Usually, when people think of vacationing on a beach with vibrant, blue water, they picture a tropical island somewhere, not a location in the United States. But in parts of the Great Lakes, you can see just that. Over the last several years, the lakes have developed the bright, clear waters typically associated with the Caribbean.
Pictured Rocks National Park from Lake Superior. Photo courtesy of icmcwaffle
It hasn't always been this way. Zebra and quagga mussels are responsible for the transformation of the waters in the Great Lakes. In the late 1980s, the first of the non-native mussels were found in the United States, believed to have been brought over in waters from Europe. Since then, they have been spreading across the Great Lakes region and moving through rivers into other parts of the country.
The mussels are filter-feeders. They pull down organic particles down and strain them through. The process eliminates organisms, like plankton, from the water, resulting in the clear, blue waters in the lakes.
"They act like a big pump at the bottom of the lakes," said Mac Strand, professor of biology at Northern Michigan University.
At first the big focus was on the zebra mussels, but Strand says it's the related species the quagga that is taking over the system now.
"They can survive colder temperatures than the zebra mussels," Strand explains. "They can go into deeper waters where the zebras couldn't."
The invasive species are doing significant damage on the ecosystem, particularly for native mussels. The zebra and quagga mussels anchor themselves onto the native mussels, which hinders their ability to function. The waters in the affected lakes are so clear because the algae and other organisms are being wiped out, which are supposed to provide a food source to many other aquatic creatures.
These species are reproducing at incredible rates (a single female can lay over a million eggs a season), and without any natural predators they aren't being slowed down. While edible to ducks, fish and people, their small size makes them not much worth the effort to open, resulting in few predators trying to eat them. Their small size also results in eggs that are undetectable by the human eye, making them easy to accidentally transport.
The best way to help prevent the further spread of the invading species is for people to not transport water from one lake to another. Any fishing, boating or other water gear should be thoroughly cleaned and disinfected before being taken to a different body of water.
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