"Rivers are characters" declared the academician Erik Orsenna. The character Vincent Prié met is none other than the Maroni River. The Maroni is 600 kilometres long and crosses Guyana and Surinam. It is now also a fragile element, like so many others, due to the various anthropic pressures it is subjected to. In order to get to know it better, Vincent Prié is setting off on an adventure with a team of scientists who, like him, are dedicated to conducting an inventory of its biodiversity.
Based on an initial inventory carried out in 2017, Vincent Prié and his colleagues are undertaking to produce a complete photograph of the river's biodiversity. This expedition is part of the Vigilife - Sentinel riversan ambitious programme of biodiversity inventories on a global scale. The first expedition in this programme took place from 8 to 30 November 2021, and since then the team has been working onanalysing the results and preparing the next explorations. This better knowledge of the environment is the first step towards its conservation. In addition, the regular analysis of the water makes it possible to assess the biodiversity.
This large-scale project is also an adventure project! Indeed, for the entire duration of the expedition, the four scientists accompanied by their two Amerindian guides lived in complete autonomy, setting up their camp in the forest each evening as they progressed. To get around, they boarded their dugout canoes with the 1 500 kg of equipment needed to take samples and capture images. And for food? The menu is based on the nature that surrounds our explorers. What better symbol of life in the tropics than a piranha dinner?
Origin of the project
Freshwater biodiversity is declining at an alarming rate, twice as fast as that of other ecosystems. Monitoring the biodiversity of large rivers is particularly difficult with traditional methods, as the organisms are often difficult to observe or capture. This is why Vincent Prié has turned to a particular method. This is the analysis of environmental DNA (eDNA).
What is eDNA?
One thing is common to all living things: all species release cells into their environment. Thanks to innovative methods, it is possible to collect and identify the DNA present in a given environment, and thus determine the organisms that occupy it. This technique has proven to be extremely effective in this context, as it allows the entire living world to be inventoried from a simple water sample and therefore without the need to capture organisms. Thus, the natural environment is not disturbed by research!
Vincent Prié has been passionate about exploring biodiversity for over twenty years. After working as a guide in southern Africa, he became a naturalist consultant. At the same time, he studied biology (doctoral thesis from the Muséum national d'Histoire naturelle obtained in 2013). Always curious about new adventures, he participates in various naturalist expeditions around the world. Between 2006 and 2020, he notably took part in the exploration of Santo aux Vanuatus, the Makay massif in Madagascar, the aquatic fauna of several African countries, Morocco, Guinea Bissau, Ivory Coast, Gabon, Namibia... Since 2015, he has been particularly interested in environmental DNA analyses, which make it possible to reveal biodiversity from water samples. He joined the SPYGEN laboratory in 2021 where he participates in R&D and develops environmental DNA analyses internationally. Today it is on the rivers that his scientific explorer's soul has led him. Thanks to this endowment, you can now embark with Vincent on a pirogue on the Maroni!
The other members of the expedition
Sébastien Brosse is a researcher at the University of Toulouse, specialising in fish and French Guiana, where he has been carrying out his research for the past twenty years. The author of numerous scientific publications, he is as comfortable in the forest as he is behind the computer, using a machete or a fishing rod.
Grégory Quartarollo is a fish specialist at the Hydreco laboratory, one of the mission's partner companies. He has carried out night fishing almost every evening and identified hundreds of small fish, some of which do not seem to correspond to any of the species described.
Rita Russo is responsible for Antilles-Guyana for the Alkios group, an ecosystem of companies serving the living world, where she works on environmental, sustainable development and eco-design issues. She took part in the first part of the mission to learn about environmental DNA sampling. Here she is seen carrying out physico-chemical analyses of the Maroni.
Manuel Lopes-Lima is a researcher at the CIBIO laboratory where he studies bivalves and specialises in environmental DNA. During the mission, he took numerous samples for genetic analysis.
Mathieu Rhoné is head of the Water Resource Knowledge and Monitoring Department at the Guiana Water Office, one of the main partners of the expedition. With 12 years of experience in tropical aquatic environments, he is the author of the mission's drone images.
The main partners of the mission are the Guiana Water Board, the company SPYGEN, the association Beauval Nature and the research laboratories EDB - University of Toulouse and WSL - Federal Institute for Forest, Snow and Landscape Research. We also thank the Amazonian Park of Guyana for its support.
Finally, we would like to thank Michel Aloïke, traditional chief of the Wayana, without whom we would never have been able to travel up the Maroni.