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5: Take-home messages

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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.

    5: Take-home messages is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts.

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