Assessment of dreissenid biodeposits as a potential food resource for invasive Asian carp

The Great Lakes are poised to be invaded by silver carp ( Hypophthalmichthys molitrix) and bighead carp ( H. nobilis). Zebra mussels ( Dreissena polymorpha) and quagga mussels ( D. rostriformis bugensis) have shifted nutrient pathways towards the benthos, partly through deposition of feces and rejected food particles called biodeposits. In a feeding experiment, fed and unfed bigheaded carp lost significant weight, although we also found that bigheaded carps did feed on dreissenid biodeposits. Energy density between fed and unfed fish was not significantly different. A small number of individual fish did gain weight while on the biodeposits diet. Our results demonstrate that biodeposits can be considered a supplemental food for bigheaded carps.