Authors: Ignacio Moreno-Garrido, Cristiano Venicius de Matos Araújo and Julián Blasco
Abstract: Microphytobentos (microscopic algae living on benthic surfaces at the photic zone of marine environments) are the most important primary producers on apparently unvegetated coastal zones. Those microalgal communities are mainly composed by diatoms and cyanophytes, although other microalgal groups can be also represented. The actual importance of microphytobentos on trophic food webs as well as on the dynamic of coastal and estuarine sediments has been only recently studied. Biomass of benthic microalgae in some habitats can match or even excess those of bacterial populations, over all in sheltered muddy locations. Recent studies stated that microphytobenthos is the basis for the maintenance of secondary producers in submerged and intertidal shallow apparently unvegetated systems. Additionally, production of exopolysaccharides by those organisms is responsible of potential higher resistance of upper sediments to tidal erosion. Difficulties inherent to the study of those communities (mud interferences, patching distribution) are currently being solved by the development of new techniques (such as new designed fluorometers and flow cytometry techniques, as well as mathematic distribution models). An overview of taxomonic studies developed in those biotopes is included in this review. Emergent topics on microphytobentos, such as development of whole-sediment toxicity bioassays, are promising fields for further studies that will be also reviewed in the text.