MEPS 298:95-100 (2005)  -  doi:10.3354/meps298095

Does the size of the microphytobenthic biofilm on intertidal mudflats depend on the available photosynthetic biomass?

O. Herlory1,2,*, G. F. Blanchard1, S. Planche1, V. Huet1, P. Richard2

1Laboratoire de Biologie et Environnement Marins (LBEM), FRE 2727, CNRS-Université de La Rochelle, Avenue Michel Crépeau, 17042 La Rochelle, France
2Centre de Recherche sur les Ecosystèmes Marins et Aquacoles (CREMA), UMR 10, CNRS-IFREMER, BP5, 17137 L’Houmeau, France

ABSTRACT: Many scientists consider that the top centimetre of the sediment on intertidal mudflats contains the photosynthetic competent biomass (PCB). Part of this biomass migrates upward to the surface of the sediment during diurnal emersion periods to form a temporary biofilm: the photosynthetic active biomass (PAB). The present study tests the hypothesis that the size of the biofilm (PAB) is functionally dependent on PCB. Therefore, we have plotted PAB as a function of PCB for a range of different environmental conditions: 3 seasons and 5 tidal situations, representing a total of 600 cores. This investigation points out that, in spring and autumn, there was a simple linear relationship between PAB and PCB, thus indicating that the maximum size of the biofilm represents a constant fraction (between 13 and 18%) of the available biomass in the top centimetre of the mud. The relationship was more complex in winter, but the general trend remained the same. The dependence of the size of the biofilm on PCB might have important ecological implications in terms of primary productivity and also the monitoring of intertidal microalgal biomass at large spatial scales.

KEY WORDS: Microphytobenthos · Intertidal mudflat · Biomass · Biofilm · Functional relationship

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