Not that I know of. It probably happens for some species, but the algae eating snails don't really have the right mouth to eat them and the copepods generally have a pretty fast short distance escape sort of behavior, so they can probably get out of the way in most cases.
They're small, though, and the rule of thumb is that if they fit in the mouth, they are sometimes eaten, so basically everything does - fish, corals, shrimp, etc.. Fewer things seek them out as food, but still a good number, however an adult can often have hundreds of babies and their full life cycle can be around 3 weeks, so they are more than capable of repopulating unless being predated pretty heavily.
