What are Aquatic Invasive Species?

And what are we doing to stop the spread of quagga mussels?

Aquatic invasive species are any nonnative plant or animal species found in water that are a threat to the abundance, health or diversity of native and/or sport aquatic species.

One example of destructive aquatic invasive species in Utah are quagga mussels, which are native to the Aral, Black and Caspian seas, and some rivers in Ukraine. They were introduced to the Great Lakes in the late 1980s (likely as a result of ballast water discharge), and spread quickly to other U.S. waterbodies via contaminated boats and other watercraft. Quagga mussels are currently only established in one Utah waterbody, Lake Powell, where they were confirmed in 2012.

Quagga mussels are bivalve (two-shelled) mollusks that are shaped like the letter “D” and vary in color from brownish yellow to black. Quagga mussels reproduce via eggs that free-float in the water until fertilized, and then the microscopic larvae — called veligers — emerge after three to five days. Veligers are dispersed in the water while they grow and are free swimming for up to a month until they are large enough to secure an attachment site on just about any kind of surface. They go through metamorphosis and grow an adult shell, reaching maturity in one to two years.

Even though quagga mussels are very small — at maturity, they’re about the size of a thumbnail — they easily attach to hard surfaces, grow very quickly and can accumulate huge colonies of thousands of mussels. Just one single mussel can reproduce over 1 million eggs per year. Unlike the mussels you find at your seafood market, quagga mussels are not edible for human consumption.

Why are quagga mussels bad?

  • As filter feeders, these nonnative mussels remove phytoplankton and other organic matter from the water. Although that may seem like a great way to keep the aquatic environment clean, quagga mussels are so efficient at removing large amounts of phytoplankton that they deplete this crucial energy source. Phytoplankton are the primary food source of another type of plankton called zooplankton. Many native fish species and sportfish rely on zooplankton, and the impacts that quagga mussels have on phytoplankton indirectly impacts fish.
  • Dead mussels wash up on beaches and release foul odors. Also, their broken shells are razor sharp, which makes walking on beaches or in shallow water dangerous for people, pets and wildlife.
  • Once established, quagga mussels cause almost immediate and widespread destruction. They clog and damage water pipes, power plant machinery, agricultural equipment and boat engines. If they got into water delivery systems in Utah, it would cost millions of dollars annually to remove them and keep the pipes free, which would result in higher utility bills for residents.

How do we get rid of quagga mussels?

Removing quagga mussels is very expensive and time consuming. Once these types of mussels are established, they are almost impossible to eradicate; they have an astounding ability to resist chemical and other methods of removal. Because of this, it is most effective to decontaminate equipment to prevent quagga mussels from being transported from one waterbody to another.

One of the most reliable methods of quagga decontamination is spraying or submerging watercraft with very hot water — water much hotter than the temperature of residential water heaters or a car wash. This is the method used at DWR decontamination stations and dip tanks, and by certified professional AIS decontamination companies. (Due to these specific requirements, DWR stations and certified professional AIS decontamination companies are the only entities authorized to perform decontaminations in the state.)

In addition to our inspection station and decontamination programs, we routinely monitor other Utah waterbodies for the presence of quagga mussels at all life stages.

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