Zooplankton were collected during the winter-spring transition during two cruises of the Aurora Australis: SIPEX in 2007 and SIPEX II in 2012. The umbrella net was 2 metres long, 28 cm2 mouth area and mesh size of 100 um. The net was lowered through holes drilled through the pack ice and lowered to 100 m. It was pulled slowly by hand to the surface, closed and brought back through the ice hole. The contents were preserved in 5% buffered formaldehyde and examined under a Leica M12 in the laboratory. Species were identified to the lowest taxon possible.

Zooplankton were collected during the winter-spring transition with an RMT8+1 net during the SIPEX voyage in 2007. Only the RMT1 data are presented here. The net was deployed on an oblique tow from the surface to 200 m. The catch in each cod-end was preserved in 5% borax-buffered formaldehyde. The samples were subsplit in the laboratory with a Folsom splitter if needed and examined under a Leica M12. Species were examined to the lowest taxon possible - to species for copepods and euphausiids and to higher levels for other taxa.

Zooplankton were collected during the winter-spring transition during two cruises of the Aurora Australis: SIPEX in 2007 and SIPEX II in 2012. To determine size and biomass, key species were measured. Measurements of Prosome, Urosome and Total length are provided. The zooplankton were taken from samples collected with umbrella nets, RMT1 net and sea ice cores. They were measured under a Leica M165C steromicroscope using an ocular micrometer. The ocular micrometer was calibrated against a stage micrometer (+/- 0.01 um).

Krill, salps and pteropods were collected with an RMT8 net during the K-Axis cruise. Specimens were removed from the samples, measured and frozen at -20C until ready for analysis in Hobart. Individuals of known species were dried at -60C, ground to a fine powder, encapsulated into tin cups and analysed with an ICP-MS in the Central Science Laboratories, University of Tasmania. Samples were analysed for delta15N and delta13C. The salp was the common Southern Ocean species Salpa thompsoni and the krill were Euphausia superba, E. triacantha, E. frigida and Thysanoessa macrura. A small number (2) of the siphonphore Diphyes antarctica were also analysed. Pteropods analysed included both shelled (thecosomes) and naked (gymnosomes) pteropods. Columns E-O in the Pteropods worksheet in the spreadsheet are expressed as ratios.

The data describe all zooplankton species abundance values estimated at each rectangular midwater trawl (RMT 1+8) target and routine sampling site collected during the 2021 TEMPO voyage on R/V Investigator. During the TEMPO voyage, zooplankton were collected using the RMT 1+8 plankton net and sorted down to the lowest taxonomic level possible. The supporting data set, in CSV format, feature abundances estimated from RMT+1 samples only. The data file is named allzooplankton.csv. The fields (columns) in the file are: "Site" – sampling site ID for each routine (RXX) and target (TXX) trawl using RMT1+8. "Date" – date of each sample collected (ie. target or routine trawl) [dd/mm/yyyy]. "Latitude" – latitude of each trawl [degrees] (-dd.ddddd). "Longitude" – longitude of each trawl [degrees] (dd.ddddd). "Chla" – Integrated estimate of chlorophyll-a (mg m^-2) averaged at depths between 10 to 200 m, which aligns with the section of the water column where zooplankton were sampled. "Depth" – Bathymetric depth estimated at each sampling station. "MLD_03" – Mixed layer depth (m). Not used in final analysis. "MLD_05" – Mixed layer depth (m). Not used in final analysis. "MLD_N2max" – Mixed layer depth (m) where the N^2 maximum is found, i.e., the pycnocline. "CT_200" – Absolute temperature (°C) averaged at depths between surface and 200 m maximum net sampling depth. Values are derived from in situ CTD measurements at each sampling site. "SA_200" – Absolute salinity (g kg^-1) averaged at depths between surface and 200 m maximum net sampling depth. Values are derived from in situ CTD measurements at each sampling site. "IceMeltDays" – Number of days since sea ice melted calculated from daily passive microwave estimated percent sea ice concentration taken from the National Snow and Ice Data Centre. "m_to_Ice" – Distance (m) estimated from sampling site to edge of ice. "IceConc" – Actual ice concentration value (%). It is the percentage of an area covered in sea ice. The remaining columns are zooplankton species abundances (individuals per 1000 cubic metres) estimated from count data, volume of original sample, split of sample analysed under the microscope and calibration of the flowmeter: "R.gigas" – Rhincalanus gigas, copepod "C.propinquus" – Calanus propinquus, copepod "C.simillimus" – Calanus simillimus, copepod "C.acutus" – Calanoides acutus, copepod "Metridia sp." – Metridia species, copepod "M.gerlachei" – Metridia gerlachei, copepod "Paraeuchaeta sp." – Paraeuchaeta species, copepod "Pleuromamma sp." – Pleuromamma species, copepod "Oncaea" – Oncaea species, copepod "O.antarctica" – Oncaea antarctica, copepod "Neo tonsus" – Neocalanus tonsus, copepod "Neo gracilis" – Neocalanus gracilis, copepod "Stephos longipes" – Stephos longipes, copepod "Ctenocalanus sp." – Ctenocalanus species, copepod "Microcal pygmaeus" – Microcalanus pygmaeus, copepod "Oithona similis" – Oithona similis, copepod "Oithona frigida" – Oithona frigida, copepod "Heterhabdus australis" – Heterorhabdus australis, copepod "Heterhabdus sp." – Heterorhabdus species, copepod "Harpacticoid" – Harpacticoid species, copepod "Haloptilus sp." – Haloptilus species, copepod "Candacia sp." – Candacia species, copepod "Solecithricella sp." – Solecithricella species, copepod "Clausocalanus breviceps" – Clausocalanus breviceps, copepod "Clausocalanus laticeps" – Clausocalanus laticeps, copepod "Clausocalanus sp." – Clausocalanus species, copepod "Aetideops antarctica – Aetideopsis antarctica, copepod "Aetide minor" – Aetideopsis minro, copepod "Euchirella rostromanga" – Euchirella rostromanga, copepod "Heterostylites longicornis" – Heterostylites longicornis, copepod "Gaidius tenuispinus" – Gaidius tenuispinus, copepod "Gammaridean amphipod" – Gammaridean, amphipod "T.gaudichaudii" – Themisto gaudichaudii, amphipod "Parathemisto sp." – Parathemisto species, amphipod "Hyperia antarctica" – Hyperia antarctica, amphipod "Hyperia sp." – Hyperia species, amphipod "Hyperiella dilatata" –

Metadata record for data from ASAC Project 229 See the link below for public details on this project. From the abstracts of some of the referenced papers: In January 1985 a net sampling survey was carried out on the distribution and abundance of euphausiid larvae in the Prydz Bay region. Euphausia superba occurred in low abundance, probably due to sampling preceding the main spawning period. Thysanoessa macrura occurred throughout the study area in consistently high abundance. Euphausia crystallorophias as marginally more abundant within its restricted range. Distinct north-south variations in larval age and development stages of T. macrura were observed indicating regional differences in spawning. Euphausia frigida was mainly confined to the upper 200 m of the Antarctic Circumpolar Current. Larvae originating on the shelf moved rapidly west in the East Wind drift. E. crystallorophias had the same westward dispersion, but some larvae appeared to return eastward via the Prydz Bay Gyre and remain in the region. The data indicate that most E. superba larvae, providing they survive injurious cold temperature and food deprivation, will leave the area, suggests that Prydz Bay krill may not be a self sustaining stock. This paper presents results of net sampling carried out in four marine science cruises between 1981 and 1985, in the Prydz Bay region of Antarctica by the Australian Antarctic Division. Krill exhibited a patchy distribution and overall low abundance. The majority of sampling sites in January 1985 returned no post-larval krill or densities of less than 1 individual per 1000 cubic metres. The estimated mean abundance of E. superba in January 1985 was 6 indivduals or 2 g (wet wt.) per 1000 cubic metres integrated for the upper 200m of the water column which represented 3.4% of the total zooplankton biomass. No more than five years-groups, including the larvae, were observed in Prydz Bay, with mean lengths of groups 1+, 2+, 3+ and 4+ being 24, 38, 46 and 53 mm (standard 1), respectively in the middle of January. A high proportion of naupliar stages observed in January 1985 indicated that spawning in Prydz Bay begins in January and examination of adult maturation showed that the spawning continues at least to March. Sixty female Antarctic krill (Euphausia superba Dana) spawned in shipboard experiments and the interval between egg-laying and ecdysis was noted. The number of eggs laid per female ranged from 263-3662, most females produced only one batch of eggs before moulting, and the post spawn ovaries of all females contained few, if any, mature oocytes. As reported in other studies, the total number of eggs produced per female was not well correlated with body size. Females appeared to spawn at all times during the moulting cycle and although no diurnal rhythm in spawning was observed, moulting occurred mainly at night-time despite the animals being kept in near-constant darkness. No evidence of synchronous moulting was detected. Data from this project were collected on five Antarctic voyages: HIMS - Heard Island Marine Science - 1990-05-04 - 1990-07-01 AAMBER II - Australian Antarctic Marine Biological Ecosystem Research II - 1991-01-3 - 1991-03-19 FISHOG - Fish and Oceanography - 1992-01-09 - 1992-03-27 KROCK - Krill and Rocks - 1993-01-05 - 1993-03-09 BROKE - Baseline Research on Oceanography, Krill and the Environment - 1996-01-02 - 1996-03-31 All data are available in the download file.

From the abstract of one of the papers: Three new zooplankton nets have been designed to enable improved collection of zooplankters from ice-covered waters. These nets also enable quantitative sampling of species not adequately sampled by other methods. The first net is a vertical tow net which can be folded like an umbrella to pass through a small ice hole (10 cm). This 'Umbrella Net' takes an integrated sample of zooplankton from all sample depths. The second net is a collapsible free-fall net designed to collect mobile zooplankters capable of avoiding towed nets. This was the only net used which was capable of collecting all furcilia stages of Euphausia crystallorophias from Ellis Fjord, Vestfold Hills, Antarctica. The third net is a diver-operated push net designed to collect zooplankters in the top 15 cm of the under-ice column. Because of the high standing crop of pytoplankton at and near the under-ice surface at particular times of the year, some species of zooplankton tend to congregate there. These species, particularly Paralabidocera antarctica, were collected in great abundance using the push net, but were rare in samples collected by other methods. The fields in this dataset are: species species density site sample

Metadata record for data from ASAC Project 492 See the link below for public details on this project. From the abstracts of the referenced papers: Diatom assemblages in two Holocene sediment cores (GC1 and GC2) from the Mac. Robertson Shelf, East Antarctica, are compared with modern sedimentary diatom assemblages from the same area. Open marine deposition commenced in Iceberg Alley (GC1), on the outer continental shelf, greater than 10.7 adj. 14C kyr BP. Chaetoceros resting spores, which may indicate water-column stabilsation from melting glacial and/or sea ice or the maximum summer sea-ice retreat, dominate the diatom assemblage. Approximately 7.5 adj. 14C kyr BP, a sea-ice diatom assemblage was deposited. This assemblage is similar to that being deposited in the surface sediments of the Mac. Robertson Shelf today and suggests that perennial sea ice has persisted in the vicinity of Iceberg Alley since that time. Interbedded within the sea-ice assemblage, however, are Corethron-rich sediment layers that suggest mid- to late-Holocene high-productivity events associated with a climatic optimum. The diatom record from Nielsen Basin (GC2), on the inner continental shelf, is relatively uniform compared to that in GC1. Glacial ice was present over the region c. greater than 5.6 adj. 14C kyr BP and a dissolution diatom assemblage was deposited beneath it. following ice retreat, an ice-edge diatom assemblage was deposited briefly before sea-ice conditions similar to that on the continental shelf today developed. There is no evidence in GC2 for the mid- to late-Holocene high-productivity events identified in GC1. Four diatom assemblages are identified from the surface sediments of Prydz Bay and the Mac. Robertson Shelf using multivariate analysis. A coastal assemblage is characterised by the sea-ice diatoms Fragilariopsis curta, F. angulata, F. cylindrus and Pseudonitzschia turgiduloides. A continental shelf assemblage is characterised by the open-water diatoms Fragilariopsis kerguelensis, Thalassiosira lenuginosa, T. gracilis var. expecta and Trichotoxin reinboldii. The Cape Darnley assemblage contains both sea-ice and open-water diatoms, but all are characteristically large and heavily silicified. Multiple regression has been used to identify the relationships between the diatom assemblages and known environmental variables. There are strong correlations between the coastal, shelf and oceanic assemblages and ecological conditions, including latitude, sea-ice distribution and ocean currents. The Cape Darnley assemblage is thought to represent an assemblage from which the smaller and more lightly silicified species have been removed by current winnowing. The palaeo-depositional environment of inner Prydz Bay, East Antarctica, has been reconstructed for the past 21,320 14C yr B.P., using diatom assemblages and sediment facies from a short, 352 cm long gravity core. Between 21,320 and 11,650 14C yr B.P., compact tillite and diamicton are present in the core, and diatom frustules are rare to absent. These data suggest that an ice sheet grounded over the site during the last glacial maximum. Following glacial retreat, siliceous muddy ooze was deposited, from 11,650 to 2600 14C yr B.P., in an open marine setting. During this stage, diatom frustules are abundant and well preserved, and Thalassiosira antarctica resting spores and Fragilariopsis curta dominate the assemblage. This assemblage suggests open marine deposition in an environment where the spatial and temporal distribution of sea ice is less than today. Since 2600 14C yr B.P., sea-ice and ice-edge diatom species have become more abundant, and neoglacial cooling is inferred. The assemblage is similar to that forming currently in Prydz Bay, where sea-ice is absent (less than 10% cover) for 2-3 months of the year and permanent ice edge and/or multiyear sea ice remains in close proximity to the site.

This dataset contains results from the Aurora Australis Voyage 7 (KROCK) 1992-93, related to mesoscale distribution of krill and zooplankton communities in Prydz Bay in relation to physical and biological oceanographic parameters. There were five objectives of this project: to define the distribution patterns and abundance of krill in the krill dominated continental shelf area of the Prydz Bay region; to define the krill population structure within this area and the distribution pattern of developmental stages, especially spawning females; to define the distribution patterns and composition of the other two principal communities, neritic and oceanic, which border the krill dominated community; to specifically determine the zooplankton composition within the main feeding area of Adelie Penguins from Bechervaise Island monitoring site, Mawson; to record and analyse various physical and biological processes, eg. salinity, temperature, ice and phytoplankton, to determine how these parameters affect the observed distribution patterns. Surveys of krill and other zooplankton were taken in Prydz Bay, Antarctica between January and February 1993. At each station, rectangular midwater trawls and CTDs/bottle casts were made. During the program, echosounders and echointegrators were operating to provide krill abundance and distribution data, in addition to that from the RMT trawls. Initial analysis has shown that Euphausia crystallorophias dominates the neritic community on the shelf, while Euphausia superba was found not to occur in high abundance in the central Prydz Bay area between 70 and 78 degrees East. This dataset is a subset of the full cruise.