Hydraulic modelling of the spatial and temporal variability in Atlantic salmon parr habitat availability in an upland stream

Luca Fabris, Iain Archibald Malcolm, Willem Bastiaan Buddendorf, Karen Jane Millidine, Doerthe Tetzlaff, Chris Soulsby

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

We show how spatial variability in channel bed morphology affects the hydraulic characteristics of river reaches available to Atlantic salmon parr (Salmo salar) under different flow conditions in an upland stream. The study stream, the Girnock Burn, is a long-term monitoring site in the Scottish Highlands. Six site characterised by different bed geometry and morphology were investigated. Detailed site bathymetries were collected and combined with discharge time series in a 2D hydraulic model to obtain spatially distributed depth-averaged velocities under different flow conditions. Available habitat (AH) was estimated for each site. Stream discharge was used according to the critical displacement velocity (CDV) approach. CDV defines a velocity threshold above which salmon parr are not able to hold station and effective feeding opportunities or habitat utilization are reduced, depending on fish size and water temperature. An average value of the relative available habitat (< RAH >) for the most significant period for parr growth - April to May - was used for inter-site comparison and to analyse temporal variations over 40 years. Results show that some sites are more able than others to maintain zones where salmon parr can forage unimpeded by high flow velocities under both wet and dry conditions. With lower flow velocities, dry years offer higher values of < RAH > than wet years. Even though < RAH > can change considerably across the sites as stream flow changes, the directions of change are consistent. Relative available habitat (RAH) shows a strong relationship with discharge per unit width, whilst channel slope and bed roughness either do not have relevant impact or compensate each other. The results show that significant parr habitat was available at all sites across all flows during this critical growth period, suggesting that hydrological variability is not a factor limiting growth in the Girnock.
Original languageEnglish
Pages (from-to)1046-1059
Number of pages14
JournalScience of the Total Environment
Volume601-602
Early online date9 Jun 2017
DOIs
Publication statusPublished - 1 Dec 2017

Fingerprint

habitat availability
Hydraulics
Availability
hydraulics
habitat
Flow velocity
modeling
flow velocity
Bathymetry
Stream flow
Hydraulic models
bed roughness
Discharge (fluid mechanics)
Fish
Time series
Intercellular Signaling Peptides and Proteins
bathymetry
Surface roughness
Rivers
low flow

Keywords

  • Salmon parr
  • Hydraulic models
  • Fish habitat
  • Flow regime
  • River bed morphology
  • Habitat restoration

Cite this

Hydraulic modelling of the spatial and temporal variability in Atlantic salmon parr habitat availability in an upland stream. / Fabris, Luca; Malcolm, Iain Archibald; Buddendorf, Willem Bastiaan; Millidine, Karen Jane; Tetzlaff, Doerthe; Soulsby, Chris.

In: Science of the Total Environment, Vol. 601-602, 01.12.2017, p. 1046-1059.

Research output: Contribution to journalArticle

Fabris, Luca ; Malcolm, Iain Archibald ; Buddendorf, Willem Bastiaan ; Millidine, Karen Jane ; Tetzlaff, Doerthe ; Soulsby, Chris. / Hydraulic modelling of the spatial and temporal variability in Atlantic salmon parr habitat availability in an upland stream. In: Science of the Total Environment. 2017 ; Vol. 601-602. pp. 1046-1059.
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title = "Hydraulic modelling of the spatial and temporal variability in Atlantic salmon parr habitat availability in an upland stream",
abstract = "We show how spatial variability in channel bed morphology affects the hydraulic characteristics of river reaches available to Atlantic salmon parr (Salmo salar) under different flow conditions in an upland stream. The study stream, the Girnock Burn, is a long-term monitoring site in the Scottish Highlands. Six site characterised by different bed geometry and morphology were investigated. Detailed site bathymetries were collected and combined with discharge time series in a 2D hydraulic model to obtain spatially distributed depth-averaged velocities under different flow conditions. Available habitat (AH) was estimated for each site. Stream discharge was used according to the critical displacement velocity (CDV) approach. CDV defines a velocity threshold above which salmon parr are not able to hold station and effective feeding opportunities or habitat utilization are reduced, depending on fish size and water temperature. An average value of the relative available habitat (< RAH >) for the most significant period for parr growth - April to May - was used for inter-site comparison and to analyse temporal variations over 40 years. Results show that some sites are more able than others to maintain zones where salmon parr can forage unimpeded by high flow velocities under both wet and dry conditions. With lower flow velocities, dry years offer higher values of < RAH > than wet years. Even though < RAH > can change considerably across the sites as stream flow changes, the directions of change are consistent. Relative available habitat (RAH) shows a strong relationship with discharge per unit width, whilst channel slope and bed roughness either do not have relevant impact or compensate each other. The results show that significant parr habitat was available at all sites across all flows during this critical growth period, suggesting that hydrological variability is not a factor limiting growth in the Girnock.",
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T1 - Hydraulic modelling of the spatial and temporal variability in Atlantic salmon parr habitat availability in an upland stream

AU - Fabris, Luca

AU - Malcolm, Iain Archibald

AU - Buddendorf, Willem Bastiaan

AU - Millidine, Karen Jane

AU - Tetzlaff, Doerthe

AU - Soulsby, Chris

N1 - Acknowledgements The authors would like to thank Marine Scotland Science and the University of Aberdeen for funding the PhD project and Marine Scotland Science for offering fieldwork assistance and providing discharge, water temperature and fish length data set.

PY - 2017/12/1

Y1 - 2017/12/1

N2 - We show how spatial variability in channel bed morphology affects the hydraulic characteristics of river reaches available to Atlantic salmon parr (Salmo salar) under different flow conditions in an upland stream. The study stream, the Girnock Burn, is a long-term monitoring site in the Scottish Highlands. Six site characterised by different bed geometry and morphology were investigated. Detailed site bathymetries were collected and combined with discharge time series in a 2D hydraulic model to obtain spatially distributed depth-averaged velocities under different flow conditions. Available habitat (AH) was estimated for each site. Stream discharge was used according to the critical displacement velocity (CDV) approach. CDV defines a velocity threshold above which salmon parr are not able to hold station and effective feeding opportunities or habitat utilization are reduced, depending on fish size and water temperature. An average value of the relative available habitat (< RAH >) for the most significant period for parr growth - April to May - was used for inter-site comparison and to analyse temporal variations over 40 years. Results show that some sites are more able than others to maintain zones where salmon parr can forage unimpeded by high flow velocities under both wet and dry conditions. With lower flow velocities, dry years offer higher values of < RAH > than wet years. Even though < RAH > can change considerably across the sites as stream flow changes, the directions of change are consistent. Relative available habitat (RAH) shows a strong relationship with discharge per unit width, whilst channel slope and bed roughness either do not have relevant impact or compensate each other. The results show that significant parr habitat was available at all sites across all flows during this critical growth period, suggesting that hydrological variability is not a factor limiting growth in the Girnock.

AB - We show how spatial variability in channel bed morphology affects the hydraulic characteristics of river reaches available to Atlantic salmon parr (Salmo salar) under different flow conditions in an upland stream. The study stream, the Girnock Burn, is a long-term monitoring site in the Scottish Highlands. Six site characterised by different bed geometry and morphology were investigated. Detailed site bathymetries were collected and combined with discharge time series in a 2D hydraulic model to obtain spatially distributed depth-averaged velocities under different flow conditions. Available habitat (AH) was estimated for each site. Stream discharge was used according to the critical displacement velocity (CDV) approach. CDV defines a velocity threshold above which salmon parr are not able to hold station and effective feeding opportunities or habitat utilization are reduced, depending on fish size and water temperature. An average value of the relative available habitat (< RAH >) for the most significant period for parr growth - April to May - was used for inter-site comparison and to analyse temporal variations over 40 years. Results show that some sites are more able than others to maintain zones where salmon parr can forage unimpeded by high flow velocities under both wet and dry conditions. With lower flow velocities, dry years offer higher values of < RAH > than wet years. Even though < RAH > can change considerably across the sites as stream flow changes, the directions of change are consistent. Relative available habitat (RAH) shows a strong relationship with discharge per unit width, whilst channel slope and bed roughness either do not have relevant impact or compensate each other. The results show that significant parr habitat was available at all sites across all flows during this critical growth period, suggesting that hydrological variability is not a factor limiting growth in the Girnock.

KW - Salmon parr

KW - Hydraulic models

KW - Fish habitat

KW - Flow regime

KW - River bed morphology

KW - Habitat restoration

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DO - 10.1016/j.scitotenv.2017.05.112

M3 - Article

VL - 601-602

SP - 1046

EP - 1059

JO - Science of the Total Environment

JF - Science of the Total Environment

SN - 0048-9697

ER -