Fast repetition rate fluorometer (FRRF) study of sea ice algae in low iron conditions. Algae were grown in an ice tank and the measurements were made at the end with a Chelsea Insrtuments FRRF. Materials and Methods (see the download document for original formatting and formulas) 1. Ice tank incubation The polar pennate diatom Fragilariopsis cylindrus, isolated from Antarctic pack ice in 2015 (Davis station, East Antarctica) was incubated in a purpose designed ice tank (Island Research, Tasmania). The ice tank, which was contructed of titanium to minimise dissolved Fe, was placed into a freezer (–20 degrees C), and the ice thickness and temperature gradient controlled by interaction between a basal heater and the adjustable ambient freezer temperature (see Kennedy et al., 2012). This enabled an ice thickness of approximately 5.5 cm to be maintained during the experiment. The diatom F. cylindrus was incubated in Aquil media (Price et al. 1989) buffered with ethylenediaminetetraacetic acid (EDTA) at 150 micro mol photons m−2 s−1 (PAR), a salinity of 35, and a Fe concentration of 400 nM, where the concentration of total inorganic forms of Fe (Fe') was 1.54 nM, this being continuously supplied to the medium and the exact value calculated using the software Visual MINTEQ, ver. 3.1 (https://vminteq.lwr.kth.se). Before a freezing cycle started, the seawater temperature was maintained at 2.5 degrees C, and a sample was obtained to assess the original physiological state of the algae (Day−5, hereafter). After obtaining the sample, the seawater temperature was set to −1.8 degrees C to initiate ice formation in the ice tank. Once ice had formed at Day−2, the under-ice seawater was partially replaced with ultrapure water to reduce the salinity down to 35, because the salinity had increased (to approximately 38) as a result of brine rejection from the ice. After a 2-day acclimation to the new salinity, ice samples were obtained every 5 days for 20 days (i.e., Days 0, 5, 10, 15, and 20). To minimize the heterogeneity among ice cores, ice samples were randomly collected from the tank chamber with a trace metal-free hand drill (2 cm in diameter) from randomly annotated grids on the ice surface, following normal random sampling numbers generated by the software R (https://www.r-project.org/). To assess the effects of melting and high light exposure, the ice was melted at 2.5 degrees C for 2 days. After the ice had completely melted, the seawater was exposed to a high light level, which was adjusted to represent the likely summer light intensity at the surface in ice-edge regions (800 micro mol photons m−2 s−1; MODIS Aqua), Seawater samples were obtained both after the melting and light exposure events (Melt and Light, respectively, hereafter). Fast repetition rate (FRR) fluorometry To monitor the photophysiology of F. cylindrus during the freezing and melting processes, variable chlorophyll a fluorescence (ChlF) measurements were conducted using a bench-top Fast Repetition Rate fluorometer (FRRf) (FastOcean Act2Run Systems, Chelsea Technologies) with Act2Run software (Chelsea Technologies). Ice samples were directly thawed at 2 degrees C in the dark for 30 min, and the slushily melted ice samples were placed in a quartz tube and their flouresence (ChlF) was measured. A single turnover protocol was applied for the ChlF measurements; 100 flashlets with 1 micro second duration at a wavelength 450 nm and 2 micro second intervals for excitation of reaction centres of photosystem II (PSII, hereafter), and 20 flahlets with 1 μs duration and 100 micro second intervals for relaxation. Eighteen light steps were applied to generate a rapid light curve (RLC) from 0 to 1800 μmol photons m−2 s−1, taking less than 5 min to complete one RLC. At each light step (~15 s), at least five induction and relaxation curves were averaged to obtain ChlF yields, described in Table, after calibrating the ChlF yields with filtered seawater. According to the models proposed

From the abstract of one of the papers: Oxygen microelectrodes were used to measure the photosynthetic rates of Antarctic fast ice algal mats. Using the oxygen flux across the diffusive boundary layer below the fast ice at Davis, a productivity range of 0-1.78mg C per square metre per hour was measured. This is at the lower end of fast ice productivity estimates and suggests that conventional carbon 14 techniques may overestimate sea ice algal mat productivity. Photosynthetic capacity (P max) approached 0.05 mg per C.(mg chlorophyl a) per hr. Onset of photosynthesis saturation, E k, was found at about 14 micromol photons per square metre per second. The irradiance of photoinhibition onset, E inh, was about 20 micromol photons per square metre per second and the irradiance at the compensation point, E c, was 4 micromol photons per square metre per second.

Public Description of the Project This project will assess the importance of the trace micro-nutrient element iron to Antarctic sea-ice algal communities during the International Polar Year (2007-2009). We will investigate the biogeochemistry of iron, including a comprehensive examination of its distribution, speciation, cycling and role in fuelling ice-edge phytoplankton blooms. A significant part of this research will concentrate on the the influence of organic exopolysaccharides on iron solubility, complexation and bioavailability, both within the ice and in surrounding snow and surface seawater. This innovative research will improve our understanding of key processes that control the productivity of the climatically-important Antarctic sea-ice zone. Project objectives: This project will assess the importance of the trace element iron (Fe) as a micro-nutrient to seasonal sea-ice algal communities in the Australian sector of Antarctica during the International Polar Year (2007-09). We will investigate the biogeochemistry of Fe, including a comprehensive examination of its distribution, speciation, cycling and role in fuelling ice-edge phytoplankton blooms. A significant part of this research will concentrate on the influence of organic exopolysaccharides (EPS) on Fe solubility and complexation (and hence bioavailability), both within the ice and in surrounding surface waters. This innovative research will improve our understanding of key processes that control the productivity of the climatically-important Antarctic sea-ice zone. This metadata record describes data collected at Casey Station as part of project 3026. Collected data from the time series experiment in sea ice near Casey station Antarctica (66 degrees 13 minutes 07 seconds S, 110 degrees 39 minutes 02 seconds E). Measurements were made at the same location during seven consecutive study days between 10 November and 2 December 2009. Variables measured were pFe (particulate Fe), TDFe (total dissolvable Fe), dFe (dissolved Fe), plFe (particulate leachable Fe), PON (particulate organic nitrogen), POC (particulate organic carbon), Chl a (Chlorophyll a), salinity, ice temperature, vb/v (brine volume fraction), mean daily air temperature, and max daily air temperature. Measurements were taken on each study day of the snow directly overlying the sea ice (SNOW), a shallow and a deep brine (B- and B+, respectively), three sections of the sea ice core at median depths 3, 33, and 73 centimeters (SI1, SI2, and SI3, respectively) as well as two consecutive sections in the lower most basal ice (SI4 and SI5). Finally, four samples were taken of the underlying seawater at 0, 5, 10 and 15 m (SW0, SW5, SW10 and SW15, respectively).

Metadata record for data from ASAC Project 102 See the link below for public details on this project. From the abstracts of some of the referenced papers: Six species of marine microalgae, namely Phaeodactylum tricornutum Bohlin, Dunaliella tertiolecta Butcher, Isochrysis galbana Parke, Porphyridium purpureum (Bory) Ross, Chroomonas sp., and Oscillatoria woronichinii Anis., have been examined with respect to their gas exchange characteristics and the inorganic carbon species taken up by the cells from the bulk medium. All species showed a high affinity, in photosynthesis, for inorganic carbon and low CO2 compensation concentrations. Such data are suggestive of operation of a 'CO2-concentrating mechanism' in these microalgae. Direct measurements of internal organic carbon pools in four of the species studied confirm this (O. woronichinii and Chroomonas were not tested). By comparison of achieved photosynthetic rates with calculated rates of CO2 supply from the dehydration of bicarbonate, it was shown that Phaeodactylum, Porphyridium and Dunaliella could utilise the bicarbonate present in the medium. Data for the other species were inconclusive although the pH dependence of K 1/2CO2 for photosynthesis by Oscillatoria indicated that this species too could utilise bicarbonate. Such observations could, however, not be used as evidence that, at least in the eucaryotic algae examined, bicarbonate was the inorganic carbon species crossing the plasmalemma as Phaeodactylum, Porphyridium and Dunaliella, and Isochrysis all showed the presence of carbonic anhydrase activity in intact cells as well as in crude extracts. 'External' carbonic anhydrase activity represented from 1/4 to 1/2 of the total activity in the cells of these algae. It is concluded that, as a consequence of a CO2-concentrating mechanism, photorespiration was suppressed in the marine microalgae examined although the data obtained did not allow any firm conclusions to be drawn regarding the species of inorganic carbon transported into the cell. Analysis of the age composition of a given species within a community is fundamental to any study of population dynamics and to the subsequent analyses of community interactions such as competition, succession and productivity. A problem exists in that calendar age often provides little information on the role played by any given individual plant within a population. For many populations the most useful definition of population structure is obtained from an analysis of both the functional age and the vitality of the component plants. Data from such studies on populations of marine macroalgae are lacking mainly because of the lack of suitable methods. This paper provides a review of the methods which have ben applied to such analyses in both terrestrial and marine communities, discusses these methods in the context of marine algae and presents the results of a case study on the analysis of population structure in the large brown alga Durvillaea potatorum. Evidence is presented for the occurrence of sexual reproduction including plasmogamy and meiosis, events previously undescribed in the life history of Ascoseira mirabilis. Ascoseira is monoecious. Gametangia are formed in chains within conceptacles. Synaptonemal complexes, structures concerned with chromosome pairing in meiosis, have been observed in the nucleus of gametangial initials. Mature male and female gametes have the same size and appearance, and resemble typical brown algal zoids. Sexual interaction begins after the female gamete settles down, and both zygotes and unfused gametes develop into sporophytes. It is concluded that Ascoseira has the same basic pattern of life history that characterises the order Fucales, and it is argued that this is probably the result of convergent evolution rather than being indicative of close phylogenetic relationship. Life histories are of central importance in understanding evolution and phylogeny of brown algae. Like other hereditary

This entry contains: Locations for sampling sites for ASAC project 2596 on voyage 3 of the Aurora Australis in the 2004/5 season, collected between December and February of 2004/5; CTD bottle-derived seawater viscosity data and CTD bottle-derived in vivo fluorescence data. Note: ASAC project 2596 operates in direct collaboration with ASAC project 2382 (Impact of viscosity on the morphology and swimming behaviour of motile bacterioplankton, phytoplankton and protozooplankton). There are four spreadsheet files in this entry. Each spreadsheet file contains several worksheets. 1) Transect 1 (CLIVAR I9 = 'I9') station and sampling details: CTD stations, CTD profiles, Surface samples. 2) Transect 2 (Kerguelen Plateau and Princess Elizabeth Trough = 'PET') station and sampling details: CTD stations, CTD profiles. 3) 10 x 10 Flow Cytometry (FCM) data, derived from a two-dimensional microscale sampling device. 4) FluoroMAP profiles. These files contain the following data: Count Date Time Pressure (milliVolts)/Depth Chlo Depth - is the pressure in milli-Volts (mV) which is can be converted to depth in meters using the manufacturers calibration, Where, depth (m) = 0.00149 * (depth (mV)) -7.5 Chlo= is short for chlorophyll fluorescence and has arbitrary units (a.u.) For all files -999 entry = missing data A word document details the sampling protocols for FCM, 10 x 10 samples and FluoroMAP profiles. See the link below for public details on this project.

This metadata record contains the results from 11 bioassays conducted with 2 species of Antarctic marine microalgae. Seven tests were conducted with Phaeocystis antarctica (Prymnesiophyceae), assessing the toxicity of copper, cadmium, lead, zinc and nickel. Four tests were conducted with Cryothecomonas armigera (Incertae sedis), assessing the toxicity of copper only. Test conditions for both algae are described in the excel spreadsheets. In summary, tests for P. antarctica and C.armigera, were carried out at 0 plus or minus 2 degrees C, 20:4 h light:dark (150-200 micro mol/m2/s, cool white 36W/840 globes), in natural filtered (0.45 microns for P.antarctica and 0.22 microns filtered for C. armigera) seawater (salinity - 35 ppt, pH - 8.1 plus or minus 0.2). For both species, filtered seawater was supplemented with 1.5 mg/L NO3- and 0.15 mg/L of PO43-. All tests were carried out in silanised 250-mL glass flasks, with glass lids. Test volumes for P.antartica and C.armigera were 50 mL and 80 mL, respectively. All tests consisted of 3-5 metal treatments, with 3 replicates per treatment, alongside 3 replicate controls (natural filtered seawater). Seawater was spiked with metal solutions to achieve required concentration. Concentrations tested are recorded in excel datasheets. The following replicate toxicity tests were completed for P. antarctica: - 5 tests with copper (1-20 micro g/L) - 4 tests with lead (10-500 micro g/L) - 3 tests with cadmium (100-2000 micro g/L) - 3 tests with zinc (100-2000 micro g/L) - 3 tests with nickel (200-1000 micro g/L) For C. armigera, 1 rangefinder test was carried out testing 6 concentrations (1-100 micro g/L), and 3 definitive test, with 5 concentrations (15-100 micro g/L). The age of P. antarctica and C.armigera at test commencement was 8-12 days, and 25-30 days, respectively. Algal cells were centrifuged and washed to remove nutrient rich media, and test flasks were inoculated with between 1-3 x103 cells/mL. Cell densities in all toxicity tests were determined by flow cytometry. The flow cytometer was also used to simultaneously measure change sin chlorophyll a fluorescence intensity, cell size and internal cell granularity. Toxicity tests were continued until cell densities in the control treatments had increased 16-fold. Toxicity tests with P. antarctica were carried out over 10 days, with cell densities in each replicate flask measured every 2 days. Toxicity tests with C. armigera were carried out over 23-24 days, with cell densities determined twice a week. The growth rate (cell division; u) was calculated as the slope of the regression line from a plot of log10 (cell density) versus time (h). Growth rates for all treatments were expressed as a percentage of the control growth rates. The pH in all treatments was measured on the first and last day of the test, as well as on day 6 for P. antarctica tests and an additional two times per week for C. armigera tests. Sub-samples (5 mL) for analysis of dissolved metal concentrations were taken from each treatment on days 0, 6 and 10 for P. antarctica tests, and on days 0, 7, 14, 21, and 24 for C. armigera tests. Sub-samples were filtered through an acid washed (10% HNO3, Merck) 0.45-micron membrane filter and syringe, and acidified to 0.2% with Tracepur nitric acid (Merck). All toxicity test results were calculated using measured dissolved metal concentrations, which were determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES; Varian 730-ES) for Cu, Cd, Pb, Ni and Zn and using inductively coupled plasma-mass spectrometry (ICP-MS; Agilent 7500CE) for lowest concentration Cu samples (nominal concentration 1 micro g/L). Detection limits for Cu, Cd, Pb, Ni and Zn were 1, 0.12, 1.7, 1.2 and 0.1 micro g/L, respectively (ICP-AES) and 0.05 micro g/L (ICP-MS) for low concentration Cu samples. The specific growth rates (u) and corresponding measured metal concentrations were used to calculate toxicity test values using Toxcalc

The abundance, biomass, and diversity of microzooplankton and their herbivorous impact on phytoplankton were examined on a cross shelf transect (see thumbnail), sampling five stations from February 2002 to December 2004, and in a pair of mesoscale eddies ~300km from the coast on the seaward side of the Leeuwin Current. Prior to this study, no research on microzooplankton from temperate waters off Western Australia had been undertaken.

Metadata record for data from ASAC Project 2702 See the link below for public details on this project. Sea-ice algae are the basis of the Antarctic food web and are essential for healthy functioning of the Antarctic ecosystem. These algae exploit a unique niche within this extreme environment. Using advanced photosynthetic analysis we will examine the mechanisms which influence the productivity of sea-ice algae. The objective of this project is to understand the processes of light acclimation and photo-protection employed by sea-ice algae under extremely low temperature conditions. Several new hypotheses have been proposed in a recent review of low temperature acclimation of higher plants (Oquist and Huner, 2003). To further understand the remarkable tolerance of sea-ice algae to photoinhibition, we propose to test several of these hypotheses. Sea-ice algae fix inorganic carbon that forms the basis of the Southern Ocean food web. Sea ice covers up to 20 million km2 of the Southern Ocean each year. Global climate change will decrease the sea-ice thickness and distribution (IPCC, 2001); however subtle changes in temperature and light penetration will also have profound negative impacts on the photosynthetic efficiency of the sea-ice microalgae before any macroscale changes take place. Sea-ice algae are essentially the only food source for invertebrates and fish for up to nine months of the year. During winter and spring, krill (Euphausia sp.) have been observed feeding directly on sea-ice algae. Further, changes in sea-ice productivity will have a cascade effect further up the food web. Therefore, understanding how physical driving forces (temperature and light) affect sea-ice algae productivity will be critical to our ability to predict the effects of climate change and sustainably manage this unique and vulnerable ecosystem. Our primary objective is: To understand the processes of light acclimation and photo-protection employed by sea-ice algae under extremely low temperature conditions, with an aim to better understanding the potential implications of global climate change on the Antarctic sea-ice ecosystem.

A collection of about 20 isolates of Antarctic microalgae from the Windmill Islands region, around Casey Station has been established in the University of Malaya Algae Culture Collection (UMACC). The Antarctic microalgae in the collection includes Chlamydomonas, Chlorella, Stichococcus, Navicula. Ulothrix and Chlorosarcina. Comparative studies on the effect of global warming and UVR stress on these Antarctic microalgae and the tropical collection are being conducted. From the abstract of one of the referenced papers: The growth, biochemical composition and fatty acid profiles of six Antarctic microalgae cultured at different temperatures, ranging from 4, 6, 9, 14, 20 to 30 degrees C, were compared. The algae were isolated from seawater, freshwater, soil and snow samples collected during our recent expeditions to Casey, Antarctica, and are currently deposited in the University of Malaya Algae Culture Collection (UMACC). The algae chosen for the study were Chlamydomonas UMACC 229, Chlorella UMACC 234, Chlorella UMACC 237, Klebsormidium UMACC 227, Navicula UMAC 231 and Stichococcus UMACC 238. All the isolates could grow at temperatures up to 20 degrees C; three isolates, namely Navicula UMACC 231 and the two Chlorella isolates (UMACC 234 and UMACC 237) grew even at 30 degrees C. Both Chlorella UMACC 234 and Stichococcus UMAC 238 had broad optimal temperatures for growth, ranging from 6 to 20 degrees C (growth rate = 0.19 - 0.22 per day) and 4 to 14 degrees C (growth rate = 0.13 - 0.16 per day), respectively. In constrast, optimal growth temperatures for Navicula UMACC 231 and Chlamydomonas UMACC 229 were 4 degrees C (growth rate = 0.34 per day) and 6 to 9 degrees C (growth rate = 0.39 - 0.40 per day), respectively. The protein content of the Antarctic algae was markedly affected by culture temperature. All except Navicula UMACC 231 and Stichococcus UMACC contained higher amount of proteins when grown at low temperatures (6-9 degrees C). The percentage of PUFA, especially 20:5 in Navicula UMACC 231 decreased with increasing culture temperature. However, the percentages of unsaturated fatty acids did not show consistent trend with culture temperature for the other algae studied. There are three spreadsheets available in the download file. ASAC_2590 - provides detail about where each species of algae was collected from. ASAC_2590a - provides data from Teoh Ming-Li et al (2004) ASAC_2590b - provides data from Wong Chiew-Yen et al (2004) The fields in this dataset are: Isolate Culture Collection number Origin (Location) Fatty acids saturated fatty acids polyunsaturated fatty acids monounsaturated fatty acids Temperature growth rate PAR UVB