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

Karzai's Legacy: Missed Opportunities?

Afghanistan's president leaves behind a much different nation than the one he inherited, yet his legacy from 13 years in power is getting mixed reviews More

US Urges Restraint in Hong Kong Protests

Protesters angered by Beijing's decision to only approve candidates that it sanctions for Hong Kong's leadership elections in 2017 More

Archive of Forgotten UCLA Speeches Offers Snapshot of History

Recordings of prominent voices in social change, politics, science and literature from 1960s, early 1970s now available on YouTube 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.
Treasure Hunters Seek 'Hidden Treasure' in Central Kenyai
X
Gabe Joselow
September 29, 2014 6:20 PM
Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Treasure Hunters Seek 'Hidden Treasure' in Central Kenya

Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Iran's Rouhani Skeptical on Syria Strikes

Iranian President Hassan Rouhani expressed skepticism Friday that U.S.-led airstrikes in Iraq and Syria could crush Islamic State militants. From New York, VOA’s Margaret Besheer reports the president was also hopeful that questions about Iran’s nuclear program could be resolved soon.
Video

Video US House Speaker: Congress Should Debate Authorization Against IS

As wave after wave of U.S. airstrikes target Islamic State militants, the speaker of the Republican-controlled House of Representatives says he would be willing to call Congress back into session to debate a formal, broad authorization for the use of military force. VOA’s Michael Bowman reports from Washington, where legislators left town 10 days ago for a seven-week recess.
Video

Video Ebola Patients Find No Treatment at Sierra Leone Holding Center

At a holding facility in Makeni, central Sierra Leone, dozens of sick people sit on the floor in an empty university building. They wait in filthy conditions. It's a 16-hour drive by ambulance to Kailahun Ebola treatment center. Adam Bailes was there and reports on what he says are some of the worst situations he has seen since the beginning of this Ebola outbreak. And he says it appears case numbers may already be far worse than authorities acknowledge.
Video

Video Identifying Bodies Found in Texas Border Region

Thousands of immigrants have died after crossing the border from Mexico into remote areas of the southwestern United States in recent years. Local officials in south Texas alone have found hundreds of unidentified bodies and buried them in mass graves in local cemeteries. Now an anthropologist and her students at Baylor University have been exhuming bodies and looking for clues to identify them. VOA’s Greg Flakus has more from Waco, Texas.
Video

Video Ebola Robs Liberians of Chance to Say Good-Bye to Loved Ones

In Liberia, where Ebola has killed more than 1,500 people, authorities have worked hard to convince people to allow specialized burial teams to take away dead bodies. But these safety measures, while necessary, make it hard for people to say good bye to their loved ones. VOA's Anne Look reports on the tragedy from Liberia.
Video

Video Reconstruction? What Reconstruction? Life After War in Gaza

It’s been a month since Israel and the Palestinians agreed to a ceasefire to end 52 days of an air and tank war that left 60,000 homes in Gaza damaged or destroyed and 110,000 homeless. Sharon Behn reports that lack of reconstruction is leading to despair.
Video

Video US, Saudi Arabia and UAE Hit Islamic State's Oil Revenue

The United States, Saudi Arabia and the United Arab Emirates have bombed oil facilities operated by Islamic State militants in Syria. It was a truly collaborative effort, with the two Arab countries dropping the majority of the bombs. The 12 refineries targeted were estimated to generate as much as $2 million per day for the terrorist group. VOA Pentagon correspondent Carla Babb has the story.
Video

Video Russia's Food Sanctions Raise Price Worries, Hopes for Domestic Production

Russia retaliated against Western sanctions imposed for its actions in Ukraine by halting food imports from the West. The temporary import ban on food from Australia, the European Union, Norway and North America has Russian consumers concerned that they could face a sharp increase in food prices. But in an ironic twist, the restrictions aimed at the Kremlin have made Russia's domestic food producers hopeful this can boost their business. VOA's Daniel Schearf reports from Moscow.
Video

Video Washington to Pyongyang: 'Shut This Evil System Down'

U.S. Secretary of State John Kerry is calling on North Korea to shut down prison camps and other human rights abuses following a United Nations Commission of Inquiry into "widespread and systematic human rights violations." VOA State Department Correspondent Scott Stearns reports from the United Nations.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid