Invasive Species

Invasive Species Introduced into an ecosystem where they out-compete native (endemic) species for resources, such as nutrients, light, physical space, water or food.

Common traits: • Fast growth • The ability to reproduce both asexually and sexually • Rapid reproduction • High dispersal ability • Phenotypic plasticity (the ability to alter one’s growth form to suit current conditions) • Tolerance of a wide range of environmental conditions (generalist) • Ability to live off of a wide range of food types (generalist) • Association with humans • Other successful invasions

Zebra Mussels • Zebra mussels made their debut in North America in 1988, after they hitched a ride in ballast water of ships from their native Russia. • A mussel may sound like the most non-threatening creature in the ocean, but the zebras are an exception: They've spread from Lake St. Clair (near Detroit) to the Mississippi River and the Great Lakes, edging out native clams and mussels, clogging industrial intake valves, changing the migratory patterns of local ducks, and bloodying feet of beach goers (they are really sharp). • And while edible, they store toxins and therefore are not recommended for eating.

Cane Toad • Setting cane toads loose in Australia seemed like a good idea at the time: The amphibians were supposed to help combat pests in sugarcane fields, and they did. • But they didn't stop there: They became a threat to all of the native species in their paths, affecting the entire country's biodiversity as they moved west toward the national parks region. • The country is now working on a $7 million, 15-year plan to rein them in.

Rats • Rats: The original stowaway. These rodents have been hiding in ships for generations, and changing the ecosystems where they land. • For example: They were the first invasive species to arrive on Macquarie Island, and efforts to rebuff them -- which included introducing cats -- only made things worse; the cats -- and the rabbits later introduced for food -- have since "resulted in the annihilation of two native bird species and the stripping of Macquarie Island's vegetation.“ • Estimated cost of fixing this "ecosystem meltdown": $16 million.

Gypsy Moths • The gypsy moth was introduced into the United States in 1868 by a French scientist living in Medford, Massachusetts, to try to make a silk caterpillar hybrid, that could resist diseases. • When some of the moths escaped from his lab, they found suitable habitat and started to multiply. Gypsy moth is now one of the most notorious pests of hardwood trees in the eastern United States • The species can decimate entire trees, stripping them of their leaves and affecting forests and native wildlife.

Starlings • There are 200 million in North America descended from 60 to 100 birds released in Central Park, New York in an attempt to introduce every bird species mentioned in the works of William Shakespeare to North America in 1890, and this turned into a terrible environmental disaster. • Starlings are among the worst nuisance species in North America. The birds travel in enormous flocks; pose danger to air travel; disrupt farms; spreads disease to other animals, "usurps nesting sites," and causes $800 million in crop damage each year. • Corrosive droppings on structures cause hundreds of millions of dollars of yearly damage. In 2008 the U.S. government poisoned, shot or trapped 1.7 million, the most of any nuisance species.

Kudzu • An invasive plant is nothing you can't handle with a pair of garden shears, right? When it comes to kudzu, wrong. This Japanese vine, originally planted as a way of preventing soil erosion, does its job a little too well. • According to The Nature Conservancy, it also "grows out of control, smothers native plants, and even uproots native trees by the sheer force of its weight.“

Brown Tree Snake • As one of the most expensive invasive species ever, according to Daily Finance, the brown tree snake is a lot more imposing than it looks. • In the 1950s, the reptiles stowed away on military planes to end up in Guam where they took over the previously snake-free island. • Now Guam is believed to be home to 13,000 of the snakes -- which were also the culprits behind the demise of the now extinct-in-the-wild Micronesian kingfisher bird.

Mountain Pine Beetles • Mountain pine beetles usually only grow to about 1/3 of an inch, but these tiny pests can have a huge impact with their tree-killing capabilities. • The beetles kill the trees by boring through the bark into the phloem layer on which they feed and in which eggs are laid. • They already cover 3.6 million acres of forest in Northern Colorado and Southern Wyoming alone, and also live throughout Canada. • They're even a threat to massive grizzlies, since the beetles eat white bark pine -- which is also a main source of pre-hibernation food for the bears in Yellowstone.

References: • http://www.treehugger.com/galleries/2011/01/10-invasive-species-that-changed-the-world-forever.php?page=11 • http://en.wikipedia.org/wiki/Invasive_species

Invasive Species