Introduction by Ship Ballast

 

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Invasive species have been introduced to new ecosystems by various pathways, including the shipping industry, both in ballast water and on fouled hulls. Ships take in a certain amount of water for stability and trim before a voyage. Once the ship arrives at its destination it releases this ballast water into the new bay. Ballast stabilizes ships in the water and is most often used in commercial shipping. Ballast is primarily composed of water and is full of stones, sediment, and thousands of living species. Over 3,000 marine species travel around the world in ships' ballast water on a daily basis. This type of transport is often referred to as "floating biological islands." The zebra mussel (Dreissena polymorpha) and the European ruffe (Gymnocephalus cernuus) are examples of exotic species introduced to the Great Lakes by ballast water. These exotic species are further spread throughout the new continent by going undetected on domestic sport and recreational vehicles.