show Abstracthide AbstractDuring expedition M157 in the Benguela Upwelling System (BUS) off the coast of Namibia we used a multidisciplinary approach to examine relationships between physical forcing, process rates, and microbial activities. For this, sampling was conducted between 18 August and 16 September 2019, using 10 L free-flow bottles (Hydrobios, Germany) attached to a rosette water sampler at 17°S, 23°S and 25°S. 16S rRNA gene and 16S rRNA sequences were generated from 1 L water samples collected on 0.22 µm pore-size polycarbonate filters. DNA and RNA was extracted using the AllPrep DNA/ RNA Mini Kit (Qiagen, Hilden, Germany). For the PCR amplifications the primers 341F (CCTAYGGGRBGCASCAG) and 806R (GGACTACNNGGGTATCTAAT), covering the V3/V4 region, were used (Sundberg et al. 2013). Sequences were generated on a MiSeq Illumina platform in a 2x300 bp paired-end run using V3 Chemistry (Illumina).