Invasive species threaten our health, economy, and environment.
Over the past two centuries, thousands of new species have been introduced to the United States; one in seven has become invasive, meaning it causes environmental, health, or economic harm. Natural Resources Defense Council
Invasive species pose serious health risks.- In 1991, a South American strain of the human cholera bacteria Vibrio cholerae O1 was found in ships arriving from South America in the port of Mobile, Alabama. This cholera strain was later found in Mobile Bay seafood, prompting a public health advisory to avoid handling or eating raw seafood. U.S. Aquatic Nuisance Species Task Force This strain killed 9,642 people in Latin America from 1991-1994. Center for Disease Control
- The invasive Asian tiger mosquito is a carrier of West Nile Virus, a disease commonly found in humans, birds, horses, and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East. West Nile Virus, first documented in the United States in 1999, has so far caused 149 human cases of severe disease and 18 deaths. West Nile Virus has been found in 27 states. Center for Disease Control
In a study published in Nature in 2000, researchers detected Vibrio cholerae in the ballast water of all tested ships arriving in Chesapeake Bay from foreign ports, including the recently emerged serotype 0139, which was isolated in Bangladesh. Sea Grant
- Ballast water release is the likely mechanism that brought red tides from Asian seas to American coastal systems. Red tide blooms are linked to fish kills and the toxins emitted from red tides produce saxotoxins that cause serious human health problems. U.S. EPA
- The cost of invasive species to the national economy has been estimated as high as $137 billion per year, and it is increasing. The Nature Conservancy
- This includes the cost of control, damage to property values, health costs and other factors. Just one species can cost government and private citizens billions of dollars. U.S. Fish and Wildlife Service
- In agricultural production, invasive plants out compete crops for soil and water resources, reduce crop quality, interfere with harvesting operations, and reduce land values. The estimated annual loss in productivity of 64 crops is $7.4 billion. U.S. Fish and Wildlife Service
- On rangelands, invasive plants crowd out more desirable and nutritious forage, cause soil erosion, and poison some wildlife and livestock species. U.S. Fish and Wildlife Service
- In natural areas, invasive plants degrade riparian areas, create fire hazards, and interfere with recreational activities. U.S. Fish and Wildlife Service
- Aquatic invasive plants clog lakes and waterways and adversely affect fisheries, public water supplies, irrigation, water treatment systems, recreational activities, and shipping. U.S. Fish and Wildlife Service
- Reductions in native fish populations (such as lake trout, walleye, yellow perch and catfish) threaten a sport and commercial fishing industry that is valued at almost $4.5 billion annually and supports 81,000 jobs. U.S. Aquatic Nuisance Species Task Force
- Invasive species wreak havoc on an ecosystem in a number of ways. Invasive animals consume resources upon which native species depend, destroy crops or sensitive habitat, and alter the food chain in an ecosystem by becoming the dominant predator. Invasive plants crowd out native species or upset an ecosystem to such an extent that native plants and animals can no longer survive.
- Invasive species have contributed to the decline of 46 percent of the country’s endangered and threatened native species. Natural Resources Defense Council
- The habitat of fully two-thirds of all threatened and endangered species is threatened by invasive species. U.S. Fish and Wildlife Service
- Three million acres, an area twice the size of the state of Delaware, are lost to invasive plants alone each year. U.S. Fish and Wildlife Service
Current management efforts lack coordination and focus.
- Management of invasive species falls under a myriad of statutes and regulations administered by a variety of agencies on the international, federal, state, and local levels.
- Laws were often passed to address a specific crisis (such as zebra mussels) and pathways of introduction of the species (such as ballast water).
- Policy studies have found that, as a result, “laws leave both obvious and subtle gaps in the regulation of [invasive species]” and “overlaps and gaps in this array of statutes often leave the Agency unsure of which authority to apply in any give case.”(1)
A state Invasive Species Council will coordinate and consolidate management efforts to meet the invasive species challenge.
- The Council will consist of representatives from each agency whose activities affect invasive species management.
- The Council will create an Invasive Species Coordination Plan that will provide a single strategy to address all types of invasive species, all causes of introduction and spread of these species, and all harms to the economy, health, and environment.
The Invasive Species Management Act provides the Department of Natural Resources (or equivalent agency) with a strong mandate for the establishment of a comprehensive administrative program that includes strategic planning, educational programs, and regional coordination. It also provides specific and environmentally protective statutory criteria for categorizing species.
| Profile of Some of America’s Worst Invasive Species: | |
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Photo courtesy of the U.S. Department of Agriculture, Agricultural Research Service |
The Asian longhorned beetle’s (Anoplophora glabripennis) recent introduction to the United States has earned it the title of pest both here and in its home country of China. The beetle is a serious threat to hardwood trees and has no known natural predator in the United States. If the Asian longhorned beetle becomes established here, it has the potential to cause more damage than Dutch elm disease, chestnut blight, and gypsy moths combined, destroying millions of acres of America’s treasured hardwoods, including national forests and backyard trees. The beetle has the potential to damage such industries as lumber, maple syrup, nursery, commercial fruit, and tourism accumulating over $41 billion in losses. U.S. Dept. of Agriculture |
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Photo courtesy of Argonne National Laboratory, a U.S. Department of Energy laboratory |
Cholera is an acute intestinal infection caused by the bacterium Vibrio cholerae. Symptoms include a copious, painful, watery diarrhea that can quickly lead to severe dehydration and death if treatment is not promptly given. The vibrio responsible for the seventh pandemic, now in progress, is known as V. cholerae O1. This pandemic began in 1961 when the vibrio first appeared in Indonesia. The disease then spread rapidly to other countries of eastern Asia and the Middle East, invading Africa in 1970. Scientists believe that cholera was brought to Latin America in 1991 within the ballast water of an Asian ship. Within the year it spread to 11 countries, and subsequently throughout the continent. It has been detected within the ballast water of ships in Galveston Bay, Chesapeake Bay, Baltimore, Norfolk, and Mobile Bay. Center for Disease Control |
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Photo courtesy of the U.S. Department of Agriculture, Agricultural Research Service |
The gypsy moth, Lymantria dispar, is one of North America’s most devastating forest pests. The species originally evolved in Europe and Asia and has existed there for thousands of years. In either 1868 or 1869, the gypsy moth was accidentally introduced near Boston, MA by E. Leopold Trouvelot. The gypsy moth is known to feed on the foliage of hundreds of species of plants in North America but its most common hosts are oaks and aspen. Gypsy moth hosts are located through most of the coterminous US but the highest concentrations of host trees are in the southern Appalachian Mtns., the Ozark Mtns., and in the northern Lake States. USDA Forest Service |
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Photo courtesy of Yahoola Flyways web site, Photographer: Jack Anthony |
A climbing, semi-woody perennial vine, kudzu was widely planted to combat soil erosion. Unfortunately, it grows out of control, smothers native plants and even uproots entire trees by the sheer force of its weight. Although most states have banned its sale, kudzu still has its adherents, who now sell the seeds via the Internet. Kudzu kills or damages other plants by smothering them under a solid blanket of leaves, encircling woody stems and tree trunks, and breaking branches or uprooting entire trees and shrubs. Once established, kudzu grows at a rate of one foot per day; as many as 30 vines may grow from a single root. The Nature Conservancy |
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Photograph courtesy of the U.S. Environmental Protection Agency, Photographer: Karen Holland |
Known as the “purple plague,” purple loosestrife (Lythrum salicaria) was first brought to New England in the early 1800s, most likely as an ornamental. This alien now exists throughout much of the United States. Purple loosestrife’s swift growth and enormous reproductive capacity allow it to spread rapidly and outcompete native plants. As a result, many wetlands are now overrun by dense stands of purple loosestrife; stands that can grow to thousands of acres in size, eliminating open water habitat. The loss of native species and habitat diversity is a significant threat to wildlife that depends on wetlands for food and shelter. Assoc. for Biodiversity Information |
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Photograph courtesy of the Great Lakes Sea Grant Network Exotic Species Graphics Library |
Sea lamprey prey on commercially important fish species, living off of the blood and body fluids of adult fish. During its life as a parasite, each sea lamprey can kill 40 or more pounds of fish. These organisms were a major cause of the collapse of lake trout, whitefish, and chub populations in the Great Lakes during the 1940’s and 1950’s.The sea lamprey was first discovered in Lake Ontario in 1835; reproducing populations were found in all of the Great Lakes by 1947. Chemical controls have reduced the population by 90%, costing U.S. and Canada $12 million annually. Sea Grant ANS Task Force |
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West Nile encephalitis is an infection of the brain caused by West Nile virus, a flavivirus commonly found in Africa, West Asia, and the Middle East. West Nile virus has been commonly found in humans and birds and other vertebrates in Africa, Eastern Europe, West Asia, and the Middle East, but until 1999 had not previously been documented in the Western Hemisphere. It is not known from where the U.S. virus originated, but it is most closely related genetically to strains found in the Middle East. It is transmitted to humans from the bite of mosquito infected with the virus. From 1999, West Nile Virus has caused 149 human cases of severe disease and 18 deaths. West Nile Virus has been found in 27 states and is spreading. Center for Disease Control |
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Photo courtesy of the Center for Great Lakes and Aquatic Sciences |
Zebra mussels, Dreissena polymorpha, are small, fingernail-sized, freshwater mollusks accidentally introduced to North America via ballast water from a transoceanic vessel. Since their introduction in the mid-1980s, they have spread rapidly to all of the Great Lakes and an increasing number of inland waterways in the United States and Canada. Zebra mussels colonize on surfaces, such as docks, boat hulls, commercial fishing nets, water intake pipes and valves, native mollusks and other zebra mussels. Zebra mussels have impacted the Great Lakes ecosystem and economy greatly. Sea Grant |
| See also The Nature Conservancy’s “Dirty Dozen” of invasive species. | |
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