Spatial and temporal scales of variability in phyto- and bacterioplankton abundance were investigated in a deep atoll lagoon (Ahe, French Polynesia), Ahe Lagoon showed a classical phytoplankton composition, but its picophytoplankton (Prochlorococcus, Synechococcus and picoeukaryotes) concentrations are higher than the mean for Polynesian atoll lagoons. Phyto- and bacterioplankton descriptors were highly variable, with mean CVs of >20% in most cases: day night, day-to-day, vertical, lagoonal and seasonal. Phytoplankton biomass, which was estimated by in vivo fluorescence, was higher in the deep layer than in the upper layer. This pattern was detected on a day night scale, showing transitory vertical gradients, and through long-term events that were... |