Influence of an Antarctic waste dump on recruitment to nearshore marine soft-sediment assemblages

Abandoned waste dumps in Antarctica pose an environmental hazard due to contaminant mobilisation in marine and terrestrial habitats. At Casey Station, east Antarctica, a shoreline waste dump has contaminated adjacent marine sediments with metals, hydrocarbons and organic carbon. This study experimentally assessed a model whereby contamination of marine sediment can lead to changes in recruitment and differences in soft-sediment assemblages. We tested the hypotheses that recruitment would be different at disturbed 'station' locations compared to controls and different in contaminated sediment compared to control sediment. We conducted 2 reciprocal sediment-transplant field experiments over 2 consecutive years in which defaunated sediments were deployed at disturbed locations and control locations and were recovered after 9 mo (March to November: winter), and also after 12 mo. The majority of fauna recruiting to the experiment were highly motile species with non-pelagic lecithotrophic larvae, such as gammarids, tanaids, isopods and gastropods. There were large differences in recruiting assemblages between all locations and there were significant differences in recruitment between disturbed and control locations. Assemblages in contaminated sediment were significantly different from those in control sediment. Differences in abundances of individual taxa between control and contaminated sediment were complex and difficult to interpret. Assemblages recruiting to the control locations were more variable than those recruiting to disturbed locations. This study provides evidence that contaminants in marine sediments adjacent to the waste dump at Casey Station may be having an environmental impact.