THE POTENTIAL OF THE BULL-CHUB (NOCOMIS-RANEYI) AS A PREDATOR OF THE ZEBRA-MUSSEL (DREISSENA-POLYMORPHA) IN MID-ATLANTIC COASTAL RIVERS

The feeding ecology and pharyngeal teeth of the bull chub (Nocomis ran eyi) were investigated to determine whether the species could potentia lly crush and ingest zebra mussels (Dreissena polymorpha), should this mollusk became established in coastal rivers of the mid-Atlantic Unit ed States. We hypothesized that if bull chubs could crush mollusks sim ilar in size and shell thickness to zebra mussels, bull chubs could su ccessfully prey upon zebra mussels. The introduced Asiatic clam (Corbi cula fluminea) was used as a surrogate for the zebra mussel. Gut conte nt analysis of larger (TL = 126 mm+) bull chubs from the James River, Virginia, revealed that mollusks were a dominant prey item, and Asiati c clams were ingested by bull chubs >125 mm TL. Shell thicknesses of z ebra mussels and Asiatic clams of equivalent shell lengths were compar ed, and Asiatic clam shells were significantly thicker (P < 0.001) tha n zebra mussel shells. Because bull chubs ingest and crush the thicker -shelled Asiatic clam, the fish could successfully prey upon the zebra mussel if it becomes established in coastal rivers of the mid-Atlanti c United States.