Editing Biomass (ecology) (section)

==Ocean biomass==
{{marine food chain}}
{{see also|Marine life}}

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:
<blockquote>
Phytoplankton → zooplankton → predatory zooplankton → [[filter feeder]]s → predatory fish
</blockquote>

[[File:Arctic food web.svg|thumb|320px|left| {{center|[[Ocean food web]] showing a network of food chains}}]]
[[File:Numbers Pyramid.svg|thumb|250px| {{center|'''[[Biomass pyramid]]s'''<br />Compared to terrestrial biomass pyramids, aquatic pyramids are inverted at the base}}]]
[[File:Prochlorococcus marinus (cropped).jpg|thumb|150px| {{center|''[[Prochlorococcus]]'', an influential bacterium}}]]

[[Phytoplankton]] are the main [[primary producer]]s at the bottom of the marine [[food chain]]. Phytoplankton use [[photosynthesis]] 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]]an microzooplankton to macroscopic gelatinous and crustacean [[zooplankton]].

[[Zooplankton]] comprise the second level in the food chain, and includes small [[crustacean]]s, such as [[copepod]]s and [[krill]], and the [[larva]] of fish, squid, lobsters and crabs.

In turn, small zooplankton are consumed by both larger predatory zooplankters, such as [[krill]], and by [[forage fish]], which are small, schooling, [[filter feeding|filter-feeding]] 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]], [[Pinniped|seals]] and [[gannet]]s.

Apex predators, such as [[orca]]s, which can consume seals, and [[shortfin mako shark]]s, which can consume swordfish, make up a fifth trophic level. [[Baleen whale]]s 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]] 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]] are members from a phylum of bacteria called [[cyanobacteria]]. Marine cyanobacteria include the smallest known [[Photosynthesis|photosynthetic]] organisms. The smallest of all, ''[[Prochlorococcus]]'', is just 0.5 to 0.8 micrometres across.<ref>{{cite journal | vauthors = Kettler GC, Martiny AC, Huang K, Zucker J, Coleman ML, Rodrigue S, Chen F, Lapidus A, Ferriera S, Johnson J, Steglich C, Church GM, Richardson P, Chisholm SW | title = Patterns and implications of gene gain and loss in the evolution of Prochlorococcus | journal = PLOS Genetics | volume = 3 | issue = 12 | pages = e231 | date = December 2007 | pmid = 18159947 | pmc = 2151091 | doi = 10.1371/journal.pgen.0030231 | doi-access = free }}</ref> In terms of individual numbers, Prochlorococcus is possibly the most plentiful [[species]] on Earth: a single millilitre of surface seawater can contain 100,000 cells or more. Worldwide, there are estimated to be several [[octillion]] (10<sup>27</sup>) individuals.<ref>{{Cite APOD |date=27 September 2006 |title=Earth from Saturn }}</ref> ''Prochlorococcus'' is ubiquitous between 40°N and 40°S and dominates in the [[oligotroph]]ic (nutrient poor) regions of the oceans.<ref>{{cite journal | vauthors = Partensky F, Hess WR, Vaulot D | title = Prochlorococcus, a marine photosynthetic prokaryote of global significance | journal = Microbiology and Molecular Biology Reviews | volume = 63 | issue = 1 | pages = 106–127 | date = March 1999 | pmid = 10066832 | pmc = 98958 | doi = 10.1128/MMBR.63.1.106-127.1999 }}</ref> The bacterium accounts for an estimated 20% of the [[oxygen]] in the Earth's [[atmosphere]], and forms part of the base of the ocean [[food chain]].<ref name="npr">{{cite web|url=https://www.npr.org/templates/story/story.php?storyId=91448837|title=The Most Important Microbe You've Never Heard Of|website=npr.org|access-date=3 April 2018|archive-date=19 October 2023|archive-url=https://web.archive.org/web/20231019060753/http://www.npr.org/templates/story/story.php?storyId=91448837|url-status=live}}</ref>