This dataset includes the genome assembly and predicted proteome of an Antarctic sea-ice diatom, Nitzschia sp. (most likely Nitzschia stellata). It also contains the endogenous viral element (EVE) sequences identified within this diatom genome, as well as the results of comparative genomic analyses between Antarctic sea-ice diatoms and non-polar diatoms. The Nitzschia sp. genome assembly was obtained through metagenomic binning of Antarctic sea-ice samples.

Dataset collected during two field campaigns in the same Antarctic fast ice site (Cape Evans, November/December 2018-19) as part of the AGP and NZARI collaboration over the grant "On Thin Ice: An in situ surveillance system for sea-ice microbial communities". The fieldwork was designed to test the scientific potentials of the IMAS/AGP developed under-ice HI system for mapping temporally dynamic and spatially varying under-ice habitats. The dataset consists of 3 terabytes of HI data acquired both in-situ under a wide range of natural and manipulated light conditions, as well as ex-situ with data acquired using a newly developed ice core scanning approach. The in-situ data are in the form of scanned transects acquired with a HI system capturing transmitted natural sunlight while being deployed beneath sea-ice. The ex-situ data was collected using external light sources illuminating horizontal and vertical sections of extracted ice cores. The dataset includes auxiliary data such as RGB imagery, TriOS RAMSES under-ice irradiance, sky irradiance, and any other measurements or information required to process the data. Other auxiliary data collected include filtered samples of ice core sections for fluorometric Chlorophyll-a (Chl-a) extraction, pigment composition via HPLC (to be processed), and particulate absorption spectra. Media footage (e.g., under-ice ROV videography, under-ice 360 videos, campaign photography of the systems and science) is also included. The dataset includes pre-processed high-resolution under-ice imagery collected from the fast-ice zone using a Sony a6300 camera mounted on a custom under-ice sled system. The imagery was acquired to document the sea-ice underside and analyse spatial patterns associated with amphipod communities from a near-horizontal, grazer-level perspective (publications pending).

This dataset was generated to assess the biological impacts of ocean alkalinity enhancement (OAE) in the Southern Ocean. Deck-board incubation experiments were conducted at five sites spanning subantarctic to sea-ice regions during the RV Investigator MISO voyage (January–March 2024). Unfiltered surface seawater was incubated for 5–8 days following additions of three alkalinity sources: sodium hydroxide (NaOH), ground olivine, and steel slag, alongside untreated controls. Measurements collected at the beginning and end of each incubation included carbonate chemistry (total alkalinity and pH), macronutrients (nitrate, phosphate, silicate), chlorophyll-a, biogenic silica, photophysiology (Fv/Fm), and plankton community composition. Phytoplankton and bacterial abundances were quantified using flow cytometry, while genus-level phytoplankton composition was determined by light microscopy. A complementary dark leaching experiment quantified dissolved trace metal release from each OAE material using ICP-MS. The purpose of the study was to distinguish the biological effects of alkalinity change alone from those arising from collateral nutrient and trace-metal release, and to evaluate how different OAE materials influence phytoplankton growth and community structure in iron-limited Southern Ocean waters. The dataset supports assessment of ecological risks and co-benefits associated with ocean alkalinity enhancement as a carbon dioxide removal strategy.