DECEMBER 2017 RESEARCH Evaluating the Aquatic Habitat Potential of Flooded Polders in The Sacramento–San Joaquin Delta John R. Durand *, 1 NSBI predictions. Because flood probabilities and Volume 15, Issue 4 | Article 4 https://doi.org/10.15447/sfews.2017v15iss4art4 repair prioritization analyses suggest that polders in the south Delta are most likely to flood and be * Corresponding author:
[email protected] abandoned, without extensive intervention, much of 1 Center for Watershed Sciences, University of California–Davis, the Delta will become a freshwater lake ecosystem, Davis, CA 95616 dominated by alien species. Proactive management of flooded tracts will nearly always hedge risks, save money, and offer more functional habitats ABSTRACT in the future; however, without proper immediate incentives, it will be difficult to encourage strong Large tracts of land in the Sacramento–San Joaquin management practices. Delta are subsided because of agricultural practices, creating polders up to 10 m below sea level that are vulnerable to flooding. As protective dikes breach, KEY WORDS these become shallow, open-water habitats that Polder, flooded island, restoration, reconciliation will not resemble any historical state. I investigated ecology, novel ecosystems, Sacramento–San Joaquin physical and biotic drivers of novel flooded polder Delta habitat, using a Native Species Benefit Index (NSBI) to predict the nature of future Delta ecosystems. Results suggest that flooded polders in the north INTRODUCTION Delta will have the ecology and fish community Twentieth-century land-use practices have accelerated composition of a tidal river plain, those in the Cache– land subsidence and polder formation around the Lindsey Complex (CLC) will have that of a tidal globe, especially where land reclamation is combined backwater, those in the confluence of the Sacramento with intensive agriculture near rivers and estuaries and San Joaquin rivers a brackish estuary, and (McCreary et al.