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Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal

Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of...

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Autores principales: Tullos, Desirée D., Finn, Debra S., Walter, Cara
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169487/
https://www.ncbi.nlm.nih.gov/pubmed/25233231
http://dx.doi.org/10.1371/journal.pone.0108091
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author Tullos, Desirée D.
Finn, Debra S.
Walter, Cara
author_facet Tullos, Desirée D.
Finn, Debra S.
Walter, Cara
author_sort Tullos, Desirée D.
collection PubMed
description Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of the press disturbance associated with the presence of dams and the introduction of a pulse disturbance associated with removal of dams. The two case studies represent different geomorphic and ecological conditions that we expected to represent low and high sensitivities to the pulse disturbance of dam removal: the 4 m tall, gravel-filled Brownsville Dam on the wadeable Calapooia River and the 12.5 m tall, sand and gravel-filled Savage Rapids Dam on the largely non-wadeable Rogue River. We evaluated both geomorphic and ecological responses annually for two years post removal, and asked if functional traits of the macroinvertebrate assemblages provided more persistent signals of ecological disturbance than taxonomically defined assemblages over the period of study. Results indicate that: 1) the presence of the dams constituted a strong ecological press disturbance to the near-downstream reaches on both rivers, despite the fact that both rivers passed unregulated flow and sediment during the high flow season; 2) ecological recovery from this press disturbance occurred within the year following the restoration action of dam removal, whereas signals of geomorphic disturbance from the pulse of released sediment persisted two years post-removal, and 3) the strength of the press disturbance and the rapid ecological recovery were detected regardless of whether recovery was assessed by taxonomic or functional assemblages and for both case studies, in spite of their different geomorphic settings.
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spelling pubmed-41694872014-09-22 Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal Tullos, Desirée D. Finn, Debra S. Walter, Cara PLoS One Research Article Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of the press disturbance associated with the presence of dams and the introduction of a pulse disturbance associated with removal of dams. The two case studies represent different geomorphic and ecological conditions that we expected to represent low and high sensitivities to the pulse disturbance of dam removal: the 4 m tall, gravel-filled Brownsville Dam on the wadeable Calapooia River and the 12.5 m tall, sand and gravel-filled Savage Rapids Dam on the largely non-wadeable Rogue River. We evaluated both geomorphic and ecological responses annually for two years post removal, and asked if functional traits of the macroinvertebrate assemblages provided more persistent signals of ecological disturbance than taxonomically defined assemblages over the period of study. Results indicate that: 1) the presence of the dams constituted a strong ecological press disturbance to the near-downstream reaches on both rivers, despite the fact that both rivers passed unregulated flow and sediment during the high flow season; 2) ecological recovery from this press disturbance occurred within the year following the restoration action of dam removal, whereas signals of geomorphic disturbance from the pulse of released sediment persisted two years post-removal, and 3) the strength of the press disturbance and the rapid ecological recovery were detected regardless of whether recovery was assessed by taxonomic or functional assemblages and for both case studies, in spite of their different geomorphic settings. Public Library of Science 2014-09-18 /pmc/articles/PMC4169487/ /pubmed/25233231 http://dx.doi.org/10.1371/journal.pone.0108091 Text en © 2014 Tullos et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Tullos, Desirée D.
Finn, Debra S.
Walter, Cara
Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title_full Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title_fullStr Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title_full_unstemmed Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title_short Geomorphic and Ecological Disturbance and Recovery from Two Small Dams and Their Removal
title_sort geomorphic and ecological disturbance and recovery from two small dams and their removal
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169487/
https://www.ncbi.nlm.nih.gov/pubmed/25233231
http://dx.doi.org/10.1371/journal.pone.0108091
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