Invasive Species

Yellow floating heart grows in dense mats. It is originally from Eurasia, the Mediterranean, China, India, and Japan.  It is believed to spread from releases from water gardens and the nursery trade.  It reproduces by seeds, stems, or broken off leaves with part of a...

Japanese knotweed is a semi woody shrub that can reach heights of 8 to 15 feet tall.  The plant resembles bamboo and is often called Japanese bamboo. It originated in Japan and made its way to the United States and Wisconsin as an ornamental plant that people planted...

Purple Loosestrife is a wetland perennial plant that originally arrived here from Europe and Asia.  It was distributed and sold by plant nurseries because of its attractive purple flowers.  People then planted this species in their yards, gardens and lake front...

This little predatory zooplankton is native to Europe and Asia.  They can grow up to ¾ of an inch in length and eat native Daphnia, which is a food source for many smaller juvenile fish species.  Young fish have difficulties eating the waterflea because the tale often...

Zebra mussels are small bivalve mollusks that are fingernail sized and native the Caspian Sea region of Asia.  These mussels are filter feeders and one mussel can filter one liter of water per day. In the water they feed primarily on phytoplankton, zooplankton, and...

There currently is not much information known about these non native snails.  What is known is they compete with native snails for the same resources and they often die off in large numbers in the summer.  The snails are not very tolerant of low oxygen levels and...

Rusty crayfish are native to streams in the Ohio River Basin states of Ohio, Kentucky, Illinois, Indiana, and Tennessee.  They were introduced to Wisconsin by anglers who used them as fishing bait. These crayfish impact native crayfish populations, aquatic plant...