Invasive species: A continued battle on the economic and environmental fronts


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By Karie Decker and Craig Allen

What is an invasive species?

Silver carp (a type of Asian carp) jumping next to a boat in the Platte River, 2006 (Dr. Mark Pegg, School of Natural Resources, University of Nebraska-Lincoln)An invasive species is a plant or animal that is not native and has, or is actively, spreading to new environments. Other terms used to describe nonnative species include exotic or alien. In some cases they are extremely damaging to the economy, the environment or human health. Not all nonnative species are harmful, however. Some nonnative species invade native habitats without noticeably disrupting the environment. Those that do cause harm have escaped their natural “enemies” and may occur at extremely high densities. Harmful invasive species often outcompete native plants and animals for food and other resources and may dominate invaded habitats.

Are invasive species a threat?

The land, water and other natural resources in Nebraska are being impacted by an increasing number of invasive species. For example, there are approximately 500 established nonnative plants in Nebraska. You probably passed dozens of them on your way to pick up a copy of Prairie Fire. Many have no documented negative impact, but others are damaging. Dr. David Pimentel and colleagues estimate that there are over 50,000 plant, animal and microbe invasive species in the United States. They estimate that we are spending more than $120 billion dollars annually dealing with problems caused by invasive species. Globally, $1.4 trillion dollars is spent on invasive species each year: This is nearly 5 percent of the global economy. Thus, from an economic standpoint, invasive species are certainly a cause for concern. Specific cost estimates of the damage caused by invasive species in Nebraska don’t currently exist—we are working on estimates. The ecological and environmental impacts of invasive species are much more difficult to quantify. Dr. Dan Simberloff estimates that of the nearly 1,900 imperiled species in the United States, half are endangered because of impacts from invasive species. In Nebraska, invasive species are the most commonly identified threat to our natural legacy, as identified in the Nebraska Legacy Plan. Invasive species have been the primary cause in the extinction of many species. For example, in the first half of the 20th century, Asian chestnut blight fungus virtually eliminated American chestnut trees from the United States. A loss of these trees led to the extinction of 10 moth species that relied solely on American chestnut for survival. Another example is the brown tree snake, which has eliminated 10 of the 11 native bird species from the forests of Guam.

Invasive species of concern in Nebraska?

There are many invasive species currently established in Nebraska and many others threatening to invade. The most recognizable to most Nebraska residents are noxious weeds. Currently, the Nebraska Department of Agriculture identifies nine noxious weeds in the state: musk thistle, plumeless thistle, Canada thistle, leafy spurge, diffuse knapweed, spotted knapweed, purple loosestrife, saltcedar and common reed (Phragmites). Common reed clogs up waterways, such as the Platte River, and has also consumed millions of dollars of Nebraskan’s money. There is a tremendous effort underway to eradicate common reed from the Platte.

There are also some invasive species that pose a significant threat to Nebraska but haven’t received much media attention. Feral hogs are an example. Escaped domestic pigs and Eurasian boars have escaped (or been illegally introduced) in several Nebraska counties. Feral hogs root up agricultural land, are host to several diseases of domestic livestock and represent a tremendous ecological and economic threat. Another species is the emerald ash borer. While not spotted in Nebraska yet, this insect has devastated populations of ash trees across the northeastern U.S. and has spread as far west as Minnesota and Missouri. ReTree Nebraska estimates that emerald ash borer represents a threat to nearly 30 million ash trees in Nebraska and could cause $1.65 billion dollars in tree removal and replacement costs.

Invasive species threatening water use

A group of invasive species that often go undetected are those that are well hidden below our waters. Often referred to as aquatic nuisance species, this group of organisms are certainly of concern. In Nebraska, we rely on our limited water sources for a number of activities such as agriculture, recreation and consumption. Aquatic nuisance species threaten the quality and availability of water. For example, nonnative plants such as hydrilla and water hyacinth (neither found in Nebraska yet) can clog water intakes on motors, which overheat and ruin engines. Zebra mussels can also clog water intakes, attach to propellers and motor parts and affect engine performance. Some harmful nonnative species, particularly plants like hydrilla and water hyacinth, are so detrimental that they completely cover the waters they invade. Waters can become so choked with these nonnative plants that it is impossible to get a boat through them or to swim. Other species such as Asian carp (silver carp, bighead carp and others) grow to such a large size (more than 50 lbs.) that they can actually cause harm to boaters. Stirred up by boat motors, Asian carp frequently jump out of the water, injuring fishermen and skiers. Industrial water users and businesses such as public utilities, power plants, municipal drinking-water facilities and manufacturing industries all need a constant, predictable supply of water. However, the proliferation of these harmful nonnative species, such as zebra mussels, has forced many industries to develop costly control methods to maintain their water intake systems. The costs incurred from these control methods are about $134 billion dollars annually in the United States, and these costs are passed onto consumers like you and me.

Aquatic nuisance species in Nebraska

There are a number of aquatic nuisance species already established in Nebraska waters, and each poses a unique threat. Established aquatic nuisance species include Asian carp, zebra mussels and Eurasian watermilfoil. There are also several species that are established in neighboring states but have yet to find their way to Nebraska (and we’d like to keep it that way). Other species have made it into Nebraska but have not become widespread yet. Two that have received much attention lately are zebra and quagga mussels. These species seem to be surrounding Nebraska—they are currently found in Colorado, Kansas, Missouri and Iowa. In Nebraska, zebra mussels are found in the Missouri River, below Gavin’s Point Dam and, until recently, in Lake Offutt on Offutt Air Force Base.

The zebra mussel scare in Nebraska

In April 2006, the Nebraska Game and Parks Commission confirmed the presence of zebra mussels in Lake Offutt, Offutt Air Force Base. Shortly after, a Zebra Mussel Working Group was formed, with 21 members representing local and regional stakeholders from federal, state and local governments. The Zebra Mussel Working Group met several times in 2007, establishing both short- and long-term goals for the control and management of zebra mussels. Their primary concern about the zebra mussel infestation in Lake Offutt was the potential for spread into the Missouri River and connected water bodies. Zebra mussel invasion into the Missouri River Watershed would lead to extensive ecological and economic damage to the entire region. Zebra mussels would negatively impact natural resources. Numerous cities, electric power companies and other industries utilizing the river would bear the economic burden of zebra mussel control. In an effort to restrict the spread of zebra mussels from Lake Offutt, the working group temporarily closed the lake to private use and closed the outlet between Lake Offutt and Bellevue Drain. In addition, the Zebra Mussel Working Group began planning for complete eradication of zebra mussels from Lake Offutt. By May 2009, Lake Offutt had received two treatments of copper sulfate, as recommended by William Haller (acting director of aquatic and invasive plants at the University of Florida) in his 2007 report specific to Lake Offutt. Post-treatment monitoring for zebra mussels in 2009 indicated that the eradication was successful, although monitoring will continue for the next two years to verify long-term eradication.

A response to the zebra mussel scare: The Nebraska Aquatic Nuisance Species Plan

The zebra mussel infestation at Lake Offutt alerted many agencies and organizations to the significant threat of aquatic nuisance species. Although the eradication of zebra mussels was successful, there will be future infestations of this and other species. Realizing that prevention is the most economic and effective way to deal with aquatic nuisance species, a group of aquatic experts representing state and federal agencies as well as public industries established a planning committee to develop a comprehensive management plan for aquatic nuisance species in Nebraska. Under guidance from the National Aquatic Nuisance Species Task Force, the Nebraska Aquatic Nuisance Species Management Plan aims to identify gaps in aquatic nuisance species management and research and to coordinate efforts across the state.

Nebraska is one of the few states without an Aquatic Nuisance Species Plan. Our plan will increase communication and collaboration among state and federal agencies, develop tools to educate and inform the public about aquatic nuisance species and, in turn, help protect Nebraska’s economy and environment. A draft of the Nebraska Aquatic Nuisance Species Management Plan will be available for public comment this spring. In addition, there will be public meetings to discuss a draft of the plan and incorporate public comment.

An ounce of prevention is worth a pound of cure

Prevention is by far the most economical and effective means of managing invasive species. For example, Colorado State Parks estimates that the costs to establish a boat inspection and decontamination program for zebra mussels and other aquatic invasive species at high-risk water bodies average less than $1 million dollars a year. However, in areas where zebra mussels are established, such as the Great Lakes, the National Aquatic Nuisance Species Task Force estimates costs to control zebra mussels to be more than $30 million dollars a year. Citizens of Nebraska can play a critical role in helping to prevent the spread of some species and the introduction of others. The Nebraska Invasive Species Project strives to educate various public groups on the impacts of invasive species on Nebraska’s land and water.

What can you do?

Plant Native. With spring approaching, always consider planting native plants rather than nonnative plants. Not only are native plants just as beautiful, they often require less water and care because they are adapted to Nebraska’s climate. Also, consider purchasing plants and seeds from local nurseries. Plants and seeds imported by nurseries have repeatedly served as a pathway for invasive species. Approximately 2.5 billion live plants are imported into the United States each year, and many arrive with unintended hitchhikers. Visit Prairie Nebraska or the Nebraska Aboretum for more information on plants native to Nebraska.

Clean Your Boat. Nebraskan’s love to spend time on and in the water. Protecting water resources is an important part of our overall enjoyment. Aquatic nuisance species can hitch a ride on our clothing, boats and items used in the water, then transfer to another lake or river. By following a simple procedure each time we leave the water, we can stop aquatic hitchhikers: (1) Remove any visible mud, plants, fish or animals; (2) Eliminate water from equipment; (3) Clean and dry anything that came into contact with water (boats, trailers, equipment, clothing, dogs, etc.); and (4) Never release plants, fish, or animals into the water (even baitfish). Complete instructions and additional information can be found at the Nebraska Invasive Species Project Boater Awareness Web page.

Don’t Move Firewood. With the increasing threat to Nebraska’s forests, we want to pay particular attention to where our firewood comes from. New infestations of tree-killing insects and diseases are often first found in campgrounds and parks. Why? Because people accidentally spread these invasive species when they bring in firewood. Don’t risk it. Leave your firewood at home, and then buy new wood near to where you’ll burn it. As the logo says, “burn it where you buy it.” Find more information on how invasive species are spread through transported firewood:

Don’t Release Your Pets. According to the U.S. Geological Survey, over 2,000 species are imported into the United States for use in the aquarium trade each year, and nearly as many snakes and birds are imported as pets. Unfortunately, a number of nonnative fish and animals are released into the wild each year. Some people may not be able to take their pets with them when they move, or they simply may lose interest in maintaining their pet. Whatever the reason, releasing pets into local forests and waters is not a good idea and is usually illegal. But there are sound biological reasons not to release pets, too: (1) Released pets may have harmful impacts on the environment; (2) They will be susceptible to parasites and diseases; and (3) They may be attacked by native predators. Instead of releasing a pet into the wild, return it to a local pet shop, give it to a friend or donate it to a public institution like a school or nursing home. Follow this link for more information:

The Power of Knowledge. By far the most important thing you can do to help prevent the spread or introduction of invasive species is to educate yourself. Learn what nonnative species are in your area and what their impacts are. Remove nonnative plants and animals from your yard, where feasible. Participate in local weed workshops or volunteer at an Earth Day event. And, most importantly, pass on what you have learned to others. Visit the Nebraska Invasive Species Project for information on invasive species.

Keep an eye out for identification tips and information on specific invasive species in Nebraska in upcoming issues of Prairie Fire.


Silver carp distribution in the U.S., March 2010.

Zebra and quagga mussel distribution in the U.S. November 2009 (USGS)


Submitted by Anonymous (not verified) on

It cannot be stressed strongly enough that you cannot move firewood!! It is so dangerous to bring in new insects and diseases. If you're going to move firewood, move it to your fireplace from your firewood rack and enjoy a nice fire! Don't do something stupid and harm Nebraska.

Submitted by Hydrilla (not verified) on

One plant species that is so invasive is the hydrilla. It is such a nuisance and very troublesome.

Immigration in Nebraska