Invasive Species

What is an Invasive Specie s?

“Exotic or invasive species are organisms-microorganisms, plants and animals-that have moved beyond their natural habitat and are competing with native species for food and territory. Invasions can be accidental or intentional, but the risk to native species is great in either instance. Exotic species compete with native species, alter habitats, change predator/prey relationships, and transmit foreign diseases or parasites. Exotic species also can cause a myriad of problems (food chain disruption, reduced biodiversity, clogging of water intakes, increased weed growth) and cannot be eliminated from a system without causing increased harm. Early detection and rapid response are essential to prevent major damage to ecosystems and the economy.”

-National Conference of State Legislatures

The Fire Ant is native to South America. It entered the United States from freight shipped to Mobile, Alabama in the 1930's. They are now stretched across North Carolina and Central Texas. The fire ant is known for damaging aquatic ecosystems. They invade nests of coastal birds such as the Herons, Great Egrets, and Spoon Bills. The fire ant is notorious for removing many native insects.

Controlling the fire ant is a problem because there are not many predators, they reproduce rapidly, and they are easy to transport. Fire ants travel by hitching rides on logs, being carried in the feathers of birds and in slow moving water. The only control method began in the 1980's when scientists created a soy bean insecticide to attract fire ants and to control their population. Other controls besides chemical pesticides (Amdro, etc) are being worked on.

The Water Hyacinth originated in Brazil in the 1880's. Residents of Florida began to purchase and plant the Water Hyacinth because of the nice flower it produces. By 1895 the plant had spread to the Pacific and Atlantic Coast. Water Hyacinths block the sunlight which lowers the dissolved oxygen levels in the water. By there being a decrease in dissolved oxygen levels, fish and other aquatic animals begin to die.

The Water Hyacinth grows both rapidly and abundantly. They reproduce vegetatively from their roots and a pod can double in a short span of 6-18 days. Since their leaf like stalks are spongy and inflate like balloons they are easily transported and can take over more of the waterways. As of now the only method to control these plants is to feed them to cattle and to send them for space voyagers to eat. The best way is that they are being used in waste water treatment plants as filters that suspend solids like lead, cadmium, mercury and sewage.

Nutria is a large rodent that weighs up to 10 pounds. They originated in South America and spread to Louisiana in the 1930's. They reside near wetlands throughout the Gulf of Mexico's coastal border. Nutria is a pest because they are grazers and extremely destructive. Nutria dig up and feed upon the rhizomes of marsh plants, and when they eat the rhizomes most of the time the plant does not recover. They are a main problem in gardens and public parks.

Nutria cannot be controlled because they have a lack of predators. They are transported on both land and water. Nutria have eaten away emergent marsh grasses, leaving bare ground susceptible to erosion. Every place they reside they have an abundance of food to live on. The current way nutria are being controlled is in Galveston they have alligators from the delta and wetland areas to take of them.

The Grass Carp was introduced to the United States as a control agent for exotic fresh water vegetation. They were first distributed from Eastern China and USSR. The Grass carp can consume up to 300% of their body weight daily. It can indirectly affect many fish species by destroying feeding and nursery habitat. The grass carp are also used for food and are popular game fishes, and are easy to prepare.

Grass Carp made way to Galveston Bay and is suspected of destroying important wetland grasses. In the lower San Jacinto River they have been known for feeding on young cord grass and in Lake Houston they have actively eaten emergment reeds and domestic grasses. Many plans are in the works to control the Grass Carp population. One way is to fish in areas where they live, and hopefully over fish them out of the water.

The Chinese Tallow Tree is native to both China and Japan. Chinese Tallow was introduced to the United States in 1776. This tree is known for being fast growing. It is known for producing 100,000 seeds per year. The Chinese Tallow Tree can grow up to 40 feet tall and 20 feet wide. A Chinese Tallow is a deciduous tree with a rounded or conical crown and has an open airy look. Other names for the Chinese Tallow are ‘Florida Aspen' and ‘Popcorn Tree'.

The Chinese Tallow causes ecosystem modification in the southeastern areas of the United States by replacing native vegetation. At one time people would plant the tallow so they can have a yard full of trees really quickly, not knowing that the tree was invasive and would soon kill every other plant around it. The tallow tree can become the dominant plant in vacant lots, abandoned agricultural land, natural wet praries and bottomland forest. After Chinese Tallow is established it is almost impossible to get rid of. Insects are not attracted to this plant. Prarie restoration has been one method of control. Weed killer has been put onto tallow sprouts to kill them when they are still small. Other methods of control are being worked on.

Works Cited:

World Book Encyclopedia 2005 ‘F'

Ecosystems of Gulf Coast: Wetlands, Rivers, and Estuaries by Brent Stafford

www.aphis.usda.gov.oa/invasive/fireant.jpg

www.aquanic.org/images/photos/la/d0565/img0072.jpg

www.uaex.edu/monroe/forestry/championtrees/Images/ChineseTallow

www.museus.org.za/bio/plants/pontederiaceae

www.all-creatures.org/ aw/nutria-004.html

http:aquat1.ifas.ufl.edu/sapium.html