Index IntroductionInvasive speciesAsian carpMountain pine beetlesEarthwormsMusselsCane toadsConclusionIntroductionAn invasive species is any type of organism that enters a new ecosystem and begins to negatively alter the region. Such negative consequences of invasive species include damage to the surrounding ecosystem and alterations to the habitat of organisms already living there. Native species are generally well armed to manage defense against other native species; when an invasive species arrives, however, native organisms are not prepared to handle unknown competitors. Even worse than harming the environment, invasive species can devastate the economy and even the health of humans. As stated by the National Wildlife Federation, a species is labeled invasive if it “grows and reproduces rapidly and spreads aggressively, with the potential to cause harm.” Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Immediate threats that follow the arrival of an invasive species include predation and competition with native animals, causing or carrying disease, and preventing native species from reproducing. Indirectly, invasive species can also alter the food web by destroying or replacing original sources and consequently providing little or no food source for wildlife. Invasive Species Asian Carp Some invasive species are brought to new locations to serve a purpose, such as Asian carp, but eventually become an invasive species. Asian carp is a common term for a group of fish that includes bighead carp, silver carp, grass carp, and black carp. These fish were originally brought to the southern United States to clear algae and vegetation from aquaculture ponds and sewage lagoons in the 1960s. Environmental causes such as floods were the reason these fish were able to escape into the wild where they began to eat the plankton that many other fish needed for food. As noted on the New York Invasive Species website, "Asian carp can consume 5 to 20 percent of its body weight per day... and can reach 110 pounds... dominating native fisheries in both abundance and biomass ". Severely impacting the food chain, these carp easily outcompete native fish. Furthermore, the elimination of plankton-eating fish takes away important prey for predatory fish in these waters. Today, the Mississippi and Illinois river systems consist of more than 95 percent of the biomass in some areas of the Mississippi Basin. Unlike the accidental influx of Asian carp into the wild, most invasive species spread accidentally through human activity. The goods we use travel around the world very quickly and often transport species from other places to new regions. Aquatic organisms generally travel in the ballast tanks of ships and on the propellers of smaller boats. Insects can travel in the wood of pallets and shipping crates, and some invasive species start out as nothing more than intentionally or accidentally released pets. Above-average temperatures and changes in rain and snow patterns will also allow some invasive plant species and mountain pine beetles to move into new areas. Mountain pine beetlesThe mountain pine beetle is a small insect that grows to about 4-7 millimeters in diameter and spreads through the movement of firewood and other wood products. The key to the survival of mountain pine beetles insome parts of North America have hot summers and mild winters; this guarantees not only the survival of the insect, but the continuation of infestations that lead to outbreaks. These beetles primarily target twisted and ponderosa pines, but are not shy of other pine species as well. Mountain pine beetles target pine trees by laying their eggs under the bark of the tree. As the beetles enter under the bark, they also introduce blue spot fungus into the sapwood which prevents the tree from repelling the killing of the attacking beetles with the flow of the tree's pitch. Tree pitch flux occurs in infected trees; “they convert a large amount of starch into sugar, which causes a flow of water from the soil to the tree by osmosis” (Kimmerer, 2014). The blue spot fungus also prevents the transport of water and nutrients through the tree. Large masses of resin, called "pitch tubes," form on the outside of the tree where the beetles entered. Between mountain pine beetle larvae feeding on the tree and fungal colonization, the host tree dies within a few weeks of attack. EarthwormsAnother example of an invasive species are earthworms. “All earthworms…in the Great Lakes region are exotic; most are European” and were brought here by settlers in the mid-1800s. Today, earthworms are continually transported through the dumping of unused fish bait, the moving of compost and mulch, and any other movement of soil. Recently, research has gathered data on dramatic changes in native hardwood forest ecosystems that have been invaded by exotic earthworms. These changes include losses of native understory plant species and tree seedlings, changes in soil structure, and a decrease in the availability of nutrients provided by the soil. Due to the mixing and breakdown of the soil, earthworms are able to directly alter the soil chemistry. In areas previously devoid of earthworms, fallen leaves and other forest waste were being tended by fungi and bacteria, a process that is much, much slower than that of earthworms. This accumulation on the forest floor serves as a home for “thousands of microorganisms, spiders, insects, and fungi that support the unique plant communities in these forests” (Hale, 2013, p. 5). Another important thing is that this layer serves as a perfect soil for the seeds of plant species, most of which take up to two years to fully germinate. However, when earthworms are introduced, they eat through this layer, eliminating the spongy forest floor and making it harder for plants to take root. As a result, the diversity and population of native forest plant communities may decline dramatically. Animals are also affected by earthworms: the loss of forest floor takes away habitat and food sources for animals such as “nesting birds, small mammals, amphibians, reptiles, insects and spiders”. In areas with high white-tailed deer populations, plant regeneration from deer feeding is slow, and earthworms only make the problem worse. Mussels Another invasive species includes quagga and zebra mussels, which are invasive aquatic species native to Eastern Europe; they originated in Ukraine and Russia, respectively. The ballast water tanks of transoceanic ships are believed to be responsible for the widespread spread of quagga and zebra mussels. These mussels have caused great suffering to the ecosystems they entered. For starters, these organisms only grow to the size of a fingernail. However, they clog water intake structures such as pipes.