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AAS_2933_Macca_Invertebrates

The following methods text is primarily extracted from a manuscript submitted for publication, with only minor modifications, the related data set includes a subset of samples, collected from Green Gorge and Bauer Bay, which are additional to that described in the publication. Study Sites Two fuel spill sites were included in this study, Main Power House (MPH) and Fuel Farm (FF), both located on the Macquarie Island isthmus at the northern end of the island. Both sites are within the vicinity of the islands research station (see map provided). The spills are in close proximity to fuel tanks, buildings, roads and other station infrastructure, they experience foot and vehicle traffic, and are thus considerably disturbed habitats. The MPH site is the location of the diesel generators which provide the stations power supply. The FF site contains a series of storage tanks that hold the stations fuel supplies. The habitats of the two sites differ; the FF site is on an elevated headland, is well vegetated and the substrate is largely fill material, while the MPH site is largely devoid of vegetation cover and has a substrate of unconsolidated coarse sand. Field Survey Sampling occurred between 23 January and 13 March 2008 in conjunction with a larger soil survey conducted by the Australian Antarctic Division to delineate the extent of contamination at the spill sites prior to site remediation. Thirty-nine pairs of intact soil cores (75 mm diameter, 70 mm depth) were collected from the Macquarie Island isthmus area. This included 15 from within each of the two fuel spill sites (FF and MPH) and nine away from the spill areas (see map provided). Twelve additional samples were also collected from down-island sites (six each at Green Gorge and Bauer Bay), well away from the influence of the station. Samples collected away from the spill sites were from ecologically comparable habitat to the spill sites; in terms of level and type of disturbance and factors such as vegetation cover, aspect, elevation and soil type. Sample locations within the spill sites covered a range of contaminant levels, including the estimated spill hot spots and spanning out to include clean zones beyond spill-impacted areas. Actual contaminant concentrations were determined after sampling. The at-depth excavations of the 30 samples collected from within the MPH and FF sites enabled measurement of fuel concentrations and other soil chemistry parameters (as per Snape et al. 2010, updated 2014) throughout the soil profile. Soil chemistry for the nine samples collected away from the spill sites were analysed for surface samples only. Invertebrates were extracted from soil cores using Tullgren funnels (light globe providing heat source) immediately following field collection. Extracted invertebrates were collected into 70 mL specimen jars and stored in 70% ethanol. Taxa were ordinal sorted and springtails separated and identified to species level where taxonomic certainty allowed, following Greenslade (2006). Three morphospeices were identified to genus only: 1. Lepidocyrtus sp. is lignorum group nr violaceus Geoffroy, 2. Sminthurides sp. is cf. malmgreni grp Tullberg and 3. Tullbergia sp. includes T. bisetosa Borner and T. templei Wise, with T. bisetosa known to be the more abundant of the two (Mooney 2013). Matched cores were analysed for a range of soil chemical parameters as described in Snape et al. (2010, updated 2014): total petroleum hydrocarbons (TPH) using Gas Chromatography with Flame Ionisation Detector (GC-FID); soil moisture by gravimetric methods; pH and conductivity of water extracts; total organic carbon via mass loss on ignition; and nutrient concentrations (nitrate, nitrite, ammonium, fluoride, bromide, chloride, sulphate and phosphate; using ion chromotography) for water and KCl extracts. Measures of TPH are for range C9-36 and are expressed in mg/kg on a dry weight basis. At each sample location physical environmental variables were assessed: 1. Vegetation percent cover over the surface of the soil cores and 2. Geographic location (latitude, longitude and elevation) measured using a Trimble ProXH GPS receiver coupled to a Trimble Zephyr antenna and differentially corrected with Trimble Pathfinder Office. Fuel plume modelling shown in the map provided was performed in ArcGIS, v10.1, with Xtools Pro extension for generation of surface rasters. Soil TPH data collected up to 2014 was included (with fresh fuel spill signatures after 2007 removed). Null values were used around the perimeter to minimise edge effects. Max TPH values occurred, on average, at 0.8 m below surface. References Snape, Ian, Stark, Scott Charles, Powell, Shane, Ferguson, Susan, Palmer, Anne, Wasley, Jane and Hince, Greg (2010, updated 2014) Characteristics of soil collected on Macquarie Island in 2008. Australian Antarctic Data Centre - doi:http://dx.doi.org/10.4225/15/54190EE461BB8