AN INDEX SHOWING BREAKDOWN OF SERIATION, RELATED TO DISTURBANCE, IN A CORAL-REEF ASSEMBLAGE

Intertidal and shallow water reef-corals usually exhibit a regular pattern of change in community structure with increasing water depth. A statistic is developed, the Index of Multivariate Seriation (IMS), which measures the degree to which this community change conforms to a linear sequence. Seriation broke down, and the IMS was reduced, when a coral community at Ko Phuket, Thailand, was subjected to increased disturbance resulting from sedimentation due to offshore dredging. The IMS is suggested as an additional index of community disturbance which might be applied to corals or other shallow-water sessile organisms.