Assessing the Influence of Different Inland Lake Management Strategies on Human-Mediated Invasive Species Spread
Species introduced to the Great Lakes region through shipping, pet trade, and as biological control have caused significant environmental damages and increased costs to boat owners and various water-dependent industries. Once established, some of these species, such as Dreissenid mussels and Eurasian watermilfoil (Myriophyllum spicatum), use recreational boaters as their primary vector of dispersal. Control efforts in the past have focused on boater education efforts and boat washing stations and inspections, yet these can be expensive methods with limited effectiveness. In this study, I construct an invasion model based on a gravity model framework to accurately describe the spread of a simulated invasive species. After parameterization, the constructed model was able to effectively model the human-mediated movements of an invasive species based on historical Dreissenid spread patterns, predicting an average of 78.2% (standard deviation = 0.01%) lakes correctly per model run. I then use the model to attempt to determine the effectiveness of three different invasive species management scenarios in Michigan: deterring boaters from lakes with a high risk of invasion, targeted education at high-risk lakes, and a large-scale education effort. Results indicated that deterring boaters from high-risk lakes is effective in the first five years of an invasion, targeted education is more effective at late stages of an invasion, and large-scale education is effective at all stages of an invasion. Depending on management intensity, the average reduction in the number of invaded lakes ranged from 0.03 at the period of least reduction to 1.49 at the period of greatest reduction when deterring boaters; targeted education and large-scale education reduced the number of invaded lakes by 0.00-1.39 and 0.17-6.00, respectively. Though the management strategies modeled here are theoretical responses to management by recreational boaters, the potential costs of each management scenario in conjunction with these modeled results can inform recommendations to managers attempting to slow the spread and mitigate damages caused by aquatic invasive species.
Ecology, Environmental Science, Natural Resource Management, invasive species, gravity models, human-mediated dispersal, Dreissenid mussels, natural resources management, predictive models, recreational boaters
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