I. Physical Features of Shallow Soft Bottom Communities (i.e.
at Scuba depths, to 30-40 meters)
Movement of bottom sediments by large waves is a dominant
physical process influencing the structure of benthic infaunal communities
along the shallow Scuba-accessible continental shelf (Oliver et al. 1980). Wave action produces
a coarse, poorly consolidated, well-sorted (i.e. low variation in grain
size), and therefore easily moved beach deposit behind the surf zone. Large waves
lift these surface sediments into a granular suspension tossed shoreward
and then seaward by the passing waves (Bascom 1964, Clifton et al. 1971).
Extreme storm waves can remove as much as a meter of surface sediments at
water depths greater than 10 meters. The physical stability of the beach
deposit increases with increasing water depth as wave-generated bottom currents
decrease. As a result, bottom sediments grade from coarse to fine sand with
increasing water depth and decreasing wave disturbance (Hodgson and Nybakken
1973, Oliver et al. 1980).
Next - Section II. Community Zonation
Shallow Soft Bottom Habitats Table of Contents