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Research Project: Enhancing Long-Term Agroecosystem Sustainability of Water and Soil Resources Through Science and Technology

Location: Water Quality and Ecology Research

Title: Impact of dams on stream fish diversity: a different result

item FAUCHEUX, NICKY - Us Army Corp Of Engineers (USACE)
item MIRANDA, LEANDRO - Mississippi State University
item Taylor, Jason
item FARRIS, JERRY - Arkansas State University

Submitted to: Diversity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2023
Publication Date: 6/1/2023
Citation: Faucheux, N.M., Miranda, L.E., Taylor, J.M., Farris, J.L. 2023. Impact of dams on stream fish diversity: a different result. Diversity. 2023,15,728.

Interpretive Summary: Dam for flood control or reservoir creation can impact fish biodiversity by limiting movement of fishes in rivers. We tested whether fish communities in five different river systems in northwest Mississippi have been impacted by construction of large flood control reservoirs. We found no difference between fish communities above and below dams which suggests that reservoirs are not impacting fish communities in the region. This is opposite of expectations and is likely due to fish communities being impacted by previous habitat impacts prior to dam construction (i.e. significant deforestation and erosion).

Technical Abstract: Impoundments can drastically change the physical and biological characteristics of fluvial systems. Changes in the physical characteristics, such as reductions in flow, increased sediment deposition, and increased surface area often influence the system’s biological components including plant, macroinvertebrate, and fish assemblages. In addition to direct effects on impounded water-bodies, impoundments can also have wide-ranging effects at the watershed scale, particularly on upstream tributary streams. The purpose of this study was to assess the magnitude of these effects. We analyzed historical data from 26 streams distributed across five sub-basins in the bluff hills region of the Yazoo Basin, MS, USA. All five major tributary rivers in this region are impounded by large (11,240 - 26,143 hectares) reservoirs for flood control. We compared fish assemblages in streams located upstream and downstream of the four reservoirs using PERMANOVA, and contrary to expectations, found no significant differences between the upstream and downstream assemblages. We explore several possible explanations for this discrepancy and suggest that stream assemblage response to impoundment may be nuanced by the regional species pool, the history of stream conditions in the watershed, and the resistance of the streams to periodic dis-turbances.