The effects of petroleum hydrocarbon and heavy metal contamination of marine sediments on recruitment of Antarctic soft-sediment assemblages: a field experimental investigation

A manipulative field experiment was conducted at Casey Station, Antarctica, to determine the effect of contamination of marine sediments on the recruitment and development of soft-sediment assemblages. Uncontaminated marine sediments were defaunated and then contaminated by adding hydrocarbons (diesel fuel and lubrication oil) or heavy metals (extracted from contaminated soil) prior to deployment on the seabed for a period of eleven weeks during an Antarctic summer (December to February) at three locations. Two of the locations were intended as reference locations (O'Brien and Sparkes Bay) and were well away from the influence of station activities, but Sparkes Bay was found to be naturally contaminated by some metals. The other location (Brown Bay) was adjacent to an abandoned waste disposal site and is contaminated by hydrocarbons and metals, and soft-sediment assemblages are different from those in control locations. Recruiting assemblages were significantly different between locations and there was a significant effect of sediment contamination. Assemblages in hydrocarbon contaminated sediment were significantly different to those in control and metal treated sediment at two of the locations (Brown and Sparkes Bay). There were no differences between assemblages in control sediment and metal-contaminated sediment. Univariate analyses (ANOVAs) indicated greater abundances of crustaceans, mainly due to several species of gammarid, in control and metal treatments than hydrocarbon-treated sediment. Further analysis (t-tests) revealed additional differences between hydrocarbon vs. both control and metal treatments, in the total abundance, and abundance of gammarids, tanaids, ostracods, isopods and copepods, particularly at Brown Bay and Sparkes Bay. There was also a trend of greater abundances of polychaetes and gastropods in hydrocarbon and metal treatments compared to the control. In comparison with the hydrocarbon treatment, the metal treatment had little effect. There was significant spatial variability in recruitment within each location. which may have obscured some effects of sediment contamination. There were also significant differences in variability of recruitment between locations. The rate of fauna recruiting to sediments in this experiment at Casey were greater than previously recorded in Antarctica. (C) 2003 Elsevier Science B.V. All rights reserved.