European Water Chestnut is an invasive aquatic plant that spreads rapidly, out-competes native bay grasses, and impedes water use and recreation. Although this invasive species has nearly been eliminated from Maryland waters after a decade of eradication efforts by the Maryland Department of Natural Resources, it still persists in some areas. Fortunately, populations are much smaller than they used to be and eradication can be completed by hand in the span of just a few days. Summer 2010 Water Chestnut removal will begin on June 28th in the Sassafras River and end later that week in the Bird River. Maryland DNR biologists, along with volunteers from the Maryland Conservation Corps, will use small boats, jet skis, canoes, and kayaks to access shallow waterways where this invasive species is found.

Water Chestnut (Trapa natans) is an aquatic plant that is native to Asia, Europe, and Africa, but not the Chesapeake Bay. The plants’ floating leaves form layers that become so thick that they block light from penetrating the water column, effectively eliminating native bay grasses where it occurs. The surface layer of floating leaves also impedes navigation and recreational water use. The seeds are a particular nuisance. One acre of water chestnut can produce enough seeds to cover 100 acres the following year. The seeds have four hard, half-inch spines that are sharp enough to penetrate shoe leather and can remain viable in sediment for up to 12 years, making on- going monitoring and eradication efforts necessary long after the Water Chestnut plants are removed.

What you can do to help:
If you observe Water Chestnut in any Maryland waterway, there are several ways you can help us with this eradication effort. First, if there are only a few plants present and you’re able to, pull them up by the roots and throw them on dry land to decompose. If you have a GPS, mark the coordinates and pass them on to your state biologists. If you have a camera, take some pictures and send them to us along with location information. Most importantly, never put any exotic aquarium species, plant or animal, in your local waterway – it’s amazing how quickly they may be able to spread.

Please contact Mark Lewandowski at 410-260-8634 or email mlewandowski@dnr.state.md.us if you see any sign of this invasive species.

Don’t forget to check back in a couple of weeks to read about our summer 2010 Water Chestnut removal effort!