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Nella Dan: AAMBER Cruise Chlorophyll a Data
The composition, size and abundance of phytoplankton and microzooplankton were measured across a transect from Prydz Bay to Australia during late March 1987. Phytoplankton populations were low, with concentrations of chlorophyll a ranging from 0.08 to 0.22 mg.m-3. Small cells predominated numerically; nanoplankton consistently represented 55 to 68% of the total cell number while picoplankton represented 27 to 44%. Microplankton never represented more than 3% of cells by number, but constituted 57 to 93% of the total cell volume, and accounted for most of the latitudinal variation in total volume. Small flagellates, not identifiable by light microscopy, were the most numerous cells encountered across the transect, with a five-fold increase in abundance at 47S. Numbers of diatoms (most less than 20 microns in size) increased markedly south of the Antarctic Convergence, with a strong correlation to the concentration of silica. Dinoflagellate numbers were relatively constant across the transect, although somewhat higher north of 50S. Those less than 20 microns in size were most numerous and accounted for most of the numerical variation. HPLC analysis of chlorophyll and carotenoid pigments showed a peak of peridinin which coincided with the flagellate peak at 47S, but not with observed dinoflagellates, suggesting that the flagellate peak included unrecognized dinoflagellates. Chlorophyll b and prasinoxanthin were also associated, suggesting a significant contribution by prasinophytes. Almost no cyanobacteria were observed south of the convergence, although very large numbers, which correlated with the abundance of zeaxanthin, were encountered to the north. Numbers of ciliates and tintinnids were quite variable although they followed each other closely. Numbers of both were low in the region of the Antarctic Convergence.
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Phytoplankton Data Collected During CPR Tows of the Southern Ocean - Australian Antarctic Division Copy
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Data are "phytoplankton counts" for each phytoplankton taxon observed, from the CPR samples collected by the Southern Ocean CPR Survey projects 472 and 4107 (Hosie et al. 2003). The SAHFOS on-silk phytoplankton count method is used (Batten et al. 2003). Phytoplankton are identified to the best taxonomic level possible, ideally to species or at least genus, in 20 fields of view (295 plus or minus 10 microns) per sample (section of silk). See Figure 2 of Batten et al. (2003). Each sample usually represents 5 nautical miles for SO-CPR. The "phytoplankton count" is the number of fields of view where a phytoplankton species/ taxon was observed, recorded for each taxon for each sample. It is effectively a frequency of occurrence score. The CPR is a device towed at normal ship speed, approximately 100 m behind the ship at a depth of 8-10 m. Plankton enter a small aperture 12.7 x 12.7 mm which then expands into a tunnel 100 x 50 mm reducing the speed by about 1/30. Plankton are then sandwiched between two sheets of 270 micron silk gauze, before rolling into a preservation tank of formaldehyde. Each tow is approximately 450 nautical miles. Regardless of ship speed the silk advances at a fixed rate of about 1 cm per nautical mile. Silks are cut into 5 nautical mile equivalent lengths and both phyto- an zooplankton are counted. Each sample is coded with time and date (GMT) and latitude and Longitude, plus averaged environmental data over the 5 nautical miles, e.g. water temperature, salinity, fluorescence, light. Zooplankton data and methods are described in Metadata record AADC-00099. Abbreviations CPR, Continuous Plankton Recorder SAHFOS, Sir Alister Hardy Foundation for Ocean Science SO-CPR , Southern Ocean CPR Survey
Phytoplankton Distribution in Surface Samples and Cores from Prydz Bay and Long Fjord and its Relationship to Sea Level and Climatic Change
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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.
Biogeochemical flux and phytoplankton assemblage variability: A unique year-long sediment trap record in the Australian Sector of the Subantarctic Zone.
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This dataset is derived from sediment trap records collected by Thomas Trull as part of the multidisciplinary SAZ Project initiated in 1997 by the Antarctic Cooperative Research Centre (ACE CRC) (Trull et al 2001b). The current submission provides data not included in Wilks et al. (submitted) 'Biogeochemical flux and phytoplankton assemblage variability: A unique year-long sediment trap record in the Australian Sector of the Subantarctic Zone.' This dataset contains three parts: Supplementary Table 1 describes sediment trap deployment information and current speed measured during deployment. Supplementary tables 2a and 2b are raw diatom counts of every species encountered at the site, at every sampling cup. Table 2a contains the 500 m trap depth record, while table 2b is for the 2000 m trap depth record. Supplementary table 3 contains environmental data (chlorophyll-a, photosynthetically active radiation, and sea surface temperature) for each cup record.
Zooplankton Abundance Umbrella net sea ice zone
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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.
Chlorophyll a data collected on the AAMBER II cruise of the Aurora Australis
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Chlorophyll a data collected on the AAMBER II cruise of the Aurora Australis from January to March of 1991. The voyage traveled to the Prydz Bay region, and data were collected en route and in the area.
Phytoplankton samples collected from the SAZ SENSE voyage (V3 of the Aurora Australis), 2007
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A list of taxa and observations of phytoplankton collected from the SAZ Sense voyage of the Aurora Australis - voyage 3 of the 2006-2007 season. These data are available via the biodiversity database. The collection contains 26 taxa and 562 observations. More information about SAZ SENSE: The overall objective is to characterise Southern Ocean marine ecosystems, their influence on carbon dioxide exchange with the atmosphere and the deep ocean, and their sensitivity to past and future global change including climate warming, ocean stratification, and ocean acidification from anthropogenic CO2 emissions. In particular we plan to take advantage of naturally-occurring, persistent, zonal variations in Southern Ocean primary production and biomass in the Australian Sector to investigate the effects of iron addition from natural sources, and CO2 addition from anthropogenic sources, on Southern Ocean plankton communities of differing initial structure and composition. SAZ-SENSE is a study of the sensitivity of Sub-Antarctic Zone waters to global change. A 32-day oceanographic voyage onboard Australia's ice-breaker Aurora Australis was undertaken in mid-summer (Jan 17 - Feb. 20) 2007 to examine microbial ecosystem structure and biogeochemical processes in SAZ waters west and east of Tasmania, and also in the Polar Frontal Zone south of the SAZ. The voyage brought together research teams from Australasia, Europe, and North America, and was led by the ACE CRC, CSIRO Marine and Atmospheric Research, and the Australian Antarctic Division. The overall goal is to understand the controls on Sub-Antarctic Zone productivity and carbon cycling, and to assess their sensitivity to climate change. The strategy is to compare low productivity waters west of Tasmania (areas with little phytoplankton) with higher productivity waters to the east, with a focus on the role of iron as a limiting micro-nutrient. The study also seeks to examine the effect of rising CO2 levels on phytoplankton - both via regional intercomparisons and incubation experiments.
Phytoplankton and zooplankton abundance off New South Wales (~30°S, 153°E), Australia in 2011/2012
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Phytoplankton and zooplankton samples were collected monthly along two cross shelf transects (CH-Line, B-Line) and one intermediate coastal station (SS) off Coffs Harbour (~30°S, 153°E), Eastern Australia, between May 2011 and September 2012. The exact sampling locations (coordinates) and times were recorded. Two of the sampling stations (CH3 and CH5) are also the sites of permanent IMOS moorings (CH070 and CH100, respectively). Two files are provided, one containing detailed data on phytoplankton (genus or species level where possible) and grouped zooplankton (copepods, larvae, ciliates), while the other reports on ciliate abundances (incl. tintinnids) only.