In five papers published in the May 22 issue of the journal Science, marine biologists who spent 3.5 years sampling the ocean’s upper layers aboard the schooner Tara unveil the first analyses of the Tara Oceans international consortium.
Planktonic organisms. Image credit: Woods Hole Oceanographic Institution.
During expeditions from 2009 through 2013, the Tara Oceans biologists sampled viruses, microbes and microscopic eukaryotes – organisms with complex cells, from single-cell algae to fish larvae – ultimately collecting over 35,000 planktonic samples from 210 stations in all the major oceanic regions.
The scientists then compiled their genetic material into comprehensive resources that are now available to the scientific community for further studies.
They created an oceanic reference gene catalog comprising more than 40 million genes, most of which are novel – a result that emphasizes the vast reservoir of uncharted genetic diversity in marine plankton communities.
“This is the largest DNA sequencing effort ever done for ocean science: analyses revealed around 40 million genes, the vast majority of which are new to science, thus hinting towards a much broader biodiversity of plankton than previously known,” said consortium member Dr Patrick Wincker of the GENOSCOPE Institut de Génomique in Evry, France.
According to the researchers, ocean temperatures appear to be the main factor driving plankton community makeup, hinting that increasing water temperature will have a big impact on oceanic microbial life.
The scientists also created a catalogue of eukaryotic biodiversity among marine phytoplankton, estimating about 150,000 genetic types of eukaryotes, many more than described in the current literature.
“In terms of eukaryotes, we sequenced nearly a billion genetic barcodes, and found that there is a greater variety of single-cell eukaryotes in plankton than was thought. They appear to be much more diverse than bacteria or animals, and most belong to little-known groups,” said Dr Colomban de Vargas of CNRS, France.
The researchers also developed an overview of how planktonic viruses are distributed in oceans worldwide.
They used all of these data sets to create a map of plankton species interactions and to understand how plankton distribution is impacted by environmental changes, like fast-moving ocean currents.
“The Tara Oceans expeditions have generated a treasure trove of data available to anyone willing to dive in and start addressing the questions,” the scientists said.
Future analysis of the Tara Oceans data is likely to help address questions about how plankton will adapt to such changes.
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