NATURE: The Serengeti Rules uncover the self-regulating mechanisms in the Serengeti National Park in Tanzania, and shows how carnivores can play a crucial role – from the top down.
Svein Hammer
Svein is a regular contributor to Modern Times Review.
Published date: March 29, 2019

Some years ago I contributed, like so many others, to spreading a little nature documentary on social media. The film was called How Wolves Changes Rivers, and portrays the return of the wolves to Yellowstone national park in USA. Many people probably thought the story of the positive and pervasive effects of the wolves had in the park was too good to be true. Such a reserve is healthy, but in actual fact the idea of reintroducing one key species into an ecosystem was supported by rigorous science.

The documentary film The Serengeti Rules provides a fascinating introduction to the background of it all. We encounter five people who in the 1960s developed a passion for investigating and understanding life – in forests, rivers and oceans. They didn’t know each other, and apparently they were researching entirely separate topics.

The main voice of the movie belongs to Robert Paine, who relates from his death-bed how he ended up uniting these dissimilar scientists in a common project. His scientific gaze had a farther reach than most, as his fundamental ambition was to uncover the self-regulating mechanisms of nature. Science had long departed from the premise that the energy of the sun provides nutrition for the plant eaters who, in turn, are devoured by the carnivorous animals in a process that goes from bottom to top. But what if the relationships in nature were more complex? What if life trickled down just as much as it grew upwards?

Some species are more important than others

Robert Paine launched a simple experiment to examine such questions. In a stretch of the intertidal zone, where 15 different species lived symbiotically together, he removed the starfish. After a short time the ecosystem was completely taken over by mussels. The fact that the carnivore (in this case, the starfish) disappeared, made it possible for another species to dominate to such an extent that it suppressed all others, thereby creating a monoculture. If Paine removed any of the other species, nothing happened. The starfish stood out. It was a keystone species in the ecosystem, decisive for its biodiversity.

When the otter disappeared in the waters outside northeast America, the consequence was a blossoming of sea urchins.

As a consequence of this new-won insight we also learned more about how humans disrupts the balance of nature. When the otter disappeared in the waters outside …

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