Restoration of Several Native Species of Bivalve Molluscs for Water Quality Improvement in Mid-Atlantic Watersheds.

Bivalve molluscs provide water quality benefits throughout mid-Atlantic watersheds, such as Chesapeake Bay and the Delaware River basins. Whereas most of the attention has focused on the role of the eastern oyster Crassostrea virginica, there are many other bivalve species, in both salt and fresh waters, that provide similar benefits. This review summarizes current knowledge regarding the capacity of diverse mid-Atlantic bivalves to filter particles and potentially enhance water clarity and quality. Species with the greatest clearance rates and population carrying capacity were also considered for their restoration and enhancement potential. Compared with eastern oysters, several additional species of saltwater bivalves and freshwater mussels are reported to filter water at rates that merit restoration attention and have been shown to attain significant population sizes. More work is needed to estimate system-carrying capacity and to eliminate restoration bottlenecks for some species—all bivalve species have constraints on their distribution and abundance. Nevertheless, a diversified, watershed-wide bivalve restoration strategy is likely to be more successful than a monospecific focus because it would address pollutant issues in more diverse places and multiple habitats along the river to estuary continuum.