Biological Monitoring of Beach Nourishment Operations in Northern New Jersey, USA: Linkages between Benthic Impacts and Higher Trophic Levels

Abstract

Between 1993 and 1999 over 19 million m 3 of sand were placed on exposed, high-energy beaches along the northern coast of New Jersey (USA) as an erosion control measure. As part of a multi-faceted biological monitoring program, potential impacts of this large-scale beach nourishment project on benthic infauna and fishes in the intertidal surf zone, nearshore habitat, and offshore borrow areas were examined. Food habits analysis was conducted on northern kingfish ( Menticirrhus saxatilis ), Atlantic silversides ( Menidia menidia ) and rough silversides ( Membras martinica ) collected in the surf zone, and winter flounder ( Pleuronectes americanus ) and summer flounder ( Paralichthys dentatus ) collected at the borrow areas to assess impacts to trophic linkages in the two project areas. Monitoring of benthos and fishery resources was conducted for three years before nourishment, during placement, and up to two years afterwards. The basic sampling design included multiple reference sites and several monitoring components integrated into a cohesive program. In general, impacts on the benthos were found to be short-term (2–6 months) and spatially limited. Stomach contents analyses revealed that the fishes examined have a diverse diet that includes non-benthic prey resources. Prey biomass in kingfish and silversides was usually greater in fishes caught at beach nourishment stations rather than at reference stations when significant differences were detected. Food habits of winter flounder, a benthic omnivore, and summer flounder, an epibenthic feeder, did not change relative to the dredging activities. Winter flounder fed primarily on anemones, which were not common at any of the borrow areas. Results of the present study call into question the need for extensive monitoring of projects where a close match exists between fill and receiving beach sediments. Further studies are definitely needed, however, where fill and receiving beach sediments aredissimilar.