The influence of Connell's species-interactions studies on community ecology is discussed.
In 1961, Joe Connell set the gold standard for species-interaction studies when he published his dissertation research in Ecology and Ecological Monographs on the effects of competition, predation and physical factors on barnacles in Scotland. His study was universally considered to be groundbreaking for two reasons. First, he used carefully-designed field experiments to test the effects of hypothesized factors controlling the abundance and distribution of species, coupled with meticulous observations of the study organisms to elucidate the causal mechanisms. Although not the first, Connell's field experiments were clearly the most rigorous in terms of proper controls and replication, and furthermore, were conducted under a remarkably natural venue. Second, Connell's synthesis on the interactive effects of biotic and abiotic factors was unprecedented, unfolding a broader and more unified view of the processes that structure communities. In addition to demonstrating the separate effects of competition and predation on barnacles, reviewed in nearly all ecology textbooks, he also showed that predation by snails reduced the strength of interspecific competition which became the foundation for studies of predator-mediated coexistence and the intermediate disturbance hypothesis.
Connell made his next major contribution studying the rocky intertidal on San Juan Island, Washington, where he found that predation was the main limiting factor for barnacles and that competition was weak. In a series of elegant experiments, he showed that barnacles coexisted with their voracious predators by having a spatial refuge and an invulnerable size class. In 1975, when a growing body of ecological research was devoted solely to competition, Joe wrote a highly influential book chapter in which he presented evidence from field experiments and models delineating the conditions under which predation and physical disturbances impeded competition. During the next decade, he continued to question the prevalence and importance of competition and called for experimental proof of its existence in the present as well as in the past.
Throughout his career, Connell was a strong advocate for the virtues of long-term studies of communities in their natural environment. Driven by his love of ecology and incredible energy, Joe was able to keep his seminal studies on coral reefs and rain forests running for over forty years. The insights he derived from this research will be appreciated for many generations.