It must be stress: obstacles to a huge dam, torrents and hungry predators.
That is what you can face when the youth salmon moves to the sea woven from the freshwater river. But very specific kinds of contamination have been found to be at least some of the fish can be edged.
According to A New studies published in Thursday and on the Journal of ScienceThe young salmon was exposed to the anti -fire faster of the water, making the dam too faster. But ecologists doubt that it means survival.
Pharmaceutical contamination is widespread. Nearly 1,000 drugs and by -products were found in the world waterway, including amazing places such as Antarctica. They enter the environment with direct pollution of drug producers, people who wash unused drugs, and direct pollution of human and animal waste.
Scientists have been studying the influence on wild animals for many years, but Michael G. Bertram, a behavioral ecology of the Swedish Agricultural Science University and a new research leader, still says that there are still many learning about how animals react to the “cocktails of other pharmaceuticals.”
Mental active drugs, such as antibiotics and antidepressants, are especially interested because they are designed to modify their actions.
Previous studies show that Benzodiazepine, a drug class used to treat anxiety and insomnia, can affect the movement of the Atlantic salmon. It can also reduce the stress response of other fish species.
In short, the fish loses anxiety like humans.
But most of the results are from laboratory experiments. The real world is more complicated. “We know a lot that the drug can change the behavior of animals in laboratory research, but it is very difficult to predict how it progresses in the natural ecosystem.”
Dr. Bertram’s team wanted to test the laboratory -based results in the wild. They focused on the smear of salmon when the youth fish moved to the sea.
They exposed salmon Small to a similar dose as a common anti -anxiety drug, opioid painkiller or fish can occur in the wild. Some controls were swimming only in unpaid water. Then the fish was installed as a tracking tag and released into the Swedish river. SMOLTS traveled about 17 miles from one week to two weeks and searched for reservoirs, ties and two hydroelectric dams full of predators before arriving in the Baltic Sea.
Dr. Bertram said, “This is a very dangerous journey.
Small exposed to the anti -fire was more likely to reach the sea than other groups. Surprisingly, there was no statistical difference in how quickly it touched the sea in any group. However, there was a difference in how quickly SMOLTS searched for the dam, and the fish in the half -end anxiety group moved several hours faster than the control group.
Researchers thought this could be explained by changes in risk supervision. Lab -based studies show that anti -anxiety drugs have increased bold. New research is associated with wild life or death. Dr. Bertram said, “Here we show that there are actually direct changes in action and change survival.
Olivia Simmons, a salmon ecological scholar of the Norwegian Institute for Nature Research, said, “It is interesting to see how one problem affects other problems.” there is.”
The researchers also tested whether the boldness had changed the natural defense against the predator and the method of the predator. They put the new fish placement in the drug and photographed school behavior in a tank without predators. Small, treated with anti -anxiety drugs, was formed loose schools, and the northern Pike was spinning.
The results supported the idea that half anxiety is more likely to take the risk of young salmon and probably more likely to explore the dam on its own. Dr. Bertram said he wanted to test the advanced tracker Roy Ideas in the Wild, where you can see whether SMOLTS moves to the group or if you have eaten alone or small.
Scientists said they are concerned that the drugs in the waterway seem to affect important fish behavior. As Dr. Bertram said, the ripple effect is not known in the ecosystem of this “natural choice”.
For example, salmon can change the migration timing and arrive when the temperature is wrong or the resources are limited. The increase in salmon can apply too much pressure on the food species to escape the ecosystem from balance. And if dangerous behavior continues in the new environment of SMOLTS, the fish may survive in the long term when surrounded by predators.
Giovanni Polverino, a behavioral ecological scholar of TUSCIA University in Italy, said, “It’s like poker.
“The more risks, the more opportunities to lose everything,” he said. “In this case, the life of the fish.”
