Potential bioremediation of antarctic sea-ice contaminated by diesel fuel and crude oil

Oil pollution of the oceans has been a problem ever since man began to use fossil fuels. The Antarctic marine ecosystem, considered one of the last remaining pristine ecosystems, is almost uncontaminated by anthropogenic hydrocarbons. However, the danger of a petroleum spillage in the polar, ice-covered regions is increasing due to the development of maritime activity. In recent years, there has been a growing interest in developing cost-effective in situ techniques for bioremediation of oil-contaminated environments. The long term effects of two different fertilizers on microbial communities of sea-ice contaminated by diesel fuel and “Arabian light” crude oil were investigated in land fast-ice located in the “Terre Adelie” area (Antarctica). Despite the pristine environmental conditions, significant numbers of indigenous hydrocarbon-degrading bacteria were observed in the control uncontaminated area. After oil and fertilizer addition, the changes in bacterial communities were studied in situ during a eight month period in austral winter 1995. All the results clearly revealed a significant response of Antarctic microbial assemblages to hydrocarbon contamination. One order of magnitude increases of total bacterial abundance occurred in sea-ice after both diesel fuel and crude oil contamination (from 10⁵ to more than 10⁶ cell ml⁻¹). Introduction of oil into sea-ice results in several orders of magnitude increase in hydrocarbon-degrading microorganisms (from less than 10 to more than 10⁴ MPN ml⁻¹). Addition of fertilizers induced clear enhancements of both total and cultivable microorganisms. The commercial slow release liquid fertilizer Inipol EAP 22^® is an efficient biostimulation agent for both types of contamination. However, fish composts represent promising efficient and low cost alternatives.