The Application of Variable Chlorophyll Fluorescence to Microphytobenthic Biofilms
Résumé
Community assemblages of diatoms, green algae and cyanobacteria comprise the microphytobenthos (MPB), which inhabit benthic sediment ecosystems (Admiraal 1984; Underwood and Kromkamp 1999; Consalvey et al. 2004). Particular attention has been paid to the analysis of intertidal soft sediment systems, e.g. cohesive mudflat and sandy substrata typical of estuarine habitats. Variable chlorophyll fluorescence has been applied to
these systems since the 1990s, in an attempt to investigate the primary productivity and photophysiology of the integrated biofilms, when viewed as a “black box system”, and also at the species level (Sections 5, 6 and 7). These transient (i.e. temporary) biofilms are not confined to such soft sediment habitats however, and more recently application of fluorescence methodologies has been applied to biofilms inhabiting rocky shores and stromatolite systems (Kromkamp et al. 2007; Perkins et al. 2007). However the large majority of published work has centred upon benthic soft-sediment biofilms,
due to their important ecosystem functions of carbon flow and sediment stability (Underwood and Kromkamp 1999). In the former their high magnitude of productivity fuels carbon flow through invertebrate and bacterial food webs to support important trophic levels of anthropogenically
exploited taxa, including coastal fish and shell fisheries and coastal avifauna. In the case of sediment stability, biogenic exopolymers, usually referred to as extracellular polymeric substances (EPS), produced by the MPB in part to facilitate mobility, may contribute significantly to sediment stability, hence increasing the sediment resistance to hydrodynamic stresses and thus resistance to coastal erosion (e.g. Underwood and Kromkamp 1999 and citations there-in). Finally, the photosynthetic production of oxygen can be regarded as an important ecosystem function.
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