The biomass is the

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...

of living biological

organism In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...

s in a given area or

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syste ...

at a given time. Biomass can refer to ''species biomass'', which is the mass of one or more species, or to ''community biomass'', which is the mass of all species in the community. It can include microorganisms, plants or animals. The mass can be expressed as the average mass per unit area, or as the total mass in the community. How biomass is measured depends on why it is being measured. Sometimes, the biomass is regarded as the natural mass of organisms ''in situ'', just as they are. For example, in a

salmon Salmon () is the common name for several commercially important species of euryhaline ray-finned fish from the family Salmonidae, which are native to tributaries of the North Atlantic (genus ''Salmo'') and North Pacific (genus '' Oncorhy ...

fishery, the salmon biomass might be regarded as the total wet weight the salmon would have if they were taken out of the water. In other contexts, biomass can be measured in terms of the dried organic mass, so perhaps only 30% of the actual weight might count, the rest being

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

. For other purposes, only biological tissues count, and teeth, bones and shells are excluded. In some applications, biomass is measured as the mass of organically bound carbon (C) that is present. The total live biomass on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

is about 550–560 billion tonnes C, and the total annual

primary production In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through ...

of biomass is just over 100 billion tonnes C/yr. The total live biomass of

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

may be as much as that of plants and animals or may be much less. The total number of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at , and weighs 50 billion

tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...

s. Around 2020, anthropogenic mass (human-made material) is expected to exceed all living biomass on earth.

Ecological pyramids

An ecological pyramid is a graphical representation that shows, for a given

, the relationship between biomass or biological productivity and

trophic level The trophic level of an organism is the position it occupies in a food web. A food chain is a succession of organisms that eat other organisms and may, in turn, be eaten themselves. The trophic level of an organism is the number of steps it ...

s. * A ''biomass pyramid'' shows the amount of biomass at each trophic level. * A ''productivity pyramid'' shows the

production Production may refer to: Economics and business * Production (economics) * Production, the act of manufacturing goods * Production, in the outline of industrial organization, the act of making products (goods and services) * Production as a stati ...

or turn-over in biomass at each trophic level. An ecological pyramid provides a snapshot in time of an ecological community. The bottom of the pyramid represents the primary producers (

autotroph An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Wo ...

s). The primary producers take energy from the environment in the form of sunlight or inorganic chemicals and use it to create energy-rich molecules such as carbohydrates. This mechanism is called

. The pyramid then proceeds through the various trophic levels to the

apex predator An apex predator, also known as a top predator, is a predator at the top of a food chain, without natural predators of its own. Apex predators are usually defined in terms of trophic dynamics, meaning that they occupy the highest trophic lev ...

s at the top. When energy is transferred from one trophic level to the next, typically only ten percent is used to build new biomass. The remaining ninety percent goes to metabolic processes or is dissipated as heat. This energy loss means that productivity pyramids are never inverted, and generally limits food chains to about six levels. However, in oceans, biomass pyramids can be wholly or partially inverted, with more biomass at higher levels.

Terrestrial biomass

Terrestrial biomass generally decreases markedly at each higher

(plants, herbivores, carnivores). Examples of terrestrial

producers Producer or producers may refer to: Occupations *Producer (agriculture), a farm operator *A stakeholder of economic production *Film producer, supervises the making of films **Executive producer, contributes to a film's budget and usually does not ...

are grasses, trees and shrubs. These have a much higher biomass than the animals that consume them, such as deer, zebras and insects. The level with the least biomass are the highest

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

s in the

food chain A food chain is a linear network of links in a food web starting from producer organisms (such as grass or algae which produce their own food via photosynthesis) and ending at an apex predator species (like grizzly bears or killer whales), de ...

, such as foxes and eagles. In a temperate grassland, grasses and other plants are the primary producers at the bottom of the pyramid. Then come the primary consumers, such as grasshoppers, voles and bison, followed by the secondary consumers, shrews, hawks and small cats. Finally the tertiary consumers, large cats and wolves. The biomass pyramid decreases markedly at each higher level.

Ocean biomass

Ocean or marine biomass, in a reversal of terrestrial biomass, can increase at higher trophic levels. In the ocean, the food chain typically starts with phytoplankton, and follows the course:

Phytoplankton → zooplankton → predatory zooplankton → filter feeders → predatory fish

Phytoplankton are the main

primary producer Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...

s at the bottom of the marine

. Phytoplankton use

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

to convert inorganic carbon into protoplasm. They are then consumed by zooplankton that range in size from a few micrometers in diameter in the case of

protist A protist () is any eukaryotic organism (that is, an organism whose cells contain a cell nucleus) that is not an animal, plant, or fungus. While it is likely that protists share a common ancestor (the last eukaryotic common ancestor), the exc ...

an microzooplanton to macroscopic gelatinous and crustacean

zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

Zooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

comprise the second level in the food chain, and includes small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s, such as copepods and

krill Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian word ', meaning "small fry of fish", which is also often attributed to species of fish. Krill are consi ...

, and the

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

of fish, squid, lobsters and crabs. In turn, small zooplankton are consumed by both larger predatory zooplankters, such as

, and by

forage fish Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the foo ...

, which are small, schooling,

filter-feeding Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

fish. This makes up the third level in the food chain. A fourth trophic level can consist of predatory fish, marine mammals and seabirds that consume forage fish. Examples are swordfish,

seals Seals may refer to: * Pinniped, a diverse group of semi-aquatic marine mammals, many of which are commonly called seals, particularly: ** Earless seal, or "true seal" ** Fur seal * Seal (emblem), a device to impress an emblem, used as a means of a ...

and

gannet Gannets are seabirds comprising the genus ''Morus'' in the family Sulidae, closely related to boobies. Gannets are large white birds with yellowish heads; black-tipped wings; and long bills. Northern gannets are the largest seabirds in the ...

s. Apex predators, such as

orca The orca or killer whale (''Orcinus orca'') is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member. It is the only extant species in the genus '' Orcinus'' and is recognizable by its black-and-white ...

s, which can consume seals, and

shortfin mako shark The shortfin mako shark (; ; ''Isurus oxyrinchus''), also known as the blue pointer or bonito shark, is a large mackerel shark. It is commonly referred to as the mako shark, as is the longfin mako shark (''Isurus paucus''). The shortfin mako can ...

s, which can consume swordfish, make up a fifth trophic level. Baleen whales can consume zooplankton and krill directly, leading to a food chain with only three or four trophic levels. Marine environments can have inverted biomass pyramids. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is larger than the biomass of primary producers. This happens because the ocean's primary producers are tiny phytoplankton which are r-strategists that grow and reproduce rapidly, so a small mass can have a fast rate of primary production. In contrast, terrestrial primary producers, such as forests, are

K-strategists In ecology, ''r''/''K'' selection theory relates to the selection of combinations of traits in an organism that trade off between quantity and quality of offspring. The focus on either an increased quantity of offspring at the expense of individ ...

that grow and reproduce slowly, so a much larger mass is needed to achieve the same rate of primary production. Among the phytoplankton at the base of the

marine food web Compared to terrestrial environments, marine environments have biomass pyramids which are inverted at the base. In particular, the biomass of consumers (copepods, krill, shrimp, forage fish) is larger than the biomass of primary producers. Th ...

are members from a phylum of bacteria called cyanobacteria. Marine cyanobacteria include the smallest known photosynthetic organisms. The smallest of all, ''

Prochlorococcus ''Prochlorococcus'' is a genus of very small (0.6 μm) marine cyanobacteria with an unusual pigmentation ( chlorophyll ''a2'' and ''b2''). These bacteria belong to the photosynthetic picoplankton and are probably the most abundant photosynth ...

'', is just 0.5 to 0.8 micrometres across. In terms of individual numbers, Prochlorococcus is possibly the most plentiful

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

on Earth: a single millilitre of surface seawater can contain 100,000 cells or more. Worldwide, there are estimated to be several

octillion Two naming scales for large numbers have been used in English and other European languages since the early modern era: the long and short scales. Most English variants use the short scale today, but the long scale remains dominant in many non-Eng ...

(10²⁷) individuals. ''Prochlorococcus'' is ubiquitous between 40°N and 40°S and dominates in the

oligotroph An oligotroph is an organism that can live in an environment that offers very low levels of nutrients. They may be contrasted with copiotrophs, which prefer nutritionally rich environments. Oligotrophs are characterized by slow growth, low rates o ...

ic (nutrient poor) regions of the oceans. The bacterium accounts for an estimated 20% of the

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

in the Earth's atmosphere, and forms part of the base of the ocean

Bacterial biomass

There are typically 50 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. In a much-cited study from 1998, the world bacterial biomass had been mistakenly calculated to be 350 to 550 billions of tonnes of carbon, equal to between 60% and 100% of the carbon in plants. More recent studies of seafloor microbes cast considerable doubt on that; one study in 2012 reduced the calculated microbial biomass on the seafloor from the original 303 billions of tonnes of C to just 4.1 billions of tonnes of C, reducing the global biomass of prokaryotes to 50 to 250 billions of tonnes of C. Further, if the average per-cell biomass of prokaryotes is reduced from 86 to 14 femtograms C, then the global biomass of prokaryotes was reduced to 13 to 44.5 billions of tonnes of C, equal to between 2.4% and 8.1% of the carbon in plants. As of 2018, there continues to be some controversy over what the global bacterial biomass is. A census published by the PNAS in May 2018 gives for bacterial biomass ~70 billions of tonnes of carbon, equal to 15% of the whole biomass. A census by the

Deep Carbon Observatory The Deep Carbon Observatory (DCO) is a global research program designed to transform understanding of carbon's role in Earth. DCO is a community of scientists, including biologists, physicists, geoscientists and chemists, whose work crosses sever ...

project published in December 2018 gives a smaller figure of up to 23 billion tonnes of carbon.

Global biomass

Estimates for the global biomass of species and higher level groups are not always consistent across the literature. The total global biomass has been estimated at about 550 billion tonnes C.Groombridge B, Jenkins MD (2000
''Global biodiversity: Earth’s living resources in the 21st century''
Page 11.

World Conservation Monitoring Centre The UN Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) is a collaboration centre of UN Environment Programme, based in Cambridge in the United Kingdom. UNEP-WCMC has been part of UN Environment Programme since 2000, and has ...

, World Conservation Press, Cambridge Most of this biomass is found on land, with only 5 to 10 billion tonnes C found in the oceans. On land, there is about 1,000 times more plant biomass (''phytomass'') than animal biomass (''zoomass''). About 18% of this plant biomass is eaten by the land animals. Hartley, Sue (2010
The 300 Million Years War: Plant Biomass v Herbivores
'' Royal Institution Christmas Lecture''. However, in the ocean, the animal biomass is nearly 30 times larger than the plant biomass. Most ocean plant biomass is eaten by the ocean animals. Humans compose about 100 million tonnes of the Earth's dry biomass,

domesticate Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...

d animals about 700 million tonnes, earthworms over 1,100 million tonnes, and annual cereal crops about 2.3 billion tonnes. Biomass by life form

The most successful

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

species, in terms of biomass, may well be Antarctic krill, ''Euphausia superba'', with a fresh biomass approaching 500 million

s. As a group, the family of

lanternfish Lanternfishes (or myctophids, from the Greek μυκτήρ ''myktḗr'', "nose" and ''ophis'', "serpent") are small mesopelagic fish of the large family Myctophidae. One of two families in the order Myctophiformes, the Myctophidae are represent ...

are among the most populous

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...

s, with some estimates suggesting that they may have a total global biomass of 550–660 million tonnes, accounting for up to 65% of all deep-sea fish biomass. However, as a group, the small aquatic

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s called copepods may form the largest animal biomass on earth. A 2009 paper in ''Science'' estimates, for the first time, the total world fish biomass as somewhere between 0.8 and 2.0 billion tonnes. It has been estimated that about 1% of the global biomass is due to phytoplankton. File:Cytisus scoparius2.jpg, Grasses, trees and shrubs have a much higher biomass than the animals that consume them File:Antarctic krill (Euphausia superba).jpg, Antarctic krill form one of the largest biomasses of any individual animal species. According to a 2020 study published in ''

Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

'', human-made materials, or anthropogenic mass, outweigh all living biomass on earth, with

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

alone exceeding the mass of all land and marine animals combined.

Global rate of production

Net

is the rate at which new biomass is generated, mainly due to photosynthesis. Global primary production can be estimated from

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisotope ...

observations. Satellites scan the normalised difference vegetation index (NDVI) over terrestrial habitats, and scan sea-surface

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

levels over oceans. This results in 56.4 billion

s C/yr (53.8%), for terrestrial primary production, and 48.5 billion tonnes C/yr for oceanic primary production. Thus, the total

photoautotrophic Photoautotrophs are organisms that use light energy and inorganic carbon to produce organic materials. Eukaryotic photoautotrophs absorb energy through the chlorophyll molecules in their chloroplasts while prokaryotic photoautotrophs use chlorophyll ...

primary production for the Earth is about 104.9 billion tonnes C/yr. This translates to about 426 gC/m²/yr for land production (excluding areas with permanent ice cover), and 140 gC/m²/yr for the oceans. However, there is a much more significant difference in standing stocks—while accounting for almost half of total annual production, oceanic

s account for only about 0.2% of the total biomass. Autotrophs may have the highest global proportion of biomass, but they are closely rivaled or surpassed by microbes. Terrestrial

freshwater ecosystem Freshwater ecosystems are a subset of Earth's aquatic ecosystems. They include lakes, ponds, rivers, streams, springs, bogs, and wetlands. They can be contrasted with marine ecosystems, which have a larger salt content. Freshwater habitats ...

s generate about 1.5% of the global net primary production. Some global producers of biomass in order of productivity rates are

References

External links

The mass of all life on Earth is staggering — until you consider how much we’ve lostTrophic levels
{{DEFAULTSORT:Biomass (Ecology) Ecology terminology Environmental terminology Ecological metrics Ecosystems Fisheries science