Economic Sectors at Risk from Invasive Aquatic Weeds for the Kissimmee Chain of Lakes in Osceola County, Florida, 2004-2005
Frederick W. Bell, Florida State University

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Economic Sectors at Risk From Invasive Aquatic Weeds at Lake Istokpoga, Florida
Frederick W. Bell, Mark A Bonn, Florida State University

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"In summary, we have concluded that many facets of the economy are at risk from invasive aquatic weeds, especially hydrilla, which fall under (1) the organized market “effects” and (2) outdoor recreation based upon common property resources and values that are not traded in an organized market (i.e., non-market). Successful hydrilla management in Lake Istokpoga will sustain almost $40 million per year in numerous “market sales” and support about $.88 million in “non-market” recreational value, placing Lake Istokpoga as an asset at a minimum of $25 million. These enormous figures should be compared with costs of invasive aquatic weed control, and in developing strategies to accommodate hydrilla management."

Summary of a Survey of the Literature on the Economic Impact of Aquatic Weeds
H. William Rockwell, Jr., Ph. D, for the Aquatic Ecosystem Restoration Foundation

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Invasive aquatic plants affect aesthetics, drainage for agriculture and forestry, commercial and sport fishing, drinking water quality, fish and wildlife habitat, flood control, habitats for other plants, human and animal health, hydropower generation, irrigation, navigation, recreational boating, swimming, water conservation and transport, and, ultimately, land values. Because most invasive aquatic plants species have been introduced to this country from abroad, they do not have natural control agents or competitors and they tend to dominate the aquatic systems to which they are exposed. The magnitude of only a few of their impacts has been measured and then, generally, over limited areas. A few well-documented studies, however, provide a basis for estimating the general scale of these affects for the nation as a whole, and might serve as a guide for an appropriate magnitude of response.

There are difficulties in estimating the economic impacts of aquatic weeds (or, conversely, the benefits of their control) due to the "public-good" nature of aquatic resources and the resulting fact that few of these impacts or benefits pass through economic markets. In spite of these difficulties, it can be conservatively estimated that the values-at-risk from aquatic invasive plants in the US is in the range of billions of dollars per year.

Significant sums (at least $100 million) are spent each year in the control of aquatic weeds, however, and the estimated benefits of control are consistently reported to be much higher than these costs. Given the continuing spread of problem species and the difficulty of organizing collective action to control aquatic weeds, it seems likely that too little is being spent on control rather than too much. Furthermore, much could be done to facilitate the further development and use of aquatic weed control techniques.

Although the costs and environmental effects of aquatic weed control have been intensively studied, new technologies for their control are continually being evaluated and developed. Continued attention seems warranted to develop weed control techniques and strategies that moderate costs, meet competing objectives, and minimize the potential for unintended environmental harm. In addition, an accelerated invasion of exotic animal species suggests a more integrated approach to the management of aquatic ecosystems.