Boat Ramp Survey for Aquatic Invasive Plant Species 
in Southern Illinois

In the summer of 2008, the River to River CWMA, in cooperation with Southern Illinois University, Cypress Creek National Wildlife Refuge, and Shawnee National Forest completed a survey of aquatic invasive plants at public boat ramps in Southern Illinois. Before this initiation of this project, little was known about the distribution of aquatic invasive plants in Southern Illinois. Out of the over 12,000 records compiled in the Southern Illinois Inventory of Non-Native Species, only 20 records of brittleleaf naiad (Najas minor), 6 records of Brazilian elodea (Egeria densa), 1 record of curlyleaf pondweed (Potamogeton crispus), 5 records of purple loosestrife (Lythrum salicaria), 82 records of moneywort (Lysimachia nummularia), and 3 records of European water-clover (Marsilea quadrifolia) existed. No records for Eurasian watermilfoil (Myriophyllum spicatum) have been recorded even though it is a common invasive in our region.

Boat ramps are an ideal point of introduction for such plants due to the transfer of boats to various bodies of water; thus, these points are best selected for initial survey efforts. Our goal was to establish a presence/absence map as baseline data for future management practices. We focused on eleven main species that would most likely be found in this area: Alligatorweed (Alternanthera philoxeroides), Brazilian Waterweed, Waterhyacinth (Eichhornia crassipes), Hydrilla (Hydrilla verticillata), Parrotfeather watermilfoil (Myriophyllum aquaticum), Eurasian watermilfoil (Myriophyllum spicatum), Brittleleaf naiad, Curlyleaf pondweed, Purple Loosestrife, European water-clover, and Moneywort which is considered a noxious weed by some, but not necessarily an invasive. We used both visual and rake surveys and assessed abundance of each invasive species found. The lake rakes were thrown a total of 6 times in a fan pattern surrounding the boat ramp/dock to cover all representative habitats at each ramp. A total of 64 boat ramps were surveyed on 27 different bodies of water. Due to excessive flooding this spring and summer, boat ramps on rivers were not surveyed. Of the eleven species we focused on, six were found at various locations. Eurasian watermilfoil was the most commonly found specie at 16 boat ramps, followed by curlyleaf pondweed found at 7 boat ramps, moneywort at 4 boat ramps, brittleleaf naiad at 3 boat ramps, purple loosestrife at one boat ramp, and Brazilian elodea at one boat ramp.

Click here for a pdf of the Aquatic Invasive Plant Identification Guide.

Click an image below for more detail.