The temporal significance of bioturbation in backshore deposits: Waterside beach, New Brunswick, Canada

(T)his paper provides an estimate of the temporal nature and environmental implications of bioturbation in upper-foreshore and backshore deposits resulting from the burrowing activity of talitrid amphipods at Waterside Beach, Bay of Fundy, Canada. Short-term preservation potential is assessed by comparing shore-normal variations in burrow morphologies and densities to grain-size distribution, and hydraulic and eolian processes. The intensity and distribution of burrowing is linked to depositional environment and provides a temporal framework for bioturbation indices in ancient upper-foreshore and backshore deposits. Bioturbation in foreshore and backshore successions provides a means for predicting short-term, autocyclic processes in the rock record, in that: (1) the initial occurrence of burrowing marks the transition from the foreshore to the backshore, and (2) the degree of bioturbation may be used to predict depositional rates and processes. At Waterside, bioturbation indices (BI) of two or less indicate a single season of colonization; BIs of two (upper end of range) and higher suggest multiple seasons of colonization. A high BI may indicate that the backshore environment was protected from wave reworking or erosion (particularly during storms) and/or was subjected to minor eolian sedimentation.