The Great Lakes serve as a resting place for over six thousand wrecked ships and over one hundred aircraft, with an estimated 30,000 people killed in accidents on their waters. The lakes serve as a time capsule for the victims of doomed voyages, their cold, pristine waters providing ideal conditions to preserve sunken vessels. But with the presence of an invasive mussel species, the remains of these ships and aircraft are facing destruction, and historians are racing to locate these wrecks before they disappear forever.
Quagga mussels originate from the Dnieper River Basin in Ukraine and are invasive in both Western Europe and North America. Quagga mussels are found in droves in four out of the five Great Lakes, with only limited amounts in high-traffic ports of Lake Superior. Biologists guess that around 750 trillion individuals live on Lake Michigan alone. As with any other invasive species, the mussels wreak havoc on the local ecosystem, competing with native species for space and resources. They’re also hardy, tolerating the cold waters of the Great Lakes. But along with environmental consequences, the species is also a grave threat to the preservation of historic wreck sites along the lakebed.
The quagga mussel sticks itself onto wood, such as the remains of a ship. One mussel is only the size of a human finger, but the sheer number of them has left thousands of wrecks coated entirely. What’s worse, the mussels release an acid that eats through metal. Holes are bored into wreckage, diminishing their stability, which can lead them to collapse altogether. Simply peeling the mussels from wrecks is not possible, as doing so would rip away parts of the ships, defeating the whole purpose.
Although the low calcium content of Lake Superior’s waters isn’t the ideal condition for a large amount of mussels, they have been found there and subsequently removed before they could establish a foothold. Efforts to keep Superior mussel-free are ongoing.
The means of fighting the threat are limited. Proposed solutions include introductions of predators or diseases to mussel populations, and the use of poisons on infested wrecks. These methods, however, would also almost certainly come with consequences for native wildlife. When it comes to a permanent, reliable solution to clear the lakes of so many invaders, nothing looks promising.
Maritime archaeologists are doing their best to document as many wreck sites as possible before they are completely destroyed by quagga mussels. Historians are left with the immense task of documenting thousands of ships and finding any undiscovered ruins while there’s still something left to find. Centuries worth of tangible sunken history are at risk of being permanently lost.