September 2007 ECOLOGICAL RESTORATION 25:3  199 Ecological Restoration Vol. 25, No. 3, 2007 ISSN 1522-4740 E-ISSN 1543-4079 ©2007 by the Board of Regents of the University of Wisconsin System. LOCAL KNOWLEDGE Rethinking Exotic Plants: Using Citizen Observations in a Restoration Proposal for Kings Bay, Florida Jason M. Evans, Ann C. Wilkie, Jeffrey Burkhardt and Richard P. Haynes ABSTRACT The Kings Bay, Crystal River complex, located in Citrus County, Florida, is one of the world’s largest spring-fed ecosystems and a critical warm-water refuge for endangered Florida manatees. Unfortunately, large areas of Kings Bay are currently in a state of ecological degradation characterized by smothering mats of the filamentous cyanobacterium Lyngbya wollei. The causes of this ecosystem shift are not well understood, although it is often suggested that human-caused nutrient loading into the Bay combined with intermittent saltwater intrusions from storm surges may be responsible. In this article, we present results from interviews with local citizens, a review of aquatic plant literature, and research into the history of ecological change in Kings Bay. Our work indicates that management efforts to eradicate invasive exotic aquatic species may also have played an important role in the dominance of L. wollei. We suggest that future restoration efforts should follow a logic of “alternative stable states” that focuses primarily on the recovery of desired ecosystem functions and relaxes the assumption that exotic plants should be minimized. The Kings Bay case study points toward a more adaptive conception of ecological restoration, one informed by local knowledge and open to the utilization of established exotic plants as a tool for maintaining or restoring important ecological attributes. Keywords: adaptive management, alternative stable states, ecological restoration, Eurasian milfoil (Myriophyllum spicatum), Florida, hydrilla (Hydrilla verticillata), invasive species, local knowledge, Lyngbya wollei, water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes) T he minimization or elimination of exotic species is one of the traditional goals of ecological resto- ration. However, many ecosystems are so drastically altered that elimi- nating established exotics may be cost-prohibitive or even impossible (D’Antonio and Meyerson 2002). Moreover, field studies indicate that some exotic species, particularly plants established in highly degraded areas, can provide functional services that are remarkably consonant with long-term conservation and restora- tion goals. Naturalized exotic plants have been found to facilitate resto- ration through various functional mechanisms, including rapid fixation of nitrogen in depleted soils (Parotta 1992), establishment of a protective canopy for forest understory develop- ment (Lugo 2004), and phytoreme- diation of harmful pollutants (Ma et al. 2001). In other cases, exotic plants targeted for eradication by ecosystem managers can provide primary feeding and breeding habitat for native fauna that these same managers are trying to protect (Chen 2001, Shapiro 2002). Eradication of one exotic plant spe- cies from a site does not necessarily result in the straightforward restora- tion of native communities, and may sometimes lead to the establishment of other exotic or invasive species more difficult to manage. his has led Ewel and Putz (2004) to suggest that strict adherence to the principle of minimizing exotic species within ecological restoration projects may at times be counterproductive. Alternative Stable States Recent research concerning “alterna- tive stable states” raises further ques- tions about the general conclusion that exotic species constitute an a priori harm (Sagoff 2005). Limnolo- gists have observed that some shallow aquatic ecosystems switch between alternative stable states (Blindow et al. 1993, Scheffer et al. 1993). In one stable state condition, large popula- tions of macrophytes create and are dependent upon clear water. In con- trast, the other stable state condition is characterized by cyanobacteria or algal communities that create and are able to thrive in highly turbid water. Switches between the two states are triggered by high-energy events, with wind, waves, and torrential rainfall from hurricanes among the most common natural disturbance factors