Distribution and Abundance of Eurasian Watermilfoil (Myriophyllum spicatum L.) and Curly-Leaf Pondweed (Potamogeton crispus L.) in Shawano Lake, Wisconsin

Shawano Lake, Wisconsin has a history of invasive aquatic plant problems, specifically curly-leaf pondweed Potamogeton crispus L. and Eurasian watermilfoil Myriophyllum spicatum L.. In addition to problems associated with invasive plant species, Shawano Lake has been experiencing declining water quality associated with phosphorus P loading potentially due to summer senescence of curly-leaf pondweed James and Owens 2006. Located in east-central Wisconsin, this 6,063-acre lake has been infested with Eurasian watermilfoil, the dominant invasive aquatic plant, since 1991, and more recently curly-leaf pondweed. Both exotic plants are problematic in the northern tier states, and are proven to negatively impact water quality, recreational usage, fisheries, native plant populations, and waterfowl usage. In an effort to document P loading associated with curly-leaf pondweed senescence James and Owens 2006, an aquatic plant survey was conducted in June 2005 to determine the frequency of occurrence for Eurasian watermilfoil and curly-leaf pondweed populations in the lake. In June 2006, plant biomass was collected to document abundance of Eurasian watermilfoil and curly leaf pondweed as well as native plants in Shawano Lake. Additionally, Eurasian watermilfoil and curly-leaf pondweed biomass samples were ground and analyzed for nitrogen, phosphorus, and potassium within plant tissue.