Summary
The Australian Antarctic Division is currently remediating fuel spills on Macquarie Island. To contribute to the development of appropriate remediation targets, the present study examines the response of springtail assemblages to Special Antarctic Blend (SAB) diesel. Springtail assemblages were sampled over three transects (ten, 1×1 m plots per transect) with an organic carbon gradient ranging from 0 to 50% organic matter (OM) to examine the influence of organic carbon on SAB toxicity. For analysis, plots were separated into three groups based on OM content: low (0 to 10%), medium (15 to 30%) and high (36 to 50%). Seven pairs of soil cores were sampled from each plot and spiked with a range of SAB concentrations from 125 to 40000 mg SAB/kg soil. Following 15 days incubation, surviving springtails were extracted and identified to species. The change in springtail assemblage was modelled as a function of SAB concentration and soil OM content to determine the SAB concentration causing a 20% change in dissimilarity (EC20), from the controls. Low OM soils had an EC20 of 445 mg SAB/kg soil; medium OM soils had an EC20 of 1545 mg SAB/kg soil; and high OM soils had an EC20 of 1032 mg SAB/kg soil. These point estimates will contribute to a risk based framework to develop petroleum hydrocarbon remediation targets for the subantarctic.
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