News / Africa

Loss of Predators Impacts Food Chain

Sharp decline upsets balance of the world’s ecosystems

Sea otters maintain kelp forests in the ocean by preying on kelp-grazing sea urchins.
Sea otters maintain kelp forests in the ocean by preying on kelp-grazing sea urchins.

Multimedia

Audio
Rosanne Skirble

A loss of species at the top of the food chain could have far-reaching effects on the environment, according to a study in the Journal Science.

Some of the world’s top predators - including lions, wolves and sharks - are in sharp decline. Human activities like pollution, habitat destruction, overfishing and hunting are largely to blame.

Jim Estes studies sea otters. The University of California, Santa Cruz professor of ecology and evolutionary biology says these furry marine mammals - once hunted to near extinction - are important to the health of coastal North Pacific ecosystems.

“We have discovered that sea otters have an important limiting effect on sea urchins and that allows the kelp forest to persist," he says. "And kelp forests, in turn, have all sorts of important functions.”

In the absence of sea otters, the ocean's kelp forest - which provides a habitat for fish and absorbs climate changing carbon emissions from the atmosphere - is left barren by sea urchins.
In the absence of sea otters, the ocean's kelp forest - which provides a habitat for fish and absorbs climate changing carbon emissions from the atmosphere - is left barren by sea urchins.

The kelp forests also provide habitat for fish and absorb climate changing carbon emissions from the atmosphere. Estes says this close connection between species health and the health of global ecosystems is a “ubiquitous phenomenon and that it occurs worldwide in all ecosystem types.”

Estes compiled the work of 24 scientists in six countries. He says the research shows the cascading ecological effects of a loss of top predators and large herbivores.  

"It eventually reaches the plant populations at the base of the food web and in many instances results either in an increase in the abundance of plants or in most cases in terrestrial systems, a decrease in the abundance of plants, influencing things like fire frequency, carbon sequestration and disease and on and on and on.”

Restoration of wolves to Yellowstone National Park has allowed vegetation to recover from over-browsing by elk. Photo on left taken in 1997, on right in 2001.
Restoration of wolves to Yellowstone National Park has allowed vegetation to recover from over-browsing by elk. Photo on left taken in 1997, on right in 2001.

Estes says an example from East Africa’s Serengeti plain shows the ripple effect of rinderpest disease on the plant-eating wildebeest and the growth of a more fire-prone landscape. “The disease, by reducing the abundance of these large animals, causes the vegetation to increase, thus increasing the intensity and frequency of wildfire.”

Yet ecosystems do recover. When rinderpest was eradicated in the 1960s, the wildebeest and other hoofed species bounced back. The shrub lands were grazed back to grasslands again, reducing the potential for lightning-sparked fires.   

Elsewhere in Africa, the loss of lions, leopards, wild dogs and hyenas has allowed baboons to increase in number, which, Estes says, has created another set of problems.  

“The increasing baboon populations have spread into areas of increased human contact that has enhanced the frequency of intestinal parasites in both the baboons and in people because of the overlap of these two species now.”

Estes says the study’s findings - observed across many different ecosystems - suggest that restoring and protecting predator species will require large-scale conservation efforts.  

“To the degree that these large animals are important in maintaining biodiversity, large tracks of land or ocean are going to be required to maintain viable populations of these large consumers," he says. "And so, I think that it bears very strongly on how we look to the future for how we are going to design conservation strategies.”

Estes says the evidence is clear that saving top predator species helps preserve the world’s ecosystems. What is also clear, his research paper concludes, is that the continuing loss of these animals is “arguably humankind’s most pervasive influence on the natural world.”

You May Like

Lesotho Faces New Round of Violence, Political Crisis

Brutal killing of military officer has sent former leaders back into S. Africa where they're watching anxiously as regional officials head in to try to restore peace More

Video VOA EXCLUSIVE: US Diplomat Expects Adoption of Bosnian Massacre Anniversary Resolution

Samantha Power says there's broad consensus about killings in Bosnia's war, but Russia calls resolution 'divisive,' backs UN countermeasure More

UN Report Exposes Widespread Boko Haram Atrocities

Damning report graphically details pattern of vicious, widespread atrocities committed by Islamist militants 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.
Olympics Construction Scars Sacred Korean Mountaini
X
July 02, 2015 4:10 AM
Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Olympics Construction Scars Sacred Korean Mountain

Environmentalists in South Korea are protesting a Winter Olympics construction project to build a ski slope through a 500-year-old protected forest. Brian Padden reports that although there is strong national support for hosting the 2018 Pyeongchang Winter Olympics, there are growing public concerns over the costs and possible ecological damage at the revered mountain.
Video

Video Xenophobia Victims in South Africa Flee Violence, Then Return

Many Malawians fled South Africa early this year after xenophobic attacks on African immigrants. But many quickly found life was no better at home and have returned to South Africa – often illegally and without jobs, and facing the tough task of having to start over. Lameck Masina and Anita Powell file from Johannesburg.
Video

Video Family of American Marine Calls for Release From Iranian Prison

As the crowd of journalists covering the Iran talks swells, so too do the opportunities for media coverage.  Hoping to catch the attention of high-level diplomats, the family of American-Iranian marine Amir Hekmati is in Vienna, pleading for his release from an Iranian prison after nearly 4 years.  VOA’s Heather Murdock reports from Vienna.
Video

Video UK Holds Terror Drill as MPs Mull Tunisia Response

After pledging a tough response to last Friday’s terror attack in Tunisia, which came just days before the 10th anniversary of the bomb attacks on London’s transport network, British security services are shifting their focus to overseas counter-terror operations. VOA's Henry Ridgwell has more.
Video

Video Obama on Cuba: This is What Change Looks Like

President Barack Obama says the United States will soon reopen its embassy in Cuba for the first time since 1961, ending a half-century of isolation. VOA White House correspondent Luis Ramirez reports.
Video

Video Hate Groups Spread Influence Via Internet

Hate groups of various kinds are using the Internet for propaganda and recruitment, and a Jewish human rights organization that monitors these groups, the Simon Wiesenthal Center, says their influence is growing. The messages are different, but the calls to hatred or violence are similar. VOA's Mike O’Sullivan reports.
Video

Video US Silica Sand Mining Surge Worries Illinois Residents, Businesses

Increased domestic U.S. oil and gas production, thanks to advances known as “fracking,” has created a boom for other industries supporting that extraction. Demand for silica sand, used in fracking, could triple over the next five years. In the Midwest state of Illinois, people living near the mines are worried about how increased silica sand mining will affect their businesses and their health. VOA’s Kane Farabaugh has more in this first of a series of reports.
Video

Video Blind Somali Journalist Defies Odds in Mogadishu

Despite improving security in the last few years, Somalia remains one of the most dangerous countries to be a journalist – even more so for someone who cannot see. Abdulaziz Billow has the story of journalist Abdifatah Hassan Kalgacal, who has been reporting from the Somali capital for the last decade despite being blind.
Video

Video Texas Defies Same-Sex Marriage Ruling

Texas state officials have criticized the US Supreme Court decision giving same-sex couples the right to marry nationwide. The attorney general of Texas says last week's decision did not overrule constitutional "rights of religious liberty," and therefore officials performing wedding services can refuse to perform them for same-sex couples if it is against their religious beliefs. Zlatica Hoke reports on the controversy.
Video

Video Rabbi Hits Road to Heal Jewish-Muslim Relations in France

France is on high alert after last week's terrorist attack near the city Lyon, just six months after deadly Paris shootings. The attack have added new tensions to relations between French Jews and Muslims. France’s Jewish and Muslim communities also share a common heritage, though, and as far as one French rabbi is concerned, they are destined to be friends. From the Paris suburb of La Courneuve, Lisa Bryant reports about Rabbi Michel Serfaty and his friendship bus.
Video

Video Saudi Leaks Expose ‘Checkbook Diplomacy’ In Battle With Iran

Saudi Arabia’s willingness to wield its oil money on the global diplomatic stage appears to have been laid bare, after the website WikiLeaks published tens of thousands of leaked cables from Riyadh’s Ministry of Foreign Affairs. VOA's Henry Ridgwell reports.
Video

Video In Kenya, Police Said to Shoot First, Ask Questions Later

An organization that documents torture and extrajudicial killings says Kenyan police were responsible for 1,252 shooting deaths in five cities, including Nairobi, between 2009 and 2014, representing 67 percent of all gun deaths in the areas reviewed. Gabe Joselow has more from Nairobi.

VOA Blogs