Here are some more examples of exotic species found in the river and stream ecosystem.

© Barry A. Rice/The Nature Conservancy

Purple Loosestrife (Lythrum salicaria)

Purple loosestrife is an exotic species which was found in North America as early as the 1800's. It is native to Eurasia. Loosestrife can be found near wetland sites, usually along rivers and streams. Loosestrife is a highly invasive plant. It can impede waterflow and have a strong impact on the biotic community.

Sea Lamprey (Petromyzon marinus) on Trout

The sea lamprey is a parasitic fish that feeds on large, slower-moving fish. The lamprey's mouth is filled with sharp teeth which it uses to attach to fish so it can feed. The sea lamprey is an exotic species that made its way into the Great Lakes through the St. Lawrence River in the 1920's. The sea lamprey can be seen migrating up rivers and streams in the spring and summer to lay their eggs.