摘要：Freshwater mussels are recolonizing the upper Illinois River following their extirpation by pollution in the early part the 20th century. From 1990 to 1999, we collected 332 individuals of 18 species between river miles 232.0 and 271.2. Age structure of the community suggests mussels began recolonizing in the early 1980s, which coincides with improvements in water quality and the upper river fish community. We found four sites with five or more species, which we considered to be recently formed mussel beds. We collected live individuals of six species (Actinonaias ligamentina, Alasmidonta marginata, Lampsilis cardium, Lasmigona costata, Pleurobema sintoxia, and Strophitus undulatus) thought to have been extirpated from the entire Illinois River mainstem, and one species (Anodonta suborbiculata) that has recently expanded its range into the upper river. Upper Illinois River tributaries and lower reaches of the Illinois River harbored source populations for the recolonizing mussels. Although the present community does not approximate the pre-disturbance fauna, these data show that given adequate time and improved conditions, mussel communities may recover from a devastating disturbance.
