By Emily Greenhalgh
PBN Web Editor
NARRAGANSETT – There is one-third less life on Earth than previously thought, according to a study published by scientists at the University of Rhode Island’s Graduate School of Oceanography and researchers in Germany.
Previous scientific estimates stated that roughly 1 trillion tons of carbon is stored in living organisms with 30 percent of that present in single-cell microbes on and below the ocean floor and 55 percent present in land plants.
The research, published in the Proceedings of the National Academy of Science, shows that the amount of carbon present in sub-seafloor microbes is closer to 4 billion tons rather than the previously estimated 300 billion tons. This reduces the total amount of carbon stored in living organisms by one-third and paints a better picture of the distribution of living biomass on Earth.
According to the URI scientists, previous estimates were derived from drill cores that were taken in very nutrient-rich areas close to shore. “About half of the world’s ocean is extremely nutrient-poor. For the last 10 years it was already suspected that sub-seafloor biomass was overestimated,” Jens Kallmeyer, from Germany’s University of Potsdam, said in a statement. “Unfortunately there were no data to prove it.”
Over a six-year period, the URI scientists and their German research associates collected sediment cores from areas of the ocean floor that were far away from both coasts and islands. Their research showed there were up to 100,000 times fewer cells in sediments from the open-ocean areas – called “deserts of the sea” – than in coastal sediments.
“Previous estimates of microbial biomass in the ocean sediments were hindered by a limited number of sample locations preferentially located in near-shore, high-productivity regions,” Rob Pockalny, URI associate marine research scientist, said in a prepared statement. “With support from the National Science Foundation, we were able to obtain samples from the middle of the Pacific Ocean in some of the lowest productivity regions in the ocean.”
From their findings, the scientists made predictions about the distribution of microbial organisms based on simple parameters such as sediment accumulation rate and distance from shore. Using this new data, the team of scientists recalculated the total biomass in marine sediments and found that values dropped dramatically compared to previous estimates.