photo: Tambako the Jaguar/Creative Commons
As Wyoming and the Department of Interior thinking appropriately managing wolves means half of them should be shot on sight, a new study in Science shows just how badly unbalanced ecosystems get when apex consumers (not just predators, removing large herbivores is also important) are eliminated--and how much of the time humans are the cause of it.
photo: Brian Snelson/Creative Commons
That this is the case has been well established for some time, but this review provides some compelling examples from across the globe:
- Apropos of the Wyoming wolf management plan, the article cites the (perhaps well-used) example of how when wolves were eliminated from Yellowstone National Park, elk began over-browsing aspen and willow, fundamentally and detrimentally changing the landscape.
- The dramatic declines of lions and leopards in parts of Africa has led to changes in olive baboon behavior which puts them in greater contact with humans, in turn causing greater incident of intestinal parasites in both humans and baboons.
- In another example directly applicable to human survival: Shellfish populations collapsed after cow-nosed rays increased following removal of sharks from an estuary.
photo: Nils Rinaldi/Creative Commons
On the human influence on this (both in a causative and restorative context), the report says,
The loss of apex consumers is arguable humankind's most perverse influence on the natural world. ...
To the extent that conservation aims toward restoring functional ecosystems, the reestablishment of large animals and their ecological effects is fundamental. You can't restore large apex consumers on an acre of land. These animals roam over large areas, so it's going to require large-scale approaches. (Science Codex)
Perverse is a very apt word there. Though admittedly not always consciously done, when we do kill off these apex consumers purposefully (often because we feel they are some threat to ourselves or our livestock) often the effect on the system as a whole is directly opposite to our intended outcome, in that the very ecosystem on which our survival ultimately depends is deeply unbalanced.