A closed loop of ideas

1) Throughout this text, I will use the word “terrestrial” to refer to the planet Earth as opposed to “space”, which slightly pains my aquatic biologist heart.
2) As a lot of the talks had some link with plant sciences, I feel like, despite this entry being space or lake focused, it also has a place on this green and leafy blog!

This week, I was lucky enough to go to Lausanne, a small Swiss city on Lac Léman, to attend the MELiSSA Workshop. What is MELiSSA? As an ecologist, it is unlikely that you are acquainted with this European Space Agency (ESA) project, which stands for Micro-Ecological Life Support System Alternative. It was created in 1989 (read more on how it began here) and brings together European and Canadian partners from 13 different countries in an attempt to fulfill human needs in outer space via the development of life in closed systems. The main ideas include: recycling waste and carbon dioxide aboard spacecraft by using bacteria; and producing food, water, and oxygen in a regenerative way to keep costs low. Put in their words, it aims “at a total conversion of the organic wastes and CO2 to oxygen, water and food”.


Terrestrial lake eco-loop. Copyright: ESA.


What drew me to this workshop is that this closed loop is based on lake ecosystems, as depicted in the diagram above. Whether lake ecosystems are truly closed is debatable, and in my opinion is rather incorrect (I still believe in the importance of allochthony!). However, in the natural terrestrial environment, lakes are probably the system that comes nearest to the idea of a closed loop, due to their ecological isolation and the limitation of external inputs. In lakes, the processing of waste products via plant and algal metabolic activity fuels the regeneration of food, clean air, and pure water – and this is why the lake aquatic ecosystem is used as a model for MELiSSA.

Concretely, they try to reproduce this via the following compartmentalization of tasks:

I Organic waste degradation & solubilisation by thermophilic anoxygenic bacteria
II Carbon compounds removal by photoheterotrophic bacteria
III Nitrification by nitrifying bacteria
IV a Food and oxygen production by photosynthetic bacteria
IV b Food, oxygen and water production by higher plants
V The crew


Which recreates the loop:


The 5 compartments of the MELiSSA loop. Copyright: ESA. See Godia et al. (2002).


The two-day workshop brought together 140 participants from 21 countries, from academia and industry, who discussed solutions to issues associated with space travel. With more than 40 speakers, you can imagine the days were long, but invigorating, and made even more enjoyable by the quality of the tea breaks and meals (a giant parmesan filled with rice for lunch!). To give you an idea of the breadth of topics discussed, here are the titles of the 6 sessions that made up the workshop: 1) Waste processing, 2) Water recycling, 3) Air recycling, 4) Food production & preparation, 5) Chemical & microbial safety and 6) System tools. These covered subjects as seemingly divergent as food production and new food sources, clean showerheads, anaerobic digestion, human feces disposal, and hydroponic plant-fish interactions.

My thoughts about space research have always been that the money put into it could instead be used to solve terrestrial problems. Scientific terrestrial problems – feeding the world, conserving biodiversity, predicting the effects of global change – urgently need solutions. As an aquatic biologist, I have heard many times that the deep sea has been infinitely less explored than the surface of the moon. Why should we keep investing into space research then? Is sending men to the Moon or to Mars a sci-fi dream, a demonstration of our technological power, or a serious and, perhaps in the future, necessary escape from a damaged planet Earth? Whichever of these it may be, I have come to understand that spending money on what may first sound utopic is actually beneficial to our planet in much more concrete and terrestrially applicable ways than I ever imagined. What the conference taught me is that there’s a kind of closed loop of ideas: space research takes from ecology, and vice versa.

And indeed, there is no doubt that the vast majority of the research and new technologies discussed throughout the workshop aims to bring more sustainable innovations or alternatives to extant ones. Ultimately, the idea of the closed loop is about recycling: anything that is part of the loop needs to be reused, recycled, and regenerated. By incorporating this ecological idea into technological principles, the closed loop can also yield a new form of economy, a “circular economy”, whereby waste is limited and the value of products is retained. Of course, I am skeptical about some of the proposed projects – too utopic, not financially viable, no real advances made. For instance, I would love to dive in underwater gardens (large glass tanks maintained at supposedly constant temperature), but I don’t understand how they could ever be part of the solution to feed the world.

In addition to this little inner discussion I had with myself, what I can really take home from this meeting is a lot of new knowledge on microbial communities – how they interact among themselves but also with their environment, how they process nutrients, and how they can be studied. One question that particularly triggered my interest is whether prosperous and diverse microbial communities that can auto-regulate are less harmful, or risk-prone, than disinfected zones whereby resistant microbes have the potential to thrive and be pathogenic? I also saw how my current research could be applied in various ways. As a PhD student, not getting results can sometimes distract you from the focus of your project, and leave you wondering why you are there and for what purpose. Seeing the potential – both theoretical and applied – of my research, gave me a surge of motivation and new ideas. It also pushed me to think of subjects that had never even crossed my mind, namely the number of issues associated with space travel – microbial contamination, food and water supply, waste removal, breathing clean air…

Finally, I would like to say that my most valued moments of the workshop were occasions to exchange ideas with Mark Nelson. Mark was part of the first Biosphere 2 mission from 1991 to 1993 (if you don’t know about this 2-year closed loop experiment, in Arizona, with 8 crew members, I recommend reading about it) and is one of the founders of the Institute of Ecotechnics. I have to admit I was a little nervous about attending the workshop, fearing that I would feel out of place amongst all these engineers and businessmen. In the first few minutes upon my arrival though, I met Mark and felt like I was in the right place, and that I could learn a lot from this workshop. Mark is an ecologist – the academic son of H.T. Odum, and the academic grandson of G.E. Hutchinson – and has been involved with MELiSSA for many years. It was truly engaging to discuss space exploration, closed systems, systems ecology, urbanization and many other exciting or demoralizing topics. Special encounters like these can give large events a whole other dimension.

In the end, I came to the conclusion that environmental thinking can successfully be integrated into space activities, and can promote synergies between space and terrestrial research. I am glad I attended this workshop, which gave me space for thought as well as a taste of something new. And to open up the discussion: how do you feel about closing the loop?


Copyright: ESA.



The future of environmentally-friendly farming?

Our first paper on the agri-environment has just appeared in this month’s issue of PLoS Biology.  This is an important piece for us as it provides a foundation for empirical work being carried out by several group members.

The paper essentially makes three main points.  The first is that we spend a lot more money subsidizing farming than trying to mitigate its environmental impacts.  We’ve tried to plot this out below.  What you can clearly see is that the purple (mitigation expenditure) is nearly invisible relative to what is spent on subsidizing farming (shown in the orange slices).

Financial support to farmers from taxpayers and consumers associated with agricultural policies as a proportion of the total value of agricultural production (VoP) at the farm gate.

The figure now provides what is essentially a map of the ‘perversity‘ of agricultural subsidies – showing where we spend money to do things that are often bad for the environment and costly to the economy.  A first step in reducing conflict between agriculture and the natural environment would be to do away with the subsidies in orange.

Continue reading

What have we been learning about the Cerrado?

Cerrado landscape invaded by sugarcane fields.

Cerrado landscape invaded by sugarcane fields

In the beginning of 2014, my adventure in the Brazilian Cerrado had just started! It’s now been a year I took the airplane to Brasília, in the heart of Brazil. We decided to study the effects of agriculture, specifically of sugarcane crops, on the gases emissions from soils of this region. Nothing would have been possible without the collaboration with the EMBRAPA Cerrados. But why there??

Cerrado woodland vegetation

Cerrado woodland vegetation

Cerrado, the richest savannah in the world and the most extensive savannah complex in the Neotropics, has been historically affected by a number of human activities. By now, it has lost half of its 2 mi km2 of native vegetation. The expansion of the sugarcane fields, often used for bio-ethanol production, is one of the current threats to this biome.

We are currently measuring the emissions of greenhouse gases, specifically the nitrous oxide (N2O), in response to the management of fertilisers. Our preliminary results show a large increase in the emissions from the combined treatment using nitrogen and vinasse*, that is, 450 times more than the native areas on average! Our longer monitoring activities will be important to understand the variation on the emissions throughout the sugarcane cycle and to assess the sustainability of this crop in the region.

*Vinasse=a waste from the ethanol production that is re-used as fertiliser.  

Experimental sugarcane field in May/2014

Experimental sugarcane field in May/2014

Experimental sugarcane field in November/2014

Experimental sugarcane field in November/2014

Applying vinasse to the field

Applying vinasse to the field


Collecting gases in the Cerrado

Collecting gases in the Cerrado

Collecting gases from the sugarcane field

Collecting gases from the sugarcane field

Part of the staff in a rare relaxing time!!!

Part of the staff in a rare relaxing time!!!

Can plants get more carbon for less water?

This week’s group meeting featured a special joint production with Molecular Physiology to welcome Prof Graham Farquhar from the Australian National University.  Graham was in the UK to receive a Rank Prize Fund award for his contributions to food security by helping to guide the breeding of wheat varieties that use water more efficiently.

His talk, “Water user efficiency and water use effectiveness, a stomatal perspective using stable isotopes” was a far-reaching overview of his amazing research career, dating back to his time as a PhD student.  But he started his talk with a very provocative and timely consideration of global changes in rainfall and human population growth.

Rainfall is inherently random.  Sometimes there is too much, sometimes there is too little.  Australia is a country that experiences both these extremes.  For example, there are often heavy floods in the monsoon region while other areas, particularly where agriculture is concentrated in the southern part of the country, is drying up.  The desire to expand cultivated land inevitably means there is more pressure on more marginal rainfall.  An astounding statistic that Graham rolled off was that 1 ha of cultivated land was needed to feed 20 people.  20 people are added to the world’s population about every second!  Clearly, that’s a problem.

Graham’s talk then focused on how plants can use the least amount of water for a fixed amount of carbon.  He began by introducing his classic work on stomatal regulation of transpiration relative to carbon assimilation, which shows the two processes are fundamentally linked.  Changing evaporation will always change assimilation.  He then considered how plants could arrange the temporal expenditure of water to maximize assimilation of CO2.  Carbon isotopes are particularly useful here for discriminating among transpiration efficiencies associated with different genotypes and can help identify future crop varieties that use water more efficiently.  In dry conditions,  greater transpiration efficiency improves crop yield and selects for low C isotope discrimination in leaf dry mater.

As we ran out of time, we were left with questions about how the process of balancing carbon and water demands might be influenced by life history strategy (perennial versus annual) and competition for water in soil.