Causes of recruitment failure in freshwater mussel populations in southeastern New York.

Populations of freshwater mussels (Unionoida) are declining or disappearing from many waters around the world. In many declining populations, recruitment fails before adult mortality occurs, resulting in relict populations that can persist for decades. We tested whether recruitment failure in populations of the freshwater mussel Elliptio complanata was associated with invasion of nonnative crayfish, loss of a primary fish host (American eel Anguilla rostrata), excessive inputs of fine sediments, or unfavorable interstitial water chemistry (too little dissolved oxygen or too much un-ionized ammonia).

Long-term changes in a population of an invasive bivalve and its effects.

Although the ecological and economic effects of non-native species probably often change through time, few studies have documented such effects. The zebra mussel (Dreissena polymorpha) is an important invader that has had large ecological and economic effects on the ecosystems it has invaded in North America and western Europe. Our 20-year study of the Hudson River, New York, showed that the characteristics of a zebra mussel population and its effects on other benthic animals both changed substantially through time.