Field investigation of the influence of bulkheads on meiofaunal abundance in the foreshore of an estuarine sand beach

A one-day field investigation was conducted on an estuarine sand beach fore shore in Raritan Bay, New Jersey to document meiofaunal abundance at sites fronting bulkheads and at an adjacent site where no bulkhead is present. Da ta on waves, water temperature and salinity were gathered over a spring tid al cycle. Data on meiofauna and sediment characteristics were gathered at l ow water across the foreshore at three sites: Site 1 where a bulkhead inter sects low on the profile; Site 2 where there is no bulkhead present; and Si te 3 where a bulkhead intersects high on the profile. Mean grain size of se diments is in the range of medium to coarse sand; mean grain size is slight ly finer at locations fronting the bulkhead at Sites 1 and 3 compared to a similar profile elevation at Site 2. Significant wave heights, measured on the low tide terrace, ranged from 0.08 m at high water to 0.27 m during ris ing tide. Peak wave periods ranged from 2.0 to 2.7 s. Greatest net change i n sand surface elevation (0.07 m) and depth of sediment activation (0.23 m) over the tidal cycle occurred at the base of the bulkhead at Site 1. Data from the top core segments at Site 1 reveal lower meiofaunal density at the base of the bulkhead compared to the sampling station lower on the profile and to sampling stations at a similar profile elevation on Sites 2 and 3. One way ANOVA reveals a significant difference in alongshore meiofaunal den sity between the sampling station fronting the bulkhead at Site 1 and at sa mpling stations at a similar profile elevation at Sites 2 and 3. Increased energy at the base of the bulkhead at Site I resulted in the transport of m eiofauna with eroded sediments. Bulkheads constructed low on the profile ca n have the greatest negative impact on individuals fi om near the base of t he structure. Construction of bulkheads higher on the intertidal profile do es not appear to alter the suitability of the beach matrix as habitat.