eDNA Helps Identify Invasive Fish, New Study Finds

A school of fish swim in an aquarium at the Scientific Center of Kuwait on 20 March 2016 [YASSER AL/ZAYYAT/AFP/Getty Images]
A school of fish swim in an aquarium at the Scientific Center of Kuwait on 20 March 2016 [YASSER AL/ZAYYAT/AFP/Getty Images]
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eDNA Helps Identify Invasive Fish, New Study Finds

A school of fish swim in an aquarium at the Scientific Center of Kuwait on 20 March 2016 [YASSER AL/ZAYYAT/AFP/Getty Images]
A school of fish swim in an aquarium at the Scientific Center of Kuwait on 20 March 2016 [YASSER AL/ZAYYAT/AFP/Getty Images]

Invasive round goby fish have impacted local fisheries in the US by competing with native species and eating the eggs of some species. This problem affects the Finger Lakes in New York.

When the researchers started their study, they realized that these invasive fish can be difficult to find and collect - especially when they first enter a new body of water in small population. However, the researchers claim they addressed the problem by analyzing the so-called environmental DNA - or eDNA - from water samples.

During the study, researchers from the University of Cornell explored the Cayuga Lake, one of the Finger Lakes, and proved that they can use this technique to detect invasive fish before they spread in large numbers. The findings were published January 12 in the journal Molecular Ecology.

"With these new advancements to eDNA methods, we can learn not only which invasive species are present in the environment, but because we identify the genetic diversity in the samples, we can also predict how many individuals there are and possibly where they came from," David Lodge, professor of ecology and evolutionary biology in Cornell said in a report published on the university's website.

"For the first time, we demonstrate that there is sufficient genetic information in environmental samples to study the status of invasive difficult to monitor species without the need for direct contact," added Jose Andrés, researcher in the Department of Ecology and Evolutionary Biology.

Since the method provides a genetic signature of individuals in a sample, scientists might be able to pinpoint where they came from by matching their DNA with populations from other areas.

"We would be able to tell genetically if round gobies were introduced by ships from Europe, which is how they originally got to the U.S. lakes, or by some other means of introduction. Knowing this information might be helpful if we hope to stem new introductions," said Andrés.



Tourist Coins Pose Giant Problem at N. Ireland's Famous Causeway Site

Tourists are pictured at the Giant's Causeway, a Unesco World Heritage Site, near Bushmills in Northern Ireland, on July 8, 2025. (Photo by PAUL FAITH / AFP)
Tourists are pictured at the Giant's Causeway, a Unesco World Heritage Site, near Bushmills in Northern Ireland, on July 8, 2025. (Photo by PAUL FAITH / AFP)
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Tourist Coins Pose Giant Problem at N. Ireland's Famous Causeway Site

Tourists are pictured at the Giant's Causeway, a Unesco World Heritage Site, near Bushmills in Northern Ireland, on July 8, 2025. (Photo by PAUL FAITH / AFP)
Tourists are pictured at the Giant's Causeway, a Unesco World Heritage Site, near Bushmills in Northern Ireland, on July 8, 2025. (Photo by PAUL FAITH / AFP)

Northern Ireland's Giant Causeway draws close to one million visitors a year but their habit of wedging tiny coins in cracks between the rocks -- to bring love or luck -- is damaging the world-famous wonder.

Now authorities are urging tourists to keep their coins in their pockets to preserve the spectacular landscape.

Some 40,000 columns mark the causeway, Northern Ireland's first UNESCO World Heritage Site.

Geologists say the natural phenomenon was created by an outpouring of basalt lava 60 million years ago.

Legend has it that the causeway was formed by Irish giant Finn McCool.

In recent decades, visitors have pushed thousands of coins into fissures in the rocks.

The gesture is "a token of love or luck", according to Cliff Henry, the causeway's nature engagement officer.

But the coins rapidly corrode and expand, causing the basalt to flake and leaving "unsightly" rust-colored streaks, Henry told AFP.

He pointed to streaks on a rock and gingerly prized out a US cent with a set of keys.

"We get a lot of euros and dollar cents. But coins from literally all over the world -- any currency you can think of, pretty much -- we have had it here," he said.

A report by the British Geological Survey in 2021 revealed that the coins were "doing some serious damage" and something had to be done about it, he noted.

Signs are now in place around the site appealing to tourists to "leave no trace".
"Once some visitors see other people have done it, they feel that they need to add to it," causeway tour guide Joan Kennedy told AFP.

She and her colleagues now gently but firmly tell tourists to desist.

At the exit from the causeway, a US couple said they were "distressed" to hear of the damage the metal caused.

"Our guide mentioned as we came up that people had been putting coins into the stones. It's really terrible to hear that," said Robert Lewis, a 75-year-old from Florida.

"It's kind of like damaging any kind of nature when you are doing something like that, putting something foreign into nature. It's not good," said his wife, Geri, 70.

As part of a £30,000 ($40,000) conservation project, stone masons recently removed as many coins as they could -- without causing further damage -- from 10 test sites around the causeway.

Henry said the trial was successful and is to be expanded across the causeway.

"If we can get all those coins removed to start with that will help the situation and hopefully no more coins will be put in," he said.

"If visitors see fewer coins in the stones and hear appeals to stop the damaging practice, the problem can maybe be solved.

"We know that visitors love and cherish the Giant's Causeway, and many form deep personal connections to it, so we want this natural wonder to remain special for future generations."