A recent study reveals cocaine residue that turns up in rivers affects endangered eels. The drugs can harm their reproductive organs and impact their survival.
Endangered European Eels
The study particularly focused on endangered European eels that initially spend 15 to 20 years swimming in European waterways. These species then cross the Atlantic Ocean to lay eggs in the Sargasso Sea, which is located east of the Caribbean and the U.S. Eastern Seaboard.
Their migration to the Sargasso Sea is important for the survival of the species. However, their relocation is impeded by overfishing and water pollutants, which, in this case, include the cocaine residue that turns up in the body of waters where they swim.
The study found that eels, like humans, became overly active when they ingested cocaine from the water. This may sound tolerable at first but through time, the eels suffered swelling and their tissues get damaged. What's worst is, their hormones changed and their bodies failed to reach sexual maturity.
The authors of the study said information about the ecological impacts of illicit drugs is scarce. Hence, as a start, they wanted to evaluate the impact of cocaine deposits on the endangered European eels.
Cocaine And The European Eels
The researchers led by Anna Capaldo, a biologist at the University of Naples Federico II, collected 150 eels for the study and divided the animals into different groups. One of the groups was exposed to small levels of cocaine similar to the average amounts detected in surface waters. The dosage was administered daily for a period of 50 days.
The study published in the journal Science of the Total Environment found that cocaine accumulates in the brain, muscles, gills, skin, and other tissues of the eels. The eels' muscles became inflamed up to the point that they became damaged.
The researchers also found that the damage was irreversible even if the eels underwent a 10-day rehabilitation period where they were devoid of cocaine once again.
Hormone And Migration
One important result from the study is that it revealed how cocaine amplifies the cortisol levels in the bodies of the eels. Cortisol is a stress hormone that triggers the body's natural accumulation of fats. If European eels do not hoard up enough fats, their bodies became incapable of swimming all the way through the Sargasso Sea where they could mate and lay eggs.
Another significant insight derived from the study is that cocaine increases the dopamine levels in the bodies of the eels. This stops their bodies from reaching sexual maturity required for them to be able to reproduce.
Capaldo noted that cocaine is just one among the many illicit drugs that could turn up in the rivers were aquatic species live. There could also be a residue of heavy metals, antibiotics, and pesticides.
"We don't know the possible consequences of such combinations of substances, but clearly they could influence the survival and/or the health status of the eels," Capaldo said, adding that similar effects seen on eels could happen to other fishes.
Capaldo now hopes that the study could inspire projects that involved wastewater treatment. Ideally, she hopes that people avoid using drugs altogether.