Man-made chemicals that end up in nature can accumulate within food chains, causing harm to wildlife and entire ecosystems. TerraChem collected samples of terrestrial wildlife and soil from six European countries for wide-ranging chemical analyses, and complemented this with metabarcoding. With this we can understand how these chemicals move through food chains and identify damage to species richness. 

TerraChem works on twelve European case studies of food chains. These address six different food chains of apex mammal species, each in a different country, of which different mammal species are the apex predators, and the food chain of the barn owl in the same six countries. Several trophic levels in each food chain are sampled for chemical analysis, including soil, plants, invertebrates and rodents.

Selected samples were processed at TerraChem partner Naturalis Biodiversity Center. “This included sorting of invertebrates into herbivorous and non-herbivorous species, and dissecting rodent soft body tissues”, says Dr Paola Movalli of Naturalis Biodiversity Centre and Environmental Institute, who leads the case studies.

Processed samples were then shipped to the National and Kapodistrian University of Athens for chemical analyses, but also to Leiden University and the University of Groningen for stable isotope analysis. “This later technique helps to understand the trophic levels of the sampled animals and how chemicals accumulate through food chains,” says Movalli.

Naturalis also compiled a species list for each soil and invertebrate sample using ‘metabarcoding’. This involves extracting DNA from each sample using magnetic beads. Selected genes that are very species-specific are amplified using a technique called PCR. A Next Gen sequencing technique can analyse and recognise multiple different species in the samples, from bacteria and fungi to invertebrates. “We have a very specific DNA database that we can compare the results to”, says Erwin Fakkert, senior research analyst at Naturalis. 

The species lists obtained for each sample will be used by TerraChem partner DTU to model the damage caused to species richness by the detected chemicals. This research can inform action to restrict the most harmful chemicals and protect biodiversity, a cause Fakkert gladly contributes to. “Doing these kinds of analyses really gives you a purpose. Generally nature isn’t doing so well. It’s great to contribute to research that makes a difference in this regard.”