Peaking hydropower and fish assemblages: an example from the Tallapoosa
River, AL
Running title: Peaking hydropower and fish assemblages
Elijah B. Lamb, Dennis R. DeVries, Russell A. Wright
Auburn University School of Fisheries, Aquaculture, and Aquatic Sciences
203 Swingle Hall,
Auburn, AL 36849
Corresponding author: Elijah Lamb ebl0020@auburn.edu
Acknowledgements
We acknowledge Tammy DeVries, Thomas Hess, Davis Walley, Colby Lee,
Raleigh Capps, Daniel Thomas, Lindsay Horne, Dustin McKee, Colin
Laubach, Jeff Baker, Colin Dinken, and Chris Lamb for their assistance
with the field and lab portions of this work. Additionally, we thank
Henry Hershey for his assistance with the programming and analyses and
Dr. Shannon Brewer for her insight regarding the analysis and
interpretation of these data. Funding for this work was provided by the
Alabama Power Company as part of the relicensing effort for the Harris
Dam Project (FERC Project No. 2628). This study was also supported by
the Alabama Agricultural Experiment Station and the Hatch program of the
National Institute of Food and Agriculture, U.S. Department of
Agriculture.
Abstract
Dams alter many aspects of riverine environments and can have broad
effects on aquatic organisms and habitats both upstream and downstream.
While dams and the associated reservoirs can provide many services to
people (hydropower, recreation, flood control, navigation, etc.), they
can negatively affect riverine ecosystems. In particular, hydropeaking
dams affect downstream fish habitats by increasing variability in
discharge and temperature. To assess the effects of Harris Dam on the
Tallapoosa River, AL, operating under an adaptive management plan
implemented in 2005, we sampled fish for community and diet analyses
from four sites on the river: three in the regulated region downstream
of the dam, and one unregulated site upstream. Fish were collected every
other month using boat/barge electrofishing. We used Shannon’s H,
nonmetric multidimensional scaling (NMDS), a multiresponse permutation
procedure (MRPP), and indicator species analysis to quantify patterns in
fish assemblage structure and determine how assemblages varied among
sites. NMDS and MRPP indicated significant fish assemblage differences
among sites with the tailrace fish assemblage being distinct from the
other downstream sites, and sites becoming more similar to the upstream,
unregulated site (relative to fish assemblages) with distance downstream
of the tailrace. The tailrace fish assemblage included higher
proportions of rheophilic species that may be better suited for variable
and/or high flows. Altered fish assemblages demonstrated continued
effects of Harris Dam on the downstream aquatic systems, particularly
close to the dam. These effects may indicate further mitigation should
be considered depending on conservation and management goals.
Keywords: fish assemblage, hydropower, flow regulation, community
ecology