The project forms part of a collaborative effort with the Department of Energy, Environment and Climate Action in Australia, as well as South African colleagues, highlighting the growing global relevance of soil biodiversity research.
Tiny worms with a huge ecological impact
Free-living nematodes – commonly known as roundworms – are among the most widespread organisms on Earth. Although microscopic, they play a crucial role in maintaining healthy soil and functioning ecosystems.
“They are roundworms belonging to the phylum Nematoda found living independently in various environments, including soil, water, and decaying organic matter,” explains Dr Jansen van Rensburg.
These organisms are far more abundant than most people realise. “In fact, a single gram of healthy soil can contain thousands to millions of nematodes,” she says.
Their importance lies in the vital ecosystem services they provide. By feeding on microbes and organic material, nematodes help release nutrients back into the soil.
“When nematodes eat microbes, they release nitrogen and other nutrients in plant-available forms. This means you will have healthier soil, better crop growth, and less reliance on fertilisers,” she notes. “So, nematodes’ tiny bodies have a huge impact.”
Natural indicators of ecosystem health
Because nematodes respond quickly to environmental change, they are increasingly used as indicators of soil and ecosystem health. “Although nematodes are only microscopic organisms, they are ecologically powerful because their communities respond quickly and predictably to environmental change,” says Dr Jansen van Rensburg.
They occupy a central role in soil food webs, feeding on bacteria, fungi, plants, and even other animals. This makes shifts in nematode communities a reliable reflection of broader ecosystem change. “Any shift in resources, disturbance, or stress shows up clearly in which nematodes are present and in what proportions they occur.”
Studying nematodes also provides valuable insight into the effects of climate change.
“Studying nematodes helps us understand ecosystem responses to climate change and environmental stress, because they react rapidly to changes in temperature, moisture, nutrient availability, and disturbance,” she explains.
Building foundational biodiversity knowledge
The NRF-FBIP Small Grant will allow Dr Jansen van Rensburg to focus on a specialised group of predatory nematodes known as Mononchida, which remain poorly studied in South Africa.
A key advancement in this new phase is the inclusion of DNA barcoding, which was previously too costly.
“With the NRF-FBIP Small Grant, I will be able to generate sequence data for three genes (COI, 18S, and 28S rDNA) from the collected specimens – analyses that were previously cost-prohibitive.”
The project will combine extensive fieldwork in Free State reserves with advanced molecular analyses, generating data that will contribute to global biodiversity platforms such as GenBank and BOLD.
“This grant makes it possible to combine extensive fieldwork with advanced molecular analyses, providing foundational data that were previously out of reach,” she adds.
Why Free State nature reserves matter
Protected areas in the Free State offer rare ecological baselines in a province where much of the landscape has been transformed by agriculture and development.
“These protected areas provide rare ecological baselines in a landscape that is otherwise heavily transformed,” says Dr Jansen van Rensburg.
She explains that nematode biodiversity in the region is significantly undersampled, particularly for predatory groups such as Mononchida.
“The Free State is significantly undersampled, even in terms of nematode biodiversity,” she notes. “The NCN database lists just seven Mononchida species from the province, dating from 1979 to 1982.”
This research will help fill critical gaps in below-ground biodiversity knowledge and support conservation management.
“Nematode research could therefore directly support the long-term protection and adaptive management of these conservation areas,” she says.
Strengthening global collaboration
The project is also strengthened through international collaboration with Australian-based researcher Dr Chantelle Girgan. “She emigrated to Australia last year, and we have decided to continue our collaboration, as we work very well together,” says Dr Jansen van Rensburg.
Dr Girgan’s expertise remains vital. “She was also the only other taxonomic researcher in South Africa specialising in free-living nematodes, so her expertise remains vital to this project.”
By working across continents, the research gains broader scientific relevance and contributes to global soil biodiversity frameworks.
“International collaboration ensures that Mononchida data generated locally can inform both national conservation strategies and global soil biodiversity frameworks,” she says.
Small organisms, big insights for the future
As climate pressures intensify, understanding the hidden biodiversity beneath our feet becomes increasingly urgent. Through nematodes, UFS researchers are unlocking new ways to monitor ecosystem resilience and detect early signs of environmental stress.
“The Free State sits at the intersection of major grassland and savanna systems that are highly sensitive to climate variability,” says Dr Jansen van Rensburg. “Long-term nematode data from reserves can therefore act as an early-warning system for climate impacts in these vulnerable ecosystems.”
With global partnerships and local stewardship, this project demonstrates how small organisms can deliver big insights into the future of biodiversity and conservation.