Dr Rachel Paterson works at the Norwegian Institute for Nature Research, where she studies host-parasite interactions in wildlife, tackling crucial aspects related to conservation and ecosystem functioning. Since 2024, she has led the IMPACT project.
The main goal of this project -funded by Biodiversa+ (European Biodiversity Partnership), the European Commission, and national funding organisations across Europe- is to integrate parasites into ecosystem monitoring and conservation policies at an international level. “These neglected organisms,” explains Dr Paterson, “may hold the key to understanding and protecting the well-being of many natural ecosystems.”
How are you, as a research group, pursuing the project’s goals, and why do you think they matter?
Rachel Paterson: Parasites are one of the most neglected groups of organisms when it comes to conservation priorities. Biodiversity monitoring and conservation policies -whether in Europe or in the rest of the world- don’t mention parasites unless there’s a risk linked to an invasive species or a parasite that infects humans.
This is an indication that many people do not recognise parasites as important. However, parasites play major roles in ecosystems, and not always negative ones.
One of our goals in IMPACT is to develop tools to integrate parasites into biodiversity monitoring. In doing so, we may understand how parasite biodiversity may be changing by coupling our research with the study of more prioritised groups. A promising opportunity comes from the field of “eDNA” (environmental DNA), the analysis of DNA fragments found in environmental samples, which is commonly used in freshwater environments to monitor fish or invertebrates.
However, to track the presence of any given species using eDNA, one must know how to genetically identify the species (so called “genetic references”). Thus, we are building this necessary information for aquatic parasites. We also work closely with stakeholders and policy makers, to understand what barriers are preventing them from considering parasites in conservation policies.
Human parasites are known to have a disproportionately bigger impact on the Global South. Is it the same for wildlife parasites, and what is their impact on European fauna?
Rachel Paterson: I wouldn’t say that there is a geographical gap in distribution for wildlife parasites, but there is a knowledge gap. If we look at the amount of research that has been carried out, we clearly see two hot spots in Europe and North America, suggesting that the wildlife parasite knowledge we have is not evenly distributed across the globe.
There are studies documenting this gap. Even in the best studied regions, there are differences in how and which wildlife parasites are studied, depending on who carries out the research; museums, universities, hospitals and so on. This applies to other lifeforms as well, as there is no universal plan for biodiversity monitoring.
Parasite-host interactions, however, generally follow the same pattern: few individuals get infected with a lot of parasites, suffer from it and possibly die. Most individuals, on the other hand, have few parasites, and experience little to no negative effects. So, parasites may not be as bad as they are often described.
IMPACT focuses on freshwaters, and it also involves people that work in those environments, such as anglers. Have you investigated what their perception of parasites is?
Rachel Paterson: Yes, one of our work packages uses a social science approach to understand how people perceive parasites. Our social scientists have carried out interviews with local communities, environmental managers and policy makers in two case studies, one from Switzerland and one from Norway. We spoke to many recreational anglers and commercial fishers as they are people that encounter fish parasites in their daily lives. We found that their perception of parasites varied a lot between the two countries. The reason probably lies in the impact that parasites have on the fish in each country.
Here in Norway, we have had experience with an invasive freshwater parasite, salmon fluke, since the ‘70s, that was responsible for large declines in juvenile Atlantic salmon populations. Many people are also familiar with salmon lice, a parasite that affects both farmed and wild salmons. The aquaculture industry in Norway is very strong and relies on salmon a lot. Thus, anglers and environmental managers alike are very conscious of these parasites.
In Switzerland, commercial fishers didn’t see parasites as such a big problem. Interestingly enough, recreational and commercial fishers in both in Norway and Switzerland clearly wanted to know more about parasites. Even if parasites sometimes harm their interests, they wanted to get a deeper understanding of those organisms that they often encounter. We take this to heart because, to engage with stakeholders, we need to provide the information that they want to have.
The concept of “One Health”, meaning that human health cannot be achieved if not by working on natural ecosystems’ health as well, has been a guide for both conservation and medical research for quite some time. Would you say that IMPACT was developed keeping in mind this idea as well?
Rachel Paterson: There are many EU funding calls that specifically focus on One Health now, and it’s great to see this happening more. However, the IMPACT project was funded by a call that focused on improving biodiversity monitoring. Even if we don’t specifically address One Health, we indirectly contribute to this framework: by studying parasite diversity, we increase our understanding of the role of parasites in healthy ecosystems that provide better services to wildlife and humans alike.
In terms of results, what are the main objectives that you have already achieved, and what are you working on for the future?
Rachel Paterson: Each of IMPACT’s four work packages (WP) has specific objectives. In WP1, our postdoc Cyril Hammoud identified knowledge gaps regarding where and how long-term trends in parasite communities are studied.
We have also reassessed parasite diversity in fish populations across Europe, some of which were last studied more than 100 years ago. We are now developing European freshwater fish parasite databases to understand how parasite diversity is changing.
In WP2, we have created parasite references where we have both morphological and genetic details that can be used to identify parasites. We have also provided new guidelines for both parasite specialists and fish biologists that explain how to collect and preserve parasite samples, to further expand this database in the future. In WP3, we have completed a year-long eDNA survey of aquatic parasites in Norway and Germany to test eDNA as a parasite monitoring tool.
By studying changes in the diversity of these parasite communities over one year, we can then identify which time of year is best for detecting all parasites that are present. This work is led by another highly motivated postdoc, Kamil Hupało. Finally, we have WP4, that uses social science approaches to understand how people perceive parasites, as we mentioned. Our final efforts will be focused on producing policy briefs, to help stakeholders implement the tools that we provided and integrate them into their biodiversity monitoring policies.
We have been granted a one-year extension, so IMPACT activities will continue until the end of 2027. Hopefully, parasites will be a less neglected group after all of this!
Regarding parasite perception and knowledge outside specialists’ groups, what do you feel is working right now, and what changes are you hoping to see?
Rachel Paterson: Media coverage of parasites tends to be very negative. For a lot of people, that’s their only source of information about parasites, and so they associate these organisms exclusively with human suffering – even though wildlife parasites are different; they rarely impact humans, and are important for ecosystem health, thus our health.
But this side of the story doesn’t get told, so it’s not surprising that people don’t consider parasites as part of biodiversity, or as something that they need to protect. If society doesn’t recognise parasite conservation as something that’s important, of course policy makers will not prioritise it.
That’s why increasing awareness of the positive, essential roles that parasites have in nature is important. As scientists, we too should get involved and learn how to communicate with policy makers to achieve real life changes.