Terrestrial diatoms: a potential tool in the study of streamflow generation

For 3 years, researchers at the Luxembourg Institute of Science and Technology (LIST) have been working together with Dutch, British and German universities to analyse the potential of terrestrial diatoms as hydrological tracers. Their objective was to determine the potential of algae living outside water which, during rainfall events, follow the passages of flood water not infiltrating the soil and because of this rapidly run off into streams.

Under the auspices of the project ECSTREAM “Eco-hydrological couplings for investigating streamflow generation processes”, funded by the National Research Fund – Luxembourg (FNR) and coordinated at LIST which has also provided its hydrological and ecological expertise, they have been able to:

• substantiate the presence of terrestrial diatoms in flood waters and thus confirm the surface run-off process, and at the same time, that of intermittent hydrological connectivity (that is to say, the spontaneous starting and stopping of surface water flowing into streams);
• describe new species of hitherto unknown terrestrial diatoms;
• establish that assemblages of terrestrial diatom species are controlled by geological substrates, soil types or even land use - thus paving the way for tracing flows over extremely large spatial scales, which is not currently possible with conventional hydro-chemical tracers.

These works have been published in various international scientific journals and been awarded prizes during the Canadian Geophysical Union congress in 2013 and the European Geosciences Union general assembly in 2016. Researchers have also identified the utilisation of terrestrial diatoms as a soil quality bio indicator as another potential area of exploration for projects undertaken in the immediate future.

> Further information about ECSTREAM on the project page