''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. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

s and a part of

zooplankton 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 ...

, which is found in enormous amounts in the northern Atlantic Ocean.

Distribution and ecology

''Calanus finmarchicus'' is most commonly found in the

North Sea The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...

and the

Norwegian Sea The Norwegian Sea ( no, Norskehavet; is, Noregshaf; fo, Norskahavið) is a marginal sea, grouped with either the Atlantic Ocean or the Arctic Ocean, northwest of Norway between the North Sea and the Greenland Sea, adjoining the Barents Sea to ...

. It is also found throughout the colder waters of the North Atlantic, especially off the coast of Canada, in the

Gulf of Maine , image = , alt = , caption = , image_bathymetry = GulfofMaine2.jpg , alt_bathymetry = , caption_bathymetry = Major features of the Gulf of Maine , location = Northeast coast of the ...

, 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

whose chief diet includes diatoms,

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 A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...

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 with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...

(0–45 μmol/L),

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phosph ...

(0–3 μmol/L) and silicate (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'. P ...

. This includes diatoms, dinoflagellates,

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a differen ...

s, 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 ...

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 Cod is the common name for the demersal fish genus '' Gadus'', belonging to the family Gadidae. Cod is also used as part of the common name for a number of other fish species, and one species that belongs to genus ''Gadus'' is commonly not c ...

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 Ocea ...

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 The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

ecosystems. ''Calanus finmarchicus'' is high in

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respon ...

and

polyunsaturated In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple es ...

omega-3 Omega−3 fatty acids, also called Omega-3 oils, ω−3 fatty acids or ''n''−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their che ...

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...

s. ''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 Overwintering is the process by which some organisms pass through or wait out the winter season, or pass through that period of the year when "winter" conditions (cold or sub-zero temperatures, ice, snow, limited food supplies) make normal act ...

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 Adenosine triphosphate (ATP) is an organic compound that provides energy to drive many processes in living cells, such as muscle contraction, nerve impulse propagation, condensate dissolution, and chemical synthesis. Found in all known forms ...

(ATP) to carbon; granted their absolute amounts of

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seve ...

, 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 ...

(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