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

Ebola Death Toll Nears 5,000 as Virus Advances

West Africa bears heaviest burden; Mali toddler’s death raises new fears More

Jordan’s Role in Fighting IS Carries Domestic Risks

There are Western concerns Islamic State militants soon may unleash offensive in kingdom that could create upheaval - though nation has solid intel, grip on banking system More

Asian-Americans Enter Public Office in Record Numbers

A steady deepening engagement in local politics pays off for politicians like Chinese-American Judy Chu 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.
After Decades of Pressure, Luxembourg Drops Bank Secrecy Rulesi
X
October 21, 2014 12:20 AM
European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video US ‘Death Cafes’ Put Focus on the Finale

In contemporary America, death usually is a topic to be avoided. But the growing “death café” movement encourages people to discuss their fears and desires about their final moments. VOA’s Jerome Socolovsky reports.
Video

Video Ebola Orphanage Opens in Sierra Leone

Sierra Leone's first Ebola orphanage has opened in the Kailahun district. Hundreds of children orphaned since the beginning of the Ebola outbreak face stigma and rejection with nobody to care for them. Adam Bailes reports for VOA about a new interim care center that's aimed at helping the growing number of children affected by Ebola.
Video

Video Young Nairobi Tech Innovator on 'Track' in Security Business

A 24-year-old technology innovator in Nairobi has invented a tracking device that monitors and secures cars. He has also come up with what he claims is the most robust audio-visual surveillance system yet. As Lenny Ruvaga reports from the Kenyan capital, his innovations are offering alternative security solutions.
Video

Video Latinas Converting to Islam for Identity, Structure

Latinos are one of the fastest growing groups in the Muslim religion. According to the Pew Research Center, about 6 percent of American Muslims are Latino. And a little more than half of new converts are female. VOA’s Carolyn Presutti travelled to Miami, Florida -- where two out of every three residents is Hispanic -- to learn more.
Video

Video Exclusive: American Joins Kurds' Anti-IS Fight

The United States and other Western nations have expressed alarm about their citizens joining Islamic State forces in Syria and Iraq. In a rare counterpoint to the phenomenon, an American has taken up arms with the militants' Syrian Kurdish opponents. Elizabeth Arrott has more in this exclusive profile by VOA Kurdish reporter Zana Omer in Ras al Ayn, Syria.
Video

Video South Korea Confronts Violence Within Military Ranks

Every able-bodied South Korean male between 18 and 35 must serve for 21 to 36 months in the country’s armed forces, depending upon the specific branch. For many, service is a rite of passage to manhood. But there are growing concerns that bullying and violence come along with the tradition. Reporter Jason Strother has more from Seoul.
Video

Video North Carolina Emerges as Key Election Battleground

U.S. congressional midterm elections will be held on November 4th and most political analysts give Republicans an excellent chance to win a majority in the U.S. Senate, which Democrats now control. So what are the issues driving voters in this congressional election year? VOA National Correspondent Jim Malone traveled to North Carolina, one of the most politically competitive states in the country, to find out.
Video

Video Comanche People Maintain Pride in Their Heritage

The Comanche (Indian nation) once were called the “Lords of the Plains,” with an empire that included half the land area of current day Texas, large parts of Oklahoma, New Mexico, Kansas and Colorado.The fierceness and battle prowess of these warriors on horseback delayed the settlement of most of West Texas for four decades. VOA’s Greg Flakus reports from Lawton, Oklahoma, that while their warrior days are over, the 15,000 members of the Comanche Nation remain a proud people.
Video

Video Turkey Campus Attacks Raise Islamic Radicalization Fears

Concerns are growing in Turkey of Islamic radicalization at some universities, after clashes between supporters of the jihadist group Islamic State (IS) or ISIS, and those opposed to the extremists. Pro-jihadist literature is on sale openly on the streets of Istanbul. Critics accuse the government of turning a blind eye to radicalism at home, while Kurds accuse the president of supporting IS - a charge strongly denied. Henry Ridgwell reports from London.

All About America

AppleAndroid