Differentiating leucine incorporation of Archaea and Bacteria throughout the water column of the eastern Atlantic using metabolic inhibitors

The abundance (based on catalyzed reporter deposition-fluorescence in situ hybrid ization, CARD-FISH) and leucine incorporation rates of Archaea and Bacteria were determined throughout the water column in the eastern Atlantic. Bacteria dominated throughout the water column, although their contribution to total prokaryotic abundance in the bathypelagic layer (1000 to 4000 m depth) was lower than in the surface and mesopelagic layers (0 to 1000 m depth). While marine Crenarchaeota Group I (MCG I) contributed 28 +/- 12% to the total prokaryotic abundance, with a generally higher contribution in the bathypelagic layer than in the surface and mesopelagic layers, marine Euryarchaeota Group II contributed