Bacterial uptake of DOM released from P-limited phytoplankton

The growth and the structure of a coastal bacterioplankton community were monitored in short term bottle experiments in order to investigate the bacterial uptake of organic carbon excreted by Cylindrotheca closterium grown in P-balanced and P-depleted conditions. Bacterial carbon demand and specific growth rates were significantly lower in the excreta from P-depleted algae (30% and 24% reduction, respectively). The origin of the excreta appeared also to affect the taxonomic composition of the bacterioplankton assemblage, mainly reducing the development of ƒ×-proteobacteria. This pattern in bacterial carbon uptake could contribute to a longer persistence of the excreta released in P-depleted conditions affecting the dynamics of carbon cycle in the marine environment