German scientists from the city of Bremen have dedicated research efforts in discovering microbes living in one of the farthest oceans, in the middle of the South Pacific. In the South Pacific Gyre (SPG), solar irradiance is severely high and the UV-index is termed as ‘extreme’. In addition, there are no dust particles and also no inflows from the land; as a result of which the waters contain very low levels of nutrients. This is one of the reasons why the ocean is also termed as ‘ultraoligotrophic’.
Although the ocean is remote, based on situ and satellite measurements, the microorganisms present in the ocean waters of the SPG form part of the global biogeochemical cycles. According to reports, the team conducted the study by means of the German research vessel FS Sonne. Moreover, the study was facilitated by Max Planck Institute for Marine Microbiology.
The study concludes that Chlorophyll-containing phytoplankton (minute algae) were present in the depths of the surface water, greater than hundred meters. This also emphasized that the surface ocean waters were the clearest in the world.
For the study, the team collected samples of microbial community from 15 stations, from water depths, ranging from 20 to 5000 meters, in other words from under the seafloor. However, the scientists discovered a third less cells in the ocean waters, in comparison to ocean gyres from the Atlantic. “It was probably the lowest cell numbers ever measured in oceanic surface waters.” The species of microbes were mostly familiar: “We found similar microbial groups in the SPG as in other nutrient-poor ocean regions, such as Prochlorococcus, SAR11, SAR86 and SAR116,” claims Bernhard Fuchs, one of the lead researchers of the study.
On the plus side however, among the well-lit water surfaces, the scientists discovered AEGEAN-169, an organism which was not previously found in deeper waters of the ocean. Moreover, the researchers concluded that composition of the organisms community changed with the availability of light, resulting into a vertical distribution pattern of microorganisms. According to Greta Reintjes, photosynthetic organism, Prochlorococcus was available in the uppermost waters within 100-150 meters of depth. On the other hand, AEGEAN-169 was present in large numbers on the surface waters of the central gyre. “This indicates an interesting potential adaptation to ultraoligotrophic waters and high solar irradiance. It is definitely something we will investigate further. AEGEAN-169 has so far only been reported in water depths around 500 metres. 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,” according to Reintjes.
The SPG is one of the least discovered and studied regions on the Earth. The current research is termed as a milestone discovery, because scientists could analyse samples right after collection, precisely 35 hours after sampling. The research has paved way to futuristic research in microbial community analysis.