PATTERNS OF ICHTHYOFAUNAL DISTRIBUTION AND CONNECTIVITY IN NAVIGABLE AND FREE-FLOWING REACHES OF A MAJOR RIVER SYSTEM: THE ALLEGHENY RIVER IN PENNSYLVANIA
Article first published online: 15 MAY 2013
Copyright © 2013 John Wiley & Sons, Ltd.
River Research and Applications
Volume 30, Issue 5, pages 631–638, June 2014
How to Cite
Argent, D. G. and Kimmel, W. G. (2014), PATTERNS OF ICHTHYOFAUNAL DISTRIBUTION AND CONNECTIVITY IN NAVIGABLE AND FREE-FLOWING REACHES OF A MAJOR RIVER SYSTEM: THE ALLEGHENY RIVER IN PENNSYLVANIA. River Res. Applic., 30: 631–638. doi: 10.1002/rra.2668
- Issue published online: 6 JUN 2014
- Article first published online: 15 MAY 2013
- Manuscript Accepted: 3 APR 2013
- Manuscript Revised: 18 MAR 2013
- Manuscript Received: 1 OCT 2012
- benthic fishes;
- pelagic fishes;
- lock and dams
Connectivity throughout large riverine networks is often compromised by lock and dam (L/D) structures designed to facilitate year-round navigation. The resultant interruption of flow inhibits free passage of aquatic biota potentially isolating mainstem and tributary communities. Our objectives were (i) to evaluate the impact of a series of navigational L/D structures on two targeted fish assemblages (TFAs): large-bodied (>250 mm total length) pelagic and benthic (darter) communities and (ii) to examine patterns of tributary and mainstem connectivity. We systematically captured fishes utilizing gillnets, benthic trawls and backpack electrofishers from an impounded and a free-flowing reach extending over 203 km of the Allegheny River in Pennsylvania. Species richness among the large-bodied targeted fish assemblage was distributed somewhat evenly throughout each pool, peaking near dams and in an undredged pool. Depauperate darter assemblages of low species richness characterized most of the navigable reach with diversity and abundance concentrated in L/D tailrace areas. By contrast, darter communities inhabiting the free-flowing reach were more diverse, abundant and evenly distributed, indicating the influence of uninterrupted connectivity. Community similarity at mainstem/tributary junctions increased with increasing tributary size with 50% of the mainstem species complement also inhabiting the largest tributary. This study underscores the importance of dams as barriers to ichthyofaunal connectivity, particularly to those benthic fishes which are relatively immobile and habitat specific, and the importance of mainstem/tributary junctions as avenues of riverine connectivity. Copyright © 2013 John Wiley & Sons, Ltd.