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Interaction between local hydrodynamics and algal community in epilithic biofilm

Graba, Myriam and Sauvage, Sabine and Moulin, Frédéric and Urrea, Gemma and Sabater, Sergi and Sanchez-Pérez, José-Miguel Interaction between local hydrodynamics and algal community in epilithic biofilm. (2013) Water Research, 47 (7). 2153-2163. ISSN 0043-1354

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Official URL: http://dx.doi.org/10.1016/j.watres.2013.01.011

Abstract

Interactions between epilithic biofilm and local hydrodynamics were investigated in an experimental flume. Epilithic biofilm from a natural river was grown over a 41 day period in three sections with different flow velocities (0.10, 0.25 and 0.40 m s-¹ noted LV, IV and HV respectively). Friction velocities u* and boundary layer parameters were inferred from PIV measurement in the three sections and related to the biofilm structure. The results show that there were no significant differences in Dry Mass and Ash-Free Dry Mass (g m-²) at the end of experiment, but velocity is a selective factor in algal composition and the biofilms' morphology differed according to differences in water velocity. A hierarchical agglomerative cluster analysis (BrayeCurtis distances) and an Indicator Species Analysis (IndVal) showed that the indicator taxa were Fragilaria capucina var. mesolepta in the lowvelocity (u* = ¼ 0.010e0.012 m s-¹), Navicula atomus, Navicula capitatoradiata and Nitzschia frustulum in the intermediate velocity (u* = ¼ 0.023e0.030 m s-¹) and Amphora pediculus, Cymbella proxima, Fragilaria capucina var. vaucheriae and Surirella angusta in the high-velocity (u* = ¼ 0.033e0.050m s-¹) sections. A sloughing test was performed on 40-day-old biofilms in order to study the resistance of epilithic biofilms to higher hydrodynamic regimes. The results showed an inverse relationship between the proportion of detached biomass and the average value of friction velocity during growth. Therefore, water velocity during epilithic biofilm growth conditioned the structure and algal composition of biofilm, as well as its response (ability to resist) to higher shear stresses. This result should be considered in modelling epilithic biofilm dynamics in streams subject to a variable hydrodynamics regime.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The original version can be found at Water Research website: http://www.sciencedirect.com/science/article/pii/S0043135413000286
HAL Id:hal-00907908
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Other partners > Université Abderrahmane Mira de Béjaïa (ALGERIA)
Other partners > Universitat de Girona - UdG (SPAIN)
Laboratory name:
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Deposited By: Frederic MOULIN
Deposited On:22 Nov 2013 08:23

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