Mitigation Potential of Habitat Replacement: Concrete Artificial Reef in Delaware Bay-Preliminary Results

Artificial reefs are being proposed as mitigation for habitat loss in estuaries and coastal areas. However, there is insufficient information to verify that artificial reefs enhance biological resources. To study their value for mitigating habitat loss, 16 prefabricated concrete terraced artificial reef modules were deployed in lower Delaware Bay in 1989. A 5-year monitoring study was begun to assess the artificial reef's value as a long-term habitat and forage area for fishery resources as compared to non-reef habitats in the Bay. After 2 years, the reef modules appear to be physically stable and support biological resources. Fishes, including juveniles, typical of reefs in the region, were observed in and near the reef. The blue mussel, Mytilus edulis, dominated the epibenthic community that developed on the modules and was primarily responsible for a mean epibenthic biomass density of 24.865 kg·m 2 (wet wt.) on module surfaces through June 1991. However, this mussel-dominated density was reduced, by approximately 95%, in August 1991 to a mean 0.596 kg·m2, with other taxa such as, sponges, corals, and anemones increasing in community importance. In comparison to the epibenthic biomass on the modules, the mean benthic infauna biomass in the silty sand sediments of the reef site ranged from 0.046 to 0.316 kg·m2 in 1991. These preliminary results suggest that this artificial reef complex enhanced gross benthic biomass at the reef site by about 147 to 895 fold over the benthic infauna in the study area, based on a standard area of Bay bottom, the reef modulc "footprint."