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Evaluating the effectiveness of restoring longitudinal connectivity for stream fish communities: towards a more holistic approach

Tummers, J.S.; Hudson, S.; Lucas, M.C.

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Authors

J.S. Tummers

S. Hudson



Abstract

A more holistic approach towards testing longitudinal connectivity restoration is needed in order to establish that intended ecological functions of such restoration are achieved. We illustrate the use of a multi-method scheme to evaluate the effectiveness of ‘nature-like’ connectivity restoration for stream fish communities in the River Deerness, NE England. Electric-fishing, capture-mark-recapture, PIT telemetry and radio-telemetry were used to measure fish community composition, dispersal, fishway efficiency and upstream migration respectively. For measuring passage and dispersal, our rationale was to evaluate a wide size range of strong swimmers (exemplified by brown trout Salmo trutta) and weak swimmers (exemplified by bullhead Cottus perifretum) in situ in the stream ecosystem. Radio-tracking of adult trout during the spawning migration showed that passage efficiency at each of five connectivity-restored sites was 81.3–100%. Unaltered (experimental control) structures on the migration route had a bottle-neck effect on upstream migration, especially during low flows. However, even during low flows, displaced PIT tagged juvenile trout (total n = 153) exhibited a passage efficiency of 70.1–93.1% at two nature-like passes. In mark-recapture experiments juvenile brown trout and bullhead tagged (total n = 5303) succeeded in dispersing upstream more often at most structures following obstacle modification, but not at the two control sites, based on a Laplace kernel modelling approach of observed dispersal distance and barrier traverses. Medium-term post-restoration data (2–3 years) showed that the fish assemblage remained similar at five of six connectivity-restored sites and two control sites, but at one connectivity-restored headwater site previously inhabited by trout only, three native non-salmonid species colonized. We conclude that stream habitat reconnection should support free movement of a wide range of species and life stages, wherever retention of such obstacles is not needed to manage non-native invasive species. Evaluation of the effectiveness of fish community restoration in degraded streams benefits from a similarly holistic approach.

Citation

Tummers, J., Hudson, S., & Lucas, M. (2016). Evaluating the effectiveness of restoring longitudinal connectivity for stream fish communities: towards a more holistic approach. Science of the Total Environment, 569-570, 850-860. https://doi.org/10.1016/j.scitotenv.2016.06.207

Journal Article Type Article
Acceptance Date Jun 26, 2016
Online Publication Date Jul 14, 2016
Publication Date Nov 1, 2016
Deposit Date Aug 16, 2016
Publicly Available Date Mar 28, 2024
Journal Science of the Total Environment
Print ISSN 0048-9697
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 569-570
Pages 850-860
DOI https://doi.org/10.1016/j.scitotenv.2016.06.207

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