services that yield to this approach and methods involving “willingness to pay” and other public preference approaches where markets do not exist. This research should then be utilized by policy makers to achieve social equity in putting costs of service losses on those responsible and using fees paid for lost services to restore those ecosystem services and thereby preserve them for the general public trust.
Finding: Many estuaries suffer from eutrophication and potentially could benefit from increasing the biomass of suspension-feeding bivalves to provide resilience to eutrophication and reduce the symptoms of excessive nutrient and sediment loading. In addition to limiting effects of eutrophication and sedimentation, restoring the beneficial biogeochemical functioning of suspension-feeding bivalves, especially oysters, could provide additional ecosystem services associated with filtration of phytoplankton and inorganic particles from the water column and deposition of organic biodeposits. These effects will be greatest in shallow and well-mixed water bodies, such as those typically found in estuaries, coastal bays, and lagoons.
Recommendation: Policies should be developed to encourage restoration of the biogeochemical filtration functions associated with suspension-feeding bivalves in estuaries. Such policies should consider both recovery of wild stocks and mariculture of (preferably native) suspension-feeding bivalves to restore the filtration functions and associated ecosystem services. For restoration purposes, particular attention should be given to (1) establishing genetic husbandry guidelines to prevent loss of genetic diversity; (2) avoiding negative effects of disturbance of vertebrates and other valued species; (3) controlling spread of nonnative fouling organisms, especially certain tunicates; (4) regulating bivalve stocking to require use of eyed larvae from certified hatcheries with an effective and comprehensive disease inspection or to first-generation seed spawned from adult bivalves under quarantine conditions in order to minimize species introductions and disease spread; (5) insuring that bivalve shellfish loading does not exceed levels that have unacceptable negative impacts on the benthos through excessive organic loading or on other components of the ecosystem through clearance of planktonic foods and organic particles from the water column; (6) preventing unacceptable damage to bottom habitat by harvest gear; and (7) assessing the social tolerance for mariculture on a site-specific basis.