. Earth Science News .

Loss of large predators disrupting multiple plant, animal and human ecosystems
by Staff Writers
Corvallis OR (SPX) Jul 22, 2011

Without wolves, the growth of young aspen trees and willow almost ground to a halt, and there were fewer beaver. Plant communities, tree growth and stream ecology all were affected. With the return of wolves, those areas are now returning to health, and in places, aspen and willow are recovering where they had been declining

The enormous decline of large, apex predators and "consumers" ranging from wolves to lions, sharks and sea otters may represent the most powerful impacts humans have ever had on Earth's ecosystems, a group of 24 researchers concluded in a new report in the journal Science.

The decline of such species around the world is much greater than previously understood and now affects many other ecological processes through what scientists call "trophic cascades," in which the loss of "top down" predation severely disrupts many other plant and animal species.

Such disruption is sufficiently severe that it now affects everything from habitat loss to pollution, carbon sequestration, wildfire, climate, invasive species and spread of disease, the scientists said. It is also a driving force in the sixth mass extinction in Earth history, which the researchers said is now under way.

"We now have overwhelming evidence that large predators are hugely important in the function of nature, from the deepest oceans to the highest mountains, the tropics to the Arctic," said William Ripple, a professor of forestry at Oregon State University, co-author of the report and an international leader in this field of study as director of OSU's Trophic Cascades Program.

"In a broad view, the collapse of these ecosystems has reached a point where this doesn't just affect wolves or aspen trees, deforestation or soil or water," Ripple said. "These predators and processes ultimately protect humans. This isn't just about them, it's about us."

Historically there has been little appreciation of how large predators affected so many other species, the researchers said, and too often such processes were studied one plant or animal at a time in a small area, failing to appreciate the larger disruption under way.

Based on the new understanding that is emerging, the scientists argued that the burden of proof should now be shifted, to assume that top predators have major effects on ecosystems until proven otherwise.

"We propose that many of the ecological surprises that have confronted society over past centuries - pandemics, population collapses of species we value and eruptions of those we do not, major shifts in ecosystem states, and losses of diverse ecosystem services were caused or facilitated by altered top-down forcing regimes," the scientists wrote.

Pioneering research done in recent years at OSU and cited in this study, for instance, has outlined the effect that the loss of wolves had in Yellowstone National Park. When wolves were removed, elk populations increased and elk behavior also changed, because they were no longer afraid of browsing young aspen trees in places where historically they might have been vulnerable to wolf attack.

Without wolves, the growth of young aspen trees and willow almost ground to a halt, and there were fewer beaver. Plant communities, tree growth and stream ecology all were affected. With the return of wolves, those areas are now returning to health, and in places, aspen and willow are recovering where they had been declining.

The scientists cited many examples in their study, both terrestrial and marine:

+ Reduction of cougar in Utah led to an eruption of deer, loss of vegetation, altered stream channels, and a decline in biodiversity.

+ Industrial whaling in the 20th century likely caused a killer whale diet shift and a dramatic decline of sea lions, seals and sea otters.

+ Decimation of sharks resulted in an outbreak of cow-nosed rays and the collapse of bay scallop fisheries.

+ Sea otters enhance kelp abundance by limiting herbivorous sea urchins.

+ The reduction of lions and leopards in Africa led to a population explosion in olive baboons, which bring intestinal parasites to humans who live in close proximity to them.

For too long, the researchers said, large animals have been seen as "riding atop the trophic pyramid" but not really affecting the species and structure below them. That's a fundamental misunderstanding of ecology, they said.

This report was done by scientists from 22 different institutions in six countries. Studies were supported by the Institute for Ocean Conservation Science at Stony Brook University, National Science Foundation, Natural Sciences and Engineering Research Council of Canada, and other organizations.

"Top-down forcing must be included in conceptual overviews if there is to be any real hope for understanding and managing the workings of nature," they wrote in their conclusion.

Related Links
Oregon State University
Darwin Today At TerraDaily.com

Get Our Free Newsletters Via Email
Buy Advertising Editorial Enquiries

. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Batman Bacteria
Los Angeles CA (SPX) Jul 22, 2011
Bacteria use various appendages to move across surfaces prior to forming multicellular bacterial biofilms. Some species display a particularly jerky form of movement known as "twitching" motility, which is made possible by hairlike structures on their surface called type IV pili, or TFP. "TFP act like Batman's grappling hooks," said Gerard Wong, a professor of bioengineering and of chemist ... read more

IAEA chief visits Japan's stricken nuclear plant

Japan passes second recovery budget

Tiny robots could find nuclear plant leaks

Japan eyes $291 bln for reconstruction: reports

China closes two fake Apple stores

'Bloom is off the rose' for 3D: DreamWorks CEO

Apple profit rockets with hot iPad, iPhone sales

Chilean copper-molybdenum mine moves ahead

Software can protect water supplies

China sub makes first dive to below 5,000m: report

China sub makes first dive to below 4,000m

Acidifying oceans could hit California mussels

Canada goes ahead with Arctic patrol ships

Fast-Shrinking Greenland Glacier Experienced Rapid Growth During Cooler Times

Lie of the land beneath glaciers influences impact on sea levels

Antarctic suvey finds undersea volcanoes

Climate change 'may make truffles a German delicacy'

Climate Adaptation of Rice

Eight jailed over Chinese tainted pork scandal

How to eat well and save the planet too

Weakened Hurricane Dora threatens Mexico's Baja

Swat rebuilds year after Pakistan floods

Floods rupture Pakistani feudal ties

Hurricane Dora strengthens away from Mexico coast

Police fire tear gas to break up Sudan water demos

Nigerian forces kill at least 23 after bomb blast: Amnesty

UN determined to back Guinea army reform after attack

I.Coast leader urges army to 'clean up' its ranks

Speed limit on babies' vision

US cryonics founder dies, has body frozen

Genetic research confirms that non-Africans are part Neanderthal

Brain's 'clock' less accurate with aging

Memory Foam Mattress Review
Newsletters :: SpaceDaily Express :: SpaceWar Express :: TerraDaily Express :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement