Filter feeding by zebra mussels could reduce plankton and decrease the food base for planktivorous fishes such as shad and shiners. By blanketing sediments, removing fine particulate matter, and depositing nutritious and non-nutritious particles as pseudofeces, zebra mussels could affect the density and biomass of native clams, immature insects, and other invertebrates. Large numbers of mussels could even cover spawning shoals used by riverine fishes.