The top predators in the ecosystem are by nature a kind of threat to the environment. They are, after all, responsible for the elimination of animals lower down on the totem pole. The belief that ecosystems need to be protected from these predators, however, has led humans to try and run interference — an often misguided effort.
A prime example of these misguided efforts is going on now in the Great Lakes region, where humans are trying to keep the overly-dominant carp under control, as I wrote about in an earlier blog entry. After releasing poison into an area adjoining the Chicago River, 200,000 pounds of fish went belly up — none of them carp.
Also, a recent study demonstrated that the elimination of predators at the top of the food chain can have an undue negative impact on the environment. Apex predators — like cougars, lions, sharks and wolves — which are at the top of the food chain, offer substantial ecological benefits. These animals do prey on weaker species, but that's not always a bad thing.
Without these apex predators to keep them in check, mesopredators — which include birds, lizards, rodents and fish — are able to thrive in large numbers, thus causing more environmental damage than they otherwise would.
Mesopredators are typically omnivorous, feeding mainly on plants and crops. They take a substantially greater environmental toll than carnivorous apex predators.
Every plant and animal has a role, and any disruption to the natural way of things causes an ecological imbalance that does a disservice to the environment.
Predators may get a bad rap, but it’s really human populations that are to blame.
http://www.globalpost.com/notebook/global-green/091206/predators-are-beneficial