There's an underwater desert in the middle of the South Pacific that's known to be one of the most remote, uninhabitable regions in the planet.
A Remote, Lifeless Desert
Known as the South Pacific Gyre, this region covers an area that's about 14.2 million square miles (37 million square kilometers), which makes it more than three times the size of the United States. It is so far from land and so devoid of life that this desert has become one of the least studied areas in existence.
Found in the oceanic pole of inaccessibility, it is a place where no complex life forms exist due to extremely high UV radiation. Since it is so isolated, there are no dust particles or inflows from land, which makes the waters extremely low in nutrient concentrations or "ultraoligotrophic."
Despite the extreme conditions of this inhospitable desert, microorganisms survive in the South Pacific Gyre and even contribute greatly to biogeochemical cycles worldwide.
To learn more about the living organisms in these waters, scientists led by the Max Planck Institute for Marine Microbiology sailed through this enormous expanse of water and collected hundreds of samples from near the surface all the way down to the seafloor.
Surprising Organisms And Their Distributions
Findings published in the journal Applied and Environmental Microbiology revealed valuable insights on the microorganisms that live in the South Pacific Gyre, including their strange distribution patterns.
"To our surprise, we found about a third less cells in South Pacific surface waters compared to ocean gyres in the Atlantic," study author Bernhard Fuchs said in a press release, adding that their findings probably featured the lowest cell numbers measured in oceanic surface waters ever. "We found similar microbial groups in the SPG as in other nutrient-poor ocean regions, such as Prochlorococcus, SAR11, SAR86 and SAR116."
Additionally, there was a clear vertical distribution pattern when it comes to microorganisms in the South Pacific Gyre. According to study author Greta Reintjes, the community composition varied with the change in depth and availability of light.
An unexpected discovery was the distribution of the dominant photosynthetic organism Prochlorococcus, which were found in greater numbers at depths of 328 to 492 feet (100 to 150 meters) than closer to the surface. On the other hand, AEGEAN-169 was found to be plentiful in surface waters, which is surprising given that it has only been previously reported in much deeper waters of around 1,640 feet (500 meters).
"This indicates an interesting potential adaptation to ultraoligotrophic waters and high solar irradiance," Reintjes explained. "It is likely that there are multiple ecological species within this group and we will carry out further metagenomic studies to examine their importance in the most oligotrophic waters of the SPG."
