“Manifest Destiny” describes the belief held by many 19th century Americans that the fledging nation was fated to expand to the West Coast. The phrase has taken on a new context in the 21st century as biological scientists have expressed fears that the spread of aquatic invasive species from the East Coast toward the west has the same underlying sense of inevitability. The principle culprits in the aquatic invasion of North America’s waterways are two invasive mollusk species — quagga and zebra mussels — which were introduced into the Great Lakes region via the ballast of freight ships originating in …