Antarctic worms discover polluted soil | Polarjournal
Many of the stations in Antarctica have been in existence for decades. Due to the climatic conditions, it is therefore not unusual for substances to have been deposited in the surrounding soil as a result of weathering. Image: Dr Michael Wenger

Antarctica was never really settled by humans. It is only in the past 200 years that we have begun to move to the southernmost continent. To ensure that our ecological footprint down there is as small as possible, continuous testing must be conducted. These environmental tests are then designed to show thresholds for when human presence will impact a given system. Australian researchers have now found a way to detect metal pollution in the soil with the help of a small nematode.

The two leaders of the research group, Dr. Kathryn Brown and Dr. Catherine King, used the nematode Plectus murrayi, which is only a few millimeters in size, to find out how high the concentration of copper in the soil is and whether it has already reached a certain toxicity level. This is because the small worm reacts very sensitively to certain amounts of this metal, which is widespread in the Antarctic. “The methods developed in this work will be used to investigate the risk of soil-dwelling organisms at contaminated sites in Antarctica. This will help determine whether cleaned soil is suitable for reuse,” explains Dr. King. “More broadly, estimates of contaminant sensitivity for Plectus murrayi will ultimately be used, along with estimates for a range of Antarctic species and soil processes, to derive specific environmental quality guidelines and remediation targets for Antarctica. These guidelines and targets allow Australia to prioritize polluted sites for remediation and determine how clean “Clean” actually is.”

The nematode Plectus murrayi lives in the soil of Antarctica. The worm, which is only a few millimeters in size, feeds on bacteria and its spread is limited only by carbon and moisture. In the picture: adult and young animal and two eggs. Image: Kathryn Brown

The nematode used by the researchers, Plectus murrayi, belongs to a group of commonly found species worldwide. In Antarctica, the worm, which is only a few millimeters in size, lives in the soil and can withstand a wide range of conditions: Drought, freezing and other forms of stress. In the laboratory, the scientists cultured the worms on agar plates at 15°C. Since the worms feed on bacteria, bacterial cultures also had to be grown on the plates. Plectus murrayi has a complex life cycle with juvenile and adult life stages. To determine which phase is the most sensitive to contaminants, eggs, juveniles, and adults were maintained in various amounts of dissolved copper for 28 days. This showed that sensitivity to the metal increased over time and that the young animals reacted most strongly to copper.

The two researchers first had to obtain their nematodes from the soil of Antarctica before they could be cultivated and used. No easy task, because nematodes are only a few millimeters in size. Image: Mark Horstman

The results of the work were published in the journal Environmental Toxicology and Chemistry published. “Our work is the first robust test using a native and very common species of Antarctic microorganism that can also be grown in a laboratory to obtain the large numbers of individuals that need to be used for toxicity testing,” said Dr. Brown. “This species is so sensitive to contaminants and is very useful for long-term testing, which is necessary in Antarctic conditions.”

Source: Australian Antarctic Division

Original work: Brown et al. (2020) Environ Toxic Chem 39 (2)

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