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

Intertidal and shallow water reef-corals usually exhibit a regular pat tern of change in community structure with increasing water depth. A s tatistic is developed, the Index of Multivariate Seriation (IMS), whic h measures the degree to which this community change conforms to a lin ear sequence. Seriation broke down, and the IMS was reduced, when a co ral community at Ko Phuket, Thailand, was subjected to increased distu rbance resulting from sedimentation due to offshore dredging. The IMS is suggested as an additional index of community disturbance which mig ht be applied to corals or other shallow-water sessile organisms.