Live O. orensanzi were found in the AAD's Marine Research Facility emerging from sediments during feeding on 3 July 2014. It is likely that live specimens were included in samples collected for another species, Antarctonemertes sp. from intertidal rocky areas at Beall Island near Casey station (66 30.4265 degree S, 110 45.851 degrees E), East Antarctica in January and February 2014. It is also possible that the O. orensanzi were collected from southeast Newcomb Bay, adjacent to Casey station on 2 and 3 of February 2012 (Figure 4), and survived in the Marine Research Facility's aquarium, but this is considered less likely. Experiments were conducted at the AAD's quarantine facility in Kingston, Tasmania, between 19 July and 2 September 2014. This metadata record contains the results from bioassays conducted to show the response of Antarctic Polychaetes Ophryotrocha orensanzi to contamination from combinations if IFO 180 fuel and the fuel dispersants Ardrox 6129, Slickgone LTSW and Slickgone NS. Test solutions were prepared following the methods of Singer et al. (2000) with modifications by Barron and Ka'aihue (2003) and others. Water accommodated fractions of fuel in water (WAF) were produced using a 1:25 (v/v) fuel to FSW ratio in accordance with studies by Payne et al. (2014) and Brown et al., (2016) to facilitate comparability of results. Chemically enhanced water accommodated fractions (CEWAF) were made following a lower 1:100 (v/v) fuel to FSW ratio. A 1:20 (v/v) dispersant to fuel ratio was used for all three dispersants, an application rate of 1:20 dispersant to fuel rate was used both because this is the standard default application rate used in the field and to increase comparability to previous studies. Dispersant only mixes were made according to CEWAF specifications, substituting FSW for fuel. Test mixes were prepared in dark temperature-controlled cabinets at 0 plus or minus 1 degree C. Mixes were made in two L or five L glass aspirator bottles using a magnetic stirrer. Mix preparation followed the pre-vortex method in which a 20 - 25 % vortex was achieved in 0 plus or minus 1 degree C FSW before addition of the test materials. Once added, fuel was allowed to cool for a further 10 minutes before subsequent addition of dispersants during CEWAF preparation. Mixes were stirred for a total of 42 h with an additional settling time of 6 h following the recommendations determined as part of the hydrocarbon chemistry component of this project (Kotzakoulakis, unpublished data). The mixture was subsequently serially diluted to achieve the desired concentrations. Test concentrations were 100%, 50%, 20% and 10% for WAF and 10%, 5%, 1% and 0.1% for CEWAF. Concentrations for dispersant only treatments mimicked CEWAF in order to be directly comparable. Test solutions were kept in sealed glass bottles with minimal headspace at 0 plus or minus 1 degree C for a maximum of 3 h before use. Test dilutions were remade each four day period to replenish hydrocarbons lost through evaporation and absorption to simulate a repeated pulse exposure to the contaminant. Ninety percent of the test solution volume was replaced for each beaker during each water change by gently tipping out the solution with minimal disturbance to the test organisms. Replacement solutions were chilled to the correct temperature and replenished immediately to avoid any temperature shock to test animals. Beakers were topped up with deionized water between water changes to maintain water quality and solution volume. Bioassays were conducted in cold temperature cabinets at 0 plus or minus 1 degree C and light regimes were set to 18 h light and 6 h dark to mimic Antarctic conditions used by Brown et al. (2017). Exposure vessels were 100 ml glass beakers containing 80 ml of test solution. Beakers were left open to allow for the evaporation of lighter fuel components. Each experiment consisted of four replicates per treatment concentration, with eight to 10 individuals per replicate (8 each for Slickgone NS, 10 each for Ardrox and LTSW). Experiments ran for 12 days with observations at 24 h, 48 h, 96 h, 7 d, 8 d, 10 d and 12 d. Mortality was assessed at each observation using a Leica MZ7.5 dissecting microscope. Mortality was determined by the absence of response to stimuli, specifically lack of movement in the maxillae or mandibles. No food was added during experiments to avoid inclusion of an additional exposure pathway. Aliquots of each test concentration were taken at the beginning and end of each experiment, as well as before and after each water change to analyse the total petroleum hydrocarbon (TPH) content. Duplicate 25 ml samples were taken for each test dilution and immediately extracted with a mixture of Dichloromethane spiked with an internal standard of BrC20 (1-bromoeicosane) and cyclooctane. Extractions were analysed using Gas Chromatography with Flame Ionisation Detection (GC-FID) and Gas Chromatography mass spectrometry (GC-MS). The measured concentrations were integrated following the methods of Payne et al. (2014) to obtain a profile of hydrocarbon content over each 12 d test period.

This metadata record contains the results from bioassays conducted to show the response of an Antarctic nemertean Antarctonemertes unilineata to contamination from combinations of Special Antarctic Blend (SAB) diesel, Marine Gas Oil (MGO) and Intermediate Fuel Oil (IFO 180), chemically dispersed with fuel dispersants Ardrox 6120, Slickgone LTSW and Slickgone NS. Note that the corresponding PhD thesis chapter refers to the species as Antarctonemertes sp., prior to being named Antarctonemertes unilineata in 2018. Experiments using SAB, MGO and IFO 180 with the dispersant Ardrox 6120, including fuel only and dispersant only treatments were conducted at Casey station. Experiments involving IFO 180 and the fuel dispersants Slickgone LTSW and Slickgone NS were conducted at the Antarctic Division’s Marine Research Facility quarantine labs. All experimental procedures, including test mix preparation and bioassays were conducted at 0 plus or minus 1 degree C. Water accommodated fractions (WAF; fuel mixed in water) and chemically enhanced water accommodated fractions (CEWAF) were made according to the specifications of Singer, Aurand et al. (2000), Barron and Ka’aihue (2003) and Kotzakoulakis (unpublished at time of writing). Dispersant only mixes were also made using filtered seawater (FSW) and dispersant volumes proportional to those used for CEWAF production. WAF was made using a loading ratio of 1: 25 (v/v) fuel to FSW, CEWAF was prepared using 1:100 (v/v) fuel to FSW ratio, and 1: 20 (v/v) dispersant to fuel ratio. Following the 48 h preparation time, the seawater WAF components of the mix were drained from the bottom of aspirator bottles and serially diluted. WAF treatment concentrations were 100%, 50%, 20% and 10%, CEWAF and dispersant only concentrations were 10%, 5%, 1% and 0.1%. Treatment solutions were replenished every four days to simulate a repeated pulse exposure to contaminants and to replace hydrocarbons lost through evaporation and adsorption and to maintain water quality parameters. WAF, CEWAF and dispersant only test solutions were remade every four days using identical methods. Tests were done in temperature-controlled cabinets set to 0 plus or minus 1 degree C following a 6 h light to 18 h dark photoperiod. Beakers were left uncovered to allow for the natural evaporation of lighter hydrocarbon components to reflect real fuel spill conditions. Experiments ran for 24 d except for the Ardrox 6120 only experiment, which ran for 16 d due to high mortality in this treatment. Sublethal and lethal endpoints were assessed at 1, 2, 4, 7, 8, 12, 14, 16, 20 and 24 d observations. Aliquot water samples for analysis of total hydrocarbon content (THC) were taken for initial and final test concentrations, and before and after each four-day water change, to obtain accurate profiles of hydrocarbon loss over the test period. Duplicate samples were taken for every treatment concentration and extracted with dichloromethane, spiked with an internal standard of 1-bromoeicosane and cyclooctane. Samples were analysed using gas chromatography with flame ionization detection (GC-FID) and gas chromatography mass spectrometry (GC-MS). Average THC concentrations for the duration of the experiment were obtained by integrating the measured concentrations to which animals were exposed following the methods of Brown et al. (2016) and Payne et al. (2014). This data submission includes one file detailing the TPH experiment analyses and one detailing the bioassay tests and results. The thesis that relates to this work is available from: https://epubs.scu.edu.au/theses/533/

Marine soft-sediment assemblages were sampled from shallow (5 - 35m) nearshore regions around Casey Station, Windmill Islands, East Antarctica in late summer (Feb-March) 1997, using a van-Veen grab (surface area 20 x 25 cm). Samples were sieved through a 1 mm mesh and sorted to species where possible. A hierarchical, spatially nested sampling design was used with locations (km's apart), sites (100s of metres apart), and plots (10s of m). Two potentially impacted, polluted locations (adjacent to a sewage outfall and an old garbage tip) were compared with two control locations. Data was analysed using both multivariate and univariate statistical methods. Significant differences in assemblages were found between locations and between sites within locations. Significant differences in the abundances of taxa at several taxonomic levels (species, family, order, phylum) were found at all three spatial scales. Significant differences were also detected between the polluted and control locations. Compared with other Antarctic locations, the assemblages were dominated by crustaceans (90 to 97 % of individuals) and there was a paucity of polychaete fauna at the locations sampled. This study represents the first description of benthic assemblages from this region. A total of 70 samples are included in this data set. Also links to ASAC 1100. The fields in this dataset are: Location Site Plot/replicate Weight Volume Species