Maroni Project - Inventory of living things - With Vincent Prié

March 16, 2022

" Rivers are characters ", declared academician Erik Orsenna. The character Vincent Prié meets is none other than the Maroni River. 600 kilometers long, the Maroni flows through French Guiana and Surinam. Today, it is also a fragile element, like so many others, due to the various anthropic pressures it is subjected to. To find out more about it, Vincent Prié sets off on an adventure with a team of scientists who, like him, are dedicated to carrying out 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 worldwide biodiversity inventory program. The first expedition in this program, it took place from November 8 to 30, 2021, and since then the team has been working onanalyzing the results and preparing future explorations. This improved knowledge of the environment is the first step towards its conservation. In addition, regular water analysis enables us to assess biodiversity.

This large-scale project is also an adventure project! For the duration of the expedition, the four scientists and their two Amerindian guides lived in complete autonomy, setting up camp in the forest each evening as they went along. To get around, they boarded their pirogues with the 1,500 kg of equipment needed for sampling and image capture. What about food? The menu is based on the nature surrounding our explorers. What better emblem 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 biodiversity in large rivers is particularly difficult with traditional methods, as organisms are often difficult to observe or capture. For this reason, Vincent Prié has turned to a particular method. It's calledenvironmental DNA (eDNA) analysis.

What is eDNA?

One thing is common to all living things: all species release cells into their environment. Thanks to innovative methods, it is now possible to sample and identify the DNA present in a given environment, and thus determine the organisms occupying it. This technique has proved to be extremely effective in this context, as it enables the entire living environment to be inventoried from a simple water sample, without the need to capture organisms. In this way, the natural environment is not disturbed by the research!

Environmental forensics" thanks to environmental DNA. All living organisms release cells into the environment. New technologies now make it possible to detect and read DNA fragments present in the environment. By comparing this environmental DNA with reference bases, it is possible to make an inventory of all living organisms from soil or water samples.

The team

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 is studying biology (PhD thesis from the Muséum national d'Histoire naturelle obtained in 2013). Always curious about new adventures, he takes part in various naturalist expeditions around the world. Between 2006 and 2020, he took part in theexploration of Santo aux Vanuatus, the Makay massif in Madagascar, and the aquatic fauna of several African countries: Morocco, Guinea Bissau, Côte d'Ivoire, Gabon, Namibia... Since 2015, he has been particularly interested in environmental DNA analysis, which reveals 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's on rivers that his soul as a scientific explorer has led him. Thanks to this endowment, you can now join Vincent aboard 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.

Our partners

The mission's main partners are theOffice de l'Eau de la Guyane, the company SPYGEN, theBeauval Nature association and the research laboratories EDB - University of Toulouse and WSL - Swiss Federal Institute for Forest, Snow and Landscape Research. We would also like to thank the Parc Amazonien de Guyane 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.

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