Antarctic nematodes to reveal diesel pollution | Polarjournal
The nematode Plectus murrayi (blue arrow) is an Antarctic soil-dweller only a few millimeters in size. Although actually simple in structure, it has a complex life cycle and is also a bioindicator that could detect diesel pollution in Antarctica. Image: AAD / Brown et al (2023)

Antarctica seems to be a hostile ice desert only at first sight. But if you look more closely with the eyes of a researcher, you will find a surprisingly large number of microscopic organisms, especially in the soil. These have adapted perfectly to the extreme conditions over millions of years. These include a small nematode that has become an increasing focus of research in recent years. Because he could be a little environmental detective.

The nematode Plectus murrayi, which is actually very inconspicuous, was used in a new study by three Australian researchers, Dr. Kathryn Brown, Dr. Jane Wasley and Dr. Catherine King, to indicate possible soil contamination from diesel. “Prior to this study, sensitivity estimates for Antarctic terrestrial species to fuel were limited to three moss species, an algae, and soil microbial processes,” explains Dr. Brown. To do this, in this first-of-its-kind work, the team needed to find out both how the widely used fuel behaves over time and whether or how the nematodes respond to it. The results show that while diesel degrades into various products over time, it also reduces toxicity. However, at least the young nematodes still reacted to it at the end, showing that despite the degradation processes within a few weeks, the consequences of possible pollution can still reverberate for a long time. “Prior to this study, estimates of the sensitivity of Antarctic terrestrial species to fuel were limited to three moss species, one alga, and soil microbial processes,” explains Dr. Brown, the paper’s lead author.

The team, which works at the Australian Antarctic Division, had added diesel to soil samples from Antarctica for its work and then allowed them to “age” for 45 weeks at the average summer soil temperature of 3°C. This showed that due to microbial degradation of the diesel, only 16 percent of the hydrocarbons were still present in the samples after 45 weeks. By washing the samples and analyzing the aqueous solutions (elutiates), the team showed that the diesel had split into various polar parts and hydrocarbons. These elutriates were then tested for their toxicity to juvenile nematodes, and surprising results were obtained: The toxicity of the samples decreased by about 50 percent within six weeks. However, even after the 45 weeks, nematodes died due to the contaminants. This shows that the risks from potential fuel spills in Antarctic soils remain over time.

The risk of fuel spills can never be completely reduced, despite all the precautions taken in Antarctica by station operators and activities. That’s why environmental regulations are always under critical scrutiny. But an important factor must come from the environmental toxicology community, which must develop new, more specific test methods. “This study demonstrates the need for toxicity tests specifically designed for and applied to Antarctic species,” Dr. Brown said. “We also need to understand the chemical degradation that takes place under cold conditions and its impact on toxicity.” That’s because such processes occur differently than in other places due to the extreme conditions that prevail in Antarctica. And organisms like Plectus murrayi, which are actually very hardy, can adapt to such new threats with great difficulty. “Because these limited ice-free habitats are so important to both Antarctic biodiversity and human settlement, we should take special care to protect them,” Dr. Brown concludes.

Dr Michael Wenger, PolarJournal

Link to the study: Brown et al. (2023) Ecotox Environ Saf 249 (1) Assessing risks from fuel contamination in Antarctica: Dynamics of diesel aging in soil and toxicity to an endemic nematode;

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