Biomass
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In the ocean, the food chain typically follows the course:
Phytoplankton is usually the primary producer (the first level in the food chain or the first trophic level). Phytoplankton converts inorganic carbon into protoplasm. Phytoplankton is consumed by microscopic animals called zooplankton. These are the second level in the food chain, and include krill, the larva of fish, squid, lobsters and crabs–as well as the small crustaceans called copepods, and many other types. Zooplankton is consumed both by other, larger predatory zooplankters and by fish (the third level in the food chain). Fish that eat zooplankton could constitute the fourth trophic level, while seals consuming the fish are the fifth. Alternatively, for example, whales may consume zooplankton directly - leading to an environment with one less trophic level.
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Global primary production can be estimated from satellite observations. Satellites scan the normalised difference vegetation index (NDVI) over terrestrial habitats, and scan sea-surface chlorophyll levels over oceans. This results in 56.4 billion tonnes C/yr (53.8%), for terrestrial primary production, and 48.5 billion tonnes C/yr for oceanic primary production. Thus, the total photoautotrophic 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 autotrophs account for only about 0.2% of the total biomass. The most successful animal species, in terms of biomass, is probably the Antarctic krill, Euphausia superba, with a biomass of about 500 million tonnes. However, as a group, the small aquatic crustaceans called copepods form the largest animal biomass on earth. |
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| Biome Ecosystem Type | Area | Mean Net Primary Production | World Primary Production | Mean biomass | World biomass | Minimum replacement rate |
| (million km²) | (gram dryC / m² / year) | (billion tonnes / year) | (kg dryC / m²) | (billion tonnes) | (years) | |
| Open ocean | 332.00 | 125.00 | 41.50 | 0.003 | 1.00 | 0.02 |
| Upwelling zones | 0.40 | 500.00 | 0.20 | 0.02 | 0.01 | 0.04 |
| Continental shelf | 26.60 | 360.00 | 9.58 | 0.01 | 0.27 | 0.03 |
| Algal beds and reefs | 0.60 | 2,500.00 | 1.50 | 2.00 | 1.20 | 0.80 |
| Estuaries & mangroves | 1.40 | 1,500.00 | 2.10 | 1.00 | 1.40 | 0.67 |
| Total marine | 361.00 | 152.01 | 54.88 | 0.01 | 3.87 | 0.07 |
| Lakes and streams | 2.00 | 250.00 | 0.50 | 0.02 | 0.04 | 0.08 |
| Terrestrial | 147.00 | 554.51 | 114.90 | 12.55 | 1,873.38 | 16.15 |
| Grand total | 510.00 | 333.87 | 170.28 | 3.68 | 1,877.29 | 11.02 |
| Source: Whittaker, R. H.; Likens, G. E. (1975). "The Biosphere and Man". In Leith, H & Whittaker, R H. Primary Productivity of the Biosphere. Springer-Verlag. pp. 305–328. ISBN 0-387-07083-4. ; Ecological Studies Vol 14 (Berlin)
Darci and Taylre are biomass specialists. |
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Read more about this topic: Wild Fisheries, Marine Fisheries