Quagga and Zebra Mussels

Quagga and Zebra mussels are currently a major threat to the United States Lakes, including Arizona and Utah’s Lake Powell. The infiltration of this invasive species is a major threat to aquatic life and has a costly effect on numerous industries. The infiltration of mussels is so serious a threat that a law was passed in 2009 to help prevent their spread. Called “Don’t Move a Mussel – NOW it’s the LAW,” this law requires boaters to “clean, drain, and dry” as well as wait 5 days between boating trips to separate bodies of water.

It is of the utmost importance that boaters take proper precautions to help prevent the spread of Quagga mussels. Once these mussels have taken up home in a body of water, there is no effective method to fully remove them. Science currently offers no solution which can kill these mussels without bringing equal harm to other natural aquatic life. The primary source of their spread is human-related so boaters should be aware of the laws surrounding Quagga mussels and the ways in which they can help prevent further invasion.


Quagga mussels (dreissena bugensis), and the similar Zebra mussels (dreissena polymorpha) are two species of invasive, freshwater, bivalve mussels. Quagga mussels, in addition to Zebra mussels, both contain striped shells. Quagga mussels are more round in shape and are lighter towards their hinge while Zebra mussels are triangular and are occasionally flat on one side. While the two species maintain a few small morphological and ecological differences, each presents the same threat to any lake.

These mussels were originally found in Eastern Europe. Formerly, they primarily inhabited the Dnieper River drainage of the Ukraine while Zebra mussels originated in the Caspian, Black, and Azov Seas. The invasive species were first found in the United States in 1988. Originally discovered within the waters of Lake Saint Clair, Michigan, they are thought to have been brought to the United States in 1986 through ballast water discharge from ocean-going ships.

Quagga mussels were discovered in Lake Mead and Lake Havasu during 2007, Lake Powell in 2012. Until then the lakes showed no sign of infiltration until the current population’s emergence.


Quagga and Zebra mussels destroy the native aquatic life that exist in the freshwater lakes they infiltrate. These mussels are filter feeders who feed extensively on small organisms called plankton that are found naturally within the water. One single mussel is capable of filtering up to an entire liter of water a day.

The effect of these mussels can be misleading as their elimination of plankton can give way to clearer water. At first glance, water clarity may be seen as a sign of cleaner water. However, this clarity actually indicates a major problem for native fish populations. The clarity comes from the lack of plankton which leaves other fish and aquatic species with nothing to eat. This problem trickles down to effect all levels of the ecosystem.

In addition to the loss of fish populations, water clarity also causes algae growth. Clearer water means that sunlight is allowed to reach the bottom of the lake, facilitating the growth of algae and the advancement of deadly algae blooms. This, in turn, can cause botulism outbreaks that subsequently kill thousands of fish and aquatic birds.

Quagga and Zebra mussels secure themselves in colossally-sized colonies that can block water intake and affect municipal water supplies as well as agricultural irrigation and power plant operations. Costing Federal, State and local agencies millions of dollars annually to control, prevent and remove these mussels.


Since their discovery in 1988, these mussels have been found in 29 states, mainly clustered around the Great Lakes. However, in 2007 they spread all the way to Lake Mead, and other freshwater lakes along the Utah-Arizona border. The mussels spread mainly by attaching to boats traveling between bodies of water. In addition to this hitchhiking method, they also spread through artificial channels such as the Chicago Area Waterways System which allows mussels to quickly and dangerously disperse themselves to surrounding waters.


Once these mussels are found in a body of water, their complete removal becomes impossible. One mussel has a lifespan of three to five years. In that time, they are able to release up to 1 million eggs each year with 100,000 of those eggs reaching adulthood. The offspring of just one mussel will bring about the reproduction of over half a billion more mussels. Today, there are an estimated 10 trillion Quagga and Zebra Mussels in the Great Lakes, all spawned between now and the late 1980’s.


These mussels cause millions of dollars of damage every year by attaching to boats, water intake pipes and ruin beaches and are known to cause extensive damage to boat motors.

Boaters are required to “clean, drain, and dry” as well as making sure not to visit any other lake for at least 7 days after visiting a lake that contains Quagga mussels.

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