An Empirical Test of Community Stability: Resistance of a Fouling Community to a Biological Patch‐Forming Disturbance

Abstract

Stability, defined as resistance to external perturbation, was evaluated for two developmental stages of an estuarine subtidal fouling community subjected to a biological patch—forming disturbance. Three stability criteria: (1) magnitude of response, (2) rate of response, and (3) recovery, were assessed on the basis of differences between control and perturbed panel communities with respect to physical structure (percent bare substrate, and sessile species volume), species richness (S), evenness (VH'), interaction diversity (H'), and community similarity, over time. Both motile and sessile species assemblages were examined, and responses of individual species were also determined. The older fouling community was found to be less stable than the younger one in terms of both measures of physical structure, for all three stability criteria. This was also true for species richness. Differences in evenness and H' between control and perturbed communities showed no consistent trend in this regard, and motile and sessile species exhibited different degrees of response. Multiple discriminant analysis indicated that fewer species contributed to the discriminant function in the younger community than in the older one. Community similarity between control and perturbed panel communities was lower overall for the older community. Individual species responses that contributed to these effects were examined. The results of our study, as well as an examination of other empirical evidence from the literature, reveal a lack of consistent support for traditional hypotheses of community stability. We conclude that evolutionary pressures, and resulting ecological strategies, are more important in determining community resistance stability than statistical properties such as species diversity.