Meet the Tiny Desert Slime that Holds our Topsoil Together. For Now.

If your eyes were microscopes and you had really good sunblock, you could lie down in the Arizona Desert and watch tiny microbes build colonies of millions around you. These greeblies, called cyanobacteria, colonize the very top layer of soil and need little more than sunshine to survive. In their wake, they leave a trail of slime that glues the soil together, allowing larger organisms like moss and lichens to grow.

It sound like something out of a Robert Heinlein novel, doesn’t it? But we should think fondly of cyanobacteria because there is mounting evidence that they are what knits our ecosystems together and their slimy calling card could save us from the killer effects of climate change.

Microscopic cyanobacteria are our best friends in a drier world. Source: University of California Museum of Paleontology.
Microscopic cyanobacteria are our best friends in a drier world. Source: University of California Museum of Paleontology.

Scientists are only starting to understand the role these microbes play but we do know they’re vital to soil fertility in the world’s driest environments and may affect how water is absorbed when it does fall, having a flow-on impact on soil erosion, according to original reporting by the New York Times.

If leading climate models are correct and our semi-arid regions are drying out, these cyanobacteria will be our best friend keeping the topsoil together. Without them, mosses, grasses and other ground cover can’t take advantage of what little rain there is and mass erosion will devastate arable soils.

Every ecosystem on earth contains a species of cyanobacteria, knitting together soil, manufacturing their own food and turning inert atmospheric nitrogen into an an organic form that plants can absorb.

At 3.5 billion years old, Cyanobacteria are the oldest fossils we’ve found.

In undisturbed lakes – like those under the ice in Antarctic waters – they form structures big enough for the naked eye to see. How cool is that?

Pinnacles and cones of cyanobacteria formed on the ocean floor under Antarctic ice. Source: Dale Andersen, ScientistAtWork blog.
Pinnacles and cones of cyanobacteria formed on the ocean floor under Antarctic ice. Source: Dale Andersen, ScientistAtWork blog.

But climate change is having an impact, as several species of cyanobacteria duke it out for dominance of a changing soil strata. Scientists are still trying to work out what will happen to our soil if areas heat up and dry out, storms shorten and become more violent, as many climate change models predict but they know cyanobacteria will be a big part of whether arid areas can continue to support more complex organisms, plants and animals – like us.

 

This post also appears at Sciengage, where I write the environmental science blog.