Defining and Identifying Functional Habitat to Inform Species Recovery on a Large Regulated River

Abstract:

Goals and objectives for the restoration of aquatic ecosystems often focus on species recovery, but often the primary tools available to managers involve the manipulation of flow regime and physical habitat. Management decisions thus rely on hypotheses about the links between management actions, the response of physical habitat, and the assumed response of a target organism. Ongoing efforts to inform management of the Missouri River as part of Missouri River Restoration Project are focused on the recovery of three endangered species, including the pallid sturgeon (Scaphirhynchus albus), which is endemic to the Mississippi River basin. Recovery of the pallid sturgeon is hampered by uncertainties surrounding the definition and dynamics of ecologically significant habitats for the fish across a range of life stages. Of special interest are constructed side-channel chutes. Construction of these features has emerged as one of the primary restoration techniques used on the Lower Missouri River, yet much remains to be learned about the effectiveness of these chutes in the effort to recover pallid sturgeon. It remains unclear whether these constructed features provide habitat that may be beneficial to the species and for which life stages. Biologists hypothesize that these areas may be critical for larval retention, refugia, food production, foraging, or spawning. We present the integration of a suite of data – high-resolution hydroacoustic data, hydrodynamic modeling, biotic inventories, and laboratory experiments – designed to refine our understanding of habitat dynamics critical during the early life stages of the pallid sturgeon. We present our findings in the context of ongoing restoration activities in the basin and describe how fundamental science exploring habitat dynamics may be incorporated within the existing adaptive management framework.