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 stud y their value for mitigating habitat loss, 16 prefabricated concrete t erraced artificial reef modules were deployed in lower Delaware Bay in 1989. A 5-year monitoring study was begun to assess the artificial re ef's value as a long-term habitat and forage area for fishery resource s as compared to non-reef habitats in the Bay. After 2 years, the reef modules appear to be physically stable and support biological resourc es. Fishes, including juveniles, typical of reefs in the region, were observed in and near the reef The blue mussel, Mytilus edulis, dominat ed the epibenthic community that developed on the modules and was prim arily responsible for a mean epibenthic biomass density of 24.865 kg.n m-2 (wet wt.) on module surfaces through June 1991. However, this muss el-dominated density was reduced, by approximately 95%, in August 1991 to a mean 0.596 kg.m(-2), with other taxa such as, sponges, corals, a nd anemones increasing in community importance. In comparison to the e pibenthic 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 k g.m(-2) in 1991. These preliminary results suggest that this artificia l reef complex enhanced gross benthic biomass at the reef site by abou t 147 to 895 fold over the benthic infauna in the study area, based on a standard area of Bay bottom, the reef module ''footprint.''