Nematodes, also known as roundworms, are invertebrates that can inhabit soil and water bodies. They have been reported in all continents and can live in extreme environments such as Antarctica or even the Atacama desert. During the ForBio, NIBIO, and UiB course (Taxonomy and DNA barcoding of soil organisms), the two PhD students of the B08 project took soil samples around Svandhov, Norway to look for nematodes, springtails and mites in order to identify them and learn about their role in soil ecosystems. The students could take part of this course thanks to an IRTG mobility grant.

There are over 200 families of nematodes with various life-styles: they can be free-living or parasites of plants or animals. They play important ecosystem roles as they can be used as bioindicators and are the food source for many taxa such as flatworms, bacteria, fish, mites and insects among others. They also have an important impact on food-security and human health. 

Even though all of these organisms inhabit soils, different sampling and extraction methods are required for each group. Compared to free-living nematodes (Nematoda) that have a size range of 0.1-5mm, springtails (Collembola) and mites (Acari) are relatively large and can to some extent be seen in nature without the need of stereoscopes or microscopes. To extract nematodes from natural soil samples, samples are set up on sprouting trays with precision wipes, the bottom of the trays are filled with water and the samples are placed on the upper part on top of the wipes. Extraction trays are left overnight so nematodes will randomly move until they are collected in the water and can be extracted for identification in the microscope.  During the course the students learned how to identify major groups (Family) of the aforementioned taxa using morphological characters.

Nematode families can be identified morphologically by the structure of pharynx and mouth parts, which reflect their eating habits (predators, bacterial feeders, fungal feeders) and their reproductive structures. During this course we found nematodes of the Family Cephalobidae, a family of bacterial feeding nematodes that is worldwide distributed and has been found in the Namib desert.

The knowledge acquired on this course will allow the PhD students of the B08 project to identify, through morphology and DNA-based methods, families of nematodes from soil samples taken in the Atacama desert.

 Author: Laura Villegas

This summer, in July 2022, both PhD students of project B08 made their way to Norway to learn more about the taxonomy of soil invertebrates and learn how to obtain good DNA barcodes of those in the course “ForBio, NIBIO, and UiB course: Taxonomy and DNA barcoding of soil organisms: nematodes (Nematoda), mites (Acari) and springtails (Collembola)” held in the NIBIO Svanhovd station (Figure 1).  The IRTG mobility grant supported the participation in the course.

Our project collaborator Dr. Oleksandr Holovachov taught us about the taxonomy of soil and freshwater nematodes and their importance in soil communities. We were taught how to perform sampling, extraction (Figure 2) and identification (Figure 3) of these invertebrates. Especially, learning all the important characteristics of the morphology of soil and freshwater nematodes will help in the on-field identification of sampled nematodes in the Atacama Desert and will help in relating found organisms to the biodiversity of the desert as some nematode species found might not be viable in culture. In combination with DNA barcoding the diversity of those desert nematodes can be documented. Extreme environments include not only dry desert but also cold environments like the polar regions and nematodes can be found in broad ranges of extreme habitats. The NIBIO Svanhovd station is located within the northern polar circle surrounded by eastern Siberian taiga and western Boreal forests. In winter temperatures sometimes fall to almost -40 °C and summers are mild with an average of about 15 °C. Even though this environment differs from the hyperarid Atacama Desert, we would expect some families of soil nematodes to occur in both environments as they are known to be generalist. For example, this is the case for the family of Panagrolaimidae or Cephalobidae where some nematode species are found to be colonizers with short generation times and tolerance to disturbed environments. As such, skills obtained during this course in Northern Norway will help both PhD students in future excursions to Chile, since they learned how to combine collection, extraction, morphological and molecular identification of soil invertebrates.

Author: Laura Pettrich 

We want to thank all speakers for their presentation and all scientists who worked within the presented projects. This lecture series gave an in-depth look into the recent status and development of our subprojects and subsequent discussion proved to be essential to further grow our understanding of the earth evolution at the dry limit and to improve our scientific interdisciplinary collaboration. Due to our ‘hybrid’ format, in persona and on the screens at home, we had the opportunity to follow the talks live in Chile, Namibia and in other parts of the world, to further strengthen our cooperation, scientific exchange and partnership to our colleagues around the world. We are looking forward to hear more exciting science and outcomes from our CRC1211 in the next lecture series.

Thank you all for your participation at this CRC1211 Summer Semester Lecture Series.

Author: B.Ritter