Zebra mussel facts for kids
Quick facts for kids Zebra mussel |
|
|---|---|
_0265_(39449820624).jpg) |
|
| Conservation status | |
| Scientific classification | |
| Genus: |
Dreissena
|
| Species: |
polymorpha
|
The zebra mussel (Dreissena polymorpha) is a small freshwater mussel. These mussels come from lakes in southern Russia and Ukraine. But they have accidentally spread to many other places. Now they are an invasive animal in many countries around the world. Since the 1980s, zebra mussels have moved into the Great Lakes, Hudson River, and Lake Travis.
A German zoologist named Peter Simon Pallas first described this species in 1769. He found them in the Ural, Volga, and Dnieper Rivers. Zebra mussels get their name from the striped patterns often seen on their shells. However, not all of them have stripes. They are usually about the size of a fingernail. But they can grow up to 50 mm (2 in) long. Their shells are D-shaped. They attach to surfaces with strong threads called byssal fibers. These threads come from the hinged side of their shell.
Contents
How Zebra Mussels Live
Zebra mussels and quagga mussels are filter feeders. This means they clean the water by removing tiny particles. Each zebra mussel can filter up to 1 litre (0.26 US gal; 34 US fl oz) of water every day. They eat some of these particles. Other particles are mixed with mucus and dropped to the lake floor. This waste is called pseudofeces.
After zebra mussels arrived in Lake Erie, the water became much clearer. It went from clear for 6 inches to clear for up to three feet in some spots. Clearer water lets more sunlight reach deeper. This helps underwater plants grow more. When these plants decay, they can wash up on beaches. This makes beaches dirty and can cause water quality problems.
Zebra mussels also help feed animals that live on the lake floor. They filter pollution out of the water. This food then becomes available for bottom-feeding animals. It also helps fish that eat these bottom-feeders. For example, the number of yellow perch caught in Lake St. Clair increased five times after zebra mussels arrived.
Zebra mussels can attach to most surfaces. This includes sand, silt, and hard rocks. Young mussels usually prefer hard, rocky surfaces. They often attach to other mussel species. These native mussels are often the most stable objects in silty areas. Zebra mussels can cover and kill these native mussels. They form colonies on native clams called unionids. This makes it hard for the clams to move, eat, and reproduce. Eventually, the native clams die. This has almost wiped out unionid clams in Lake St. Clair and western Lake Erie. The same thing is happening in Ireland. Zebra mussels have removed two types of freshwater mussels from several waterways there.
In 2012, the National University of Ireland, Galway warned about zebra mussels. They said the mussels could cause "considerable ecological and economic damage." This was after they were found in Lough Derg and the lower Shannon River in 1997.
Zebra Mussel Life Cycle
A zebra mussel lives for about four to five years. A female zebra mussel starts to reproduce about 6–7 weeks after it settles down. An adult female can produce 30,000 to 40,000 eggs in each breeding cycle. This means over 1 million eggs each year.
Their tiny, free-swimming babies are called veligers. They float in the water for several weeks. Then, they settle onto any hard surface they can find. Zebra mussels can live in many different conditions. Adult mussels can even survive out of water for about 7 days.
Zebra Mussels and Pollution
Zebra mussels can help us find out about water pollution. They are good at showing if there are risks to humans from environmental dangers. When zebra mussel gill cells are exposed to pollutants, their DNA can get damaged. This damage can be measured.
Who Eats Zebra Mussels?
Scientists have studied animals that eat zebra mussels. In Europe and North America, birds (36 species) and fish (15 species eating veligers, 38 eating attached mussels) are predators. In Lake Constance, winter birds eat over 90% of zebra mussels in shallow areas.
Most of the zebra mussel's natural enemies are not found in North America. Similar animals exist, but they probably cannot get rid of the mussels that are already here. They also don't control them as well as their European relatives.
Crayfish can eat many zebra mussels. An adult crayfish can eat about 105 zebra mussels every day. That's about 6,000 mussels in one season. However, they eat fewer mussels when the water is cold. Some fish, like the Smallmouth bass, also eat zebra mussels in North America. But in European lakes, fish do not seem to control the number of zebra mussels.
Sometimes, many fish die in winter. This happened in the winter of 1994–1995 in Lake Simcoe. This was partly due to crayfish eating the mussels. But it has not been enough to solve the problem.
Other Ways to Control Zebra Mussels
On June 4, 2014, Canadian authorities announced a successful test. They used liquid fertilizer to kill invasive zebra mussels. This test was done in a harbor in Manitoba. However, zebra mussel outbreaks continue in Lake Winnipeg.
Similar tests were done in Illinois, Minnesota, and Michigan. They used a biopesticide called zequanox. Another chemical, Niclosamide, also works well to kill zebra mussels in cool water.
Zebra Mussels as an Invasive Species
Europe
Zebra mussels originally lived in the Black Sea and Caspian Sea in Eurasia. They have become an invasive species in North America, Great Britain, Ireland, Italy, Spain, and Sweden. They harm ecosystems by taking over areas. They also damage harbors, waterways, ships, and power plants. Water treatment plants are especially affected. This is because water intakes pull the tiny mussel larvae directly into the facilities. Zebra mussels also stick to pipes underwater and clog them.
Zebra mussels were seen in Hungary in 1794. They quickly spread in Britain. They were found in Cambridgeshire in the 1820s, London in 1824, and near Edinburgh in 1834. In 1827, they appeared in the Netherlands at Rotterdam. Canals that connect many European waterways helped them spread early on. They are not native to the Czech Republic. They have been in the Elbe River since 1893. Around 1920, the mussels reached Lake Mälaren in Sweden.
The first time they appeared in northern Italy was in Lake Garda in 1973. In central Italy, they showed up in Tuscany in 2003.
Zebra mussels are a problem in British waterways. Many water companies have issues with mussels sticking to their pipes. Anglian Water estimates it costs them £500,000 each year to remove the mussels. Zebra mussels have also affected fishing. For example, at Salford Quays, their arrival changed the environment for fish.
The mussels have pushed out native mollusc species in Lake Constance. They can reach densities of up to 10,000 mussels per square metre (930/sq ft). The mussels are a food source for water birds. This has caused bird numbers to double in the last 30 years. By the end of winter, birds can reduce zebra mussel populations by 95–99% in shallow areas.
North America
Zebra mussels were first found in Canada in the Great Lakes in 1988. They were in Lake St. Clair. It is thought that they were accidentally brought into the lakes by the ballast water of large ships. These ships traveled through the St. Lawrence Seaway. Another possible way they spread is on anchors and chains. Adult zebra mussels can live out of water for several days if it's cool and humid. So, anchor storage areas could hide mussels. These could then be released when ships drop anchor in freshwater ports. Because they are an invasive species in North America, there are laws to control them. One example is the National Invasive Species Act (1996).
Scientists predicted that zebra mussels would likely spread to the Southern United States. This prediction has since been proven true. By March 2016, zebra mussels had affected hundreds of lakes in the Midwest. This includes Lake Michigan and Lake Winnebago.
Experts believe that zebra mussels have cost businesses and communities over $5 billion since they first arrived. Power companies alone have spent over $3 billion because of them.
On March 2, 2021, the US Geological Survey learned about zebra mussels. They were found in marimo moss balls. These are common aquarium plants sold in pet stores. By March 8, the mussels were found in moss balls in 30 different states. This happened at many stores. The first discovery was at a Petco in Seattle. Infected moss balls were also found from online sellers and smaller stores. A fisheries biologist, Wesley Daniel, said about 30% of the moss balls pulled from shelves had zebra mussels.
After working with the USGS, PetSmart and Petco removed their moss balls from sale. This was because of the harm zebra mussels could cause to local ecosystems. As of November 2021, moss balls have not returned to shelves.
Where They Are Found
Since 1988, zebra mussels have spread to many waterways in North America. This includes Lake Simcoe, the Mississippi, Hudson, St. Lawrence, Ohio, Cumberland, Missouri, Tennessee, Huron, Colorado, and Arkansas rivers. They are also in 11 lakes and five river basins in Texas.
In 2009, zebra mussels were found in Laurel Lake in the Berkshires. That same year, live zebra mussels were found in Pelican Lake in Minnesota. This was the first time they were confirmed in the Red River Valley. This area stretches into Manitoba. In 2013, their presence in Manitoba's Lake Winnipeg was confirmed. Efforts to get rid of them in 2014 did not work. New contamination was found in Lake Winnipeg in 2015. They were also found in the Red River near the lake in 2015. Many were seen at Grand Beach in 2017.
In July 2010, zebra mussel larvae were confirmed in the Red River. This was between Wahpeton, North Dakota, and Breckenridge, Minnesota. California also reported invasions as recently as 2008.
In 2011, zebra mussels caused a water pipeline to shut down in Dallas. This led to less water during a drought year. It made water restrictions worse in the Dallas area.
Scientists believe zebra mussels will keep spreading. They will move passively by ships and pleasure boats. This spread can be stopped. Boaters must clean and dry their boats and equipment very well. This should be done before moving them to new bodies of water. No North American predator has been shown to greatly reduce zebra mussel numbers. So, if they spread, they will likely stay permanently in many North American waterways.
In the summer of 1993, the Seneca River had much less dissolved oxygen. This was caused by many zebra mussels in the area. The Seneca River also had less chlorophyll in the water. This shows less phytoplankton, which is food for other animals.
The Cost of Zebra Mussels
It costs a lot to fight zebra mussels at power plants and other places that use water. The Center for Invasive Species Research says managing zebra mussels in the Great Lakes alone costs over $500 million each year. Another study estimated total costs of $267 million for power and water plants in the U.S. from 1989 to 2004. A 2009 study by the US Department of State estimated the total cost of the zebra mussel invasion at $3.1 billion over the next 10 years.
There are also worries about zebra mussels in home aquariums. If zebra mussels had reached open water in Seattle, Washington, it would have cost the state $100 million each year. This would be for maintaining power and water systems.
What Zebra Mussels Do
Like most clams, zebra mussels are filter feeders. They open their shells in the water to take in tiny bits of food. Their shells are very sharp. They are known for cutting people's feet. So, it's important to wear water shoes where they are common.
Since they arrived in the Great Lakes, they have covered the bottoms of docks, boats, and anchors. They have also spread into streams and rivers across the U.S. In some places, they completely cover the bottom of the water. They sometimes cover other freshwater mussels. They can grow so thick that they block pipelines. This clogs water intakes for cities and hydroelectric companies. Zebra mussels do not stick to certain metal alloys. These can be used to coat grates, buoys, boats, and motors where the mussels often gather.
Zebra mussels are thought to cause deadly avian botulism poisoning. This has killed tens of thousands of birds in the Great Lakes since the late 1990s. Zebra mussels can be eaten. But they are very good at filtering water. This means they can collect pollutants and toxins. So, most experts advise against eating them.
They are causing many species in the Great Lakes to almost disappear. They compete with native species for food. They also grow on top of and suffocate native clams and mussels. Zebra mussels affect all types of algae. This leads to less food for native freshwater mussels and fish in the Great Lakes.
However, zebra mussels and other non-native species have also helped some fish. The number and size of smallmouth bass in Lake Erie have increased. The same is true for yellow perch in Lake St. Clair. They clean the water in lakes. This lets more sunlight reach deeper. It helps native algae grow more. This cleaning also makes the water clearer and filters out pollutants. Each mussel filters about 1 litre (1 US quart) of water per day in small tanks. In lakes, their filtering usually affects only areas near the bottom.
In Lake Pleshcheyevo (Russia), zebra mussels have greatly changed the fish community. All fish species stayed in the lake. But the number of fish caught changed a lot. More large roach and perch were caught in shallow areas. Vendace were more common in open water. Fish that eat bottom-dwellers increased slightly. This was because zebra mussels became a big part of their diet. The growth rates of roach and silver bream increased. But the growth rates of bream, which prefer soft bottom food, decreased. The zebra mussels also likely changed where fish live in the lake. Small roach disappeared from open water areas. This was probably due to changes in food sources. It also likely increased competition for food among fish in open water.
Because zebra mussels damage water intakes, new methods are being used. These include adding chemicals, heat, drying out pipes, and mechanical removal. Pipe coatings are also becoming more common.
Stopping Their Spread
Zebra mussels can stick to boat motors. Boat owners should take steps to stop the spread of these mussels. This should be done before putting their boats into a new lake. It should also be done after taking boats out of infected lakes.
Boat owners should:
- Inspect their boat, trailer, and other equipment that touched water.
- Remove all mud, plants, or animals.
- Drain all water from their boats, engines, and equipment. This includes bilge water, live wells, and bait buckets.
- Wash all parts of their boats, paddles, and other equipment that touched water. Use warm, soapy water.
- Dry their boats and trailers in the sun for five days. Do this before launching into another body of water. This is important because adult zebra mussels can close their shells. They can survive out of water for several days.
If you bought marimo moss balls around March 2021, you should clean them. You can boil them for at least one minute. You can also freeze them for at least 24 hours. Another way is to put them in diluted chlorine bleach. Or, you can soak them in undiluted white vinegar for at least 20 minutes. After doing one of these methods, put the moss balls in a bag. Then throw them in the trash. This stops them from spreading to local waterways.
Even if moss balls with zebra mussels are in an aquarium, they could still spread. This is especially true in areas where they are not yet found. People sometimes dump aquariums or unwanted pets. This can spread invasive species. It is against the law to own, sell, or give away zebra mussels in the U.S. If you see them, either in an aquarium or in nature, contact your local Department of Natural Resources (DNR).
See also
In Spanish: Mejillón cebra para niños
