Summary
As zooplankton is an important food source for consumers, and a major source of recruits to the benthic community, impacts on sensitive zooplankton communities have the potential to significantly alter nearshore marine ecosystems in Antarctica. With increasing human activity in coastal regions of Antarctica, it is important to determine the effects of petroleum fuels on the zooplankton community as a whole, and not only single component species. This study takes a community based approach to testing the effects of a commonly used diesel fuel on the zooplankton community, using both multi-species and single-species acute toxicity tests. Multi species tests were conducted between December and February 2010/11 at Davis Station to determine the response of the changing zooplankton community, to exposure to water accommodated fraction (WAF) of Special Antarctic Blend (SAB) Diesel fuel. In addition, single-species tests were done with three of the most abundant copepod species from within the community. SAB WAF was acutely toxic to the zooplankton community at concentrations between 54-103?/L TPH. Significant mortality was observed within 1-4d in response to undiluted WAF (608-2855?/L TPH) and within 2-7d in response to a 50% WAF dilution (148-248?/L TPH). The sensitivity of the community varied between tests as the species composition of the community changed. The three most abundant species had very similar sensitivities when tested in single species tests, however all three species were more sensitive when exposed within the single-species tests than within the multi-species tests. Our results highlight the importance of determining critical hydrocarbon thresholds at both the species and community level. Results from this research will be used in remediation and environmental guidelines, and methods develop with whole communities will be used in risk assessment procedures for coastal Antarctic waters.