Aquatic plants and animals rely on each other for survival; when parts of the ecosystem are out of balance, the whole lake can be in jeopardy. The Lake Wingra community members and organizations were concerned with the high levels of carp present in the lake. To evaluate the situation and discern what actions should be taken to remedy the issue, the Wisconsin Department of Natural Resources approved a July 8th, 2004 grant for the Lake Wingra Shoreline Habitat Restoration Project. The recommendations were made by the Friends of Lake Wingra Watershed Management Plan in order to protect the Lake Wingra habitat from this post-colonial, invasive species. They created an enclosure and removed all the common carp, which were introduced in the 1880's, from the rest of the species present in Lake Wingra. The enclosure and the rest of the lake are being monitored to determine whether carp are having a negative impact on the ecosystem. If it turns out that they are, steps will be taken to continue the suppression of the carp population. However, complete elimination of the species from the area has proven difficult, since the Wingra dam provides access for future carp migrations from other lakes.
Our initial question pertained to how the removal of carp from Lake Wingra would affect the growth of plant populations. We set out to answer this question by using fast-growing, water-borne plant, duckweed (Lemna minor, Lemnaceae family) in a controlled experiment using water from outside and within the Lake Wingra carp-free enclosure. The fact that duckweed, the smallest species of flowering plant, reproduces asexually by creating "daughter" fronds from a central bud, makes its population growth easily observable (Cronquist). Duckweed is a sturdy species that can survive in a variety of environments, making it a good indicator for an environment's health. Since duckweed also absorbs nutrients through all of its surfaces, it can be used as a tool for judging over-all water quality (Raven, et al). As of August 9th 2006, the LTER data shows that Lake Wingra's phosphorus (P) levels within the enclosure at 0.005 micrograms per liter while levels outside the enclosure are at 0.091. This may be due to many factors, but the carp are the most visible controllable aspect differentiating the two environments. We tested the effects of water from Lake Wingra from both inside and outside the carp enclosure and water with varying levels of hydroponic nutrient solution added on the vegetative reproduction of duckweed. With phosphorus levels higher outside the enclosure, our prediction is that the duckweed will grow better in the water with carp living in it.