You have been researching lichens for nine years at the Charles Darwin Research Station on the Galápagos Islands. What fascinates you about these humble organisms?
Frank Bungartz: For me, when I started, it was a whole new world that opened to me. When I looked at the organisms under the magnifying glass, I saw structures that are more fantastic than many pieces of art. But lichens are also very interesting as far as biology is concerned.
In what way?
We are not at all the individuals we imagine. We are dependent on a symbiosis with other species: without our intestinal flora we could not survive. Lichen is the prime example par excellence. They are made up of at least two different species: fungus and algae. The fungus holds algae cells, which carry out photosynthesis and produce sugars from which the fungus also feeds. Thus, lichens are capable of pretending to be plants - even though they are not plants. The biology behind it is incredibly fascinating.
Frank Bungartz collecting lichens at Galapagos (Frauke Ziemmeck/Charles Darwin Foundation )
Biologist Frank Bungartz collecting lichens in the Galapagos
And what does the algae get out of this life partnership?
The mushroom stores it in its mycelium and builds a kind of house for the algae. Together, they can settle in places where fungi or algae alone would not be able to - even in the Antarctic, the Namib Desert in Africa and the Atacama Desert in South America.
How can lichens grow in such conditions?
Lichens are able to survive even without water. They can completely dry out - they are inactive, but not dead. When there is enough moisture available, the lichen begins to live again and to carry out photosynthesis. This is almost a resurrection from death, and it is repeated regularly.
The Namib Desert in Africa, for example, is one of the driest places in the world - but fog banks are always passing by. The moisture in the fog banks is enough for lichens. Therefore, fog deserts are very rich in lichens.
But Galapagos is not a desert. Aren't there many more interesting creatures there than lichens?
The giant tortoises are of course the main tourist attraction on Galapagos. No tourist travels to Galapagos to see lichens. But if you look at species richness on Galapagos, the balance shifts. Vertebrates are only a very small group, while lichens are extremely rich in species.
Ecuador giant turtle with lichen on the shell (Charles Darwin Foundation/F. Bungartz )
Lichens even grow on shells of the Galapagos' iconic giant tortoises
When I started working at Galapagos in 2005, there were only about 200 species of lichens known. Since then, over 600 species have been registered. My colleagues and I have already described 50 kinds. We know, however, that there are up to 1,000 species and we are working on the description of further species. And we estimate about one fifth of all lichen species on Galápagos are endemic - so they only exist there.
Is this unusual? It is well known that because the islands are so far from the South American mainland, Galápagos has many endemic species.
Yes, but it has long been believed that this is not the case with lichens. Lichens spread through microscopic spores or lichen fractures. It had therefore been assumed that they develop everywhere where the conditions of life are favorable. But that is not the case there.
How did you hit on lichens as your research topic?
Frank Bungartz with his daughter(Robert Lücking/Botanisches Museum Berlin-Dahlem)
Frank Bungartz with his daughter
I was studying in Norwich, England, and I spent a lot of my time cycling. I noticed then that many of these small churches have cemeteries on which the gravestones are full of lichens. And so I had the idea for my thesis. I compared the lichen communities on tombstones in the country with those in the city, since lichens are bio-indicators for air pollution.
So, if the air quality is poor, many lichen species cannot grow - why is this?
Lichens do not have roots - they take up all nutrients from the air, also the water. Therefore, they are extremely sensitive to pollutants in the air.
Is it still possible to find lichens in cities?
Oh sure! They had disappeared for a long time, because in Europe at the time of the industrial revolution, many cities suffered greatly from pollution. At that time everyone was heating with coal-burning stoves, and above the cities used to lie a haze. There was a lot of toxic sulfur dioxide in the air. But over time, the air has improved and the lichens, which had not yet completely died out, have slowly returned.
