Stormwater ponds: Evaluating the benefits and unintended consequences of an expanding designer ecosystem

Basil V. Iannone III, School of Forest Resources and Conservation, University of Florida, Gainesville, FL, James S. Sinclair, The Ohio State University, Kayla Hess, University of Florida, Alexander J. Reisinger, Soil and Water Sciences Department, University of Florida, Gainesville, FL, Carrie Reinhardt Adams, Environmental Horticulture, University of Florida, Gainesville, FL, Lindsey S. Reisinger, Fisheries and Aquatic Sciences Program, University of Florida, Gainesville, FL and Eban Bean, Agricultural and Biological Engineering, University of Florida, Gainesville

Background/Question/Methods
Stormwater ponds (SWPs) are an increasingly common engineered ecosystems in urban landscapes. These ecosystems are designed for flood control and to protect natural water bodies from polluted urban stormwater runoff. Despite providing effective flood control, SWPs need improvements regarding pollution mitigation. Furthermore, SWPs being highly connected, hydrologically dynamic, and nutrient-rich, may facilitate plant invasions. Despite these shortcomings, the abundance of SWPs is increasing at rates that parallel those of urbanization. The objectives of this talk are to present findings from research on SWP ecology and management conducted throughout the sub-tropical urbanizing area of Gainesville, Florida, USA pertaining to (1) SWP abundance, (2) the efficacy of SWP in protecting downstream aquatic ecosystems, (3) the effects of SWPs on invasive plants, and (4) the effects of SWP plant community management on ecological communities.
Results/Conclusions
Mapping SWPs revealed greater than 76,000 SWPs in Florida alone, covering nearly as much space as urban recreational and industrial areas. We found that urban wetlands either protected or not by SWPs both have similar plant communities dominated by lower-quality, nonnative and facultative species. These similarities are related to elevated levels of nutrients, suggesting that SWPs are not protecting downstream aquatic ecosystems from nutrient-rich urban runoff. We also found a high diversity of invasive plants, with 28 species detected in just 30 ponds. Regardless of these negative impacts, SWPs can provide habitat for native species, including macroinvertebrate communities as or more diverse than those of natural ponds. Regarding plant communities, SWPs vary greatly in plant community management, with some being highly manicured for aesthetics and others being unmanaged allowing plant communities to self-assemble. We found that this variation in plant community management affects the composition of macroinvertebrate communities and traits of invasive plant species both directly, and indirectly via effects on water quality. This management-driven variation in species and trait composition suggests the ability to enhance regional urban biodiversity via spatial variation in SWP vegetation management. Future work needs to identify management and design strategies to improve the ability of SWPs to protect downstream ecosystems and enhance urban biodiversity.