Invasive Species Essay

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Register to read the introduction… Fish). Now seventy years after the initial invasion, there are …show more content…
The U.S. Geological Survey estimates there to be over 6,500 different invasive species present and established in the United States. This however, seems to be a very conservative estimate. Cornell University researchers estimate there to be 50,000 alien invasive species in the United States (Pimental). This gross difference can be in part due to the definition of invasive species and what is being counted. Regardless of numbers of species, what will be considered for the purposes discussed here is by definition of Executive Order 13112. Invasive species involve all levels and niches of ecosystems and enter our ecosystems for a number of reasons. Research does show, that there is a trend when it comes to invasive species and their introduction methods. “Most plant and vertebrate animal introductions have been intentional, whereas most invertebrate animal and microbe introductions have been accidental (Pimentel).” Though this is certainly a trend it is certainly not an all-inclusive rule and this should be address when considering invasive species and introduction methods. Species such as the chestnut blight, a microorganism, zebra mussels, and the brown tree snake were introduced unintentionally to the United States territory of Guam (Shwiff). The first two certainly follow the generalized introduction method as discussed in Pimental’s …show more content…
This increasingly dense clustering is one of the tactics used by the mussel to deprive indigenous species of resources. Additionally, zebra mussels clog pipelines like water intake pipes, which an infestation in 1989 caused the city on Monroe Michigan to be without water for three days (USGS). The invasive mussel was introduced to the Great Lakes, from Russia, in the ballasting of ships and was first discovered in Lake Sinclair, and spread throughout much of the North East United States. Control cost and prevention to keep zebra mussels from water intake, filtration, and power generation is estimated by Cornell University at $1 billion dollars a year. United States Geological Survey estimates $5 billion dollars of negative economic impact on the Great Lakes region alone due to this mussel. It has single handedly has caused the “near extinction of native American unionid clams in Lake St. Clair and in the western basin of Lake Erie (USGS).” Zebra mussels have become nearly impossible to control and even more difficult to rid lakes of. U.S. Geological Survey reports in their fact sheet on zebra mussels, “once zebra mussels become established in a water body, they are impossible to eradicate with the technology available today. Many chemicals kill zebra mussels, but these exotics are so tolerant and tough that everything in the water would have to be poisoned to destroy the mussel

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