The brief movie opens with two questions: “So what determines what number of species dwell in a given place? Or what number of people of the species can dwell someplace?”
The analysis that offered solutions to those questions was set in movement by key experiments by ecologists Robert Paine and James Estes. Robert Paine’s starfish exclusion experiments on the coast of Washington state confirmed that eradicating starfish from this marine ecosystem has a big effect on the inhabitants sizes of different species, establishing the starfish as a keystone species. James Estes and colleague John Palmisano found that the kelp forest ecosystems of the North Pacific are regulated by the presence or absence of sea otters, which feed on sea urchins that devour kelp. These direct and oblique results of sea otters on different species describe a trophic cascade. These early research had been the inspiration for a whole lot of investigations on different keystone species and trophic cascades, in addition to ongoing research into the regulation of inhabitants sizes and species numbers.
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