Toxicity of IFO 180 fuel and Slickgone NS dispersant to larval Sterechinus neumayeri Antarctic sea urchins

Brief description

This metadata record contains the results from bioassays conducted to show the response of larval Antarctic Sterechinus neumayeri sea urchins to contamination from combinations if IFO 180 fuel and the fuel dispersant Slickgone NS. AAS project 4142.

Experiments used an intermediate grade Fuel Oil (IFO 180) and an internationally approved fuel dispersant, Slickgone NS, produced by Dasic International LTD. Treatments included a physically dispersed treatment of IFO 180 only, a chemically dispersed treatment of IFO 180 treated with Slickgone NS and a Slickgone NS only treatment to determine the toxicity of the dispersant. Treatments were experimentally mixed using a magnetic stirrer to combine treatment substances and filtered seawater (FSW) in temperature-controlled cabinets at 0oC to create a Water Accommodated Fraction (WAF). WAFs were produced in 2 L and 5 L glass aspirator bottles following the methods of Singer, Aurand et al. (2000) with adaptations by Barron and Ka'aihue (2003) and Kostzakoulakis (chemistry section, project 4142) stirring for 42 h with a settling time of 6 h.

WAF treatments used concentrations of 100%, 50%, 20% and 10%, CEWAF and dispersant only treatments used concentrations of 10%, 5%, 1% and 0.1%. Toxicity tests were conducted in temperature-controlled cabinets at 0 oC using uncapped, forty-millilitre glass headspace vials, each containing 15.5 ml of test solution and 0.5 ml of embryo suspension. Fertilisation methods followed standard procedures for Sterechinus neumayeri.
Two tests were conducted to determine the effect of a single pollution event (test 1) compared with a recurring repeated pulse pollution event (test 2). Test 1 required no water changes, while test 2 required renewal of the test treatments on a 4-day basis.

Three endpoints were used, un-hatched blastula (48 h to 48.5 h) to represent the embryonic phase, gastrula (10 d) and 4-armed pluteus (16 d to 18 d). At the termination of each endpoint, 1 ml of 10% buffered formalin was added to each relevant vial and recapped. At the conclusion of the experiments, preserved embryos were observed under a dissecting microscope to determine the number of normal, abnormal and unfertilised embryos relative to controls.

Samples for analysis of total petroleum hydrocarbon content were taken throughout the 2 experiments to determine the actual concentrations to which embryos and larvae were exposed. The measured concentrations were integrated following the methods of Payne et al. (2014) to obtain a profile of hydrocarbon content over each test period.

Two spreadsheets are included in this metadata record detailing survival data and results of hydrocarbon analysis. The survival data file includes test condition details on the first tab, with data for tests 1 and 2 on the second and third tabs. Test treatment and concentration are listed on the left of each data block and count categories are defined in the top left panel. Development stage, date preserved and age of organism is defined for each data block, representing the three endpoints included in the experiments: unhatched blastula, gastrula and 4-armed pluteus.

The hydrocarbon analysis, TPH (total petroleum hydrocarbon) file details chemical analysis results produced by K. Kotzakoulais at Macquarie University as part of project 4142. Row terminology explanations are as follows:

TPH metadata
Test name- indicates the tested species
Exp number-indicates whether the data belongs to test 1 or test 2
Water change- details the identification of the sample in relation to the 4-day water change regime. Start samples represent the beginning of the experiment. Pre samples are taken at the end of the corresponding 4-day period, before the water is changed. 'Post' samples are taken of newly made test solutions. The chronological order of sampling is therefore: Start, pre4d, post4d, pre8d, post 8d etc. Only 'pre' samples were taken for test 1, as there were no water changes.
less than C9 - greater than C28- Hydrocarbon content of samples was broken down into four compound size classes detailed for each analysis.
Contamination- contamination was detected in samples, the source of contamination remains unclear, however it was established that contamination occurred during the sampling process and therefore did not come into contact with organisms. Contamination was therefore excluded from calculations. The hydrocarbon content of 0.1% dilutions was unable to be reliably analysed due to accuracy of the equipment and interfering contamination.

Control data indicates spot checks to confirm the presence or absence of fuel. Very small amounts of hydrocarbons were detected as lighter fuel components evaporated and dissolved into control water within the cabinet. These very small amounts are negligible.

Abnormality metadata
Tab 1 details test conditions
Tab 2 'Test 1' includes the data for test 1
Tab 2 'Test 2' includes the data for test 2.
All observational categories are defined within the spreadsheet.

Lineage

Progress Code: completed

Statement: Control mortality was lower than ideal and was corrected for using Abbot's correction.

Some contamination of hydrocarbon samples occurred during sampling, which test organisms were not exposed to. Contamination levels were therefore excluded from calculations of exposure concentrations. The hydrocarbon content of 0.1% dilutions was unable to be reliably analysed due to accuracy of the equipment and the interfering contamination.

Notes

Purpose
The purpose of the data set was to investigate the response (in terms of abnormality) of larval Sterechinus neumayeri to physically dispersed IFO 180 fuel WAF, IFO 180 chemically dispersed with Slickgone NS and Slickgone NS only treatments.