The grounding of the Bahia Paraiso: Microbial ecology of the 1989 Antarctic oil spill

Abstract

On 28 January 1989 the Bahia Paraiso ran aground and sank near Palmer Station, Antarctica. At least 6.8 × 10⁵ liters of diesel fuel arctic (DFA) were released into semi-enclosed Arthur Harbor and deposited in the nearby intertidal regions. Approximately 6 weeks later, a group of scientists was deployed to evaluate the impact of the oil spill on the surrounding coastal marine ecosystem.

Microbial hydrocarbon oxidation potential (¹⁴CO₂ evolved from ¹⁴C-labeled hexadecane) was detected throughout both the oil-impacted and control regions. Hexadecane was mineralized at extremely low rates (0.13–1.21 pmol g⁻¹ sediment dry weight day⁻¹); microbiological turnover time exceeded 2 years. The acute effects of DFA (measured over exposure periods of 3–7 days) on the metabolic activities of sedimentary microorganisms appear to be negligible even at seawater saturation concentrations of DFA. Long-term exposure (120 days) to varying concentrations of DFA resulted in significant decreases (>90%) in total ATP, but had either no effect or a slight stimulatory effect on metabolic activity and production. In contrast to planktonic microbial communities, increasing incubation temperatures of between 0 and 30°C had a positive effect on rates of metabolism and production of sedimentary assemblages. These results may influence the overall weathering rates of hydrocarbons deposited in the intertidal and supratidal regions of Arthur Harbor and other polar regions.