CONTROL OF THE SHORT-TERM DYNAMICS OF INTERTIDAL MICROPHYTOBENTHOS BYTHE EXONDATION-SUBMERSION CYCLE

We test herein the hypothesis that the succession of low tides - durin g which biomass increases - and high tides - during which biomass decr eases - controls the dynamic behaviour of the microphytobenthic compar tment. Results indeed show that during a complete lunar cycle (14 d) b iomass exhibits a series of oscillations due to biomass increases duri ng low tides and decreases during high tides. Moreover, the datasets s how that the production level is in the range of previously recorded v alues and they indicate that the major part of the photosynthetically produced biomass during low tide can be exported into the water column during high tide. This dearly suggests that microphytobenthos is the major autochtonous source of organic matter production in the littoral zone and that it directly supplies the associated pelagic trophic web . ((C) Academie des sciences / Elsevier, Paris.).