A stalactite formation in a Hawaiian cave system in this study with copper minerals and white microbial colonies. Although copper is toxic to many organisms, this formation is home to a microbial community. (Credit: Kenneth Ingham)
Hundreds of years ago, the volcanic processes that created the Hawaiian Islands also formed a network of underground tunnels and caves.
They are cold, dark and full of toxic gases and minerals. Therefore, almost inhospitable to most life forms.
However, scientists have discovered that these volcanic vents actually contain colonies of highly complex microbes.
These are the smallest known living organisms on Earth and we really don’t know much about them.
In fact, estimates suggest that 99.999 percent of all microbial species remain unknown. As a result, some refer to these mysterious life forms as “dark matter.”
However, they still represent a large amount of Earth’s biomass.
Thick microbial mats hang beneath a rock ledge at steam vents that run along the East Rift Zone on Hawaii Island. Image (Credit: Jimmy Saw)
What makes experts so interested in Hawaii’s lava caves is that the conditions are as close as you can get to those on Mars or other distant planets.
And if microbes can survive in these 600- to 800-year-old lava tubes, we might find some on Mars at some point.
The researchers found that older lava caves, dating back more than 500 years, typically contained a more diverse population of microbes.
Therefore, they believe that it takes a long time for these little creatures to colonize the volcanic basalt. As the environment changes over the eons, so does its social structure.
When the caves are younger and even more active, the microbial colonies approach each other in terms of species.
“This leads to the question: do extreme environments help create more interactive microbial communities, with microorganisms more dependent on each other?” said microbiologist Rebecca Prescott of the University of Hawaii at Mānoa.
‘And if so, what is it about extreme environments that helps create that?’
Green and purple biofilms and microbial mats are common at geothermally active sites on Hawaii Island. (Credit: Stuart Donachie)
Although there is much we do not know, scientists suspect that competition is a stronger force in harsher environments.
“Overall, this study helps illustrate the importance of studying microbes in co-culture, rather than growing them alone (as isolates),” added Prescott.
“In the natural world, microbes don’t grow in isolation. Instead, they grow, live, and interact with many other microorganisms in a sea of chemical signals from those other microbes. This can alter their gene expression, affecting their work in the community”.
The results of the study have been published in the journal Frontiers in Microbiology.
MORE: ‘Sharkcano’: Undersea volcano erupts with mutant sharks photographed by NASA satellite
MORE: Skittles ‘unfit for human consumption,’ lawsuit claims