IISG recently released a new WATCH card featuring two new invasive species—the Brazilian elodea and hydrilla. These costly noxious weeds have been invading and causing harm in parts of the U.S.

“They have the potential to crowd out native species, alter habitat, and hinder recreational activities such as boating and fishing,” said IISG aquatic invasives extension associate Kristin TePas.

Costs have quickly added up in Indiana in efforts to control these invaders. According to TePas, in 2006 an infestation of hydrilla was found in a 735-acre lake that is expected to cost the state $1.5 million to remove. This followed a previous infestation of Brazilian elodea in a 109-acre impoundment, which cost the state $135,000 to eradicate.

Both hydrilla, native to Asia, and Brazilian elodea found their way into U.S. waters through aquarium trade. Recently these plants have been spread to new waters via boats and recreational equipment and as a hitchhiker on other plant materials.

Boaters and anglers can help by regularly cleaning their boat equipment when they leave a water body and by reporting any sightings. Hobbyists can help by purchasing plants other than Brazilian elodea and disposing of unwanted aquarium and water garden plants in the trash rather than nearby water bodies.

The new WATCH card provides a brief description of the plants as well as illustrations and a photograph of the two species. It also includes a clear description of how to tell them apart from native elodeas, as they are similar in appearance. The card also provides useful information to help prevent the spread of these invaders and what to do to report a new sighting.