In 2021, Professor Frédérik De Laender was approached by American researchers to contribute to a study on the evolution of aquatic diversity in rivers in the USA. The aim: to analyze changes in aquatic diversity and identify the factors behind them. To answer this question, the researchers analyzed data collected over thirty years, covering 389 fish species in nearly 3,000 rivers and streams.

"There was already a lot of data on aquatic diversity in the USA, but it was scattered, recorded in different formats and produced using a variety of techniques and methodologies," explains Frédérik De Laender. "The challenge was therefore to harmonize them, in order to form a coherent whole, capable of revealing trends over several decades and on a continental scale."

In this study entitled "Diverging fish biodiversity trends in cold and warm rivers and streams" researchers studied 389 fish species in 2,992 rivers and streams, between 1993 and 2019. The results show contrasting trends depending on water temperature:

• In cold waters (< 15.4°C), the number of fish fell by 53% and the number of species by 32%. Small fish have declined, replaced by larger species often introduced for sport fishing.
• In warm waters (> 23.8°C), by contrast, the number of individuals has increased by 70% and diversity by 16%, with small opportunistic species dominating.
• Intermediate streams (15-24°C) showed little change.

These trends show that temperature changes and the introduction of certain fish species for fishing are helping to transform local aquatic communities.

Frédérik De Laender is a theoretical community ecologist who studies the links between environmental change, biodiversity and ecosystem functioning. Primarily focused on modeling, he has also conducted experiments on plankton and contributed to meta-analyses. His work focuses in particular on ecological stability and coexistence, to better understand the mechanisms that determine community composition.

The beluga whale (Delphinapterus leucas) of the St. Lawrence Estuary (SLE) in Quebec, Canada, lives in a marine ecosystem heavily impacted by human activities and has shown no signs of recovery for several decades. Also known as the white whale or white dolphin, the beluga has a life expectancy of around 70 years. Infectious diseases and an increase in post-partum mortality in females have been observed, but the exact causes remain undetermined. However, exposure to contaminants is thought to be one of the causes of the increase in early mortality observed in recent years.

One of the main limitations to assessing the health of individuals in this population in relation to contaminant exposure is the lack of a method for determining the age of live beluga whales in the ESL.

Until now, the most reliable method for determining their age was to count the growth streaks on the inside of their teeth. The expertise of Namur-based researchers at Professor Frédéric Silvestre's Laboratoire de Physiologie Évolutive et Adaptative (LEAP) will enable the development of a new "epigenetic clock" and its use to estimate the age of living belugas, ultimately improving conservation strategies to help this threatened population recover.

The project is entitled: "Une horloge épigénétique pour estimer l'âge des belugas du Saint-Laurent et son impact sur l'accumulation de contaminants, le stress et la santé de cette population menacée"

Epigenetics is the study of changes in gene activity, not involving modification of the DNA sequence, that can be transmitted during cell divisions. One of the elements that "regulate" gene expression is methylation: a chemical group that attaches itself to certain places on the DNA strand to promote or limit gene expression. In recent decades, it has been discovered that methylation changes in a predictable way during aging, according to a pattern known as the "epigenetic clock". Once this clock has been established for a given population of individuals, it is therefore possible to deduce an individual's age by looking for the presence or absence of methylation on DNA. All it takes is a few cells, such as skin cells.

A team of top scientists from both regions is involved.

• Pr Frédéric Silvestre and Dr Alice Dennis - UNamur, Belgium
• Dr Krishna Das - ULiège, Belgium
• Dr Jonathan Verreault - Université du Québec à Montréal, Canada
• Dr Stéphane Lair - Université de Montréal, Canada
• Dr Magali Houde - Environment and Climate Change Canada
• Dr Véronique Lesage - Fisheries and Oceans Canada
• Dr Robert Michaud - Group for Research and Education on Marine Mammals (GREMM), Quebec, Canada

The research team will validate this new method and investigate the link with contaminant accumulation, physiological stress and overall health in this threatened population, comparing the ESL population with a healthier population of belugas from the Canadian Arctic.

In summary, this research aims to better understand how biological age, as measured by the epigenetic clock, influences the vulnerability of belugas to environmental stressors and their health.

This project will address fundamental research questions never before explored in beluga whales,

A new PhD student will join the Namur team, under the supervision of Frédéric Silvestre and will work in collaboration with researcher Justine Bélik on the basis of the EpiClock she developed for the mangrove rivulus.

Along with a project on mangrove rivulus in Florida and Belize, and one on fish and invertebrate populations in the Ecuadorian mountains, this is the third scientific project to use Namur researchers' expertise in ecological epigenetics in wild animals to help preserve biodiversity.

Collaborative research F.R.S.-FNRS - FRQ (Fédération Wallonie-Bruxelles - Québec)

The F.R.S.-FNRS has launched PINT-Bilat-P calls for bilateral research projects with the Fonds de Recherche du Québec. These calls are part of a drive to develop strategic partnerships. The aim of this bilateral research program is to create a leverage effect for scientific excellence and to encourage researchers from the Wallonia-Brussels Federation and Quebec to develop innovative joint research projects.

• Long-term effects of pollution in our rivers, oceans and lakes
• Understanding epigenetics to conserve biodiversity

In recent months, the commune of Gesves, in the province of Namur, was confronted with the presence of a herd of mouflons, wild sheep recognizable by their impressive spiral horns. At the origin of this one: a male and a female probably escaped from a private hunt, who settled and reproduced in the meadows of this rural commune in 2019, until forming a full-fledged herd of 17 individuals in 2024.

While these sheep won the affection of the locals, local farmers deplored the damage caused to their crops. Their complaints led in August 2024 to a destruction authorization from the Department of Nature and Forestry (DNF). Several individuals were also shot during the hunting season.

Touched by the fate of these animals, a handful of local residents have been carrying out a veritable rescue operation for the seven mouflons still present on the meadows since January. The maneuver promised to be complex, to say the least: on the one hand, it was necessary to gather the official authorizations required to capture and transport the mouflons to a suitable location, and on the other hand, to set up an infrastructure to capture them.

Alongside this initiative, the mobilized local residents - including Nathalie Kirschvink, a veterinarian and professor at UNamur's Faculty of Medicine - called on the expertise of the laboratories of UNamur's Environmental and Evolutionary Biology Research Unit (URBE) to clarify a crucial question: the origin of the mouflons. Indeed, in our regions, mouflons are considered game and therefore huntable, while mouflons from certain lineages benefit from protection.

Nathalie Kirschvink therefore entrusted fresh samples made up of hair and dung to Alice Dennis, professor and researcher at the URBE. Sequencing the DNA contained in these samples enabled Alice Dennis and technician Jérôme Lambert to identify kinship links between the Gesves bighorn sheep and those from a Corsican lineage, whose genome had already been described in the scientific literature.

This expertise lies at the heart of URBE's research, which uses the tools of molecular ecology to study both the physiology of organisms (such as snails for Alice Dennis) and their interactions with their environment. The methodology used can be applied to very concrete, local cases, such as that of the Gesves bighorn sheep, but, more broadly, serve to better understand genetic diversity between species with a view to safeguarding biodiversity.

The FAB's regular actions in the Belgian university context include awarding grants, prizes and subsidies, organizing a chair, contributing to the organization of colloquia, doctoral schools or study days. It collaborates with a network of Belgian and foreign partners: individuals, public and private associations, institutions and companies.

In consultation with the Department of Biology at the University of Namur, the Fonds Adrien Bauchau has awarded financial assistance for the first time in the amount of 25,000 euros to support a young professor or post-doctoral fellow in biology at the institution in the early stages of their professional career.

In May 2025, the FAB Board of Directors awarded this grant to Professor Eli Thoré, an academic in the Unité de Recherche Environnementale et Evolutive (URBE), for the development of his work.

The 2025 Scholarship has been awarded to Justine Bélik, whose thesis promoter is Professor Frédéric Silvestre, for her participation in the 3rd international EPIMAR 2025 "Epigenetics in marine and aquatic research" congress, organized at the end of May 2025 in Barcelona, Spain.

The grant is intended for a young researcher to enable his/her participation in a conference abroad. The amount awarded depends on the cost of this participation; it can be up to €750.

The Biology Department conducts cutting-edge international scientific research. This is divided between 5 research units tackling a variety of themes: cell biology (URBC), microbiology (URBM) or methodology and didactics (UMDB). The two award-winning researchers are part of the Environmental and Evolutionary Biology Research Unit (URBE) and are members of the Institute of Life, Earth and Environment (ILEE), which is committed to addressing pressing environmental issues.

Professor Frédéric Silvestre, Justine Bélik's thesis sponsor, heads the Laboratory of Evolutionary and Adaptive Physiology (LEAP). This laboratory studies the impacts of environmental change on aquatic organisms at different levels, from the perspective of integrative physiology.

Professor Eli Thoré heads the Adaptive Biodynamics Laboratory (LAB). He uses an integrative approach to understand how animals respond to environmental changes, particularly those induced by human activity in space and time.