In 2015, an underwater volcano in the South Pacific erupted, forming Hunga Tonga Hunga Ha’apai Island, destined for a short life of seven years. A research team led by the University of Colorado Boulder and the Cooperative Institute for Research in Environmental Sciences (CIRES) took advantage of the rare opportunity to study the first microbial colonizers of a newly formed landmass and, to their surprise, the researchers discovered a unique microbial community that metabolizes sulfur and atmospheric gases, similar to organisms found in deep-sea vents or hot springs.
“These kinds of volcanic eruptions happen all over the world, but they don’t usually produce islands. We had an incredibly unique opportunity,” said Nick Dragone, CIRES Ph.D. student and lead author of the study published this month in mBio. “Nobody had comprehensively studied microorganisms in this type of island system at such an early stage before.”
“Studying the microbes that first colonize islands gives us a glimpse of the earliest stage of ecosystem development, even before plants and animals arrived,” said CIRES fellow Noah Fierer, professor of ecology and evolutionary biology at CU Boulder and corresponding author of the study.
A multi-agency team of field researchers collected soil samples from the island and then shipped them to the CU Boulder campus. Dragone and Fierer could then 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 colonizer species, but instead we found a unique group of bacteria that metabolize sulfur and atmospheric gases.”
The island of Hunga Tonga Hunga Ha’apai, Kingdom of Tonga (latitude, 20.536°S; longitude, 175.382°W). The locations of the 32 surfaces where samples were collected are shown. The background image is from August 19, 2018 and is orthorectified. The inset image shows the islands of Hunga Ha’apai (west) and Hunga Tonga (east) on September 11, 2010, before the 2014-2015 eruption. Worldview image-2. Credit: 2010, 2018 Maxar; mBio (2023). DOI: 10.1128/mbio.03313-22
And that was not the only unexpected twist in 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 obliterated the island, removing the option for the team to continue monitoring their site.
“We all expected the island to stay,” Dragone said. “In fact, the week before the island blew up we were starting to plan a return trip.”
However, the same fickle nature of the 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 likely fuels the unique taxa we found,” Dragone said. “The microbes were most similar to those found in hydrothermal vents, hot springs like Yellowstone, and other volcanic systems. Our best guess is that the microbes came from such sources.”
The expedition to HTHH required close collaboration with members of the Kingdom of Tonga government, who were willing to work with the researchers to collect samples from land not normally visited by international guests. Coordination took years of work by partners at the Sea Education Association and NASA: a Tongan observer must approve and oversee any sample collection taking place within the Kingdom.
“This work attracted so many people from all over the world and we learned a lot. Of course we are disappointed that the island has disappeared, but now we have a lot of predictions about what will happen when islands form,” Dragone said. “So if something were to form again, we would love to go there and collect more data. We would have a game plan for how to study it.”
Nicholas B. Dragone et al, The first microbial colonizers of a short-lived volcanic island in the Kingdom of Tonga, mBio (2023). DOI: 10.1128/mbio.03313-22
Provided by the University of Colorado at Boulder
Citation: Rare opportunity to study short-lived volcanic island reveals sulfur-metabolizing microbes (Jan 19, 2023) Retrieved Jan 19, 2023 from https://phys.org/news/2023-01-rare-opportunity- short-lived-volcanic-island.html
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