LONDON: It was something of an accidental discovery, admits Volker Vahrenkamp with a smile.
“Sometimes these things need a little luck.
Vahrenkamp, a professor of geology at King Abdullah University of Science and Technology in Thuwal on the Red Sea coast of Saudi Arabia, set out with a team of colleagues to take a closer look at a coastal geological phenomenon they had recorded in satellite images.
So-called teepee structures, tent-shaped bulges of sedimentary deposits in intertidal zones, are valuable indicators of environmental change, both ancient and modern.
The team was delighted to discover that the examples were practically on their doorstep – just 400 kilometers up the coast from KAUST, off the southern tip of Sheybarah Island, best known for the luxury Red Sea Global tourist resort of the same name.
“There really aren’t many good examples of teepee structures where people can study how they are formed,” Vahrenkamp told Arab News.
“Then we noticed it, and it’s the most amazing example I know of.”
Satellite images showed that there were two teepee fields in the intertidal zone of the island, and after a short boat trip overland on a converted fishing boat, we “landed on the island, explored one field, and then walked another.”
And then when they crossed the bank between the two, “we literally stepped on these stromatolites.”
Stromatolites are layered rock-like structures formed by tiny microbes, individually invisible to the naked eye, some of which trap sediment in their filaments.
They live on rocks in the intertidal zone, covered and exposed daily by the coming and going of the tides, and slowly turn the dissolved minerals and grains of sand they capture into solid matter in a process known as biomineralization.
Human beings and every other living thing on Earth that relies on oxygen to survive owe its existence to tiny, so-called cyanobacteria, which have been building stromatolites for about 3.5 billion years.
Cyanobacteria were one of the first forms of life on Earth at a time when the planet’s atmosphere consisted mainly of carbon dioxide and methane. When they appeared about 3.5 billion years ago, they had a special skill – the ability to create energy from sunlight.
This process, photosynthesis, had an essential by-product – oxygen. Scientists now believe that microscopic cyanobacteria were responsible for the biggest thing to ever happen to the planet – the Great Oxidation Event, which saw Earth’s atmosphere transform and set the stage for the development of oxygen-dependent life as we know it today.
Most stromatolites are only fossils today. As other life evolved on Earth, they lost their foothold in the planet’s oceans to competitors such as coral reefs.
However, in several places around the world, “modern” living stromatolites, “analogs of their ancient counterparts,” as Vahrenkamp says, still grow.
“Stromatolites are a remnant of the earliest life on Earth,” he said. “They ruled the Earth for an incredible amount of time, about 3 billion years.
“They’re part of the rock record in many parts of the world today, but it’s impossible to tell from these old rocks what type of microbes they were and exactly what they did.”
INNUMBERS
• 400 kilometers Distance of teepee fields from KAUST campus
• 3 billion The years when rock-like stromatolites ruled the Earth
• 120 Meters by which the sea level was lower during the last ice age
That’s why the discovery of a rare colony of living stromatolites like the one-time Sheybarah Island is such a boon to geologists, biologists and environmental scientists.
“When you find a modern example like this, it is likely that you will be able to better understand how the interaction of this microbial community led to the formation of stromatolites.”
Other examples are known, but they are almost always found in extreme environments, such as alkaline lakes and ultra-saline lagoons, where competitors cannot thrive.
One previous colony had been found in a more normal marine environment, in the Bahamas – which Vahrenkamp had visited and thus easily recognized what he was walking on at Sheybarah Island – but this is the first example of living stromatolites discovered in Saudi Arabia. water.
It’s not yet clear how old these stromatolites are, “but we can kind of pin it down,” Vahrenkamp said.
“We know that during the last ice age the sea level was 120 meters lower here, so they weren’t there 20,000 years ago. The area where they are found was flooded about 8,000 years ago to a height of about 2 meters above where it is now, and then the sea level receded again to where it is now about 2,000 years ago.”
This does not mean that the stromatolites are 2000 years old. No one knows how long it takes microbes to build their sedimentary layer cake, and “no one has yet come up with a good way to date the layers.
“The tide and the waves come in and throw up sand and material from the surrounding reefs, so all kinds of ages can be present.” Therefore, it is very difficult to accurately date stromatolites and estimate growth rates.”
That’s why Vahrenkamp and colleagues are now devising an experiment to recreate the natural environment of rising and falling tides and alternating sunlight and darkness in an aquarium, in an effort to grow stromatolites under controlled, easily observed conditions.
Whether that will take weeks or many years, “we honestly don’t know.”
The team is also working to genetically sequence many of the thousands of different types of microbial bacteria at work in the stromatolite factory.
“It’s a matter of figuring out ‘who’ is there and who’s doing what,” Vahrenkamp said.
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“But then there’s also the question of what functions these bacteria have and whether we can use them in other ways, perhaps in medical applications.”
“Scientists are now closely examining the microbial composition of our guts to find out which microbes cause, for example, cancer and which prevent it. Microbacteria active in stromatolites could contain functional secrets that we simply do not yet know about.
The discovery also resonates with the environmental ambitions of the Saudi Green Initiative, announced in 2021 by Crown Prince Mohammed bin Salman, which, along with the Middle East Green Initiative, aims to combat climate change through regional cooperation.
As Vahrenkamp and his seven co-authors wrote in an article published recently in Geology, the journal of the Geological Society of America, “the discovery of the Sheybarah stromatolite fields has important implications not only from a scientific perspective, but also from an ecosystem service and environmental heritage awareness perspective, consistent with ongoing projects for sustainability and development of ecotourism supported by Saudi Arabia.
In this paper, KAUST scientists thank Red Sea Global for support in accessing the stromatolite site, which is currently being considered for protected zone designation.
As for tourists relaxing in the spectacular new overwater villas on the crystal clear Al-Wajh Lagoon on Sheybarah Island, another attraction now is that a short walk along the beach will take them back in time for a glimpse of life on Earth at 3, 5 billion years. before.
