January 10, 2014
Decline Of Large Predators Affects Ecosystems
[ Watch the Video: Global Consequences Of Predator Loss ]
Brett Smith for redOrbit.com - Your Universe Online
"Many of them are endangered," he said. "Their ranges are collapsing. Many of these animals are at risk of extinction, either locally or globally. And, ironically, they are vanishing just as we are learning about their important ecological effects."
In the review, scientists considered published scientific reports and singled out seven species for their widespread ecological effects or "trophic cascades": African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.
The researchers concluded that a loss of these large predators could lead to an increase in the population of browsing animals such as deer and elk. An overabundance of these grazers disrupts the local vegetation, changes the dynamics of birds and small mammals and alters other parts of the ecosystem in a myriad of ways.
In Australia, a 3,400-mile dingo-proof fence enabled scientists to examine the wild canines’ effect on ecosystems. In some parts of Africa, declining lion and leopard populations have correspond to a striking increase in olive baboons, which raid farmers’ fields and livestock. In the waters off Alaska, predation by killer whales has led to a decline in sea otters – and a corresponding rise in sea urchins and loss of kelp.
[ Watch the Video: As Predators Disappear, Ecosystems Suffer ]
The authors said the classic notion of large predators as harmful animals that deplete fish and wildlife is outdated. They called for wildlife managers to embrace a deeper understanding of the complex roles that carnivores play in ecosystems – as well as their social and economic benefits.
Ripple noted that famed ecologist Aldo Leopold recognized that predators are a vital part of a sustainable ecosystems, but Leopold’s recognition of that point was mostly ignored for decades after his death in 1948.
"Human tolerance of these species is a major issue for conservation," Ripple said. "We say these animals have an intrinsic right to exist, but they are also providing economic and ecological services that people value."
The review authors noted that large predations have a role in carbon sequestration, riparian restoration, maintaining biodiversity and disease control. They pointed to the restoration of wolves in Yellowstone or Eurasian lynx in Finland, both of which have caused the surrounding ecosystems to respond quickly.
"I am impressed with how resilient the Yellowstone ecosystem is,” Ripple said. “It isn't happening quickly everywhere, but in some places, ecosystem restoration has started there."
He noted that a loss of vegetation in these ecosystems has led to soil erosion and other negative effects, making full restoration in the near future quite difficult.
"Nature is highly interconnected," Ripple said. "The work at Yellowstone and other places shows how one species affects another and another through different pathways. It's humbling as a scientist to see the interconnectedness of nature."
The review authors said an international initiative to conserve large predators is necessary and could be modeled on the Large Carnivore Initiative for Europe.