Western Mail Profiles: Dr Aditee Mitra

‘The day of the triffids has now dawned’

Dr Aditee Mitra is a research scientist at the Centre for Sustainable Aquatic Research, Swansea University, and is currently investigating the impacts of food quality and quantity in marine ecology.

HAVE you ever wondered what our planet would be like if John Wyndham’s triffids became reality?

It may be hard to believe but our planet is already home to countless millions of triffids. Fortunately, these are not 10 feet tall like those in the novel, but are microscopic organisms living in the oceans, lakes and even ponds.

In spite of their size (rather lack of), they can be useful and yet also just as life-threatening to humans as those in the book. Scientifically both the triffids and their microscopic counterparts are “mixotrophs” – organisms which can make food from sunlight (like plants) and feed (like animals).

The predatory nature of the real, microscopic, mixotrophs was one of the reasons which drew my attention to these fascinating organisms. I am a biologist who designs mathematical models of ecology on computers. Such models enable us to create a replica of the real organism and provide opportunities to study the in-depth mechanisms of how these organisms function especially in a changing world. I develop and deploy models to look at how energy is transferred from the marine food producers (microscopic plant-like algae, the phytoplankton) to the fish communities via the zooplankton (e.g., copepods, krills, fish larvae). Just like humans, zooplankton have different food preferences and depending on what and how much they eat, they are either fat (and survive) or are skinny (and die).

While investigating how the changes in the quality and quantity of the algae affect the zooplanktonic consumers, I found that some of the microscopic zooplankton were not digesting all their food. Instead they were retaining parts of the algae which then enabled these hunters to photosynthesize like a plant.

Further investigations revealed that such mixotrophs are extremely common, and are important parts of the food chain leading to fish. On the negative side, some mixotrophs can kill humans. They do so by making plant-like toxins that infect our seafood. In Wales, mixotrophs can impact our shell-fisheries, while elsewhere they have caused mass fish-kills.

These organisms are typically ignored in mainstream research, especially those associated with long-term predictive studies such as for fisheries and climate-change. The reason cited is that as Jack-of-all-trades, the mixotrophs cannot possibly be a master as well. Our work, however, indicates that this epithet is misplaced.

In fact these microscopic triffids are the masters; they are everywhere. In order to improve our understanding of the workings of these mixotrophs and their effect on the environment and ultimately on humans, we have set up an International network of experts, funded by the Leverhulme Trust.

A major role that I play in this programme is investigating if climate-change events may promote the importance of these organisms still further.

So the next time you sit there blissfully looking out to sea, think of the microscopic triffids feeding by sucking out the contents of their living prey, engulfing them, or even swarming around animals much larger than themselves. But rest easy, because fortunately for us, they are not going to turn up on land.

You can contact Aditee at A.Mitra@swansea.ac.uk

This article first  appeared in the Western Mail‘s Health Wales supplement on 4th February 2013, as part of the Welsh Crucible series of research profiles.