Alternative Substrates Used for Oyster Reef Restoration: A Review

Oyster populations and reef habitats have notably declined in the last century around the world. The ecological, economic, and cultural values of oysters have led to a variety of restoration efforts seeking to recover these lost benefits. Limitations of the native oyster shell substrate and the large-scale nature of many restoration projects have resulted in the increased use of a variety of alternative, or artificial, substrates to create reef structures. A text mining package was used to conduct a review of alternative substrates used for oyster restoration. Specifically, the review (1) assessed commonly used alternative substrates, (2) locations where alternative substrates are used, and (3) common performance metrics used to evaluate alternative substrates. The review demonstrated that (1) the most common substrates included porcelain, concrete, limestone, noncalcium stone, nonoyster shell, dredged shell, and engineered reefs; (2) oyster restoration with alternative substrates occurs worldwide, but evaluations of alternative substrates were primarily (79%) within the United States of America; and (3) four main categories of performance metrics are used to assess alternative substrates-biological, structural, chemical, and economic acceptability. Within the four performance metrics, however, there exists a substantial variety in terms of specific metrics used and application of metrics to assess alternative substrates. Results highlight the need for common metrics across projects to ease comparison between alternative substrate options.