Contribution
Carbon fluxes across water, sediment and benthos along a gradient of disturbance intensity: adaptive responses of the sediment feeders
Martinet, Fabrice; Juget, Jacques; Riera, Pascal
Archiv für Hydrobiologie Volume 127 Number 1 (1993), p. 39 - 56
41 références bibliographiques
publié: Apr 19, 1993
DOI: 10.1127/archiv-hydrobiol/127/1993/39
ArtNo. ESP141012701003, Prix: 29.00 €
Abstract
This study deals with one particular bioenergetic aspect of stream dynamics. Sediments and zoobenthos were selected to study the modalities and the importance of allogenous energetic processes in a former braided channel only connected with the main channel at its downstream end (Upper-Rhone River, France). Upstream-downstream gradients occurred in texture, porosity, carbon content and C/N ratio of the backwater sediments. They revealed the increasing rate of connectivity of backwater sediments with the main channel and simultaneously the increasing rate of disturbance. The dominant zoobenthos were tubificid oligochaetes, especially Limnodrilus. Energetic consequences of the relations between sediment and sediment feeders were studied by analyzing spatial distribution, densities, biomasses and P/B productivity index of the tubificids. A higher productivity was found in areas of higher disturbance in the backwater. The production efficiency of the tubificids was estimated as the ratio between their annual total net production and the annual sedimentation rate of TOC. Allochthonous material from the main channel caused a high sedimentation rate (246 to 471 g TOC • m-2 • y-1); each year 4.4 to 6.4 % of this input was converted into tubificid biomass.
Mots-clefs
Limnodrilus • main channel • Upper-Rhone River • tubificid • oligochaetes • backwater • France