A FUNCTIONAL-GROUP APPROACH TO THE STRUCTURE OF ALGAL-DOMINATED COMMUNITIES

We suggest that relatively few species attributes are of overriding im portance to the structure of benthic marine algal communities and that these are often shared among taxonomically distant species. Data from the western North Atlantic, eastern North Pacific and Caribbean sugge st that patterns in algal biomass, diversity and dominance are strikin gly convergent when examined at a functional group level relative to t he productivity and herbivore-induced disturbance potentials of the en vironment. We present a simple graphical model that provides a way to predict algal community composition based on these two environmental a xes. This predictability stems from algal functional groups having cha racteristic rates of mass-specific productivity, thallus longevity and canopy height that cause them to ''behave'' in similar ways. Further, herbivore-induced disturbances have functionally similar impacts on m ost morphologically and anatomically similar algae regardless of their taxonomic or geographic affinities. Strategies identified for marine algae parallel those of a terrestrial scheme with the addition of dist urbance-tolerant plants that characteristically coexist with and even thrive under high levels of disturbance. Algal-dominated communities, when examined at the functional group level, appear to be much more te mporally stable and predictable than when examined at the species leve l.