Zooplankton

Zooplankton (/ˈzoʊ.əˌplæŋktən, ˈzuː(ə)-, ˈzoʊoʊ-/,[1] /ˌzoʊ.əˈplæŋktən, -tɒn/)[2] are heterotrophic (sometimes detritivorous) plankton (cf. phytoplankton). Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word zooplankton is derived from the Greek zoon (ζῴον), meaning "animal", and planktos (πλαγκτός), meaning "wanderer" or "drifter".[3] Individual zooplankton are usually microscopic, but some (such as jellyfish) are larger and visible to the naked eye.

Zooplankton sample including fish eggs, doliolids, several species of copepods, and gastropod and decapod larva

Ecology

Zooplankton is a categorization spanning a range of organism sizes including small protozoans and large metazoans. It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile, benthic existence. Although zooplankton are primarily transported by ambient water currents, many have locomotion, used to avoid predators (as in diel vertical migration) or to increase prey encounter rate.

  • Typical models featuring zooplankton
  • Right: Ecosystem models

    Lower left: Size-spectra models

    These models also have temporal and spatial components.[4]

Ecologically important protozoan zooplankton groups include the foraminiferans, radiolarians and dinoflagellates (the last of these are often mixotrophic). Important metazoan zooplankton include cnidarians such as jellyfish and the Portuguese Man o' War; crustaceans such as copepods, ostracods, isopods, amphipods, mysids and krill; chaetognaths (arrow worms); molluscs such as pteropods; and chordates such as salps and juvenile fish. This wide phylogenetic range includes a similarly wide range in feeding behavior: filter feeding, predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton, phytoplankton, other zooplankton (sometimes cannibalistically), detritus (or marine snow) and even nektonic organisms. As a result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant.

Just as any species can be limited within a geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, ‘patches’ of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic, specific species of zooplankton are strictly restricted by salinity and temperature gradients; while other species can withstand wide temperature and salinity gradients.[5] Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration.[5] The physical factor that influences zooplankton distribution the most is mixing of the water column (upwelling and downwelling along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production.[5]

Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs, as a resource for consumers on higher trophic levels (including fish), and as a conduit for packaging the organic material in the biological pump. Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance, during the spring bloom. Zooplankton are also a key link in the biomagnification of pollutants such as mercury.[6]

Zooplankton can also act as a disease reservoir. Crustacean zooplankton have been found to house the bacterium Vibrio cholerae, which causes cholera, by allowing the cholera vibrios to attach to their chitinous exoskeletons. This symbiotic relationship enhances the bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen.[7]

Zooplankton diversity
Sloppy feeding by zooplankton
DOC = dissolved organic carbon. POC = particulate organic carbon. Adapted from Møller et al. (2005),[8] Saba et al. (2009)[9] and Steinberg et al. (2017).[10]
gollark: It was for wireless redstone.
gollark: I actually did write code for redstone communications!
gollark: You realise that "uses rednet" also isn't the same as "will do things if you send random messages to their ID", right?
gollark: Superuberpotatowhatever: LabelNet.
gollark: Ultrachad websocket-based systems.

See also

References
  1. "zooplankton - definition of zooplankton in English from the Oxford dictionary". OxfordDictionaries.com. Retrieved 2016-01-20.
  2. "Zooplankton". Merriam-Webster Dictionary.
  3. Thurman, H. V. (1997). Introductory Oceanography. New Jersey, USA: Prentice Hall College. ISBN 978-0-13-262072-7.
  4. Everett, J.D., Baird, M.E., Buchanan, P., Bulman, C., Davies, C., Downie, R., Griffiths, C., Heneghan, R., Kloser, R.J., Laiolo, L. and Lara-Lopez, A. (2017) "Modeling what we sample and sampling what we model: challenges for zooplankton model assessment". Frontiers in Marine Science, 4: 77. doi:10.3389/fmars.2017.00077. Material was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
  5. Lalli, C.M. & Parsons, T.R. (1993). Biological Oceanography An Introduction. Burlington, MA: Elsevier. p. 314. ISBN 978-0-7506-3384-0.
  6. "How We Do Things at IISD-ELA: Researching Mercury". IISD. 2017-04-05. Retrieved 2020-07-06.
  7. Jude, B.A.; Kirn, T.J.; Taylor R.K. (2005). "A colonization factor links Vibrio cholerae environmental survival and human infection". Nature. 438 (7069): 863–6. Bibcode:2005Natur.438..863K. doi:10.1038/nature04249. PMID 16341015.
  8. Møller EF, Thor P, Nielson TG (2003) "Production of DOC by Calanus finmarchicus, C. glacialis and C. hyperboreus through sloppy feeding and leakage from fecal pellets". Marine Ecology Progress Series, 262: 185–91. doi:10.3354/meps262185.
  9. Saba GK, Steinberg DK, Bronk DA (2009) "Effects of diet on release of dissolved organic and inorganic nutrients by the copepod Acartia tonsa". Marine Ecology Progress Series, 386: 147–61. doi:10.3354/meps08070.
  10. Steinberg, D.K. and Landry, M.R. (2017) "Zooplankton and the ocean carbon cycle". Annual Review of Marine Science, 9: 413–444. doi:10.1146/annurev-marine-010814-015924.
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