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 In Ukraine's Nikishino, No House Untouched by Fighting

Ninety percent of homes in one small village were damaged or destroyed as government forces failed to stop a rebel advance More

Pakistan’s 'Last Self-Declared Jew' Attacked, Detained

Argument about the rights of non-Muslims in Pakistan allegedly results in mob beating well-known Jewish Pakistani More

Turkey Cracks Down on Political Dissent, Again

People daring to engage in political dissent ahead of upcoming general elections could find themselves in jail 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.
In Their Own Words: Citizens of Kobanii
X
Mahmoud Bali
March 06, 2015 8:43 PM
Civilians are slowly returning to Kobani, after Kurdish fighters backed by coalition airstrikes fought off a four-month siege of the northern Syrian town by Islamic State militants. VOA Kurdish Service reporter Mahmoud Bali talked to some of those who have returned. We hear about the devastation of Kobani through their own words.
Video

Video In Their Own Words: Citizens of Kobani

Civilians are slowly returning to Kobani, after Kurdish fighters backed by coalition airstrikes fought off a four-month siege of the northern Syrian town by Islamic State militants. VOA Kurdish Service reporter Mahmoud Bali talked to some of those who have returned. We hear about the devastation of Kobani through their own words.
Video

Video In Ukraine's Nikishino, No House Untouched by Fighting

In the village of Nikishino, in eastern Ukraine, recent fighting has brought utter devastation. Ninety percent of the houses are damaged or destroyed after government forces tried and failed to stop rebels advancing on the strategically important town of Debaltseve nearby. Patrick Wells reports for VOA from Nikishino.
Video

Video Crime Scenes Re-Created in 3-D Visualization

Police and prosecutors sometimes resort to re-creations of crime scenes in order to better understand the interaction of all participants in complicated cases. A Swiss institute says advanced virtual reality technology can be used for quality re-creations of events at the moment of the crime. VOA’s George Putic reports.
Video

Video Sierra Leone Ebola Orphans Face Another Crisis

There's growing concern about the future of an orphanage run by a British charity in Sierra Leone, after a staff member and his wife died this week from Ebola. The Saint George Foundation Orphanage in Freetown is now in quarantine, with more than 20 children and seven staff in lock-down. The BBC has agreed to share Ebola-related material with Voice of America because of the difficulties faced by media organizations reporting the crisis. Clive Myrie reports from Sierra Leone.
Video

Video Growing Concerns Over Whether Myanmar’s Next Elections Will Be Fair

Myanmar has scheduled national elections for November that are also expected to include a landmark referendum on the country's constitution. But there are growing concerns over whether the government is taking the necessary steps to prepare for a free and fair vote. VOA Correspondent Steve Herman was recently in Myanmar and files this report from our Southeast Asia bureau in Bangkok.
Video

Video Nigeria’s Ogonis Divided Over Resuming Oil Production

More than two decades ago, Nigeria’s Ogoni people forced Shell oil company to cease drilling on their land, saying it was polluting the environment. Now, some Ogonis say it’s time for the oil to flow once again. Chris Stein reports from Kegbara Dere, Nigeria.
Video

Video Fuel Shortages in Nigeria Threaten Election Campaigns

Nigeria is suffering a gas shortage as the falling oil price has affected the country’s ability to import and distribute refined fuels. Coming just weeks before scheduled March 28 elections, the shortage could have a big impact on the campaign, as Henry Ridgwell reports for VOA.
Video

Video Report: Human Rights in Annexed Crimea Deteriorating

A new report by Freedom House and the Atlantic Council of the United States says the human rights situation in Crimea has deteriorated since the peninsula was annexed by Russia in March of last year. The report says the new authorities in Crimea are discriminating against minorities, suppressing freedom of expression, and forcing residents to assume Russian citizenship or leave. Zlatica Hoke has more.
Video

Video 50 Years Later African-Americans See New Voting Rights Battles Ahead

Thousands of people will gather to mark the 50th anniversary of a historic civil rights march on March 7th in Selma, Alabama. In 1965, dozens of people were seriously injured during the event known as “Bloody Sunday,” after police attacked African-American demonstrators demanding voting rights. VOA’s Chris Simkins introduces us to some civil rights pioneers who are still fighting for voting rights in Alabama more than 50 years later.
Video

Video Craft Brewers Taking Hold in US Beer Market

Since the 1950’s, the U.S. beer industry has been dominated by a handful of huge breweries. But in recent years, the rapid rise of small craft breweries has changed the American market and, arguably, the way people drink beer. VOA’s Jeff Custer reports.
Video

Video Video Claims to Show Shia Forces in Iraq Executing Sunni Boy

A graphic mobile phone video is spreading on the Internet, claiming to show Iraqi forces or Shia militia executing a handcuffed Sunni boy. Experts have yet to verify the video, but already Islamic State followers are publicizing it across social media, playing on deep-rooted sectarian fears. VOA’s Jeff Seldin reports.
Video

Video Ukrainian Authorities Struggle to Secure a Divided Mariupol

Since last month's cease-fire went into effect, shelling around the port city of Mariupol has decreased, but it is thought pro-Russian separatists remain poised to attack. For the city’s authorities, a major challenge is gaining the trust of residents, while at the same time rooting out informants who are passing sensitive information to the rebels. Patrick Wells reports for VOA.

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