The Anthropocene Era: How humans are downgrading life on Earth

Removing those apex consumers produces what’s called “trophic downgrading,” which refers to the cascade of damage that can occur when an intact ecosystem is disrupted in such a significant way. It’s a relatively new concept for ecologists and conservationists, who long studied nature one plant or animal at a time. But as we now know, everything is connected. Actually, revise that—everything is connected, but some species are more connected than others, and when they’re taken out of the picture, ecosystems can change utterly or even collapse altogether. A few examples from the Science paper…

The lesson here is that in nature, almost everything comes with a price. We can’t harvest an entire species—or “manage” them, as we long did with predators like wolves—without blowback, to use the defense parlance. The trouble, of course, is that these changes are very hard to model, because the web of species interactions is invisible—until we come along in our bumbling fashion and perturb it, like a hiker walking through a spiderweb. What the Science authors are suggesting is that the burden of proof has shifted—we should assume that top-line predators are vital to their ecosystems, and think twice before disturbing them.