The Great Lakes are some of the largest bodies of freshwater in the world. There are five of them: Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario.
These lakes are also famous for having some of the best- shipwrecks anywhere!
The lakes are cold, which slows down the process of decay, like a fridge does with food. And unlike oceans or seas, there is no salt, which can corrode, or damage, metals. These conditions have kept wrecks in amazing shape for hundreds of years.
But now shipwrecks are suddenly decaying fast. Researchers are struggling to record all the information they can before the wrecks are gone forever.
There are two reasons that these shipwrecks are in danger. The first is that climate change is bringing stronger storms and warmer waters. Storms can stir up waters, damaging ships that are normally in more peaceful water.
But the biggest problem facing these shipwrecks is foreign shellfish from Europe. Zebra and quagga mussels are what are known as . This is any species that is not naturally a part of a particular ecosystem.
Invasive species can harm an ecosystem because the animals and plants there are not used to them. For example, invasive species can eat food that other species need to survive. Or without natural predators to eat them, their numbers can grow too rapidly.
Zebra and quagga mussels have had this kind of devastating effect on the Great Lakes. Zebra and quagga mussels first arrived there in the 1980s. They were accidentally brought over by international ships bringing supplies through the Great Lakes. You could say that they hitched a ride across the ocean!
Once they arrived, these mussels multiplied quickly. They have driven local mussel species almost to extinction. And they cover almost every underwater surface—including shipwrecks—in thousands upon thousands of tiny shells.
As they cover the shipwrecks, the mussels gradually destroy the wrecks of both wooden and metal ships. The mussels use tiny threads called filaments to attach themselves to surfaces. These dig into the wood, causing it to crumble. Meanwhile, their poop contains an acid that slowly eats through metal!
Experts have agreed that there is no real way to save the shipwrecks from destruction. Durrell Martin is a scuba diver and president of a group called Save Ontario Shipwrecks. He told CBC that “we can't stop this. Shipwrecks we thought would be here another 200 years from now [will] probably [be gone] within the next 10 to 20 years.” This means that we could lose these pieces of history forever.
This is why some people are working harder than ever to record what we know about the wrecks. Ken Merryman is a diver and computer programmer from Minnesota. He has helped create a website called 3Dshipwrecks that has models of 160 sunken ships. He and his team use a technique called . Divers swim down to take several different images of the wreck from all sides. Then a computer combines the information into one single master 3D image.
He hopes to eventually map out the 1,400 known shipwrecks in the Great Lakes. Even if the wreck collapses, the information will stay intact!
Updated October 19, 2023, 5:03 P.M. (ET)
By John Crossingham
