An assessment of an oil spill in Gladstone, Australia : impacts on intertidal areas at one month post-spill

In January 2006, 25 tonnes of heavy fuel oil spilled into the Port of Gladstone in Queensland, Australia, from the breached hull of a bulk carrier ship. Over the following days, approximately 18 tonnes of the oil was recovered, however a certain amount of oil was deposited in the intertidal areas of Port Curtis leaving a highly visible, viscous residue. The objectives of this research were to assess the immediate impacts on the intertidal habitat and to gain baseline information for future comparative assessments. Sediment PAH and metal concentrations, mangrove communities and intertidal macroinvertebrates were assessed within one month post-spill at oil-impacted sites; adjacent sites which were not visibly impacted; and reference sites which were located outside the recorded distribution of the oil spill. Highest PAH concentrations were found at the impacted sites, with concentrations of some PAHs exceeding Australian and New Zealand Sediment Quality Guidelines (ANZECC/ARMCANZ, 2000). These sites contained very few or no crab holes in the high intertidal area, indicating a low crab density in comparison to reference sites. Little immediate impact was evident on the mangrove and macrobenthic communities, however future surveys may show evidence of longer-term impacts on these communities.