Abstract
Data on biomass variability and production/biomass ratios of seagrass communities were analysed to describe the relationship between the trophic (i.e. primary production) and structural (i.e. biomass) roles of marine submerged macrophytes. The analyses revealed that most (>70%) of the biomass variability appears to reflect seasonal responses, and that the extent of variability is constrained by the latitudinal position of the plant stands, those at lower latitudes sustaining a more uniform biomass throughout the year. Annual production/biomass ratios are quite variable, although tend to be greater (average = 4.6) than those for freshwater submerged plants, and tend to increase at lower latitudes. This trend is not attributable to greater daily production/biomass ratios for tropical and subtropical communities, but appears to be a consequence of their small biomass seasonality.