The Erie canal was of tremendous economic importance at the time of its construction, but carried with it some devastating ecological consequences. The construction of the canal is now credited with being responsible for the introduction of a number of exotic species to the Great Lakes to the east of Lake Ontario. Niagara falls was not only a barrier to easy human traffic on the water ways, but also kept aquatic species from invading those systems.

The most famous of these invaders is the sea lamprey, which quickly spread throughout lakes Erie, Huron, Michigan and Superior after the opening of the canal. The species had devastating effects on the native salmonid (trout) communities, and they are still widespread today despite intensive and expensive control measures.