Summary
A 5 yr field experiment was carried out comparing the effects of Special Antarctic Blend (SAB) diesel, synthetic lubricant (Mobil 0W40), used synthetic lubricant (used Mobil 0W40) and a biodegradable lubricant (Titan GT1) on Antarctic benthic microbial communities. Sediment from an uncontaminated site was collected, spiked with one of the oils and deployed in O’Brien Bay, East Antarctica. Sediment samples were then collected over 5 yr. All the oils caused changes in the microbial community in the top 1 cm of sediment, as determined by 16S ribosomal ribonucleic acid (rRNA) gene-based terminal restriction fragment length polymorphism analysis. The greatest effect was observed in the SAB diesel treatment. The biodegradable oil did not have a significant effect on the communities initially, but the communities present at 2 and 5 yr were significantly different to the controls. The unused and used lubricants were both significantly different to the control treatment. All the oils degraded, with 39% of the SAB, 15% of the unused lubricant, 15% of the used lubricant and 12% of the biodegradable oil, remaining after 5 yr. These results show that the effects of all these oils will be evident in the Antarctic benthic ecosystem for longer than 5 yr. This highlights the need for studies into the longevity and ecotoxicology of oil products in the Antarctic environment.