LAUSR

Effects of river regulation on floodplain ecosystems are understudied, despite the importance of connectivity between these two ecosystems. We investigated the effects of river regulation on a floodplain specialist, Neoporus spp. (Coleoptera: Dytsicidae), regarding its distribution, behavior, and physiology. We used flood pulses (induced in the regulated river system, natural in the unregulated system) to determine if and how 60 years of river regulation has impacted Neoporus populations. We found distinct distributions of Neoporus across the regulated and unregulated floodplains, with the regulated population being limited to permanent oxbow lakes (as compared to Neoporus in the unregulated system accessing temporary and permanent aquatic habitats to an equal degree). Following flood pulses, both the regulated and uregulated river population distributions remained the same. Aerial dispersal percentages did not change in the regulated population pre- vs. post-flood, but dispersal within the unregulated population decreased. Lipid and protein concentrations in Neoporus did not differ between habitat types. Our study provides evidence of long-term effects of river regulation on a floodplain specialist and further emphasizes the significant contribution provided by flood pulses and their importance to the overall functioning of floodplain ecosystems.