This data set contains concentrations of phytoplankton, protozoa, total bacteria and metabolically active bacteria assessed by flow cytometry on transects 12, 1, 3, 5, 7, 9 and 11 of the BROKE-West survey of the Southern Ocean between January and March 2006. Only total bacterial concentrations were assesed for transect 11. Between 4 and 12 depths were sampled for marine microbes and concentations were assesed using FACScan flowcytometer. Phytoplankton were identified and counted based on the autofluorescense of chlorophyll a when excited by the 488 nm laser of the FACScan. Protozoa were identified and counted after staining with the acid vacuole stain Lysotracker Green. Total bacteria were identified and counted using the cell permeant SYTO 13 nucleic stain. Metabolically active bacteria were identified and counted after staining for intracellular esterases with the esterase stain 6CFDA. Data collected by the Australian Antarctic Division. Sourced from: http://data.gov.au/dataset/broke-west-microbial-concentrations-voyage-3-of-the-aurora-australis-2005-2006