New estimate of living biomass: One third less life on planet Earth

Aug 27, 2012
Satellite measurements of the nutrient content of the oceans. Dots mark places where seaborne measurements were taken. In the southern Pacific a vast area is found where nutrient contents were not existent. © GFZ, Jens Kallmeyer

Estimates of the total mass of all life on Earth should be reduced by about one third, based on the results of a study by a team of scientists at the University of Rhode Island's Graduate School of Oceanography and colleagues in Germany.

The research was published this week in the Proceedings of the National Academy of Science.

According to previous estimates, about one thousand billion tons of carbon is stored in living organisms, of which 30 percent is in single-cell microbes in the ocean floor and 55 percent reside in land plants. The researchers have now revised the number downward. Instead of 300 billion tons of carbon in subseafloor microbes, they estimate these organisms contain only about 4 billion tons. This reduces the total amount of carbon stored in living organisms by about one-third.

"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," explained Rob Pockalny, URI associate marine research scientist. "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."

Earlier estimates were based on drill cores that were taken close to shore or in very nutrient-rich areas.

"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," explained Jens Kallmeyer at the University of Potsdam, Germany. "Unfortunately there were no data to prove it."

So the research team, which also included URI oceanographers David Smith and Steven D'Hondt, collected sediment cores from areas that were far away from any coasts and islands. The six-year work showed that there were up to 100,000 times fewer cells in sediments from open-ocean areas, which are dubbed "deserts of the sea" due to their extreme nutrient depletion, than in coastal sediments.

Pockalny said that the scientists were able to make predictions about microbial distributions in some regions of the world's oceans based on simple parameters like sediment accumulation rate and distance from shore.

With this new data, the scientists recalculated the total biomass in marine sediments and found drastically lower values. The new findings contribute to a better picture of the distribution of living biomass on Earth.

Despite of the high logistical and financial efforts for marine drilling operations, there are more data about the abundance of living biomass in the sea floor than about their abundance on land.

Explore further: NASA image: Volcanoes in Guatemala

More information: Jens Kallmeyer et al.: "Global distribution of microbial abundance and biomass in subseafloor sediment", PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1203849109

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User comments : 9

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Jeddy_Mctedder
2 / 5 (4) Aug 27, 2012
yet another reason to focus ocean research on the coastal shelves and not on deep sea studies.
Torbjorn_Larsson_OM
not rated yet Aug 27, 2012
In which case we would never have found this out. The "deep biosphere" is important, no less for astrobiology.
Cave_Man
1 / 5 (1) Aug 27, 2012
...30% of life on earth is on the ocean floor. That's what people want to dredge for more resources and rare earth elements. I'm sure that wont have unintended consequences...
Cornelius2008
not rated yet Aug 27, 2012
So are these living organisms on the sea floor that they thought made up the 400 billion tons, or single celled organisms that die and float down to the sea floor and build up a type of sediment layer?
Squirrel
not rated yet Aug 28, 2012
The paper is free via Open Access ie not paywalled at the above link.
triplehelix
1 / 5 (2) Aug 28, 2012
"Instead of 300 billion tons of carbon there are only about 4 billion tons stored in subseafloor microbes. This reduces the total amount of carbon stored in living organisms by about one third.

"

4 billion is one third of 300 billion?

You cant create or destroy matter. Earth has a finite amount of carbon. It's all locked up in crude oils and coal deep deep in the Earth, not to be seen again for many years unless we dig it up. Burn it, make CO2, plants utilize CO2 for sugars, more algae, plants etc, more carbon sources for herbivores, ergo more carbon sources for carnivores. We're carbon based and a lot is locked up from 500 millions years of deaths of organisms and getting stuck underground, "forever" lost in the carbon cycle (until we started digging it up)
antialias_physorg
5 / 5 (1) Aug 28, 2012
4 billion is one third of 300 billion?

No.
4 billion instead of 300bn in SUBSURFACE organisms means one third less of TOTAL carbon summed over ALL organisms (land dwelling, ocean dwelling, and subsurface)

You cant create or destroy matter

No. What you cannot create or destroy is its ENERGY content. You can destroy matter by turning it into energy (and you can create matter by turning energy into matter).

Destruction of matter happens in every nuclear reactor (actually in every exothermic reaction/conversion that uses a solid/liquid/gas as fuel - even in your car engine the mass of the exhausts is less than the mass of he gasoline)
Creation of matter happens in places like the LHC.

The rest of your post makes absolutely no sense. But from the mistakes in the first parts I would guess it's wrong, also.
Deathclock
1 / 5 (2) Aug 28, 2012
one thousand billion?

Is there something wrong with the word "trillion" that I am not aware of?
Deathclock
1 / 5 (2) Aug 28, 2012
No. What you cannot create or destroy is its ENERGY content. You can destroy matter by turning it into energy (and you can create matter by turning energy into matter).


I'd hesitate to use the word destroy here, a more apt word would be convert... It's all a matter of semantics and classification anyway, and I am sure we both realize that, but the fact that we have never witnessed the actual creation or destruction of anything (rather than the semantic "destruction" of a defined "thing" by converting into another "thing") is an important point in debating the creationist idiots.

I don't know if you share this view, but I consider matter simply the physical manifestation of energy above a certain density. With enough energy in a small enough area it behaves as matter. I consider matter to be energy, it's an arbitrary defined state of energy.

And I am sure you know that we can calculate the energy content of any object using only it's mass via mass-energy equivalency, e=mc^2

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