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

    Video How Aleppo Rebels Plan to Withstand Assad's Siege

    Rebels in Aleppo are laying plans to withstand a siege by Syrian President Bashar al-Assad’s forces in likelihood the regime cuts a final main supply line running west of city

    Scientists Detect Gravitational Waves in Landmark Discovery

    Researchers likened discovery to difference between looking at piece of music on paper and then hearing it in real life

    Prince Ali: FIFA Politics Affected International Fixtures

    Some countries faced unfavorable treatment for not toeing political line inside soccer world body, Jordanian candidate to head FIFA says

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

    By the Numbers

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    NATO to Target Migrant Smugglersi
    X
    Jeff Custer
    February 11, 2016 4:35 PM
    NATO has announced plans to send warships to the Aegean Sea to target migrant smugglers in the alliance's most direct intervention so far since a wave of people began trying to reach European shores.
    Video

    Video NATO to Target Migrant Smugglers

    NATO has announced plans to send warships to the Aegean Sea to target migrant smugglers in the alliance's most direct intervention so far since a wave of people began trying to reach European shores.
    Video

    Video Russia's Catholics, Orthodox Hopeful on Historic Pope-Patriarch Meeting

    Russia's Catholic minority has welcomed an historic first meeting Friday in Cuba between the Pope and the Patriarch of Russia's dominant Orthodox Church. The Orthodox Church split with Rome in 1054 and analysts say politics, both church and state, have been driving the relationship in the centuries since. VOA's Daniel Schearf reports from Moscow.
    Video

    Video Used Books Get a New Life on the Streets of Lagos

    Used booksellers are importing books from abroad and selling them on the streets of Africa's largest city. What‘s popular with readers may surprise you. Chris Stein reports from Lagos.
    Video

    Video After NH Primaries All Eyes on South Carolina

    After Tuesday's primary in New Hampshire, US presidential candidates swiftly turned to the next election coming up in South Carolina. The so-called “first-in-the-South” poll may help further narrow down the field of candidates. Zlatica Hoke reports.
    Video

    Video US Co-ed Selective Service Plan Stirs Controversy

    Young women may soon be required to register with the U.S. Selective Service System, the U.S. government agency charged with implementing a draft in a national emergency. Top Army and Marine Corps commanders told the Senate Armed Services Committee recently that women should register, and a bill has been introduced in Congress requiring eligible women to sign up for the military draft. The issue is stirring some controversy, as VOA’s Bernard Shusman reports from New York.
    Video

    Video Lessons Learned From Ebola Might Help Fight Zika

    Now that the Ebola epidemic has ended in West Africa, Zika has the world's focus. And, as Carol Pearson reports, health experts and governments are applying some of the lessons learned during the Ebola crisis in Africa to fight the Zika virus in Latin America and the Caribbean.
    Video

    Video Smartphone Helps Grow Vegetables

    One day, you may be using your smartphone to grow your vegetables. A Taipei-based company has developed a farm cube — a small, enclosed ecosystem designed to grow plants indoors. The environment inside is automatically adjusted by the cube, but it can also be controlled through an app. VOA's Deborah Block has more on the gardening system.
    Video

    Video Illinois Voters Have Mixed Emotions on Obama’s Return to Springfield

    On the ninth anniversary of the launch of his quest for national office, President Barack Obama returned to Springfield, Illinois, to speak to the Illinois General Assembly, where he once served as state senator. His visit was met with mixed emotions by those with a front-row seat on his journey to the White House. VOA's Kane Farabaugh reports.
    Video

    Video Exhibit Turns da Vinci’s Drawings Into Real Objects

    In addition to being a successful artist, Renaissance genius Leonardo da Vinci designed many practical machines, some of which are still in use today, although in different forms. But a number of his projects were never realized — until today. VOA’s George Putic reports.
    Video

    Video Heated Immigration Debate Limits Britain’s Refugee Response

    Compared to many other European states, Britain has agreed to accept a relatively small number of Syrian refugees. Just over a thousand have arrived so far -- and some are being resettled in remote corners of the country. Henry Ridgwell reports on why Britain’s response has lagged behind its neighbors.
    Video

    Video Russia's Car Sales Shrink Overall, But Luxury and Economy Models See Growth

    Car sales in Russia dropped by more than a third in 2015 because of the country's economic woes. But, at the extreme ends of the car market, luxury vehicles and some economy brands are actually experiencing growth. VOA's Daniel Schearf reports from Moscow.
    Video

    Video Jordanian Theater Group Stages Anti-Terrorism Message

    The lure of the self-styled “Islamic State” has many parents worried about their children who may be susceptible to the organization’s online propaganda. Dozens of Muslim communities in the Middle East are fighting back -- giving young adults alternatives to violence. One group in Jordan is using dramatic expression a send a family message. Mideast Broadcasting Network correspondent Haider Al Abdali shared this report with VOA. It’s narrated by Bronwyn Benito
    Video

    Video Civil Rights Pioneer Remembers Struggle for Voting Rights

    February is Black History Month in the United States. The annual, month-long national observance pays tribute to important people and events that shaped the history of African Americans. VOA's Chris Simkins reports how one man fought against discrimination to help millions of blacks obtain the right to vote
    Video

    Video Helping the Blind 'See' Great Art

    There are 285 million blind and visually impaired people in the world who are unable to enjoy visual art at a museum. One New York photographer is trying to fix this situation by making tangible copies of the world’s masterpieces. VOA correspondent Victoria Kupchinetsky was there as visually impaired people got a feel for great art. Joy Wagner narrates her report.