Lichens are the curious result of cohabitation between algae and fungi. Biologist Frank Bungartz tells DW about his passion for lichens - and why seeing them disappear should ring alarm bells.
DW: 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.
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.
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?
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.
Ironically, people are worried because their tree in the garden suddenly has so many spots. Is it sick? But the colorful spots are only lichens, which do not harm the tree at all. One can rather be glad that the air has obviously become better. That's a good sign.
What hopes do you have for the future of lichens?
That we question the exaggerated illusion of cleanliness, and do not scrub our burial stones or polish walkways and walls with high-pressure cleaners. Instead, we should look forward to the magnificent lichen world - because it even protects the rock from decomposition. In England, not only old churches and their cemeteries are under monumental protection - the authorities even expressly protect the biodiversity of lichens.
So next time we're walking through a town or forest, perhaps we should take a closer look at the life around us?
Definitely! You can pass by a cemetery wall or across the sidewalks, you can see spots everywhere, and these are quite often lichen: living creatures. If you take a closer look - perhaps even with a magnifying glass in your hand - this world that you otherwise overlook will surprise you!
Frank Bungartz is a biologist specialized in lichens. For his PhD at Arizona State University in the United States, he studied crustose lichens living inside rocks in the Sonoran Desert. For the last 12 years, he has been researching lichens in the Galápagos, where he has lived with his family for nine years.
The interview was conducted by Brigitte Osterath.