Invasive Zebra Mussels Continue to Disrupt
Natural Ecosystems in Local Lakes
by Makya Rodriguez, age 15
Many of us enjoy the local lakes here in Madison. But what people might not know is that our lakes are being invaded.
Zebra mussels are D-shaped mussels that can grow up to two inches in length. They usually have yellow and brown shells with stripes. This invasive species was first discovered in the Madison lakes in 2015 by a class of University of Wisconsin students, although evidence suggests the mussels were present in Lake Mendota as early as 2012. Since that time, zebra mussels have spread to other area lakes including Monona, Wingra, and Waubesa.
These invasive freshwater animals now live in about 250 of Wisconsin’s lakes and rivers, according to the Department of Natural Resources. They arrived in North America as microscopic larvae traveling from Europe or Asia in the ballast water of ships and have since spread through the Great Lakes and various connected water systems.
Zebra mussels cause bad effects in the water systems in which they live. The mussels compete for food, algae and resources needed by native fish. One of the things that zebra mussels don’t eat is cyanobacteria, also known as blue-green algae. This type of algae is a huge problem in Madison lakes because it is toxic to humans and it thrives in areas where zebra mussels are present.
Zebra mussels also help filter a lake's water, and although that might sound helpful, it’s really not. Filtering these lakes allows sunlight to hit the lakebed which creates layers of filamentous algae. This kind of algae often washes up on shorelines where it creates unpleasant smells and makes the lake shore less inviting.
There are several methods to try to remove zebra mussels. Some of these methods include large vacuums or manual removal. It is, however, very difficult to get zebra mussels under control once they have established themselves in large lakes like Lake Mendota.
Zebra Mussels do have some natural predators such as fish or birds. But because these predators consume only limited amounts zebra mussels, they do little to control the problem. People can help limit the spread of zebra mussels by cleaning their boats and removing mud and plants before moving them from one lake to another lake. Furthermore, people should not release plants or fish that are not native to the lake, including aquarium plants, fish, or animals.
Zebra mussels are probably here to stay, so next time you are at a lake, watch out for a sharp zebra mussel which might be right under you. They not only hurt your feet, but they also hurt our lakes and disrupt the natural ecosystems of other Wisconsin waterways.
[Sources: cleanlakesalliance.org; Madison.com; Wisconsin DNR]