Interaction between local hydrodynamics and algal community in epilithic biofilm

WATER RESEARCH

卷:47

Article

Graba, Myriam^1,2,3,8  Sauvage, Sabine^1,2  Moulin, Frederic Y.^4,5  Urrea, Gemma⁶  Sabater, Sergi^6,7  Sanchez-Perez, Jose Miguel^1,2 

[1] Univ Toulouse, INP, UPS, EcoLab,Lab Ecol Fonct & Environm, F-31326 Castanet Tolosan, France

[2] CNRS, EcoLab, F-31326 Castanet Tolosan, France

[3] Univ Abderrahmane Mira, Bejaia 06000, Algeria

[4] Univ Toulouse, INPT, ENSEEIHT, UPS,IMFT, F-31400 Toulouse, France

[5] CNRS, IMFT, F-31400 Toulouse, France

[6] Univ Girona, Fac Sci, Inst Aquat Ecol, Girona 17071, Spain

[7] Univ Girona, Catalan Inst Water Res, Girona 17003, Spain

[8] Univ Abderrahmane Mira, Dept Hydraul, Bejaia 06000, Algeria

关键词: Epilithic biofilm;    Experimental flume flow;    Friction velocity;    Biomass dynamics;    Turbulent boundary layer;    Algal composition;   

DOI  :  10.1016/j.watres.2013.01.011

来源: Elsevier

【 摘 要 】

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 (Bray-Curtis distances) and an Indicator Species Analysis (IndVal) showed that the indicator taxa were Fragilaria capucina var. mesolepta in the low-velocity (u*. = 0.010-0.012 m s(-1)), Navicula atomus, Navicula capitatoradiata and Nitzschia frustulum in the intermediate-velocity (u*. = 0.023-0.030 m s(-1)) and Amphora pediculus, Cymbella proxima, Fragilaria capucina var. vaucheriae and Surirella angusta in the high-velocity (u*. = 0.033-0.050 m 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. (C) 2013 Elsevier Ltd. All rights reserved.

【 授权许可】

Free