Functional equivalence of constructed and natural intertidal eastern oyster reef habitats in a northern Gulf of Mexico estuary

Ecosystem functional equivalence of constructed and natural intertidal eastern oyster Crassostrea virginica reefs was evaluated over 2 yr using oyster density, taxa richness, phyletic abundance, and carbon and nitrogen stable isotope ( 13 C and 15 N) values of faunal assemblages as metrics at 3 sites in Mississippi's Grand Bay National Estuarine Research Reserve. Constructed reefs generally developed higher oyster density, similar or greater taxa richness, and higher phyletic abundance than their natural counterparts over the course of the study. Similar faunal assemblages and food web structures were found between paired constructed and natural reefs, and the stable isotope values for consumers at constructed reefs were not significantly different from those of their natural counterparts. Cluster analysis of 13 C and 15 N values for the few ubiquitous taxa sampled showed that constructed and natural reef pairs were isotopically more similar within bayous (constructed vs. natural) than among bayous but varied to some extent by year. Consumer 13 C values showed larger spatial and temporal differences that were coincident with long-term salinity changes than 15 N values, which were similar across sites and time.