A 'minimum stress inflexion' in relation to environmental and biotic influences on the dynamics of subtidal encrusting communities?

The sedentary fauna of sublittoral boulders was studied at five sites with very different environmental conditions within Lough Hyne Marine Nature Reserve (51 degrees 30' N, 9 degrees 18' W). The degree of competition was assessed through the construction of competitive hierarchies built up from the results of nearly 3000 interactions between organisms. Communities at all sites were predominantly hierarchically organised with few stand-offs recorded. Density of interactions was correlated with total space occupation. Flow speed at all sites was logged over 24 h and this factor also correlated with space occupation. Degree of disturbance was assessed through the use of marked boulders at each site. Species diversity peaked where all factors were 'moderate' and was lowest at 'extreme` sites. The effects of these environmental variables and biotic factors in determining community composition are discussed. and a working model detailing a 'Minimum Stress Inflexion is described. This represents an extension of the intermediate disturbance hypothesis in that it is proposed that disturbance in this system may serve to reduce sediment load as opposed to preventing space monopolisation in the classical model.