Linking fish trait responses to in‐stream habitat in reconstructed valley‐plugged stream reaches of the Coastal Plain, U.S.A.

Abstract

Valley‐plug formation is a challenging consequence of stream channelization especially in physiographic regions with highly erodible soils. Upstream channel degradation and incision results in accelerated sediment delivery processes wherein downstream aggradation decreases stream power and creates sand‐clogged channels. Channel reconstruction is now meeting hydrogeomorphic goals related to valley‐plug remediation, yet there exists a need to understand how this practice also facilitates ecological restoration. We evaluated fish trait response to in‐stream habitat conditions in channelized, recently restored, and “least‐disturbed” reference reaches of Coastal Plain streams in West Tennessee. Restored reaches were ecologically similar to channelized reaches, having higher proportions of nest‐guarding omnivores that were correlated with higher percentages of pool habitats and lower wetted width:depth ratios compared to reference reaches. Reference reaches had higher proportions of fast‐water dwelling and specialized insectivores that were correlated with high abundance of large woody debris, high‐wetted width:depth ratios, and low percentages of pool habitats. We conclude that in‐stream habitats in reconstructed channels have yet to promote reach‐scale ecological restoration relative to fish assemblage organization because trait‐habitat associations were not similar to reference conditions. However, our results lend to the development of ecological restoration targets that can be incorporated in future channel reconstruction projects in valley‐plugged, channelized streams of the Coastal Plain.

Expansive, positive changes to fish habitat diversity following the formation of a valley plug in a degraded desert river

“…We hypothesized the valley plug facilitated the successful restoration of high‐quality, complex habitat for native fishes in a desert river tributary of the American Southwest, and the results of this study indicate that the introduction of a channel occlusion and the subsequent hydrologic and geomorphic responses of the riverscape did in fact initiate expansive, positive changes to habitat complexity and persistence. Prior research identified that valley plugs can have negative ecosystem implications including various land‐use challenges and alterations to both floodplain and sedimentation dynamics (Fore et al, 2019; Pierce & King, 2008; Shields et al, 2000); however, we observed that in the SRR, the valley plug has facilitated a positive return to near‐historic conditions at reach level (~7.36 km). We also observed that variable inundation types can be considered a direct metric of habitat complexity due to the habitat‐forming processes accompanying changes in flow.…”

Expansive, positive changes to habitat diversity following the formation of a valley plug in a degraded desert river

“…The results of this study indicate the introduction of a channel occlusion and the subsequent hydrologic and geomorphic responses of the riverscape have initiated expansive, positive changes to habitat diversity. Prior research identified that valley plugs can have negative ecosystem implications including various land-use challenges and alterations to both floodplain and sedimentation dynamics (Shields Jr., Knight, & Cooper, 1999;Pierce & King 2008;Fore, Alford, Blackwood, & Blanchard, 2019); however, we observed that in the SRR, the valley plug has facilitated a positive return to near-historic conditions. Accounts of the SRR valley during the early 20th century describe abundant cottonwoods, willows, sedges, and wetlands suggesting the water table was near the surface in much of the valley, similar to what we have seen over the past decade with the evolution of the valley plug (Fortney et al, 2011).…”

Description of a new species of cryptic snubnose darter (Percidae: Etheostomatinae) endemic to north-central Mississippi

“…As described earlier, the species has low genetic diversity and is nowhere abundant outside of small stream reaches associated with some road crossings. Streams in western Tennessee and northern Mississippi are among the most altered in the United States and suitable habitat for several imperiled snubnose darters including E. faulkneri is lacking (Shields Jr, Knight & Cooper, 1995;Warren Jr, Haag & Adams, 2000;Keck & Etnier, 2005;Fore et al, 2019). Urban development in the Y.R.…”