Hmm. Well, I imagine you are right but it would have been helpful to know so some of the locals could have begun importing it into the area to help with combating this upcoming threat.
According to Wiki, zebra mussels are eaten by crayfish, smallmouth bass, and some species of birds, although it doesn’t name the birds.
http://www.biokids.umich.edu/critters/Dreissena_polymorpha/ has a list of fish that will eat them.