It is likely that current environmental conditions and commercial mariculture practices, when coupled with predicted changes, such as ocean acidification, will facilitate and accelerate carbonate loss in estuarine and coastal systems. Thus, management of shell-producing commercial species must also include management of the habitat that will maximize production of carbonate. Long-term sustainability of mollusc stocks depends upon the maintenance of a positive shell budget for carbonate, as well as provision of habitat that supports recruitment, growth, and survival of bivalves. Mariculture of bivalve molluscs can contribute favorably to shell production and preservation in coastal ecosystems if the operators return the shell resource to the environment after harvest. However, regulations requiring the return of shells to the estuarine, lagoonal, or coastal bottom after shucking may be required to achieve this goal. Habitat Creation and Maintenance Shell adds hard substrate and habitat complexity to soft substrates, thereby increasing species diversity