FEEDING AND BURROWING BEHAVIORS OF JUVENILE RAINBOW MUSSELS, VILLOSA-IRIS (BIVALVIA, UNIONIDAE)

This study characterized the relationship between juvenile rainbow mus sels (Villosa iris) and the sediment they inhabit. Dye studies in a fe eding chamber, video recordings of feeding, and gut content analysis w ere used to determine mechanisms of feeding, the primary food source, and the origin of substances taken up by 1- 14-d-old juveniles. Within 20 min of placement, 98.5% of the juveniles were able to burrow in th e sediment. Although juveniles burrowed < 1 cm into the sediment, they were not exposed to the overlying water. Exposure to sediment comes n ot only through direct contact, but also through filtration of interst itial water and sediment-associated fine particulate organic matter. j uveniles fed on bacteria and bacterial-sized particles as well as alga e. Their predominant food source appears to vary with age. Pedal-locom otory and pedal-sweep feeding behaviors are used to facilitate movemen t of particles into the pedal gape. Pedal-locomotory behaviors were us ed more frequently in the presence of detrital particles while pedal-s weep feeding was most frequently observed in a tri-algal suspension.