Inesperadamente, los científicos encontraron una población microbiana única que puede metabolizar el azufre y los gases atmosféricos, similar a los microorganismos detectados en los respiraderos hidrotermales de aguas profundas o en las aguas termales geotérmicas.
Un equipo dirigido por CU Boulder descubrió una comunidad microbiana distinta que reside en la antigua isla de Hunga Tonga, Hunga Ha’apai.
En 2015, un volcán submarino en el Pacífico Sur hizo erupción, dando lugar a la efímera isla Hunga Tonga Hunga Ha’apai. La Universidad de Colorado Boulder y el Instituto Cooperativo para la Investigación en Ciencias Ambientales (CIRES) dirigieron un equipo de investigación que aprovechó la oportunidad inusual de investigar a los primeros habitantes microbianos de una masa de tierra recién formada. Sorprendentemente, detectaron una población microbiana única que puede metabolizar el azufre y los gases atmosféricos, de forma similar a los organismos presentes en los respiraderos hidrotermales de aguas profundas o en las aguas termales geotérmicas.
“Este tipo de erupciones volcánicas ocurren en todo el mundo, pero no suelen producir islas. Tuvimos una oportunidad increíblemente única”, dijo Nick Dragone, CIRES Ph.D. estudiante y autor principal del estudio publicado recientemente en mBio. «Nadie ha estudiado exhaustivamente los microorganismos en este tipo de sistema insular en una etapa tan temprana antes».
«Estudiar los microbios que colonizan por primera vez las islas permite vislumbrar la etapa inicial del desarrollo del ecosistema, incluso antes de que lleguen las plantas y los animales», dijo el miembro de CIRES Noah Fierer, profesor de ecología y biología evolutiva en CU Boulder y autor correspondiente del estudio. .
Un equipo multiinstitucional de investigadores de campo recolectó muestras de suelo de la isla y las envió al campus de CU Boulder. Dragone y Fierer podrían luego extraer y secuenciar[{» attribute=»»>DNA samples from the samples.
“We didn’t see what we were expecting,” said Dragone. “We thought we’d see organisms you find when a glacier retreats, or cyanobacteria, more typical early colonizer species—but instead we found a unique group of bacteria that metabolize sulfur and atmospheric gases.”
And that wasn’t the only unexpected twist in this work: On January 15, 2022, seven years after it formed, the volcano erupted again, obliterating the entire landmass in the largest volcanic explosion of the 21st century. The eruption completely wiped out the island and eliminated the option for the team to continue monitoring their site.
“We were all expecting the island to stay,” said Dragone. “In fact, the week before the island exploded we were starting to plan a return trip.”
However, the same fickle nature of the Hunga Tonga Hunga Ha’apai (HTHH) that made it explode also explains why the team found such a unique set of microbes on the island. Hunga Tonga was volcanically formed, like Hawaii.
“One of the reasons why we think we see these unique microbes is because of the properties associated with volcanic eruptions: lots of sulfur and hydrogen sulfide gas, which are likely fueling 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 the microbes came from those types of sources.”
The expedition to HTHH required close collaboration with members of the government of the Kingdom of Tonga, who were willing to work with researchers to collect samples from land normally not visited by international guests. Coordination took years of work by collaborators at the Sea Education Association and NASA: a Tongan observer must approve and oversee any sample collection that takes place within the Kingdom.
“This work brought in so many people from around the world, and we learned so much. We are of course disappointed that the island is gone, but now we have a lot of predictions about what happens when islands form,” said Dragone. “So if something formed again, we would love to go there and collect more data. We would have a game plan of how to study it.”
Reference: “The Early Microbial Colonizers of a Short-Lived Volcanic Island in the Kingdom of Tonga” by Nicholas B. Dragone, Kerry Whittaker, Olivia M. Lord, Emily A. Burke, Helen Dufel, Emily Hite, Farley Miller, Gabrielle Page, Dan Slayback and Noah Fierer, 11 January 2023, mBio.
DOI: 10.1128/mbio.03313-22
