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Alien species: A slow motion explosion

Zebra mussels, spotted thistle, kudzu and spiny pigweed are just a few of the more than 2,000 alien species quietly threatening biodiversity in the United States   


Zebra mussels, spotted thistle, kudzu and spiny pigweed are just a few of the more than 2,000 alien species quietly threatening biodiversity in the United States.

Forest fires, tornadoes, flooding, earthquakes and mudslides are the rock stars of nature's mass destruction capabilities, but when it comes to actual damage, exotic weeds, pests and diseases are hands down more costly, according to government officials.

Many scientists believe the spread of exotic species is one of the most serious, yet least known threats to biodiversity. Conservative estimates count 2,000 alien plant species that have established themselves in the United States, 350 of which experts say are serious and dangerous invaders. Non-native animal species cause $123 billion worth of damage each year to crops, range land and waterways, according to a report by the federal government.

Weeds infest 100 million acres in the U.S., spreading 14 percent a year, and on public lands consume 4,600 acres of wildlife habitat a day. At least 1.5 million acres of national park land are severely infested and need immediate treatment, according to the National Park Service.

The ocean serves as a highway in transporting invasive species into U.S. waters. Every minute 40,000 gallons of foreign ballast water are dumped into U.S. harbors. This water contains a multitude of non-indigenous organisms that could alter or destroy America's natural marine ecosystems, according to the National Oceanic and Atmospheric Administration.

And each year, the problem gets worse. Aliens we're currently doing battle with include:

  • Red fire ants native to South America have established themselves in much of the south.

  • Tomato bushy stunt virus, an exotic disease that was first isolated in Ireland in 1935, has a toehold in agricultural crops of Southern California. Unlike most viruses, which are spread from plant to plant by insects, tomato bushy stunt virus resides in soil and water.

  • Persea mite and avocado thrips are threatening avocado growers in California, where 90 percent of the nation's avocados are grown. Agricultural economists say that the combination of rising production costs, decreasing quality and increased market prices could result in increased imports from Chile and Mexico and total loss of the avocado industry in the U.S.

  • Zebra mussels can shut down electrical utilities by clogging water intake pipes and threaten to cause an estimated $5 billion in damages by 2002 if left unchecked.

  • Leafy spurge causes more than $144 million in livestock forage damage each year in Montana, North Dakota, South Dakota and Wyoming, reducing the productivity of grazing land by 50 to 75 percent.

  • Sea lampreys caused the collapse of lake trout and other Great Lakes fisheries, costing the U.S. and Canada $13 million annually to control.

  • Yellow starthistle, a spiny weed introduced from Chile during the gold rush now chokes native plants out of 15 to 20 million acres of California's range land and wild land areas. It spreads at 10 percent a year.

  • Brown tree snakes have caused more than 200 snakebites, 1,200 electrical outages and the extinction of most native forest birds on Guam. The Interior Department is spending $4.5 million annually to prevent the spread of the brown tree snake from Guam.

  • Asian long-horned beetles infested Brooklyn, N.Y. More than 2,000 trees had to be destroyed, costing the federal and state government more than $5 million. A similar infestation now plagues Chicago.

  • Purple loosetrife has a beautiful flower and spreads like wildfire. Now found in 36 states, it costs $45 million annually to manage. Florida spends $11 million each year to manage water hyacinth. Tropical soda apple, first reported in Florida, now covers 370,000 acres and costs the state $28 million.
President Clinton established an interagency council in February and gave its members 18 months to come up with a management plan. In the meantime, prevention, eradication and control activities are already in place in some instances, as are research efforts. But it will take coordinated efforts across federal state and local governments, and adequate funding from Congress to begin to win the war on invasive species, according to NOAA.

"These aliens are quiet opportunists, spreading in a slow motion explosion," concludes a recently released government report.

Copyright 1999, Environmental News Network, All Rights Reserved

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Groups cite successes of Endangered Species Act
June 10, 1999
Invasive species threaten healthy ecosystems
May 17, 1999

Book documents invasion of U.S. waters
Invasive species threaten healthy ecosystems
BLM to intensify war on weeds
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Exotic grasses lead to decline in bird species

U.S. Forest Service
U.S. Department of the Interior
Nonindigenous Aquatic Species
Bureau of Land Management Invasive Weeds
Weed Images and Descriptions, Rutgers University
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