Without top predators, ecosystems suffer

[Robbien]

When the construction of a hydroelectric dam on Venezuela's Caroni River was finally completed in 1986, it flooded an area twice the size of Rhode Island (6,290 square kilometres) creating one of South America's largest human-made lakes: Lake Guri. As floodwaters turned hilltops into islands, a key group of animals _ predators such as jaguars, harpy eagles and armadillos _ disappeared from the islands.

In the predators' absence, their plant-eating prey began multiplying. Soon they had devoured most of the once-pristine forest.

. . .


Not surprisingly, the mass exodus of these creatures had a huge impact on their prey. Populations of howler monkeys, iguanas and leaf-cutting ants exploded.

. . .

The loss of top predators could also explain the disappearance of aspens and willows in the oldest national park in the United States: Yellowstone. Scientists determined that aspens stopped regenerating in Yellowstone in the 1930s, around the time that wolves went extinct in the area. Research suggests that the elimination of Yellowstone's wolves allowed one of their prey animals, elk, to browse aspens and willows undisturbed. This led to the disappearance of trees and streamside vegetation _ and the loss of beaver habitat.

Since wolves were reintroduced to Yellowstone in 1995, aspen and willow have begun growing again, and a few beavers have returned to the park.

http://www.bangkokpost.com/en/Outlook/09May2005_out04.php

[kliljedahl]

1. Funny how we have to go overseas

to get accurate & honest news reporting.


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