Scientific exploration at the ends of the earth: mission to the Kerguelen IslandsInterview from Gaëlle Brahy, doctoral student in the H2020 MSCA Cofund EDENE programme
The Kerguelen Islands, often dubbed the "Islands of Desolation," rise majestically in the heart of the southern Indian Ocean. These remote, wind-swept lands, shrouded in mystery, offer an invaluable natural laboratory for scientists. It is within this grand setting that the scientific mission led by Jacques Labonne, director of the Behavioral Ecology and Fish Population Biology Laboratory (Ecobiop), a joint research unit of INRAE and UPPA, takes place. His team includes Gaëlle Brahy, a doctoral candidate in the European EDENE program, co-supervised by Sylvie Muratorio. From December 2024 to February 2025, this extraordinary expedition focused on studying evolutionary dynamics in a colonization context, with particular attention to the brown trout, a species introduced to the archipelago.
How did you reach the Kerguelen Islands, and how long does the journey take?
The journey begins from Réunion Island. We board the Marion Dufresne, a vessel chartered by the French Southern and Antarctic Lands (TAAF) administration, which supplies the districts of Crozet, Kerguelen, and Saint-Paul and Amsterdam with cargo, personnel, and fuel.
The voyage to Crozet takes about five days, where we stay for approximately three days during the port operation (OP): disembarking outgoing personnel, boarding incoming personnel, and unloading cargo containing equipment, food, etc. Then, it's another three days of navigation to Kerguelen, where a new OP occurs, and we disembark.
In total, it's about ten days from departing Réunion Island to our first night on the Kerguelen district.
How did you prepare mentally and physically for such isolation?
Some medical tests are conducted before departure to ensure our physical health, as access to healthcare is very limited on-site. However, although the geographical isolation of the archipelago may seem daunting, we are not truly socially isolated; quite the opposite. We go during the summer campaign, the time of year when the most people are present. During our stay, there were about 80 people on the base.
What are the main objectives of your mission in the Kerguelen Islands, and what type of research are you conducting?
This summer campaign in Kerguelen is part of the SALMEVOL program, which aims to study evolutionary dynamics in a colonization context, particularly focusing on the brown trout introduced to the Kerguelen Islands. After their introduction into a few rivers of the archipelago in the 1950s, the trout naturally colonized other rivers via ocean passages. The goal of the SALMEVOL program, led by the ECOBIOP unit of INRAE, is to monitor the state of river colonization by the species and the evolution of individuals along the expansion front.
Additionally, in collaboration with the University of Bilbao, part of the program aimed to study the establishment of ecosystems in post-glacial rivers after glacier retreat, as well as the impact of trout presence on the river ecosystems of the archipelago. This study helps understand ecosystem modifications and individual adaptations in a post-glacial context under the influence of climate change.
The data collected during this mission will enrich the Kerguelen salmonid database, a valuable resource for better understanding evolutionary trajectories in extreme contexts. Ultimately, this work could refine species colonization models and shed light on the effects of climate change on freshwater ecosystems.
What are your living conditions on-site (accommodation, food, communication)?
We spend a lot of time in the field, as we have about six weeks to work on 19 rivers. We need to work on rivers far from the base, which means we depend on the Curieuse, a 25-meter vessel designed to provide logistical support for science in the Indian Ocean. The Curieuse serves as our transport to mission sites and as our living and resting place during missions (lasting from 3 to 7 days), thanks to the work and hospitality of the seven crew members.
We also conduct some missions on foot from the base, either for a day or over several days, staying in cabins. In this case, we carry scientific equipment, sleeping and food supplies, and a portable radio to check in with the base every 24 hours.
Between field missions, we return to the base, often for one or two nights. These are moments of rest and camaraderie with the rest of the staff. Today, the internet is available in many of the base's buildings, which is relatively recent. When we are on the base for a few days of rest, we can communicate with others via written messages or phone calls. There is also a postal service on the base, but mail can only arrive and depart four times a year, during each OP.
What climatic or local fauna characteristics influence your work?
Sometimes, weather conditions prevent us from working, particularly river flow conditions. In Kerguelen, it often rains, and wind speeds frequently exceed 100 km/h, so we must learn to work with these conditions.
In the field, we must manage the sensation of cold due to wind, humidity, and temperatures that can approach 0°C, as well as physical fatigue from travel. We can cover more than 20 km per day, in addition to working on the rivers, carrying our equipment.
Additionally, the presence of penguins and elephant seals sometimes requires us to adjust our work sites on the rivers.
Will you collaborate with other scientists on-site? If so, in which fields?
We will collaborate with oceanographers from the MARGO program (Sorbonne University) to date the retreat of glaciers in Kerguelen.
How does human presence impact the environment of the Kerguelen Islands?
Measures are taken to best preserve the natural reserve. Human activity is concentrated on the base, and land travel is done only on foot. We vacuum, disinfect, and inspect all our belongings before disembarking from the ship upon arrival in Kerguelen and between each transit to avoid introducing and spreading biological species as much as possible.
Of course, despite these measures, human presence still impacts the environment.
Do you have an anecdote or memorable experience you'd like to share?
We were fortunate to visit isolated places due to our work on glacial rivers in the western part of the archipelago and thanks to the Curieuse, which transported and housed us. Early morning departures in a small boat connecting the Curieuse to the land, in the mist, wind, rain, or sun, were always magical moments. Being very close to the water, sometimes accompanied by Commerson's dolphins, and often surrounded by cliffs, waterfalls, and mountains.
We are also frequently near wildlife when in the field and even on the base. Finally, the encounters and social aspects were also a significant part of the experience for me.
Between science and awe in the face of raw nature, this mission to the Kerguelen Islands is more than just a research expedition: it's a journey to the ends of the earth and a sharing of scientific knowledge, illustrating that research is also a human adventure and a lesson in humility in the face of the elements.
