This record presents data used in the paper 'Controls on polar Southern Ocean deep chlorophyll maxima: viewpoints from multiple observational platforms,' Philip W Boyd 𝘦𝘵. 𝘢𝘭., submitted to Global Biogeochemical Cycles, November 2023. All methods for the following datasets are detailed and cross-referenced in the paper. Data were collected from a range of methods, including: • vertical profiles (from 1 m resolved profiling using sensors on a CTD rosette: temperature, salinity, chlorophyll fluorescence, transmissivity - all calibrated) • vertical profiles (from discrete samples collected from CTD rosette or trace metal clean rosette, for nutrients, chlorophyll, POC, dissolved and particulate iron, active fluorescence, net primary productivity, biological iron uptake) • tow-body sections (undulating tow body (Triaxus) for temperature, salinity, chlorophyll fluorescence, transmissivity (and the ratio of chlorophyll fluorescence, transmissivity) • time-series observations from a robotic profiling float (BGC-ARGO) for temperature, salinity, chlorophyll fluorescence, and transmissivity).

This record presents genetic data underlying the paper 'From the Surface Ocean to the Seafloor: Linking Modern and Paleo-genetics at the Sabrina Coast, East Antarctica (IN2017_V01)' by Armbrecht et al. In this study, we provide the first taxonomic overview of the modern and ancient marine bacterial and eukaryotic communities of the Totten Glacier region, East Antarctica, using a combination of 16S and 18S rRNA amplicon sequencing (modern DNA) and shotgun metagenomic (sedimentary ancient DNA, sedaDNA) analyses, respectively. We explore environmental and geochemical variables that drive these biodiversity patterns. Our data show considerable differences between eukaryote and bacterial signals detected via DNA analyses in the water column vs. the sediments. Organisms that are well represented in deeper waters appear are to have a higher likelihood of becoming preserved in the sediments. The study provides the first assessment of DNA transfer from ocean waters to sediments, while also providing a broad overview of the biological communities occurring in the climatically important Totten Glacier region. (Please note that this record is mirrored in the UTAS Research Data Portal, here: https://rdp.utas.edu.au/metadata/8628529b-49cf-42d4-9459-3c1e97f70d98)