Geomorphic-Biotic Interactions on Beach Foreshores in Estuaries

Abstract

This review of research on estuarine beaches in the USAexamines the linkages between geomorphology and biota and impacts of shore protection strategies. The effects of timing and frequency of storms, wave processes, and tidal range on morphologic response, sediment activation, infiltration and exfiltration of water through the foreshore, and litter distribution on the surface are evaluated along with the impacts of human adjustments, including bulkhead construction and beach nourishment. The effects of these factors on faunal activity are illustrated by evaluating the suitability of beaches as spawning areas for horseshoe crab egg production and the resulting effect on migratory shorebirds. Future research is recommended to: 1) time biological sampling to episodic storm events to evaluate impacts of habitat modification; 2) identify spatial differences in the dimensions of the low tide terrace that control the dynamics and biological functions on the foreshore above it; 3) design biological sampling plans according to geomorphic process regimes rather than static morphologic features on the beach; 4) standardize sampling locations to facilitate comparison among different sites; 5) conduct simultaneous studies of sediment activation by waves and by fauna; 6) determine the role of litter on faunal community structure and function; 7) conduct detailed physical and biological studies at bulkheads to determine the significance of position on the intertidal profile; and 8) determine the significance of nourishing a beach with fill material significantly different from native materials.