Historians race to find Great Lakes shipwrecks before quagga mussels destroy the sites

Historians are racing to locate Great Lakes shipwrecks before a seemingly unstoppable invasive mussel destroys them and erases part of the region's heritage. Quagga mussels are finger-sized mollusks native to Russia and Ukraine. They were discovered in 1989 in the Great Lakes, which touch eight U.S. states and the Canadian province of Ontario. Similar to zebra mussels, they can attach themselves to almost anything and have spread throughout the lower Great Lakes, outcompeting zebra mussels. Now they have carpeted thousands of shipwrecks, layering themselves so thickly their weight could topple bulkheads and decks on wooden vessels. They also can produce acid that eats away at metal shipwrecks.