Allison Cartwright is our ECS Publications Officer. After a trip to the Canaries, she looks at bacteria that colonise cooling lava flows.
I was fortunate enough to spend Easter break on the beautiful volcanic island of Lanzarote. As a leader for the Duke of Edinburgh Award, I’ve developed an obsession with mountains, so I had to visit the volcanic national park of Timanfaya.
The national park is protected and volcanoes can only be viewed from a coach tour around the area. The park contains lava flows from eruptions occurring between 1730-1736. Although it is approaching 300 years since the last eruption, it’s amazing to learn how diverse life is here, containing 180 species of lichen alone.
Lichen are composite organisms containing a fungus with either an algae or cyanobacteria. This got me thinking about the microbes which would be found on cooled lava and at what point they might appear after a volcanic eruption.
Lava first sight
Would the bacteria diversity pattern on lava flows reflect those of lichen? How long does it take before lava cools enough to support volcanic life? The recent eruption of Eyjafjallajökull volcano in Iceland gave scientists a chance to find out.
Dr Laura Kelly and her team from Manchester Metropolitan University investigated the lava flows from an eruption in April 2010 and sampled them for microbial life just 3-4 months later.
Using 16S (bacterial) and 18S (fungal) sequencing they found a bacterial community dominated by Betaproteobacteria but included Actinobacteria, Bacillariophyta, Chlorophyta, Cyanobacteria, Alphaproteobacteria, Deinococcus-Thermus, Firmicates, Gammaproteobacteria, and the fungi Ascomycota. A very impressive list of microbes, found only a few months after the rock beneath them had been molten lava!
On average between 1.6 – 2.6 x 106 cells were found per g of lava sample. As an average of 108 cells are found in a g of soil, which is a less harsh environment, the number of microbes on lava flows is surprising. However, the diversity in this newly created environment will be lower.
It’s easy to imagine cooling lava flows as an inhospitable environment. They are warm and low in nutrients. But over time, this changes. In GCSE geography, we studied plant succession, where mosses or a similar hardy plant colonise a small crack in a rock. As it grows, it breaks down the rock, releasing any trapped minerals. Eventually, this process creates a basic soil for a new plant groups to colonise. This pattern continues until you have a woodland.
A similar pattern emerges with microbial communities on lava, but the early colonies seem to prevail in reduced quantities as more and more phyla compete with them for space as a harsh environment turns into a thriving landscape.
Dr Nick Cutler and his team investigated the microbes on Icelandic lava flows of 165, 621 and 852 years old. Plants had become established on all these lava flows, but only the oldest supported trees.
The microbes were identified by pyrosequencing and revealed that most of the fungi were from the taxa Basidiomycota and Ascomycota on all ages of lava flow, but genus such as Cryptococcus and Epicoccum were not found on the 165 year old lava flow.
Eruption of life
They also found 24 phyla of bacteria with Proteobacteria and Acidobacteria being the most common. Between the ages of lava, there were little change in the phyla diversity of bacteria, but Actinobacteria increased with age.
Therefore, the earlier microbial community seems to prevail over time, but additional groups join the competition for space and resources.
Although I was surprised by the microbial diversity on lava flows and how quickly they colonise this habitat, I can’t help but think that all the life on our beautiful planet stemmed from the ability of amazing microbes to cope in a hostile, hot and somewhat semi-solid environment.
Next time I am encouraging Duke of Edinburgh Award kids onto a mountain, I plan to tell them of the amazing microbes that first colonised the mountains we climb, dormant volcanoes more than 23 million years old.
As they drag their feet and legs out of the peat bogs, I’m sure they’ll wish that some of the volcanic heat remained to dry the soggy landscape.
Cutler, N.A., Dominique, L.C., Van der Gast, C.J. (2014) Long-term changes in soil microbial communities during primary succession. Soil Biology and Biochemistry, 69, 359-370.
Kelly, L.C., Cockell, C.S., Thorsteinsson, T., Marteinsson, V., Stevenson, J. (2014) Pioneer Microbial Communities of the Fimmvörðuháls Lava Flow, Eyjafjallajökull, Iceland. Microbial Ecology, 68, 504-518.
Raynaud, X., Nunan, N. (2014) Spatial Ecology of Bacteria at the Microscale in Soil, PLoS one, 9, 1-9.
Categories: Feature Articles