Unique Microbes Inhabited Tonga’s Vanished Volcano Island

Jan. 20 () –

A unique microbial community that metabolizes sulfur and atmospheric gases, similar to those at deep-sea vents, inhabited the volcano island of Tonga that blew up in 2022.

In 2015, an underwater volcano in the South Pacific erupted, forming Hunga Tonga Hunga Ha’apai Island. A research team led by the University of Colorado at Boulder and the Cooperative Institute for Research in Environmental Sciences (CIRES) seized the rare opportunity to study the first microbial colonizers of a newly formed landmass. Their findings are published in ASM Journals.

“These types of volcanic eruptions occur all over the world, but they don’t usually produce islands. We had an incredibly unique opportunity,” says Nick Dragone, a CIRES doctoral student and lead author of the study published this month in mBio. “No one before had comprehensively studied the microorganisms of this type of island system at such an early stage.”

“Studying the microbes that colonize the islands for the first time allows a glimpse of the earliest stage of ecosystem development, before the plants and animals even arrive,” says Noah Fierer, a CIRES fellow, professor of ecology and evolutionary biology at CU Boulder, and corresponding author of the study.

A multi-institutional team of researchers on the ground collected soil samples from the island and sent them to the UC Boulder campus. Dragone and Fierer were then able to extract and sequence DNA samples from the samples.

“We didn’t see what we expected” Dragone said. “We thought we would see organisms found when a glacier recedes, or cyanobacteria, more typical early colonizing species… but instead we found a unique group of bacteria that metabolize sulfur and atmospheric gases.”

And that was not the only unexpected twist to this work: On January 15, 2022, seven years after its formation, the volcano erupted again, leveling the entire land mass in the largest volcanic explosion of the 21st century. The eruption completely wiped out the island, removing the option for the team to continue monitoring its location.

“We all expected the island to stay,” Dragone says. “In fact, the week before the island exploded, we were starting to plan a return trip.”

However, the same fickle nature of Hunga Tonga Hunga Ha’apai (HTHH) that caused it to explode also explains why the team found such a unique set of microbes on the island. Hungary Tonga was formed volcanically, like Hawaii.

“One of the reasons we think we see these unique microbes is because of the properties associated with volcanic eruptions: lots of sulfur and hydrogen sulfide gas, which probably feed the unique taxa we found“Dragone said. “The microbes were very similar to those found in hydrothermal vents, hot springs like Yellowstone and other volcanic systems. Our best guess is that the microbes came from those types of sources.”