The Role of Biodiversity for the Functioning of Rocky Reef Communities

A major focus of ecological research has been on understanding the processes that determine the diversity of organisms at a particular location (Hutchinson 1959) . Many important classic studies elucidating these local-scale processes have been conducted in marine hard-bottom communities (e.g. Kitching and Ebling 1961 ; Paine 1966 ; Menge and Sutherland 1976 ; Connell 1978 ; Lubchenco 1978 ; Sousa 1979 ; Fletcher 1987) . These studies and subsequent work have shown that diversity in rocky intertidal and subtidal systems is regulated by a combination of abiotic (e.g. disturbance, productivity, nutrient availability) and biotic (e.g. competition, consumption) processes (Worm et al. 2002 ; Nielsen 2003 ; Graham 2004 ; Bracken and Nielsen 2004 ; see Part II of this book). However, the organisms inhabiting these ecosystems are not only influenced by the performance of the systems—they also, in part, determine it. Growing evidence from a variety of systems indicates that organisms, by virtue of their roles in mediating ecosystem performance, influence the rates of biogeochemical processes, stability, and other attributes of the ecosystems in which they live (Naeem 2002 ; Kinzig et al. 2002 ; Cardinale et al. 2006) . Because of the unique roles that different organisms play in mediating ecosystem performance, there is a growing awareness that the diversity of organisms in a system can influence that system’s performance (reviewed in Hooper et al. 2005) . Recent studies have illustrated several key ways in which organisms inhabiting temperate and tropical reefs—and, by extension, the diversity of those organisms—influence the performance of marine ecosystems (reviewed in Worm et al. 2006) . Below, we review studies from hard-bottom marine ecosystems and provide suggestions for future research into the functional roles of marine biodiversity in temperate and tropical hard-bottom communities. Accumulated evidence and theoretical reasoning suggest that the diversity of benthic communities may be an important property for the functioning of these ecosystems.