Courtney Holt

Ph.D. Candidate, University of Georgia

Conference Travel Grant Type 2 (Society of Freshwater Science)

Impacts of flow regulation on distribution, behavior, and physiology of Neoporus sp. (Coleoptera: Dytiscidae), a common inhabitant of southeastern floodplains

“Lack of regular flood events on regulated rivers can have wide-ranging effects on the distribution of floodplain inhabitants. This study aims to determine the effects of flow regulation on the predaceous diving beetle Neoporus sp., a widespread southeastern U.S. floodplain inhabitant. Floodplains of three regulated and three unregulated river systems were investigated over a three-year period to determine differences among the systems regarding Neoporus (1) distribution across the floodplains, (2) propensity for flight (dispersal), and (3) lipid and protein stores. The data show distinct differences between the two rivers: Neoporus populations were restricted to permanent waters on the regulated floodplains, while on the unregulated floodplains they regularly access temporary waters (p<0.001). Behaviorally, populations in regulated systems were significantly less likely to disperse via flight (p<0.001). Physiologically, individuals in regulated systems contained significantly lower concentrations of lipids than those in unregulated systems (p=0.03). Protein concentrations did not differ. These results suggest that a lack of regular flood events has significantly affected multiple aspects of Neoporus populations in regulated systems. Thus, Neoporus may be a useful indicator of overall floodplain connectivity.”