Life On Earth Just Got Smaller
August 28, 2012

Researchers Find That There Is One Third Less Life On Planet Earth

April Flowers for - Your Universe Online

A German research team has deduced that the total biomass of all life on our planet is approximately one-third less than was previously estimated.

The study, published in the current online issue of Proceedings of the National Academy of Science, shows that previous estimates of seafloor biomass were off by quite a bit. Earlier estimates put the total mass at about one thousand billion tons of carbon being stored in living organisms, of which 30% was in single-cell microbes in the ocean floor and 55% reside in land plants.

Dr. Jens Kallmeyer of the GFZ German Research Centre for Geosciences and the University of Potsdam, along with his research team, has revised this original number. Instead of 300 billion tons of carbon in subseafloor microbes, there are only about 4 billion tons. This reduced the total amount of carbon stored in living organisms by about one third.

Based on drill cores that were taken close to shore or in very nutrient-rich areas, previous estimates were skewed.

"About half of the world's ocean is extremely nutrient-poor. For the last 10 years it was already suspected that subseafloor biomass was overestimated" explains Dr. Jens Kallmeyer. "Unfortunately there were no data to prove it"

Kallmeyer, along with colleagues from the University of Potsdam and the University of Rhode Island, collected sediment cores from areas that were far away from any coasts or islands. The six-year study showed that there were up to one hundred thousand times less cells in sediments from open-ocean areas, which are dubbed "deserts of the sea" due to their extreme nutrient depletion, than in coastal sediments.

This new data allowed the team to recalculate the total biomass in marine sediments, finding these new, drastically lower values.

Despite prohibitive financial and logistical concerns for marine drilling operations, there are more data of the abundance of living biomass in the seafloor than of their abundance on land.

"Our new results show the need to re-examine the other numbers as e.g. the amount of carbon in deep sediments on land," Jens Kallmeyer states. In particular the research into the "Deep Biosphere" is still in the fledgling stages; this is life that can be found in kilometer's depth inside the Earth's crust. The new findings contribute to a better picture of the distribution of living biomass on Earth.