When Large Animals Disappear, Ecosystems are Hit Hard

What’s the News: The loss of large animals is wreaking havoc on Earth’s ecosystems, according to a scientific review published in Science on Friday, causing food chains to fall into disarray, clearing the way for invasive species, and even triggering the transmission of infectious diseases. The decline and disappearance of these large animals, due in large part to human factors such as hunting and habitat loss, has such strong and wide-ranging effects that the review’s authors say it may well be “humankind’s most pervasive influence on nature.” How the Heck:

• The researchers reviewed data from recent studies investigating the loss of so called “apex consumers,” large predators and megaherbivores, from terrestrial, freshwater, and marine ecosystems around the world.
• Whether on land or at sea, the researchers found, the result was the same: Remove the apex consumer and the whole ecosystem suffers, as the initial loss sets off a cascade of changes all the way down the food chain. “Predators have a huge structuring influence,” ecologist Stuart Sandin, one of the researchers, told LiveScience. “When you remove them you change the biology, which is typically profound and complex. And in many cases it’s not necessarily predictable.” While removing an ecosystem’s top dog—or shark, or wolf, or elephant—is bound to have a big impact, just what that impact will be varies widely.

Read More: http://blogs.discovermagazine.com/80beats/2011/07/18/when-large-animals-disappear-ecosystems-are-hit-hard/