Calanus finmarchicus

{{Short description|Species of crustacean}} {{Speciesbox | image = FMIB 36348 Copepod Culanus finmarchicus from the West Coast of Scotland.jpeg | taxon = Calanus finmarchicus | authority = (Gunnerus, 1770) | synonyms = {{hidden begin|title = List}} * ''Calanus arietis'' Templeton, 1836 * ''Calanus borealis'' Lubbock, 1854 * ''Calanus elegans'' Lubbock, 1854 * ''Calanus mundus'' Dana, 1849 * ''Calanus perspicax'' Dana, 1852 * ''Calanus quinqueannulatus'' Krøyer, 1842 * ''Calanus recticornis'' Dana, 1849 * ''Calanus sanguineus'' Dana, 1849 * ''Calanus septentrionalis'' (Goodsir, 1843) * ''Calanus spitzbergensis'' Krøyer, 1843 * ''Cetochilus finmarchicus'' (Gunner, 1765) * ''Cetochilus septentrionalis'' Goodsir, 1843 * ''Cyclops finmarchicus'' Müller O.F., 1776 * ''Monoculus finmarchicus'' Gunner, 1765 {{hidden end}} }}

'''''Calanus finmarchicus''''' is a species of copepod and a component of the zooplankton, which is found in enormous amounts in the northern Atlantic Ocean.

==Distribution and ecology== ''Calanus finmarchicus'' is most commonly found in the North Sea and the Norwegian Sea. It is also found throughout the colder waters of the North Atlantic, especially off the coast of Canada, in the Gulf of Maine, and all the way up to western and northern Svalbard.

''Calanus finmarchicus'' is one of the most commonly found species of zooplankton in the subarctic waters of the North Atlantic. Sometimes confused with ''C. helgolandicus'' and ''C. glacialis'', ''C. finmarchicus'' is a large planktonic copepod whose chief diet includes diatoms, dinoflagellates, and other microplanktonic organisms. In fact, some studies have shown that heterotrophic microplankton provide a "prey resource sufficient for net lipid synthesis as well as egg production".<ref name="Ohman">{{cite journal |author1=Mark D. Ohman |author2=Jeffrey A. Runge |year=1994 |title=Sustained fecundity when phytoplankton resources are in short supply: omnivory by ''Calanus finmarchicus'' in the Gulf of St. Lawrence |journal=Limnology and Oceanography |volume=39 |issue=1 |pages=21–36 |doi=10.4319/lo.1994.39.1.0021 |bibcode=1994LimOc..39...21O |doi-access=free }}</ref> ''C. finmarchicus'' is a key component in the food web of the North Atlantic, providing sustenance for a variety of marine organisms including fish, shrimp, and whales.

Although the organism prefers these types of habitats, it has demonstrated that it is capable of surviving a wide range of environmental conditions. In terms of depth, ''C. finmarchicus'' can be found living anywhere from the ocean surface down to about {{convert|4000|m}} deep. It can also live in waters as cold as {{convert|-2|C|F}} and as warm as {{convert|22|C|F}}. Other environmental conditions and their ranges include salinity (18–36 pps), oxygen (1–9 mL/L), nitrate (0–45 μmol/L), phosphate (0–3 μmol/L) and silicate (1–181 μmol/L) levels.{{Citation needed|reason=Previous reference was circular|date=August 2023}}

''Calanus finmarchicus'' primarily feeds on different forms of phytoplankton. This includes diatoms, dinoflagellates, ciliates, and other photosynthetic marine organisms. Some scientific evidence suggests that copepods like ''C. finmarchicus'' are feeding on microzooplankton as well.<ref>{{cite journal |author1=Jens C. Nejstgaard |author2=Ingrid Gismervik |author3=Paul T. Solberg |year=1997 |title=Feeding and reproduction by ''Calanus finmarchicus'', and microzooplankton grazing during mesocosm blooms of diatoms and the coccolithophore ''Emiliania huxleyi'' |journal=Marine Ecology Progress Series |volume=147 |pages=197–217 |doi=10.3354/meps147197 |bibcode=1997MEPS..147..197N |doi-access=free }}</ref>

Mesozooplankton are among the most important components of their regional food web. Several species of harvestable fish, including cod, herring and red fish (along with a plethora of other marine life) depend on ''C. finmarchicus'' for some form of nourishment. Scientists working in Canada estimate that 90%–100% of larval redfish prey on ''Calanus'' eggs in the Gulf of the St. Lawrence.<ref name="Ohman"/>

''Calanus finmarchicus'' is especially important ecologically because it shows rapid responses to climate variability, including shifts in species' distribution and abundance, timing of life history events, and trophic relationships.<ref>{{cite journal |author1=Petra H. Lenz |author2=R. Patrick Hassett |author3=Christine M. Smith |author4=Ann Bucklin |author-link4=Ann Bucklin|author5=Andrew E. Christie |author6=David W. Towle |year=2012 |title=Functional genomics resources for the North Atlantic copepod, ''Calanus finmarchicus'': EST database and physiological microarray |journal=Comparative Biochemistry and Physiology D |volume= 7|issue=2 |doi=10.1016/j.cbd.2011.12.001 |pmid=22277925 |pages=110–23|pmc=3586334 }}</ref>

== Physiology == ''Calanus finmarchicus'' is considered to be a large copepod, being typically {{convert|2|-|4|mm|2}} long.{{Citation needed|reason=Previous reference was circular|date=August 2023}} Copepods like ''C. finmarchicus'' represent a major part of dry weight (biomass) mesozooplankton in pelagic ecosystems.<ref>{{cite journal |author1=Pierre Helaouët |author2=Gregory Beaugrand |author3=Philip Chris Reid |year=2011 |title=Macrophysiology of ''Calanus finmarchicus'' in the North Atlantic Ocean |journal=Progress in Oceanography |volume=91 |issue=3 |pages=217–228 |doi=10.1016/j.pocean.2010.11.003|bibcode=2011PrOce..91..217H }}</ref> ''Calanus finmarchicus'' is high in protein and polyunsaturated omega-3 fatty acids.<ref name="Tande">{{cite journal | last1=Tande | first1=Kurt S. | last2=Vo | first2=Trung D. | last3=Lynch | first3=Barry S. | title=Clinical safety evaluation of marine oil derived from Calanus finmarchicus | journal=Regulatory Toxicology and Pharmacology| volume=80 | year=2016 | issn=0273-2300 | pmid=27233921 | doi=10.1016/j.yrtph.2016.05.030 | pages=25–31}}</ref>

''Calanus finmarchicus'' has survived intense periods of climate change. During the last ice age (approx. 18,000 years ago), the species migrated north in order to maintain its large populations.<ref>{{cite web |title=Fish food: ''Calanus finmarchicus'' survived global warming in the past |url=https://www.science20.com/news_releases/fish_food_calanus_finmarchicus_zooplankton_survived_global_warming_in_the_past |date=September 23, 2008 |access-date=February 21, 2012 |work=Science 2.0}}</ref> The organism's overwintering strategy, known as diapause, gives it the ability to survive during long periods of food shortage, typical of temperate and high latitudes.<ref>{{cite journal |author=H.-J. Hirche |year=1996 |title=Diapause in the marine copepod ''Calanus finmarchicus'' – a review |journal=Ophelia |volume=44 |issue=1–3 |pages=129–143 |doi=10.1080/00785326.1995.10429843}}</ref> During this six-month period of hibernation, many of these organisms will sink to depths of 500–2,500m in the ocean, where they remain at rest until the following spring when they awake and return to the surface waters to breed.<ref>Zooplankton and Climate Change - The Calanus Story. Fisheries Research Services. http://www.scotland.gov.uk/Uploads/Documents/ME02Zooplankton.pdf</ref> Many scientists believe that ''C. finmarchicus'' use this strategy as a survival method by reducing physiological costs and predation risk.<ref name="Hind">{{cite journal |author1=Alasdair Hind |author2=William Gurney |year=2000 |title=Overwintering strategies in ''Calanus finmarchicus'' |journal=Marine Ecology Progress Series |volume=193 |pages=95–107 |doi= 10.3354/meps193095|bibcode=2000MEPS..193...95H |url=https://www.int-res.com/articles/meps/193/m193p095.pdf |doi-access=free }}</ref> This ability leads scientists to believe that they may be able to track some of the current changes in climate using the habits of these planktonic organisms.

The overwintering strategy employed by ''C. finmarchicus'' helps it survive intense starving periods and plays a significant role in the organism's life cycle. During these starving periods ''C. finmarchicus'' has shown that it is able to maintain a consistent rate of egg production as well as a constant proportion of adenosine triphosphate (ATP) to carbon; granted their absolute amounts of carbon, nitrogen, and ATP vary significantly.<ref name="Balch">{{cite journal |author=Norval Balch |year=1972 |title=ATP content in ''Calanus finmarchicus'' |journal=Limnology and Oceanography |volume=17 |issue=6 |pages=906–908 |doi=10.4319/lo.1972.17.6.0906 |doi-access=free|bibcode=1972LimOc..17..906B }}</ref> Scientists look at these levels of ATP because they usually remain constant over a range of physiological conditions, making them useful indicators of biomass.<ref name="Balch"/> Both egg production and ATP composition were previously thought to have varied directly with food availability on a linear scale. More recently, it has been shown that despite low concentrations of phytoplankton (one of the organism's primary food sources), ''C. finmarchicus'' maintained relatively high rates of egg production. In fact, these rates were strikingly similar to the egg production rates of those recorded in the lower St. Lawrence estuary, where the water had a much higher concentration of chlorophyll (indicating a larger presence of phytoplankton).<ref name="Ohman"/>

Adults reproduce almost exclusively in surface waters.<ref name="Hind"/> ''Calanus'' eggs are typically {{convert|0.05|mm|abbr=on}} in diameter, and hatch in 2–3 days.<ref>{{cite web |title=Zooplankton and Climate Change – The ''Calanus'' Story |publisher=Fisheries Research Services |url=http://www.scotland.gov.uk/Uploads/Documents/ME02Zooplankton.pdf |access-date=February 21, 2012}}</ref>

== See also == * Atlantic Mackerel

== References == {{Reflist}}

== External links == * [http://www.marinespecies.org/aphia.php?p=taxdetails&id=104464 ''Calanus finmarchicus'' at the World Register of Marine Species (WoRMS)]

Category:Calanoida Category:Copepods of the Atlantic Ocean Category:Crustaceans described in 1770 Category:Taxa named by Johan Ernst Gunnerus