Anthropogenic Effects on Invasive Species in Six Lakes in Kenosha County, Wisconsin

Abstract

The United States Office of Technology reported that between 1906 and 1991 over $97 billion was spent in damages caused by invasive species and since then millions more have been spent. Besides causing economic problems, invasives can have negative impacts on the environment by reducing biodiversity. Humans have been known transporters of invasive species, and in the case of aquatic species the movement of boats between waterways has been identified as a major component of new introductions. Also, runoff from development around lakes is thought to allow invasives to thrive further. In this study, submerged aquatic vegetation was sampled in six lakes of differing boat traffic and sizes. Plants were sorted, identified, and recorded by percent of sample. In addition to field sampling, land cover/use analysis was conducted for the land surrounding the sites using GIS to determine if there were correlations between land use types and percent of invasive species in the lakes. One non-native species (curly-leaf pondweed) was found in lakes with little or no boat traffic. However, invasive species were most dense at lakes with more boat traffic. The presence of invasives at lakes with less anthropogenic disturbance suggests that species may be spreading “naturally”, but increased densities at lakes with higher boat traffic suggest that humans may be playing a significant role in the dispersal of these plants. In the land use analysis, a strong positive correlation was found between the percent of developed land (open space, low, medium, and high intensity) and the percent of aquatic invasive species in the lake. These results are important to help determine how invasive species are being spread and what factors are favoring their growth.