Field investigations conducted at three sites on the intertidal sandy foreshore at Cliffwood Beach and Keyport Harbor, Raritan Bay, New Jersey reveal the relationship between meiofaunal density, wave and beach characteristics at sites where bulkheads and seawalls are present and at an adjacent site where they are not.

Wave characteristics were gathered at 2 hz over the tidal cycle with a pressure transducer. Three replicate core samples, to a depth of 0. 10 m, were gathered at four sampling stations across the foreshore at low tide to determine meiofaunal density. A fourth core sample was used to determine grain size, sorting and moisture content. Net change, depth of sediment activation, and beach elevation were measured at low tide.

At Cliffwood Beach, significant wave heights were 0.05-0.13 m with periods of 5.9 - 7.7 s. Meiofaunal. densities ranged from I - 309 ind./10cm2. Sediments are finer (0.29 mm) and better sorted (0.54 Φ) immediately fronting the seawall resulting in lower meiofaunal densities. One-way analysis of variance revealed differences between meiofaunal densities, within the bottom 0.07 m of the core, immediately fronting the seawall and at a similar elevation at the control site.

At Keyport Harbor, significant wave heights were 0.08-0.27 m with periods of 2.0 s. Meiofaunal densities ranged from 2-207 ind./10 cm2. Sediments are finer (0.4 mm.) and better sorted (0.47 Φ) immediately fronting the bulkheads. One-way analysis of variance revealed differences between meiofaunal densities, within the top 0.03 m of the core, immediately fronting the bulkheads and at a similar elevation at the control site. Depth of activation was 0.23 m at sampling station immediately fronting the bulkhead.

Shore-parallel structures have greatest influence when wave energies are high or when the structure is located bayward of wave breaking at high water.