Movement through Dams Facilitates Population Connectivity in a Large River

Even in heavily impounded river ecosystems, aquatic populations and communities retain limited connectivity via movement through dams. This connectivity has the potential to influence population dynamics but has been infrequently characterized. We used 1995-2008 paddlefish mark-recapture data to perform the following: (i) quantify rates of movement through dams and (ii) examine the influence of dam discharge on fish passing dams. We found that there are substantial one-way (upstream to downstream) population connections maintained via fish passing dams and that dam discharge is a key driver of downstream fish movement. Results of our study suggest that population connections maintained by fish passing dams can play an important role in population dynamics depleting upstream populations and subsidizing downstream populations, particularly in years with high flow events. We suggest that the influence of hydrology on maintaining populations in fragmented ecosystems is an increasingly important consideration for conservation and management of aquatic ecosystems in the face of predicted hydrological changes from climate change. Copyright (c) 2014 John Wiley & Sons, Ltd.