The marine zooplankton species Calanus finmarchicus is a free-living copepod (crustacean) with a one-year life-cycle. Calanus finmarchicus is the key food source for most of the commercially important fish species in the North Atlantic. However, in the North Atlantic ecosystem only 10-20% of the energy from the vast biomass of Calanus finmarchicus is being incorporated in fish and mammals higher up in the food chain.
As Calanus finmarchicus lives scattered in the oceanic waters at the bottom of the marine food chain, only grazing on microscopic algae and protozooplankton, it is virtually free of pollutants. This fact, taken together with its abundance and biochemical composition, makes this species extraordinarily attractive compared to both pelagic fishes and krill as a source of value-added products for humans.
Scientific study preformed by: the Cardiovascular Research Group, Department of Medical Biology, Faculty of Health Sciences, Institute of Medical Biology, University of Tromsø, N-9037 Tromsø, Norway.
To study: the effects of Calanus finmarchicus (Calanus oil) on diet-induced obesity and obesity-related disorders in mice.
Boreal North Atlantic species. Mass presence in the Norwegian Sea, Greenland Sea, Barents Sea and the western part of the Arctic Basin, abundant in the North Sea, Davis Strait. This species in not assumed to reproduce in Arctic waters.
Filter-feeders, feed on various components of the phytoplankton, primarily diatoms
Near England goes through 2 generations a year, in the Barents sea – 1. General pattern for life cycle is as follows:
Forms an overwintering stock from mainly C5 copepodites, which sinks to the deeper layers and falls into diapause. By the end of march the copepodites rise into the surface layers, where reproduction takes place. The new generation reaches C3-C4 by June-July. With the surface water temperature increasing by July-August, they sink below to the deeper layers.
The ventral surface of the genital segment from lateral view forms a straight line posteriad of the genital pore. The genital structures are very similar to that of C. glacialis and C. marshallae. The genital plate is smoothly curved in its posterior part and cut-off in the anterior, covering the proximal part of the chitinized seminal receptacles, which are slightly tilted toward the long axis of the body. The posterior corners of the last thoracic segment are always rounded. The serrated line on the coxopodite of C5 carries from 24 to 41 serrations, 34.71 on average. The serrations are dull and very densely spaced. This line is less curved in C. finmarchicus than in C. glacialis. The medial line of the 2nd segment of the basipodite of P5 is more curved than in other species. The spiniform process on the distal front edge of the P5 basipodite is always thin and sharp. The distal corner of the 1st segment of the endopodite narrows smoothly, while in C. glacialis this corner is thicker and more dull. The inner edge of the 1st endopodal segment of P1 carries 1 seta, the inner and outer edges of the 3rd endopodal segment of P5 carry 3 setae. The photoreceptory glands are placed near the lateral gland.
The P5 has an almost equal number of setae on the right and left branch. The outer distal process on the 2nd endopodal segment of the left P5 reaches to or beyond the distal edge of the 1st exopodal segment of this leg.
In the North Atlantic is a main food source for herring and other harvestable fish
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". 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 4,000 metres (13,000 ft) deep. It can also live in waters as cold as −2 °C (28 °F) and as warm as 22 °C (72 °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.
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.
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.
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.
Calanus finmarchicus is considered to be a large copepod, being typically 2–4 millimetres (0.08–0.16 in) 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 (indicating a larger presence of phytoplankton).