5: Take-home messages
- Page ID
- 25881
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- The census of biomass distribution (≈550 Gt C) on Earth provides an integrated global picture of the relative and absolute abundances of all kingdoms of life: plants (≈450 Gt C), bacteria (≈70 Gt C), archaea (≈7 Gt C), and animals (≈2 Gt C) ;
- Terrestrial biomass is about two orders of magnitude higher than marine biomass, and a total of ≈6 Gt C is estimated in marine organisms;
- Plant biomass (which dominates the biosphere) is mostly located on land; it accounts for less than 10% of the total biomass in the ocean.
- Animals, protists, and bacteria together account for ≈80% of marine biomass, whereas on land they account for only ≈2%.
- The animal biomass is predominantly marine; it consists of small mesopelagic fish and crustaceans, mainly copepods, shrimp, and krill.
- The marine environment is primarily occupied by microbes, primarily bacteria and protists, which account for ≈70% of the total marine biomass. The remaining ≈30% is primarily composed of arthropods and fish.
- Viruses dominate the ocean in terms of numbers but constitute only ≈1% of the total biomass.
- The deep subsurface holds ≈15% of the total biomass of the biosphere. It is mainly composed of bacteria and archaea.
- The global marine biomass pyramid contain much more consumers (≈5 Gt C) than producers (≈1 Gt C). Conversely, on land, the biomass of primary producers (≈450 Gt C) is much larger than that of primary and secondary consumers (≈20 Gt C).
- The mass of humans is an order of magnitude greater than that of all wild mammals combined.
- Humans have had a historical impact on the overall biomass of most important taxa, namely:
- The huge decrease in total biomass of wild animals, including fish;
- The gain in total mammalian biomass due to livestock husbandry;
- The profound reshaping in the total quantity of carbon sequestered by plants.
- The main gaps in our knowledge concern the distribution of biomass among different microbial taxa, such as bacteria, archaea, protists and fungi.
- Our knowledge of the biomass composition of the different taxa is mainly determined by our ability to sample, for example, in deep marine subsurface environments.