Credit: U.S. Fish and Wildlife Service
It goes without saying that invasive species are dangerous to the natural environment; however, many people may be shocked by the sheer quantity of them and how pervasive this problem truly is for the United States.
The National Invasive Species Council, or NISC, defines invasive species as non-native species to a particular ecosystem that pose a serious threat to said ecosystem, its inhabitants, or humans. This also means that not all non-native species are invasive species; some could even be beneficial to the environment according to the NISC.
Examples of Invasive Species
Native to South America, the water hyacinth was introduced to the United States in the 1800s according to the NISC. Since then, according to the U.S. Department of Agriculture, it inhabited the Gulf States and California. An aquatic plant species, the water hyacinth reproduces so quickly that it crowds out native vegetation, blocking sunlight for submerged plants, which in turn depletes oxygen underwater resulting in a decreased number of phytoplankton, significant enough to affect fisheries. In an effort to combat this, research has been conducted to find the plant’s natural predator. This biological approach, as opposed to herbicides, has been widely successful, utilizing insects such as weevils and pyralid moth.
Having arrived in the 1940s for scientific research on pregnancy, the African Clawed Frog was probably released as pets to the public, according to Smithsonian National Zoological Park, and their highly prolific nature is one of the reasons why it is classified as an invasive species. Invading mostly Southern California, where climate is ideal, these frogs eat anything they can find including amphibians, small fish, and crustaceans. Efforts to remove the frog are largely unsuccessful, and in San Francisco’s Lily Pond, the frog population is so massive that U.S. Wildlife and Fisheries are at a loss of how to remove it, as reported in the San Francisco Chronicle last year. Even draining the pond may not remove them, as the frogs may migrate to another pond.
Credit: freedigitalphotos.net Tom Curtis
The mute swan from Eurasia threatens the Chesapeake Bay because of the competition for food sources according to a 2003 report by the Chesapeake Bay Executive Council. Its appetite for submerged aquatic vegetation is harming other native species, like the crab, which are dependent on the underwater plants. The birds are highly territorial, often displacing other native waterfowl, like ducks and geese, and killing their young. There are only two ways to remove them, either by destroying eggs or removing adults. Though still popular today as means of population control, both measures are extremely costly.
The hemlock woolly adelgid, a native Asian insect, threatens the hemlock trees in the Smoky Mountains and along the east coast according to the National Park Service. These insects infest the hemlocks and effectively kill the trees. The National Park Service has used insecticides and are now introducing predatory beetles to help control these invasive insects.
This is the hemlock woolly adelgid.
The nutria, an aquatic rodent, is an invasive species in the Gulf States according to the Gulf of Mexico Regional Panel for Aquatic Nuisance Species. The South American rodents’ appetite furthers coastal erosion by eating marsh grass, the vegetation that keeps the wetlands together. Other than educating the public and protecting native plants, other efforts to control the population include bounty programs in Louisiana.
It should be noted that not only ecosystems, but also the economy suffers from the invasion of these non-native species. According to the U.S. Department of Agriculture Forest Service, the influences of invasive species cost $138 billion a year.
Response to the Invasive Species
In 1999, the NISC was created as an interdepartmental entity tasked specifically with responding to the invasive species problem. The NISC mediates between various departments, such as the Environmental Protection Agency, U.S. Wildlife and Fisheries, and Forest Service, and between federal and non-federal experts. Coordinating experts and departments helps pool resources and research for the sole purpose of combating invasive species.
The Forest Service cites four steps in the fight against invasive species—prevention, early detection and rapid response; control and management; and rehabilitation and restoration. Each step relies on having an emergency task force to respond to the threat of invasive species immediately and effectively.
This is a nutria.
There are new scientific techniques developed to help combat invasive species. An article on Science Daily reported that researchers at the University of Notre Dame have combined two technologies to help with early detection and prevention of invasive species and their subsequent spread. By combining environmental DNA, also known as eDNA, with Light Transmission Spectroscopy, or LTS, one could identify a possible threat from an invasive species before it spreads by measuring nanoparticles over time. The eDNA helps to identify particles, such as fish scales in water samples, and LTS measures the size of nanoparticles found in the eDNA.
Sometimes, however, the four steps to combat invasive species have simple solutions; for instance the National Oceanic Atmospheric Administration suggests cleaning, draining, and drying all equipment and vehicles before entering a body of water. The Forest Service supports this as they report that many invasive species are hitchhikers.
Invasive species are an ecological and economic disaster, but with diligence even an ordinary person can stop their spread by simply being aware of their surroundings and taking care to not carry unwanted species in a new environment.
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