Bickerton, M.

Hill, Graham

Maddock, Ian

English

University of Worcester Research and Publications

Glossiphoniidae (8) Rhyacophilidae (13)0.00 0.000.10 0.100.20 0.200.30 0.300.50 0.500.70 0.700.90 0.901.40 1.40-0.25 v(m/s)0 0.1 0.2 0.3 0.5 0.7 0.9 1.5 -0.25 v(m/s)0 0.1 0.2 0.3 0.5 0.7 0.9 1.5Are Surface Flow Type Mesohabitats Biologically Distinct?1 1 2Graham Hill (g.hill@worc.ac.uk), Ian Maddock  and Melanie Bickerton1 Department of Applied Science, Geography and Archaeology, University of Worcester, Henwick Grove, Worcester 2  School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, BirminghamBackgroundTraditionally river ecologists have focused on the microhabitat scale, fluvial geomorphologists the mesohabitat scale. Legislation operates at the macroscale. Recently the biological realism of some widely-used techniques (PHABSIM) has been questioned (Booker et al., 2006). Surface Flow Types (SFT) are the standard hydraulic descriptor in the River Habitat Survey (Environment Agency, 2003), although their biological significance is unknown. This study examines the physical andbiological relevance of mesohabitats defined by SFT.MethodMultiple mesohabitat surveys of several lowland English rivers were completed, mesohabitats were defined by SFT (figure 1). Depth, velocity, substrate and other data were collected from each mesohabitat. Benthic macroinvertebrates (MI) were collected from representative mesohabitats together with further depth, velocity and substrate data from each MI sample point (microhabitat).ReferencesBooker, D.J., Acreman, M.C., Dunbar, M.J., Goodwin, T., Gowing, I. and Young, A. (2006), “Rapid assessment of physical habitat-discharge relationships” In Proceedings, International conference on Riverine Hydroecology: Advances in research and applications, University of Stirling, 14th – 18th August 2006.Environment Agency (2003) River Habitat Survey Field Guidance Manual (2003 version). Environment Agency, Bristol.Le Coarer, Y. (2005), "HydroSignature software for hydraulic quantification” In: Harby, A. et al. (Eds), COST 626 - European Aquatic Modelling Network. Proceedings from the final meeting, Silkeborg, Denmark 19-20 May 2005. National Environmental Research Institute, Silkeborg, Denmark.ResultsAnalysis showed there are statistically significant differences between depth and velocity (table 1) and substrate and embeddedness of fine material across five SFT mesohabitats. Table 1. Results from Mann-Whitney U test analysis of depth and velocity data from five surface flow type habitats. (Significant: P = <0.05, Not Significant: P = >0.05).Depth No Perceptible Smooth Rippled Unbroken waveNo Perceptible (NP)Smooth (SM) SignificantRippled (RP) Significant SignificantUnbroken wave (UW) Significant Significant SignificantUpwelling (UP) Significant Significant Significant SignificantVelocity No Perceptible Smooth Rippled Unbroken waveNo Perceptible (NP)Smooth (SM) SignificantRippled (RP) Significant SignificantUnbroken wave (UW) Significant Significant SignificantUpwelling (UP) Significant Not SignificantSignificant Not SignificantFigure 1. Habitat types from three surveys of the same reach of Leigh Brook, Worcestershire, UK. 'A' shows a small backwater inundated only high discharge and 'B' a bed controlled area of unbroken wave.HydroSignature analysis (Le Coarer, 2005) identified clusters of SFT mesohabitat by depth/velocity class (figure 2). No Perceptible mesohabitats cluster in slow/deep cells (left) and unbroken wave mesohabitats in faster/shallower areas (upper right). There is a strong probability of correctly identifying depth/velocity classes associated with SFTs, NP (90%), UW (73%) and UP (78%) whilst for SM (44%) and RP (33%) depth/velocity classes are less reliably identified.Figure 2. Distribution of depth and velocity classes by surface flow type from mesohabitat data based on HydroSignature analysis.cell containing the mean depth/velocity from all sites, the deep orange represents the 25th - 75th percentile range and the light orange the observed maximum/minimum range. LIFE score velocity classes are shown for comparison. Similar matrices can be derived from substrate and embeddedness data.Figure 3. Depth and velocity matrices for Glossipjhoniidae and Rhyacophillidae. LIFE flow groups shown in yellow in the x-axisConclusion·Mesohabitats defined by SFT have statistically distinct physical characteristics and appear capable of consistent identification. ·Macroinvertebrates have depth/velocity and substrate/embeddedness preferences.·Therefore, SFT mesohabitats may provide a way of mapping rivers at the macroscale whilst retaining biological relevance.AcknowledgementsI am grateful to Dr I Maddock and Ms M Bickerton for their help and guidance in this research and  to  Universityof Worcester and University of Birminghamfor financial assistance. My thanks go to my family for their support, the  co-operation of many landowners and the willingness of a small army of field assistants without whom this work could not have taken place.Using depth/velocity data from MI sample points, a preference matrix was constructed for each MI family group (figure 3). The red cell shows the

Are Surface Flow Type Mesohabitats Biologically Distinct?

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