Some are excreted in the body and pass through the wastewater treatment plant, and often lack the ability to completely remove. Others penetrated the waterway through agricultural leaks, inappropriate disposals or manufacturing waste. Unlike many natural pollutants, medicines are made to persist. – It is designed to maintain the active state at low dose and to target certain biological paths. In the environment, this is a problem.

The co -author said, “Pharmaceutical contaminants are emerging worldwide problems. Dr. Marcus MichelangeliEcological instructor at Griffith University. “Especially the problem is mental active substances such as antidepressants and painkillers, which greatly interferes with wildlife brain function and behavior.”

Benzodiazepine and opioide – Commonly used drugs to treat anxiety, pain and sleep disorders – Do not stay in the water. They accumulate in the tissues of fish and other aquatic organisms, including the brain. Even at a very low concentration, you can interfere with major neurological courses, changing how animals move, socialize and respond to threats.

Laboratory -based research Exposure to this drug shows that it can change everything with the ability to avoid predators from the tendency of fish. Preliminary work In addition, benzodiazepine, such as Clobazam, weakens the stress response of the fish.

Michelangeli said, “Most previous studies, which have investigated the effects of pharmaceutical contaminants on wildlife, are carried out under the controlled laboratory conditions, so they cannot fully capture the complexity of the natural environment.”

What happens when the fish meets these drugs in the wild, interacting with underwater temperature, predators, human infrastructure and other species? And how can such exposure can affect major life events – Like breeding or migration?

For migratory species, such as the Atlantic salmon, steaks are particularly high. Many salmon population, which is rich in Europe and North America, has experienced dramatic decrease in recent decades. Although overfishing, habitat sculpture and climate change played an important role, chemical pollution is becoming more and more threats. Understanding how pharmaceutical contaminants affects migration behavior and wild survival is important not only to preserve these species, but also to protect the ecosystem that helps them maintain.

Trace salmon and sleeping drugs in the wild

In the biggest field -based study, the team traveled from fresh water to the sea, tracking 730 youth salmon or small or small. This study focused on two drugs that were regularly seen in the aquatic ecosystem of Clobazam, a benzodiazepine prescribed with anxiety and sleep disorders, and the opioid painkillers, which were prescribed by anxiety and sleep disorders. Both are designed to act on the brain and nervous system. – And both are traces of rivers around the world, but are found biologically at the active level.

Small

The life stage of the Atlantic salmon when a youth fish suffer from physiological changes to prepare to move from fresh water to seawater environment. It is an important and vulnerable stage in the salmon life cycle.

To imitate the actual exposure, the researchers used a slow release pharmaceutical implant surgically inserted into the fish and delivered environmentally associated drugs. The fish were randomly assigned to one of the four groups of control (no drugs), clovadam, tramadol, or clovatamadol mixture. All of them are equipped with sound remote measurement tags to monitor movements in 28 km of river, including hydroelectric dams.

Michelangeli said, “This study is unique because it investigates the effects of these contaminants directly on the field. In the natural context, we can better understand how it affects wildlife behavior and migration.

Small exposed to Clobazam was more likely to reach Baltic Sea than other groups.

On average, the fish can pass two to three times faster than the other groups of the two dams, suggesting that the drug can change the behavior by helping the drug to overcome the physical barriers faster. In älvkarleby, the Clobazam fish passed in about 8 hours in a mixture group in about 64 hours.

But among the fish that had completed the trip, there was no big difference in the overall speed of movement. – It means that Clobazam does not necessarily have to swim faster fish swimming with the main choke points.

In contrast, the Tramadol alone did not have the effect of almost measuring the migration success or the speed of passing the dam similar to the control group.

The Clova Dam Tramadol mixture also did not perform Clova Sammann performance, but the fish’s fish still had a higher success than the control group.

To investigate the behavioral changes in these patterns, the team conducted a subsequent laboratory experiment. They tested if Clobazam affected the way youth salmon formed a swarm.

If you are threatened by a general predator (northern pike), the chlobadam exposed fish showed weaker hair behavior than the control fish. The drug seemed to increase the risks and encourage fish to escape the safety of the group.

Ecological meaning and future

At first glance, the discovery of salmon research can look like good news. More fish seem to make it in the sea. But digging deeper, more complicated and photographs. The increase in migration of the clovatam exposure salmon was led by the change of their behavior, and it was likely to be more likely due to the decrease in the cohes and the increase in risk. In the wild, such changes do not come without trade off.

Dangerous actions can help fish overcome the barriers, but it can be more vulnerable to predators, interfering with the group migration, or changing the timing of major life histories such as maritime entry or spawning.

Michelangeli said, “The increase in the success of salmon exposed to Clobazam may seem like a beneficial effect, but it is important to recognize that the natural behavior and ecology of the species will have a broader negative result for both the species and the surrounding wildlife community.

Clobazam did not change fish behavior. It was able to change the migratory results to reconstruct an important step in the salmon life cycle. The interaction between other drugs, species and stress factors can have a ripple effect that science began to solve.

Michelangeli said, “Considering the realistic exposure scenario where the entire ecosystem is exposed, the potential results are much more complicated when encompassing multiple species and various pollutants.

To solve this problem, a multi -level approach is required. One path is to upgrade the wastewater treatment infrastructure to better filter pharmaceutical residues before reaching the river and lake. The other is in the design of the drug itself.

Michelangeli said, “Advanced wastewater treatment is more effective in reducing pharmaceutical contamination, and the green chemical approach has promising potential, which can greatly alleviate the environmental impact of pharmaceutical contamination by designing a faster or less harmful drug after use.

In the future, scientists say that more field studies are urgently needed to understand the behavioral effects of pharmaceutical contaminants and to track long -term results for population survival, reproductive success and ecosystem stability.

reference: Brand JA, Michelangeli M, Shry SJ, etc. Pharmaceutical contamination affects work migration in the river of the Salmo Salar. science. 2025. Doi: 10.1126/Science.adp7174

This article is a re -work of the press release published by Griffith University. Data on length and content have been edited.