There's a 'Desert' in The Middle of The Pacific, And We Now Know What Lives There
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Despite taking up 10 percent of the ocean's surface, the South Pacific Gyre (SPG) – the largest of Earth's five giant ocean-spanning current systems – is generally considered a 'desert' in terms of marine biology.
Nonetheless, stuff does live there, even if organic life in these waters (and the seabed below it) is few and far between, due to a range of factors.
These include distance from land (and the nutrient matter it provides), the way water swirling currents isolate the centre of the gyre from the rest of the ocean, and high UV levels in this part of the ocean.
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During a six-week expedition aboard the German research vessel FS Sonne from December 2015 to January 2016, a crew led by the Max Planck Institute for Marine Microbiology sailed a 7,000-kilometre (4,350 miles) journey through the SPG from Chile to New Zealand.
En route, they sampled the microbial populations of the remote waters at depths between 20 to 5,000 metres (65 ft to 16,400 ft), using a newly developed analysis system that enabled the researchers to sequence and identify organic samples en route in as little as 35 hours.
"To our surprise, we found about a third less cells in South Pacific surface waters compared to ocean gyres in the Atlantic", said one of the researchers, microbial ecologist Bernhard Fuchs, back in July 2019.
"It was probably the lowest cell numbers ever measured in oceanic surface waters."
Among the microbes the team found, 20 major bacterial clades dominated the lot. These were mostly organisms scientists have encountered in other gyre systems, such as SAR11, SAR116, SAR86, Prochlorococcus, and more.
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One of the populations identified, called AEGEAN–169, was particularly numerous in the surface waters of the SPG, whereas previous research had only discovered them at 500-metre depths.
"This indicates an interesting potential adaptation to ultraoligotrophic [low in biological productivity] waters and high solar irradiance", said one of the team, microbiologist Greta Reintjes.
"It is definitely something we will investigate further."
https://www.sciencealert.com/there-s-a-desert-in-the-middle-of-the-pacific-and-we-now-know-what-lives-there