About Invasive Species

What Are Exotic and Invasive Species?

Exotic species are plants, animals and microorganisms that exist in habitats outside of their native range. People transport exotic species around the world intentionally or accidentally through pathways such as the horticulture trade, pet and aquarium trade, seafood trade, boat hull and trailer fouling, and ship ballast water. Invasive species are those exotic species that establish, reproduce and spread in the new region where they are introduced.

The Problem

Invasive species cause negative impacts to the environment, the economy and human health. Invasive species outcompete native species, transforming native habitats and altering food webs, water quality and fire regimes. Invasive species also impact commercial trade, infrastructure, and recreational enjoyment of our natural resources. Invasive species can introduce parasites and pathogens to wildlife and humans.

Invasive species exist in terrestrial and aquatic habitats throughout the State of Texas. Once an invasive species is established, particularly in aquatic habitats, it is very difficult and costly to control. Once introduced, an invasive species is nearly impossible to eradicate unless the invasion is detected early and control efforts are launched quickly.

Invasive Species in the Houston-Galveston Region

Estuaries around the U.S. experience numerous invasive species introductions. As a hub of human activity, the Upper Texas Coast, Houston-Galveston Region and Galveston Bay are no exception. This digital guide highlights invasive species currently found in the Houston-Galveston region as well as invasive species that could potentially invade the Upper Texas Coast.

Regulatory Approaches to Control Invasive Species

The most cost effective way to control the spread of invasive species is to prevent their introduction in the first place. Regulations are one tool used by state and federal agencies to limit invasive species introductions in Texas.

The Texas Parks and Wildlife Department (TPWD) maintains a list of prohibited aquatic animals and plants that are identified as being exotic, harmful, or potentially harmful to the State of Texas. Species prohibited by the agency cannot be imported, sold, possessed, or released by individuals without a permit.

The Texas Department of Agriculture (TDA) identifies noxious and invasive plants that have the potential to cause economic or ecological harm in Texas. Unless permitted by the TPWD or TDA, a person cannot sell, distribute or import live plants listed as prohibited in Texas. Violations of the TPWD and TDA prohibited species rules can be reported to a local TPWD law enforcement office and are punishable as a Class C misdemeanor. See Stop the Invasion for contact information.

At the federal level, the U.S. Department of Agriculture (USDA) establishes quarantine areas to restrict the movement of materials (soil, wood, and plant products) that may be infested by invasive species. The U.S. Fish and Wildlife Service manages invasive species through existing legislation such as the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 and the Lacey Act as well as through executive orders issued by the President of the United States.

Non-Regulatory Approaches to Control Invasive Animals

Many agencies and local organizations act in a nonregulatory capacity to provide information to the public, control species invasions, and restore habitats impacted by invasive species. Local examples of these organizations include the Armand Bayou Nature Center, Bayou Preservation Association, Galveston Bay Foundation, Houston Audubon, TPWD, Texas Commission on Environmental Quality, Galveston Bay Estuary Program, U.S. Fish and Wildlife Service, and others.

Best Practices for Removal of Invasive Species

Integrated Pest Management (IPM) is the preferred practice for the removal of invasive species. IPM is an environmentally sensitive approach with a focus on prevention, the application of multiple control and removal strategies, and the judicious use of herbicides and pesticides only as needed. IPM has four basic steps:

  1. Create a plan,
  2. Prevent introduction and spread,
  3. Eradicate, control or contain, and
  4. Monitor your results and repeat as necessary.
Successful invasive species control efforts often require multiple treatments using varied techniques. Control methods include:
  • Physical Removal
    (e.g. manual removal from land or water, mowing, and prescribed burns for large expanses of land by professionals only!);
  • Biological Controls
    (deploying invasive species predators and parasites, e.g. Salvinia weevils, alligator weed flea beetles, etc.);
  • Chemical Methods
    (limited and targeted use of herbicides and pesticides away from waterways);
  • Combined Controls
    (using multiple control methods together such as cut stump and limited application of herbicide); and
  • Rehabilitation and Restoration
    (e.g. minimize disturbed soils and increase native species diversity).
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