Invasive aquatic plants can be free floating, floating and rooted in sediment, rooted and submergent (underwater), or emergent (partly under and partly above the water’s surface). They can affect recreational activities (e.g., boating, fishing, swimming), displace native vegetation, slow down water flow, and alter oxygen levels. Aquatic plants are introduced and continue to spread by shipping vessels, recreational and commercial boating, and the aquarium and water garden trade.