Freshwater mussels can furnish diverse and valuable ecosystem services in rivers, streams and lakes when they are healthy and abundant. The service generating the greatest interest is their propensity for filtering large quantities of microparticulate seston , thereby improving water clarity and potentially removing or transforming particulate pollutants such as nitrogen, phosphorus and some human pathogens. T he magnitude of these services depends on complex relationships among the population biomass, physiological status, temperature, seston quantity and composition, and system hydrodynamics. T he species diversity, abundance and distribution of natural mussel populations has been in steep decline worldwide, however . Hatchery propagation and aquaculture practices are seen as useful tools to help stem the decline, driven foremost by conservation interests and laws (e.g., the Endangered Species Act in the United States). In the last 10 years, there has also been a growing interest in the restoration of natural mussel assemblages that form mussel beds, driven by emerging interest in ecosystem services (e.g., the Clean Water Act in the U.S.).
The significance and viability of these restoration efforts is an active area of research, but the prospects for recovery of natural populations appears to be plausible at least for some areas thanks to advances in the restoration aquaculture of freshwater mussels. Thinking beyond the restoration of natural assemblages in natural settings, can freshwater mussels be deployed in designed, nature-based systems aimed at delivering specific ecosystem services where those services are most needed? R esults from ongoing projects suggest that hatchery-propagated mussels of two species native to the Delaware River Basin can persist, grow and contribute water quality benefits in various man-made aquatic systems, including a living shoreline, impoundment, reservoir, and stormwater pond s (Table 1). When their requireme nts are met, freshwater mussels can therefore be included in engineered aquatic systems, helping to address water quality impai rment closer to pollutant sources and in urban landscapes where traditional restoration practices are constrained.