''Calanus finmarchicus'' is a species of

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...

s and a part of 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 Svalbard ( , ), also known as Spitsbergen, or Spitzbergen, is a Norwegian archipelago in the Arctic Ocean. North of mainland Europe, it is about midway between the northern coast of Norway and the North Pole. The islands of the group range ...

. ''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

whose chief diet includes

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

dinoflagellate The dinoflagellates (Greek δῖνος ''dinos'' "whirling" and Latin ''flagellum'' "whip, scourge") are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered algae. Dinoflagellates are ...

s, and other

microplankton Marine microorganisms are defined by their habitat as microorganisms living in a marine environment, that is, in the saltwater of a sea or ocean or the brackish water of a coastal estuary. A microorganism (or microbe) is any microscopic living ...

ic organisms. In fact, some studies have shown that heterotrophic microplankton provide a "prey resource sufficient for net lipid synthesis as well as egg production". ''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 deep. It can also live in waters as cold as and as warm as . Other environmental conditions and their ranges include

salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

(18–36 pps), oxygen (1–9 mL/L),

nitrate Nitrate is a polyatomic ion A polyatomic ion, also known as a molecular ion, is a covalent bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zer ...

(0–45 μmol/L), phosphate (0–3 μmol/L) and

silicate In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is al ...

(1–181 μmol/L) levels. ''Calanus finmarchicus'' primarily feeds on different forms of

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

. This includes diatoms, dinoflagellates, ciliates, and other

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

marine organisms. Some scientific evidence suggests that copepods like ''C. finmarchicus'' are feeding on microzooplankton as well.

Mesozooplankton Zooplankton are the animal component of the planktonic community ("zoo" comes from the Greek word for ''animal''). Plankton are aquatic organisms that are unable to swim effectively against currents, and consequently drift or are carried along by ...

are among the most important components of their regional food web. Several species of harvestable fish, including cod,

herring Herring are forage fish, mostly belonging to the family of Clupeidae. Herring often move in large schools around fishing banks and near the coast, found particularly in shallow, temperate waters of the North Pacific and North Atlantic Oceans, i ...

and

red fish ''Red Fish'' is an album by the Northern Irish rock band The Moondogs The Moondogs are a Northern Irish rock band formed in 1979, and consisting of Gerry McCandless, Austin Barrett and Jackie Hamilton. Their career spans three albums, four ...

(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. ''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.

Physiology

''Calanus finmarchicus'' is considered to be a large copepod, being typically long. Copepods like ''C. finmarchicus'' represent a major part of dry weight (biomass) mesozooplankton in pelagic ecosystems. ''Calanus finmarchicus'' is high in protein and polyunsaturated omega-3 fatty acids. ''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. The organism's overwintering strategy gives it the ability to survive during long periods of food shortage, typical of temperate and high latitudes. During this six-month period of hibernation, many of these organisms will sink to depths from 500-2,500m in the ocean. They tend to remain at rest until the following spring when they awake and return to the surface waters. Many scientists believe that ''C. finmarchicus'' use this strategy as a survival method by reducing physiological costs and predation risk. 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. Scientists look at these levels of ATP because they usually remain constant over a range of physiological conditions, making them useful indicators of biomass. 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 Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

(indicating a larger presence of phytoplankton). Adults reproduce almost exclusively in surface waters. ''Calanus'' eggs are typically in diameter, and hatch in 2–3 days.

References

External links

''Calanus finmarchicus'' at the Worls Register of Marine Species (WoRMS)
{{Taxonbar, from=Q312953 Calanoida Crustaceans of the Atlantic Ocean Animals described in 1770 Taxa named by Johan Ernst Gunnerus