One thousand and one intermittent rivers

In Bolivia, Thibault Datry, an eco-hydrologist at Irstea, had the madcap idea of marshalling researchers from around the world to study intermittent rivers. About 2000 emails later, an international initiative has been launched in partnership with IGB [1] and IRBAS [2] The 1000 intermittent rivers project.

Our idea was simple: one single, identical, easy and low cost experiment performed on 1000 rivers around the world to cover a maximum number of situations. This will give us a unique set of data which, when analyzed, will allow the field to progress significantly.” This was a project without funding that used volunteer researchers. It is difficult to believe, but 80 laboratories are currently involved in almost 25 countries from Namibia to Antarctica, and even including Ecuador and India. It is expected that around 400 rivers will be included across all continents.

© The 1000 intermittent rivers project

Playing catch-up

Why launch such an initiative? Although intermittent rivers represent half of the global river network, they have been ignored for many years by researchers and managers as they have been considered uninteresting from both hydrological and biological perspectives. This has resulted in very little data being available for these ecosystems, which is significantly limiting our understanding of their operation and their biodiversity, as well as our ability to manage and protect them,” explains Datry. "Specifically, the overall quantification of the contribution of rivers to the carbon cycle and to global warming largely underestimated the role of these rivers despite the fact that even when they don’t have water they are very biologically active!

Indeed, when rivers are dry, they accumulate organic matter (wood, dead leaves, biofilms, etc.), sometimes in very large quantities. When they are refilled, all this organic matter undergoes partial biological decomposition before being carried away downstream. The consequences of rivers refilling with water are poorly understood but can be devastating. “For example, in Australia, water pulses with very low levels of dissolved oxygen are spread across thousands of kilometers downstream from intermittent sectors, with catastrophic consequences for aquatic ecosystems.

Using the implemented protocol, scientists will acquire data on the amount and type of organic matter that accumulates in dry sections of specific rivers. A quantitative description will be carried out, taking into account the context (presence of plants, duration of dry period, climate, etc.). Subsamples will then be sent to laboratories for a more qualitative description: “We will describe the biological reactivity of this material, quantify the carbon dioxide/methane flow that it generates and characterize microbial communities. Will we find the same bacteria in dried riverbeds across the world? Or are we dealing with inert matter that will be transported to the sea, or with very reactive organic matter that will have an impact on global warming and be a threat to the quality of any aquatic ecosystems found downstream?"

Between 2000 and 5000 samples are expected over the next 2 years. To deal with them, the University of Grenoble, the University of the Basque Country, IGB and Irstea in Lyon will all partake in the analyses. “We will have so much data from a variety of conditions -– including Antarctica! -– that we will be able to make very powerful inter-system and inter-continental comparisons,” points out Datry, enthusiastic.

An international network

Behind this participative science approach, a whole network of international partners is being set up. "It is the first time that a network stretching beyond Europe has brought people working on intermittent rivers together!" This initiative follows on from a project, also led by Datry, to summarize and analyze the biodiversity of intermittent rivers [2].

What next? “We can imagine many other experiments, particularly to describe the communities of terrestrial invertebrates found in intermittent rivers. The aim is for this project to run for a long time.” Intermittent rivers, then, but continuous research…

On social media

Partnerships are continuing online on social networks. Researchers are using Twitter in particular to announce their participation or for real-time experiments. >> #1000IRP

[Ross Vander Vorste is a PhD student at Irstea Lyon-Villeurbanne]

Consult the project website

For more information

[2] IRBAS: Intermittent River Biodiversity Analysis and Synthesis. Project launched in 2013, supported by CESAB (FBR) and ONEMA and led by T Datry. This project resulted in a biodiversity database for intermittent rivers. IRBAS brings together influential and productive scientists working in the field of intermittent river ecology. The 1000 Rivers project is an extension of the project. For more information.