Invasive Species in Terrestrial Ecosystems

The issue

Invasive Species are one of the world's leading threats to environmental health (Marks, 2006). As well as being a threat to environmental health, invasive species have become a priority concern for conservation biologists and land managers (DAntonio, 2002). Invasive species refers to a subset of introduced species or non-native species that are rapidly expanding outside of their native range. A species is regarded as invasive if it has been introduced to a location, area, or region where it did not previously occur naturally (Ecological Society of America). Invasive species can be plants, animals, or other types of organisms.

Biologists have described a total of between 3.6 million to 100 million species on the planet (Wilson, 2000). More than 50% of these species that are listed as threatened or endangered under EPA are adversely affected by invasive species (National Agricultural Library).

List of invasive species: [1]

Geographic Location

Invasive species are found everywhere around the world, meaning they are an international problem. Invasive species are found anywhere from croplands, wilderness areas, forests, and water.

• The picture shows the estimated number of invasive species in each state in the U.S.

(Williams, James D. & Meffe, Gary K.)

Humans have intensified invasive species existence in several ways and times throughout history, but invasive species have been in existence forever (Cunningham, 2001).

Emerging invasive species

Some emerging invasive species include: (National Agricultural Library) the Glassy-winged sharpshooter (recently found in California), the Gladiolus Rust (found in Florida), the Apple Moth and the Quagga Mussels (both found in California), and new mussels (found on Lake Mead).

Names of current invasive species

Some invasive plant species (in North America) include: Chinese Privet, Cotton thistle, Coral ardisia, Curly-leaf pondweed, Tree-of-Heaven, Purple loosestrife, Dog-strangling vine, English ivy, Garlic mustard, Japanese honeysuckle, Musk Thistle, and Kudzu. (Douce, G. Keith)

Some invasive insects (in North America) include: Africanized honeybee, Argentine ant, Asian long-horned beetle, Asian tiger mosquito, Cactus moth, European gypsy moth, Japanese beetle, Red imported fire ant, and Varroa mite. (Douce, G. Keith)

Some invasive fish (in North America) include: Asian swamp eel, Bighead carp, Eurasian ruffe, Flathead catfish, Sea lamprey, Northern Snakehead, Round goby, Silver carp, and Common carp. (Douce, G. Keith)

Some invasive reptiles and amphibians (in North America) are: Brown tree snake, Bullfrog, and the Cane toad. (Douce, G. Keith)

Some invasive birds and mammals (in North America) are: Coypu or Nutria, European Starling, Wild Boar, Mute Swan, and Rock Pigeon. (Douce, G. Keith)

Some invasive pathogens are: Dutch elm disease, Exotic Newcastle disease, Plum pox, Soybean rust, Sudden Oak Death, West Nile virus, and Whirling Disease. (Douce, G. Keith)

Most common invaders

• The most ubiquitous invaders in the U.S. are the European starling, Kudzu, Zebra mussel, and the Purple loosestrife. (Marks, 2006).

Name: European Starling

Description: Medium sized bird with a yellow bill and reddish legs

Native Range: Eurasia and North Africa

Invasive Range: All throughout the U.S.

(Marks, 2006)

Name: Kudzu

Description: Deciduous vine, 35-100 feet long

Native Range: Japan and China

Invasive Range: Most severe in the southeastern U.S. but can occur as far north as Connecticut and Illinois

(Marks, 2006)

Name: Zebra Mussel

Description: Tiny striped shells

Native Range: European waters

Invasive Range: Atlantic waters

(Marks, 2006)

Name: Purple loosestrife

Description: A purple, perennial herb

Native Range: Eurasia

Invasive Range: Found in all of the United States except Florida (Gutin, 1999)

Impacts of invasive species

Invasive species negatively impact native species in a number of ways, including eating them, competing with them, interbreeding with them, or introducing new pathogens and parasites that can sicken or kill them. Most importantly, these invasive species effect the habitats and ecosystems of the native species and also weaken biodiversity (National Agricultural Library). Biodiversity is the sum total of all plants, animals, fungi, and microorganisms on Earth (Raven, 2003).

The positive impacts of invasive species include: possible medical breakthroughs and the possible increase in species diversity. (Douce, G. Keith)

Also, a new finding suggests that since Zebra Mussels invaded the Great Lakes in 1988 from the European waters, these mussels may be helping to restore the populations of some bottom-dwelling aquatic plants to the Great Lakes (, 1996).

Human Impacts on invasive species

Humans effect invasive species in many ways. Humans spread/carry pathogens, humans bring invasive species from other countries, and do not take proper precautionary methods to protect the environment from invasive species. Introductions of invasive species by humans can be incidental or accidental (Marks, 2006).

Economic Impacts of Invasive Species

(Marks, 2006) According to Raissa Marks, some negative economic impacts of invasive species include major financial losses in agriculture and forestry. Invasive species impact the economy through the loss of potential economic output, such as: the loss of crop production and reductions in livestock fitness (ability to survive).

How do we deal with invasive species?

In order to deal with invasive species, many laws have been enacted.

Some general acts that deal with invasive species include: the National Invasive Species Council Act, the Species Protection and Conservation of the Environment Act, the Public Land Protection and Conservation Act, and the Community and Forest Protection Act. (National Agricultural Library)

Some acts that are applied to individual invasive species or their habitats include: the Harmful Invasive Weed Control Act, the Nutria Eradication and Control Act of 2003, the Northern Rockies Ecosystem Protection Act, the Calfed Bay-Delta Authorization Act, the Salt Cedar and Russian Olive Control Demonstration Act, the Brown Tree Snake Control and Eradication Act of 2004, the Great Lakes Ecology Protection Act of 2003, the Migratory Bird Treaty Reform Act of 2004, and the Noxious Weed Control Act of 2004. (National Agricultural Library)

Fixing the Problem

The U.S. spends $120 billion every year on the control and impacts of more than 800 invasive species infestations. This does not account for the values of species extinctions and losses in biodiversity, ecosystems, services and aesthetics (National Agricultural Library). The loss of habitat by humans and invasive species is the predominant force in extinction. 0.1-1 species per million species becomes extinct each year. (Raven, 2003)

References:

(Cunningham, 2001) (National Agricultural Library) Williams, James D. & Meffe, Gary K. (Douce, G. Keith) (Ecological Society of America) (Raven, 2003) (Marks, 2006) (, 1996) (Gutin, 1999) (DAntonio, 2002) (Wilson, 2000)