Vol. 110: 177-185.1994 MARINE ECOLOGY PROGRESS SERIES Mar. Ecol. Prog. Ser. Published July 2 1 Short-term dynamics of tropical macroalgal epifauna: patterns and processes in recolonisation of Sargass urn fissifolium Keith Michael Martin-Smith Marine Biology Department, James Cook University of North Queensland, Townsville. Queensland 4811, Australia ABSTRACT: Aspects of the stability of a community of invertebrate epifauna associated with the large brown alga Sdrgassum fjssjfolium were investigated on a fringing, mixed coral/algal reef in Australia. In 2 field experiments S. fissifolium plants were defaunated using fresh water and subsequent recoloni- sation by mobile invertebrates was monitored over time scales of 0 to 6 and 0 to 28 d. together with unmanipulated controls. In both expenments recolonisation was very rapid, with some individuals of most common taxa present within 6 h of defaunation. Multivariate statistics showed that the system displayed high elasticity and amplitude, re-establishment of epifaunal communities indistinguishable from controls occurring within approximately 2 wk. This was against a dynamic background wherein control conununities exhibited little short-term vanation (within 6 d) but showed much greater changes in abundance and composition over a longer time-scale (28 d). Different taxa generally showed one of 2 distinct recolonisation patterns: (1) 'monotonic' or 'asymptotic' where abundance increased steadily until control levels were attained and (2) 'overshoot' where abundance increased rapidly, peahng at levels significantly higher than control levels before returning to control levels. These data demonstrate that this tropical epifaunal community has the ability to recover rapidly from short-duration, high- magnitude disturbance episodes. KEY WORDS: Stability . Recolonisation . Epifauna INTRODUCTION How stable are natural communities? This question is of fundamental importance in understanding the role of disturbance in structuring communities (Pickett & White 1985, Karlson & Hurd 1993).The stability of a system depends upon its resistance to perturbation and its adjustment stability - the amplitude of perturba- tion from which it can recover and the rate of recovery, usually known as the elasticity of the system (Connell & Sousa 1983). Highly stable communities can have high resistance to perturbation, high adjustment stabil- ity or both. The stability of a community can be evalu- ated by its response to experimental perturbation (e.g. Smedes & Hurd 1981, Farrell 1988). Macroalgae and seagrasses support large popula- tions of mobile invertebrates which may be subject to periodic disturbances of some magnitude, often as a result of bad weather (e.g.Fenwick 1976, Dean & Con- nell 1987). However, such communities normally dis- play predictable cycles of abundance (Edgar 1983a, Arrontes & Anadon 1990, Martin-Smith in press) implying high community stability. Whilst epifaunal populations have been shown to rapidly colonise defaunated substrata (Gunnill 1982, Edgar 1983b, Stoner 1985, Virnstein & Curran 1986), this has not usually been set against the dynamic background of changes in unmanipulated communities (Smedes & Hurd 1981, Karlson & Hurd 1993). Furthermore, such studies have almost invariably been carried out in northern hemisphere temperate or subtropical areas (but see Stoner 1985) where the frequency and inten- sity of disturbance may be very different to that in the tropics (Pickett & White 1985). Thus, the primary aim of this study was to investigate the elasticity and amplitude of a community of epi- O Inter-Research 1994 Resale of full article not permitted