In a bid to better understand these microscopic lifeforms, a team of scientists spent six weeks sailing through the South Pacific Gyre—an ocean void covering an area greater than 14 million square miles.
The South Pacific Gyre is home to the oceanic pole of inaccessibility—the point on Earth that is farthest from any continent. It sits 1,670 miles from the nearest land, an uninhabited atoll to the north, Easter Island to the northeast and Antarctica to the south.
It is so remote and uninhabited, it is used as a spacecraft cemetery. It is also known to have a garbage patch, where plastic pollution has accumulated.
There are a number of reasons why life struggles to exist there. Solar radiation is extremely high, having the UV Index label “extreme.” This means anything exposed to the Sun is at risk of significant damage. The water is also particularly poor in nutrients—its distance from any land means there is a limited inward flow of dust particles—and phytoplankton, which forms the best of many aquatic food webs, is only found deep beneath the surface.
Finally, a gyre by definition is a massive system of rotating ocean currents—so the movement of the water means the area is largely isolated.
Despite this, satellite images show there is some life in the South Pacific Gyre—in the form of microscopic organisms.
Researchers from the Max Planck Institute for Marine Microbiology in Bremen, Germany spent six weeks sailing through the South Pacific Gyre to make an inventory of this microbial community. The team took water samples along a 4,350 stretch of the ocean desert. The samples were taken from depths between 65 feet and 3.1 miles—the sea floor. Using an onboard tool, the team was able to analyze the microbial organisms in the water instantly.
Findings showed that the South Pacific Gyre surface waters had about a third fewer cells than the gyres in the Atlantic, Bernhard Fuchs, one of the expedition leaders, said in a statement. “It was probably the lowest cell numbers ever measured in oceanic surface waters,” he said, adding that they found similar microbe groups in their samples as in other nutrient poor regions of the ocean.
However, the surface water was also found to contain AEGEAN-169, an organism that has only ever been discovered in deeper waters. This suggests it has adapted to the extreme solar irradiance. “It is definitely something we will investigate further,” Greta Reintjes, another of the research leaders, said.
Publishing their findings in the journal Applied and Environmental Microbiology, the team says the analysis technique they developed will help drive the understanding of microbial communities—including those in extreme and remote regions like the South Pacific Gyre.