Patterns of survival and behavior in Antarctic benthic invertebrates exposed to contaminated sediments: field and laboratory bioassay experiments

Abstract

Benthic invertebrates were exposed to chemically contaminated sediments (primarily petroleum hydrocarbons) from a well-defined pollution gradient around McMurdo Station, Antarctica in a series of field and laboratory bioassay experiments. The patterns of survival and behavior in these experiments corresponded to patterns observed in standard U.S. Environmental Protection Agency laboratory bioassays. The contaminated end of the pollution gradient is Winter Quarters Bay where total hydrocarbons are as high as 4500 μg·g sediment −1. Mortality of Heterophoxus videns K.H. Barnard, a phoxocephalid amphipod crustacean, in standard laboratory bioassays was highest in sediment from Winter Quarters Bay, high in sewage outfall sediments, and generally decreased in sediments from increasing distances from the bay. Similar survival patterns were documented for several other crustacean species. Amphipods, tanaids, and cumaceans consistently avoided sediments from Winter Quarters Bay in the survival bioassays and were more abundant in uncontaminated sediments in laboratory habitat choice experiments. Fewer H. videns and the heart urchin, Abatus shackletoni Koehler, burrowed into Winter Quarters Bay sediment compared with uncontaminated sediment in field and laboratory assays. We exposed H. videns and Eudorella splendida Zimmer, a cumacean, to Winter Quarters Bay and uncontaminated sediments for 10 and 28 days in field bioassays. Greater mortality was evident in Winter Quarters Bay sediment but the difference between treatments was not significant. In contrast, when benthic communities were transplanted along the pollution gradient and sampled a year later, there were dramatic changes in community structure in Winter Quarters Bay, less at the edge of the bay, and little at an uncontaminated site. Overall, these assays showed similar patterns of increased survival decreased avoidance of sediment along a steep and well-defined pollution gradient.