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Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.
Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
The biological pump (or ocean carbon biological pump or marine biological carbon pump) is the ocean's biologically driven sequestration of carbon from the atmosphere and land runoff to the ocean interior and seafloor sediments. In other words, it is a biologically mediated process which results in the sequestering of carbon in the deep ocean away from the atmosphere and the land. The biological pump is the biological component of the "marine carbon pump" which contains both a physical and biological component. It is the part of the broader oceanic carbon cycle responsible for the cycling of organic matter formed mainly by phytoplankton during photosynthesis (soft-tissue pump), as well as the cycling of calcium carbonate (CaCO3) formed into shells by certain organisms such as plankton and mollusks (carbonate pump).
The mesopelagiczone, also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins at the depth where only 1% of incident light reaches and ends where there is no light; the depths of this zone are between approximately 200 to 1,000 meters below the ocean surface.
The oxygen minimum zone (OMZ), sometimes referred to as the shadow zone, is the zone in which oxygen saturation in seawater in the ocean is at its lowest. This zone occurs at depths of about 200 to 1,500 m (700–4,900 ft), depending on local circumstances. OMZs are found worldwide, typically along the western coast of continents, in areas where an interplay of physical and biological processes concurrently lower the oxygen concentration and restrict the water from mixing with surrounding waters, creating a "pool" of water where oxygen concentrations fall from the normal range of 4–6 mg/L to below 2 mg/L.
Thin layers are concentrated aggregations of phytoplankton and zooplankton in coastal and offshore waters that are vertically compressed to thicknesses ranging from several centimeters up to a few meters and are horizontally extensive, sometimes for kilometers. Generally, thin layers have three basic criteria: 1) they must be horizontally and temporally persistent; 2) they must not exceed a critical threshold of vertical thickness; and 3) they must exceed a critical threshold of maximum concentration. The precise values for critical thresholds of thin layers has been debated for a long time due to the vast diversity of plankton, instrumentation, and environmental conditions. Thin layers have distinct biological, chemical, optical, and acoustical signatures which are difficult to measure with traditional sampling techniques such as nets and bottles. However, there has been a surge in studies of thin layers within the past two decades due to major advances in technology and instrumentation. Phytoplankton are often measured by optical instruments that can detect fluorescence such as LIDAR, and zooplankton are often measured by acoustic instruments that can detect acoustic backscattering such as ABS. These extraordinary concentrations of plankton have important implications for many aspects of marine ecology, as well as for ocean optics and acoustics. Zooplankton thin layers are often found slightly under phytoplankton layers because many feed on them. Thin layers occur in a wide variety of ocean environments, including estuaries, coastal shelves, fjords, bays, and the open ocean, and they are often associated with some form of vertical structure in the water column, such as pycnoclines, and in zones of reduced flow.
Diel vertical migration (DVM), also known as diurnal vertical migration, is a pattern of movement used by some organisms, such as copepods, living in the ocean and in lakes. The word "diel" comes from Latin: diēs, lit. 'day', and means a 24-hour period. The migration occurs when organisms move up to the uppermost layer of the sea at night and return to the bottom of the daylight zone of the oceans or to the dense, bottom layer of lakes during the day. It is important to the functioning of deep-sea food webs and the biologically driven sequestration of carbon.
Calanus finmarchicus is a species of copepod and a component of the zooplankton, which is found in enormous amounts in the northern Atlantic Ocean.
Neuston, also called pleuston, are organisms that live at the surface of a body of water, such as an ocean, estuary, lake, river, or pond. Neuston can live on top of the water surface or may be attached to the underside of the water surface. They may also exist in the surface microlayer that forms between the top side and the underside. Neuston have been defined as "organisms living at the air/water interface of freshwater, estuarine, and marine habitats or referring to the biota on or directly below the water’s surface layer."
Gelatinous zooplankton are fragile animals that live in the water column in the ocean. Their delicate bodies have no hard parts and are easily damaged or destroyed. Gelatinous zooplankton are often transparent. All jellyfish are gelatinous zooplankton, but not all gelatinous zooplankton are jellyfish. The most commonly encountered organisms include ctenophores, medusae, salps, and Chaetognatha in coastal waters. However, almost all marine phyla, including Annelida, Mollusca and Arthropoda, contain gelatinous species, but many of those odd species live in the open ocean and the deep sea and are less available to the casual ocean observer. Many gelatinous plankters utilize mucous structures in order to filter feed. Gelatinous zooplankton have also been called Gelata.
Ocean deoxygenation is the reduction of the oxygen content in different parts of the ocean due to human activities. It occurs firstly in coastal zones where eutrophication has driven some quite rapid declines in oxygen to very low levels. This type of ocean deoxygenation is also called "dead zones". Secondly, there is now an ongoing reduction in oxygen levels in the open ocean: naturally occurring low oxygen areas are now expanding slowly. This expansion is happening as a consequence of human caused climate change. The resulting decrease in oxygen content of the oceans poses a threat to marine life, as well as to people who depend on marine life for nutrition or livelihood. Ocean deoxygenation poses implications for ocean productivity, nutrient cycling, carbon cycling, and marine habitats.
Acartia hudsonica is a species of marine copepod belonging to the family Acartiidae. Acartia hudsonica is a coastal, cold water species that can be found along the northwest Atlantic coast.
The benthic boundary layer (BBL) is the layer of water directly above the sediment at the bottom of a body of water. Through specific sedimentation processes, certain organisms are able to live in this deep layer of water. The BBL is generated by the friction of the water moving over the surface of the substrate, which decrease the water current significantly in this layer. The thickness of this zone is determined by many factors, including the Coriolis force. The benthic organisms and processes in this boundary layer echo the water column above them.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
Particulate organic matter (POM) is a fraction of total organic matter operationally defined as that which does not pass through a filter pore size that typically ranges in size from 0.053 millimeters (53 μm) to 2 millimeters.
Mark D. Ohman is an American Biological Oceanographer. He is Distinguished Professor of the Graduate Division at the Scripps Institution of Oceanography, University of California, San Diego. He is Director and Lead Principal Investigator of the California Current Ecosystem Long-Term Ecological Research site, supported by the U.S. National Science Foundation.
The lipid pump sequesters carbon from the ocean's surface to deeper waters via lipids associated with overwintering vertically migratory zooplankton. Lipids are a class of hydrocarbon rich, nitrogen and phosphorus deficient compounds essential for cellular structures. This lipid carbon enters the deep ocean as carbon dioxide produced by respiration of lipid reserves and as organic matter from the mortality of zooplankton.
A micronekton is a group of organisms of 2 to 20 cm in size which are able to swim independently of ocean currents. The word 'nekton' is derived from the Greek νήκτον, translit. nekton, meaning "to swim", and was coined by Ernst Haeckel in 1890.
Carin Jessica Ashjian is an American biological oceanographer who is an associate scientist at the Woods Hole Oceanographic Institution. She studies how the physical environment influences the distribution of plankton in the Beaufort Sea.
Kendra Lee Daly is an oceanographer known for her work on zooplankton, particularly in low oxygen regions of the ocean. She is a professor at the University of South Florida, and an elected fellow of the American Association for the Advancement of Science.
References
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- ↑ Wishner, Karen Frances (1980). The biomass and ecology of the deep-sea benthopelagic (near-bottom) plankton (Thesis). Ann Arbor, Mich: Univ. Microfilms International. OCLC 935018063.
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- ↑ Howarth, Colin (April 5, 2018). "Worthy 'Endeavor': Community invited to participate in vessel's whale research mission". The Independent. Retrieved 2021-12-04.
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- ↑ Wishner, K. F.; Meise-Munns, C. J. (1984). "In situ grazing rates of deep-sea benthic boundary-layer zooplankton". Marine Biology. 84 (1): 65–74. doi:10.1007/BF00394528. ISSN 0025-3162. S2CID 85233397.
- ↑ Wishner, Karen; Levin, Lisa; Gowing, Marcia; Mullineaux, Lauren (1990). "Involvement of the oxygen minimum in benthic zonation on a deep seamount". Nature. 346 (6279): 57–59. Bibcode:1990Natur.346...57W. doi:10.1038/346057a0. ISSN 0028-0836. S2CID 4310917.
- ↑ Poppick, Laura. "The Ocean Is Running Out of Breath, Scientists Warn". Scientific American. Retrieved 2021-12-04.
- ↑ Wishner, K. F.; Seibel, B. A.; Roman, C.; Deutsch, C.; Outram, D.; Shaw, C. T.; Birk, M. A.; Mislan, K. A. S.; Adams, T. J.; Moore, D.; Riley, S. (2018). "Ocean deoxygenation and zooplankton: Very small oxygen differences matter". Science Advances. 4 (12): eaau5180. Bibcode:2018SciA....4.5180W. doi:10.1126/sciadv.aau5180. PMC 6300398 . PMID 30585291.
- ↑ Wishner, Karen F.; Gowing, Marcia M.; Gelfman, Celia (1998). "Mesozooplankton biomass in the upper 1000m in the Arabian Sea: overall seasonal and geographic patterns, and relationship to oxygen gradients". Deep Sea Research Part II: Topical Studies in Oceanography. 45 (10–11): 2405–2432. Bibcode:1998DSRII..45.2405W. doi:10.1016/S0967-0645(98)00078-2.
- ↑ Wishner, Karen F.; Gowing, Marcia M.; Celia, Gelfman (2000). "Living in suboxia: Ecology of an Arabian Sea oxygen minimum zone copepod". Limnology and Oceanography. 45 (7): 1576–1593. Bibcode:2000LimOc..45.1576W. doi: 10.4319/lo.2000.45.7.1576 . S2CID 86359538.
- ↑ Wishner, Karen F.; Graff, Jason R.; Martin, Joel W.; Carey, S.; Sigurdsson, H.; Seibel, B.A. (2005). "Are midwater shrimp trapped in the craters of submarine volcanoes by hydrothermal venting?". Deep Sea Research Part I: Oceanographic Research Papers. 52 (8): 1528–1535. Bibcode:2005DSRI...52.1528W. doi:10.1016/j.dsr.2005.03.012.
- ↑ Maas, Amy E.; Frazar, Sarah L.; Outram, Dawn M.; Seibel, Brad A.; Wishner, Karen F. (2014-11-01). "Fine-scale vertical distribution of macroplankton and micronekton in the Eastern Tropical North Pacific in association with an oxygen minimum zone". Journal of Plankton Research. 36 (6): 1557–1575. doi: 10.1093/plankt/fbu077 . ISSN 1464-3774.
- ↑ Wishner, Karen F.; Outram, Dawn M.; Seibel, Brad A.; Daly, Kendra L.; Williams, Rebecca L. (2013). "Zooplankton in the eastern tropical north Pacific: Boundary effects of oxygen minimum zone expansion". Deep Sea Research Part I: Oceanographic Research Papers. 79: 122–140. Bibcode:2013DSRI...79..122W. doi:10.1016/j.dsr.2013.05.012.