Jump to results: data
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 (Version 5.0.23, TidePool Scientific Software, San Francisco, CA, USA). Data were tested for normal distribution using Shapiro-Wilk's test (p greater than 0.01); and equal variances using Bartlett's test (p = 0.09). The inhibitory concentration which reduced population growth rate by x% (ICx) compared to controls was calculated using linear interpolation. The Dunnett's multiple comparison test was used to determine which treatments were significantly different to the control (2 tailed, p less than or equal to 0.05), and to calculate the no observable effect concentration (NOEC) and the lowest observable effect concentration (LOEC). Data for each toxicity test are provided in individual excel spreadsheets, identified by the species tested, the test number for that species and the date the test started. A summary table of details for the 11 tests is provided in the file: Summary table.xlsx. The first worksheet for each test file is titled "Test Conditions". This sheet provides information on the toxicity test e.g. species and metals tested, dates, test conditions, as well as explanation of abbreviations, definitions of toxicity values etc. The second worksheet includes the raw cell densities determined in each flask, the calculated growth rates, and the measured pH and metal concentrations. For C. armigera data sheets, there is an additional worksheet, "Measured Cu and pH" which includes all measured pH values and metal concentrations across the 24-day period. Following the growth rate sheets are the statistical outputs for each metal, which were all generated using Toxcalc. Finally, if additional cellular parameters were measured (Chlorophyll a fluorescence, cell size and internal cell granularity), the raw data for each parameter is include in a worksheet, "Metal cellular parameters". Data were collected in an Australian laboratory (CSIRO Land and Water, Centre for Environmental Contaminants Research, Lucas Heights, 2234, NSW) during May 2013 - April 2014. The tests used microalgal strains that had been previously collected from the Southern Ocean and are cultured within the microalgal collection at the Australian Antarctic Division (AAD). Daughter daughter cultures were transferred to CSIRO, where they were cultured for this work.
This data describes the cellular metal concentrations of Phaeocystis antarctica and Cryothecomonas armigera following exposure to metals singly and in mixtures in laboratory studies. Microalgae were cultured in 80 mL of filtered (less than 0.45 um) seawater and low concentrations of nutrients supplemented with metal stocks to give a range of single and mixture exposures to the metals cadmium, copper, nickel, lead, and zinc. The cellular accumulation and partitioning are used to explain the metal's toxicity (cellular metal fractions are compared to the toxicity data provided in 10.4225/15/5ae93ff723ff8) and assess the risk bioaccumulation of metals to Antarctic marine microalgae may pose in the Southern Ocean food web.
This study assessed the performance of diffusive gradients in thin-films (DGT) with a binding resin that used Chelex-100 (iminodiacetic acid functional groups) to measure cadmium, copper, nickel, lead, and zinc contaminants in Antarctic marine conditions. To do this, three sets of experiments were done: (I) the uptake of metals to DGT samplers was assessed over time when deployed to three metal mixtures of known concentrations (DGT performance page). This allowed for the determination of metal diffusion coefficients in Antarctic marine conditions and demonstrated when metal competition for binding sites were likely to occur. (II) the DGT were deployed in the presence of the microalga Phaeocystis antarctica at a concentration of 1000-3000 cells/mL to investigate how environmentally realistic concentrations of an Antarctic marine microalgae affect the uptake of metals (DGT uptake with algae page). Finally, the DGT-labile concentrations from part (II) were used in reference toxicity mixture models to predict toxicity to the microalgae so they could be compared to a previous study that investigated the toxicity of metal mixtures to Phaeocystis antarctica and Cryothecomonas armigera (DGT toxicity modelling page).
This metadata record contains observed and predicted toxicity data from bioassays with two species of Antarctic marine microalgae: Phaeocystis antarctica (Prymnesiophyceae) and Cryothecomonas armigera (Cercoza). Bioassay exposures were of mixtures of 5 metals at two ratios, an Environmental (ENV) and Equitoxic (EC) mixture. The measured dissolved metal concentrations were used in two mixture reference models, Independent Action (IA) and Concentration Addition (CA), to predict toxicity as population growth rate inhibition. A Flow Cytometer (BD-FACSVerse) was used to measure the density of microalgae over time, which was then converted to a growth rate. An inductively coupled plasma-atomic emission spectrometry (ICP-AES; Varian 730-ES), was used to measure metal concentrations. Data for each microalga is provided in individual excel spreadsheets, identified by the species tested. A word document is provided that contains the R code used to predict toxicity to the two microalgae by the reference models Independent Action and Concentration Addition. The R code also includes the steps required to extend the models to include a deviation parameter “a” that allows for departure from model additivity. A nested F-test then tests for significance between the fit of each test to observed toxicities. This R code has been adapted to use EC10 as parameter estimates, rather than EC50s. The code was adapted from the approach outlined in Hochmuth, J. D.; Asselman, J.; De, S. Are Interactive Effects of Harmful Algal Blooms and Copper Pollution a Concern for Water Quality Management? Water Res. 2014, 60, 41–53. DOI: 10.1016/j.watres.2014.03.041. Single-metal toxicity data and experimental protocols for P. antarctica from the following paper: and C. armigera used in this study can be found in the following papers: A robust bioassay to assess the toxicity of metals to the Antarctic marine microalga Phaeocyctis antarctica. Francesca Gissi, Merrin S. Adams, Catherine K. King, Dianne F. Jolley (2015). Environmental Toxicology and Chemistry. 2015 Feb 20. doi: 10.1002/etc.2949. Chronic toxicity of five metals to the polar marine microalga Cryothecomonas armigera – Application of a new bioassay. Darren J. Koppel, Francesca Gissi, Merrin S. Adams, Catherine K. King, and Dianne F. Jolley, (2017). Environmental Pollution, Volume 228, 2017, Pages 211-221, doi.org/10.1016/j.envpol.2017.05.034.
This metadata record contains the results from 3 bioassays conducted with the Antarctic marine microalgae Cryothecomonas armigera (incertae sedis). These tests assessed the toxicity of copper, cadmium, lead, zinc and nickel. 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 (60-90 micromol/m2/s, cool white 36W/840 globes), in 80 mL natural filtered (0.22 microns) seawater (salinity - 35 ppt, pH - 8.1 plus or minus 0.2). 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. Tests 1 and 2 consisted of metal treatments, with 3 replicates per treatment, alongside 3 replicate controls (natural filtered seawater). Test 3 consisted of metal treatments in an increasing series (no replicates) alongside 3 replicate controls. Seawater was spiked with metal solutions to achieve required concentration. Concentrations tested are recorded in excel datasheets as dissolved metal concentrations measured on day 0, and day 24. The average of the dissolved metal concentrations were used for further statistical analysis. The age of C.armigera at test commencement was 25-30 days. Algal cells were centrifuged and washed to remove nutrient rich media, and test flasks were inoculated with between 1-3 x10^3 cells/mL. Cell densities in all toxicity tests were determined by flow cytometry. 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 flow cytometer was also used to simultaneously measure changes in the following cellular parameters: chlorophyll a autofluorescence intensity (FL3), cell size (FSC) and cell complexity (SSC). The molecular stain BODIPY 493/503, was used to measure neutral lipid concentrations. Changes in cellular parameters were measured by applying a gate that captured greater than 95% of control cells in a region, R2. Changes in cellular parameters were observed in metal treatments as a shift of the cell population from the R2 region to R1 (for relative decreases) or to R3 (for relative increases). The proportion of cells in each region is expressed as a percentage of the total cell population. The pH was measured on the first and last day of the test. Sub-samples (5 mL) for analysis of dissolved metal concentrations were taken from each treatment on 24. Sub-samples were filtered through an acid washed (10% HNO3, Merck) 0.45-microns membrane filter and syringe, and acidified to 0.2% with Tracepur nitric acid (Merck). Metal concentrations were determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES; Varian 730-ES) for Cu, Cd, Pb, Ni and Zn. Detection limits for Cu, Cd, Pb, Ni and Zn were 1.0, 0.3, 3.2, 1.4, and 1.0 micrograms per litre, respectively. Calculations of effect concentrations (EC 10 and 50) were made using the 'Dose Response Curve' package of R statistical analysis software. Concentration-response curves had several models applied to them, and were tested for best fit by comparing residual standard errors and Akaike's 'An Information Criterion' function . Generally, log-logistic models with 3 parameters provided the best fit. Data for each toxicity test is combined in a single excel spreadsheet, "Cryothecomonas armigera single metal toxicity". The first worksheet is titled "Test Conditions" which provides information on the toxicity test, e.g. species and metals tested, dates, test conditions, as well as explanation of abbreviations, definitions of toxicity values etc. The second worksheet includes the raw cell densities determined in each flask, the calculated growth rates, and measured metal concentrations. The third worksheet contains the measured physiological parameters: Neutral lipid concentrations (BODIPY 493/503), chlorophyll a autofluorescence (FL3), cell complexity (SSC), and cell size (FSC). The final worksheet contains the output of statistical analysis; dose-response curves for each metal with applied log-logistic model and 95% confidence interval, a table summarising the effect concentrations (EC10 and EC50), and No Effect Concentration (NEC) is also provided. The file "C. armigera combined.csv" contains rows representing individual exposures with columns for the metal treatment (Metal), averaged dissolved metal concentration for each exposure (Conc), growth rate (Growth), and growth rate as a percent of the control (Pcon). This data was used for data analysis in R statistics. Note that this contains data from all bioassays conducted with C. armigera, including those conducted by Francesca Gissi (doi:10.4225/15/551B2B65A73F3) The script used for data analysis is provided in the document "R statistics script for C. armigera single metal.docx"