News / USA

Alien Species Not Always Welcome Visitors

Some non-native species are harmless, but others wreak havoc on other species, human health and the economy

Sea lampreys attach to fish with a suction cup mouth ringed with sharp teeth.
Sea lampreys attach to fish with a suction cup mouth ringed with sharp teeth.

Multimedia

Audio
Rosanne Skirble

Not all non-native species are created equal, says ecologist Mark Davis. He wants to do away with the popular view that divides the natural world into two opposing camps - native species and non-native species.  

In an essay in the journal Nature, the Macalester College biology professor joins 18 other scientists to argue that action to protect ecosystems should be based on species impact and not species origin.  

He urges conservation managers to order their priorities around how non-native species impact other species, human health, waterways and the economy.  

“What we should focus on is what is the species doing?" he says. "What are its functions within the community and then (decide) to keep or not."  In some cases those would be non-native species and in other cases, not native.

Davis and his colleagues do not deny that real problem species exist.  “Some of them are native. Some are non-native.  The ones that are non-native we should try to keep them out from countries in which they are not currently inhabiting.  But once the species are in, you often have to learn to live with them.”  

But that’s not always an option. Jennifer Nalbone is director of Invasive Species Navigation with Great Lakes United. The U.S. Canada coalition is dedicated to keeping aggressive invaders out of the lakes, and controlling those already there.  

She points to the on-going struggle with zebra mussels. They arrived in the mid-1980’s in ship ballast water from the Black and Caspian Sea region, and have become a major threat to wildlife, navigation, and boating.  “You could look back in history to the (19)80s and (19)90s in Monroe, Michigan when a power plant and the city’s water supply were shut down because its intake pipes were clogged with zebra mussels. Mussels contributed to a valve problem in the 1990s at the Nine Mile Nuclear Power plant in Lake Ontario.”

Each year zebra mussels cost the region between $100 million to $200 million.

Sea Lamprey is an eel-like fish native to the U.S. Atlantic coast that is also now found in the Great Lakes. Twenty million dollars are spent each year to fight this parasitic pest. Nalbone says with that in mind, the focus is on stopping the next big invader - Asian Carp. “These are burdens that the Great Lakes are struggling under right now and we don’t want another one in the region.”

Yet, she says, the Asian Carp, which can grow up to a meter long and weigh as much as 45 kilograms, is making its way north.  The voracious eater, imported by Midwestern fish farmers in the 1970s, could end up devastating the region’s 7 billion dollar fishing industry.

All that is holding it back now is an electric fence. Nalbone says keeping carp from Chicago is high on her list.

However, not all non-native species pose such a threat.

The large, bell-shaped Devil's claw, which is native to Central and South America, was introduced into Australia in the 19th century.
The large, bell-shaped Devil's claw, which is native to Central and South America, was introduced into Australia in the 19th century.

Take the Devil’s Claw, a Mexican herb that today grows wild in Australia. The campaign to eradicate the weed has mobilized hundreds of volunteers. Despite those efforts, Devil’s Claw persists and Davis says there is little evidence that the ecosystem is at risk.

“This tendency to jump to conclusions, the assumption of negative impacts, that has cost us a lot of money and resources directed to areas where there really wasn’t a lot of harm which meant they were not available to be used on species which were really causing harm.”

Another example is tamarisk. The shrub was imported from Eurasia and Africa in the mid-1800s to control soil erosion in the American Southwest, but it spread to river systems across the West and up mountainsides, to elevations of 2,000 meters.

After tamarisk removal, some land managers are turning to an innovative grow-out method called long-stems.
After tamarisk removal, some land managers are turning to an innovative grow-out method called long-stems.

While millions of dollars have been spent to suppress tamarisk, Davis, says the shrubs are not all bad.

“In fact (they) are now providing important habitat for some of the wildlife there, and if we eradicate them, we are actually making things worse.”

Stacey Kolegas, director of the Tamarisk Coalition, says tamarisk control is part of a coordinated plan for river health. She agrees with Davis that conservation must be science-based and site specific.  

“A community that has monoculture of tamarisk running through their downtown right where their river runs is going to be managing tamarisk for fire mitigation, whereas a wildlife area is going to be managing tamarisk because they want to increase the berry producing shrubs on their land to enhance wildlife habitat.”

You May Like

Video Positive Messaging Helps Revamp Ethiopia's Image

In country once connected with war, poverty, famine, headlines now focus on fast-growing economy, diplomatic reputation More

Russian Activist Thinks Kremlin Ordered Nemtsov's Death

Alexei Navalny says comments of Russian liberals who think government wasn't involved are 'nonsense.' More

Video Land Disputes Rise Amid Uganda Oil Boom

Investors appear to be cashing in by selling parcels of land to multiple buyers More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Positive Messaging Transforms Ethiopia's Imagei
X
Marthe van der Wolf
March 03, 2015 9:03 PM
Ethiopia was once known for famine and droughts. Now, headlines more often point to its fast-growing economy and its emergence as a regional peacemaker. How has Addis Ababa changed the narrative? VOA's Marthe van der Wolf reports.
Video

Video Positive Messaging Transforms Ethiopia's Image

Ethiopia was once known for famine and droughts. Now, headlines more often point to its fast-growing economy and its emergence as a regional peacemaker. How has Addis Ababa changed the narrative? VOA's Marthe van der Wolf reports.
Video

Video Cyber War Rages Between Iran, US

A newly published report indicates Iran and the United States have increased their cyber attacks on each other, even as their top diplomats are working toward an agreement to guarantee Iran does not develop a nuclear weapon and to free Iran from international sanctions. The development is part of a growing global trend. VOA’s Al Pessin reports from London.
Video

Video Answers Elude Families of MH370 Passengers

For the families on board Malaysia Airlines flight MH370, an airline official’s statement nearly one year ago that the plane had lost contact with air traffic control at 2:40 AM is the only thing that remains confirmed. William Ide reports.
Video

Video Land Disputes Arise Amid Uganda Oil Boom

Ugandan police say there has been a sharp increase in land disputes, with 10 new cases being reported each day. The claims come amid an oil boom as investors appear to be cashing in by selling parcels of land to multiple buyers. Meanwhile, the people who have been living on the land for decades are chased away, sometimes with a heavy hand. VOA's Serginho Roosblad reports.
Video

Video In Russia, Many Doubt Opposition Leader's Killer Will Be Found

The funeral has been held in Moscow for Boris Nemtsov, the opposition leader who was assassinated late Friday just meters from the Kremlin. Nemtsov joins a growing list of outspoken critics of Russia under the leadership of President Vladimir Putin who are believed to have been murdered for their work. VOA’s Daniel Schearf reports from Moscow.
Video

Video Simulated Astronauts Get Taste of Mars, in Hawaii

For generations, people have dreamed of traveling to Mars to explore Earth's closest planetary neighbor. VOA's Mike O'Sullivan reports that while space agencies like NASA are planning manned missions to the planet, some volunteers in Hawaii are learning how humans will cope with months in isolation on a Mars base.
Video

Video Destruction of Iraq Artifacts Shocks Archaeologists

The city of Mosul was once one of the most culturally rich and religiously diverse cities in Iraq. That tradition is under attack by members of the Islamic State who have made Mosul their capital city. The Mosul Museum is the latest target of the group’s campaign of terror and destruction, and is of grave concern to archaeologists around the world. VOA’s Kane Farabaugh reports.
Video

Video Smartphones May Help in Diagnosing HIV

Diagnosing infections such as HIV requires expensive clinical tests, making the procedure too costly for many poor patients or those living in remote areas. But a new technology called lab-on-a-chip may make the tests more accessible to many. VOA’s George Putic reports.
Video

Video Afghan Refugees Complain of Harassment in Pakistan

Afghan officials have expressed concern over reports of a crackdown on Afghan refugees in Pakistan following the Peshawar school attack in December. Reports of mass arrests and police harassment coupled with fear of an uncertain future are making life difficult for a population that fled its homeland to escape war. VOA’s Ayesha Tanzeem reports from Islamabad.
Video

Video Ukrainian Volunteers Prepare to Defend Mariupol

Despite the ongoing ceasefire in Ukraine, soldiers in the city of Mariupol fear that pro-Russian separatists may be getting ready to attack. The separatists must take or encircle the city if they wish to gain land access to Crimea, which was annexed by Russia early last year. But Ukrainian forces, many of them volunteers, say they are determined to defend it. Patrick Wells reports from Mariupol.
Video

Video Moscow Restaurants Suffer in Bad Economy, Look for Opportunity

As low oil prices and Western sanctions force Russia's economy into recession, thousands of Moscow restaurants are expected to close their doors. Restaurant owners face rents tied to foreign currency, while rising food prices mean Russians are spending less when they dine out. One entrepreneur in Moscow has started a dinner kit delivery service for those who want to cook at home to save money but not skimp on quality. VOA's Daniel Schearf reports.
Video

Video Presidential Hopefuls Battle for Conservative Hearts and Minds

One after another, presumptive Republican presidential contenders auditioned for conservative support this week at the Conservative Political Action Conference held outside Washington. The rhetoric was tough as a large field of potential candidates tried to woo conservative support with red-meat attacks on President Barack Obama and Democrats in Congress. VOA Political Columnist Jim Malone takes a look.
Video

Video Southern US Cities Preserve Civil Rights Heritage to Boost Tourism

There has been a surge of interest in the American civil rights movement of the 1950s and '60s, thanks in part to the Hollywood motion picture "Selma." Five decades later, communities in the South are embracing the dark chapters of their past with hopes of luring tourism dollars. VOA's Chris Simkins reports.
Video

Video Deep Under Antarctic Ice Sheet, Life!

With the end of summer in the Southern hemisphere, the Antarctic research season is over. Scientists from Northern Illinois University are back in their laboratory after a 3-month expedition on the Ross Ice Shelf, the world’s largest floating ice sheet. As VOA’s Rosanne Skirble reports, they hope to find clues to explain the dynamics of the rapidly melting ice and its impact on sea level rise.

All About America

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More