Summary
In 2001 a unique field experiment was established to compare the longevity and effects of four different oils on the Antarctic benthic ecosystem. Clean sediment was collected, spiked with one of the oils: Special Antarctic Blend (SAB) diesel, synthetic lubricant (Mobil 0W-40), used synthetic lubricant (used Mobil 0W-40) or a biodegradable lubricant (Titan GT1), and deployed in O’Brien Bay near Casey station, East Antarctica. Sediment was collected periodically over the next five years and the microbial community structure was examined by a combination of culture-dependent and molecular methods. We found that although all the oils degraded to some extent over the five years, there was still between 15 and 40% of the initial oil remaining in the sediment. All the oils caused changes in the microbial community structure although they differed in their effect. The greatest effect was observed in the SAB diesel treatment whilst the biodegradable oil did not have a significant effect on the communities until two years after deployment. The clean and used lubricant treatments were also significantly different to the control sediment. The diversity of the alkane mono-oxygenase gene in the sediment exposed to SAB diesel was also examined by the creation of a clone library. A range of alkane mono-oxygenase sequences were recovered, some of which were similar to sequences recovered by other workers from different Antarctic sediments.