Estuarine sediments present a particularly challenging problem for anyone attempting to predict the consequences of human modifications to the structure of an estuary. Although much research has been conducted on the dynamics of coarse, non-cohesive sediments, relatively less is known about the dynamic properties of finer sediments, especially where these contain measurable quantities of clay. Coarse, non-cohesive sediments are influenced primarily by physical factors such as current velocity and turbulence, and behave in ways that are determined largely by their predominant grain size. In finer sediments, however, factors such as water and organic matter content, exposure to atmospheric conditions during low tide, and biological phenomena, become increasingly important. The potential importance of biological processes in affecting sediment stability of finer sediments means the results of studies based on samples returned to a laboratory may bear little relationship to the in situ properties of the sediment.

During a broad study of a macrotidal flat in Minas Basin, Amos et al. (1988) found significant seasonal changes in the apparent strength of an intertidal sediment, and concluded that exposure at low tide during hot dry conditions resulted in an effective 'armouring' of the surface. It was also recognised, however, that the activities of benthic organisms were extensive, and probably played an important, interactive role. In order to elucidate more clearly the relative roles of physico-chemical atmospheric, sedimentological and biological processes, a comprehensive, multidisciplinary study was carried out on the Starrs Point tidal flat during July 1989. Entitled LISP (Littoral Investigation of Sediment Properties), an attempt was made to examine all parameters that might have an influence on the stability of the sediment surface, and to monitor atmospheric and oceanographic conditions continuously during a spring-neap cycle.