Ecohydrology is generally defined as an interdisciplinary science that links ecology and hydrology, typically exploring how physical processes interact with biodiversity and ecological processes. For me, and perhaps due to my limited background in physics, it resonates simpler as I am focusing on how the lack of flow or water, due to drying events, determine biodiversity and ecological processes in river networks. In other words, I study the ecohydrology of rivers without water.
What are your undergraduate and graduate degrees in?
My undergraduate degrees are in Zoology and Environmental Sciences, from the Université de Lyon. My MS and PhD are in General Ecology from the same University.
How did you arrive at working in/thinking about ecohydrology?
During my MS and PhD, I explored the ecohydrology of hyporheic zones and shallow alluvial aquifers. Both systems are ideal arenas to develop strong interactions between physical and biological disciplines. Not much can be understood about the ecology of these ecosystems without quantifying their physical functioning (eg SW-GW interactions, vertical hydraulic gradients, water residence times, sediment hydraulic conductivity and porosity). After this, I moved to the south island of New Zealand (at NIWA), where the hyporheic zones and aquifers I was supposed to study were underneath an intermittent (and quite famous) river, the Selwyn River flowing across the Canterbury plain by Christchurch. This gradually drove me to explore some sort of “extreme” ecohydrology, where the absence of flow and water in river networks can be so determinant for explaining ecological patterns in space and time that the physical-biological interactions occurring during flowing phases become somehow secondary. Exciting too is the idea of whether a saturated zone located below a dry riverbed can be called a hyporheic zone and function like hyporheic zones in perennial rivers and streams.
What do you see as an important emerging area of ecohydrology?
In my opinion, a pivotal emerging area of river ecohydrology is a paradigm shift: for decades, we assumed river channels were perennial and those experiencing drying events were marginal. We today know intermittent rivers and ephemeral streams are dominating most landscapes across every continents and climates, and this will certainly increase due to global change. However, all riverine conceptual models and most applied tools and guidelines that have been produced come from, and are intended for, perennial rivers! Thankfully, various efforts are on-going in different countries to accompany or push this paradigm shift!
I also think the ecohydrology of hyporheic zones is still lagging behind “surface” ecohydrology and recent methodological developments (sampling methods, tracers, molecular tools, modelling, …) allow today to explore further how water flow influences the biodiversity and ecological functions in hyporheic zones and subsurface environments. While most scientists and managers are today aware of the importance of hyporheic zones, producing flow-ecology relationships in these hidden ecosystems is needed to help incorporating them into conservation, restoration and management plans and practices.
Another emerging area is be to spatialized ecohydrological processes at the network scale, following the recent conceptual development of meta-ecosystems. For example, how SW-GW (surface water-ground water) interactions are organized spatially within river networks, are they general, transferable rules and patterns, what are the key drivers and their temporal dynamics? A key component to consider at such scale is how humans benefit from and alter (physically, chemically, biologically) these interactions, in a context of global change. Another path is coupling physical (flow dynamics, including flow intermittence in the longitudinal, vertical and lateral dimensions), biogeochemical (resources dynamics, including dissolved and particulate compounds) and biological (consumer metacommunity dynamics, including functional aspects) processes at such scale, in the lens of global change. Using process-based models and meta-modelling will allow, from a management perspective, to identify tipping points and bottlenecks to avoid and thus determine safe operational spaces. Besides improving our understanding of the ecological integrity of river networks, such efforts will help bridging the gap between disciplines (hydrology, geomorphology, biogeochemistry, ecology, modelling) and domains (terrestrial and aquatic, surface and groundwater). This is what we are now trying to do through a starting H2O20 project on drying river networks prone to climate change (@DRYvER_H2020).
Do you have a favorite ecohydrology paper? Describe/explain.
This is a rather hard question as there are so many excellent ecohydrology papers that have been produced the past 2 decades! With respect to one of my favorite research themes, I would mention a review on the significance of the hyporheic zone, led by Andrew Boulton, who is a fantastic and inspiring colleague, a pioneer in several ecohydrological fields and has become a wonderful friend. All co-authors of this review have been very inspiring to my research path.
Boulton, A. J., Findlay, S., Marmonier, P., Stanley, E. H., & Valett, H. M. (1998). The functional significance of the hyporheic zone in streams and rivers. Annual Review of Ecology and Systematics, 29(1), 59-81.
What do you do for fun (apart from ecohydrology)?
One long-standing passion is music: I play the accordion (Balkan and jazz music) and keep enjoying moments with friends in different bands. I also play more and more with my 2 kids as they grow up and start playing too (trumpet, piano and guitar). We live in a fully autonomous house, off-grid in the middle of a forest of the Jura mountains by another famous intermittent river (the Albarine): gardening, looking after our goats, sheep, chicken, bees and fruit trees is another occasion to have fun (not only though!). Last, I’m back into caving after a 6y-long break as our kids can now enjoy being underground with us. Somehow, this is another way to explore SW-GW interaction.