Revisiting Paine's 1966 Sea Star Removal Experiment, the Most-Cited Empirical Article in the American Naturalist

"Food Web Complexity and Species Diversity" (Paine 1966) is the most-cited empirical article published in the American Naturalist. In short, Paine removed predatory sea stars (Pisaster ochraceus) from the rocky intertidal and watched the key prey species, mussels (Mytilus californianus), crowd out seven subordinate primary space-holding species. However, because these mussels are a foundational species, they provide three-dimensional habitat for over 300 associated species inhabiting the mussel beds; thus, removing sea stars significantly increases community-wide diversity. In any case, most ecologists cite Paine (1966) to support a statement that predators increase diversity by interfering with competition. Although detractors remained skeptical of top-down effects and keystone concepts, the paradigm that predation increases diversity spread. By 1991, "Food Web Complexity and Species Diversity" was considered a classic ecological paper, and after 50 years it continues to influence ecological theory and conservation biology.