Jaws, Sabretooth, Anaconda—it’s scary stuff, right? Well, not scarier than life without sharks, tigers, and other apex predators, according to a recent study by WCS Conservationist Joel Berger. In the study, which appears in the July 15 issue of the journal Science, Berger concludes that the loss of large predators in the wild may be humankind’s most pervasive influence on nature.
Author of the book The Better to Eat You With and co-author of the recent paper “Trophic Downgrading of Planet Earth,” Berger reviewed findings from a growing body of scientific data on the effects of removing large predators, or “apex consumers,” from nature. Until recently in human history, these animals have been omnipresent and their influence has often been associated only with what they eat.
It turns out that removing these top-tier consumers from the food chain has more far-reaching consequences than originally understood. Negative effects can cascade throughout the predators’ associated ecosystems, reverberating to other species and ecosystem processes, too. “The disruption of top-down control in an ecosystem is something that much of the public once viewed as good but is now recognizing as disturbing and [having] expensive consequences that affect all forms of our lives and economies,” said Berger. So called “trophic cascades” resulting from removing apex predators have now been documented in all of the world’s major biomes and in terrestrial, freshwater, and marine systems. Moreover, in following a trail of complex cause-and-effect relationships, the scientists noted unanticipated impacts to processes as diverse as the dynamics of disease, wildfire, carbon sequestration, invasive species, and biogeochemical cycles. As an example, the reduction of lions and leopards in parts of Africa has led to changes in numbers and behavior of olive baboons. The effects have caused the baboons to come into increasing contact with people, and led to higher rates of intestinal parasites in the baboons and their human neighbors.
Berger cites the urgent need for interdisciplinary research to forecast the effects of trophic downgrading on process, function, and resilience in global ecosystems. “If we continue with business as usual and lack an on-the-ground presence to reverse the alarming trends, we continue down a path of repeating history, one mistake at a time, rather than benefitting from past mistakes, as egregious as they have been,” he said. Read the media availability >>