Nonnative species are also referred to as introduced, exotic, or alien species. The National Park Service defines nonnative as species that occur in a given place as a result of direct, indirect, deliberate, or accidental actions by humans. Plant species that are brought into an area as food, fiber, or ornamental landscape plantings can "jump the fence" and become established in the wild.
Likewise, nonnative animal species can be introduced into an area deliberately, for agricultural use or fish stocking; or by "hitching a ride" on objects like boat hulls and outboard motors. Many species find their way to new locations in crop seed, soil or nursery stock.
Although many introduced species have had a negative impact on our society, primarily in agriculture, these species would not have evolved with the native species and therefore are not a natural component of the ecological system. In extreme cases, invasive nonnative species can displace native species, thereby degrading the integrity and diversity of native communities. Alien species can also become pests, such as Asian lady beetles and zebra mussels.
These mussels are not currently present in the Wild & Scenic designated stretches of the Missouri. They can only move upstream or overland by hitchhiking on boats and trailers. For this reason, it it essential that any and all boats and trailers coming from other waterways be properly washed and/or dried before launching in uncontaminated waters.
Did You Know?
Before the 1950s, the Missouri River carried an average of roughly 140 million tons of sediment per year past Yankton. After closure of the dams in the 1960s, an average of roughly 4 million tons per year moved past the same location.