Calanus finmarchicus

From Wikipedia, the free encyclopedia - View original article

Calanus finmarchicus
Scientific classification
Kingdom:Animalia
Phylum:Arthropoda
Subphylum:Crustacea
Class:Maxillopoda
Order:Calanoida
Family:Calanidae
Genus:Calanus
Species:C. finmarchicus
Binomial name
Calanus finmarchicus
(Gunnerus, 1770)
 
Jump to: navigation, search
Calanus finmarchicus
Scientific classification
Kingdom:Animalia
Phylum:Arthropoda
Subphylum:Crustacea
Class:Maxillopoda
Order:Calanoida
Family:Calanidae
Genus:Calanus
Species:C. finmarchicus
Binomial name
Calanus finmarchicus
(Gunnerus, 1770)

C. finmarchicus is a zooplankton species, which is found in enormous amounts in the northern Atlantic Ocean.

Distribution and ecology[edit]

C. 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".[1] 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.[2]

C. 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.[3]

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.[1]

C. 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.[4]

Physiology[edit]

C. finmarchicus is considered to be a large copepod, being typically 2–4 millimetres (0.08–0.16 in) long.[2] Copepods like C. finmarchicus represent a major part of dry weight (biomass) mesozooplankton in pelagic ecosystems.[5]

C. finmarchicus is high in protein and contains valuable omega-3 fatty acids. It contains also high amounts of antioxidant.

C. 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.[6] The organism's overwintering strategy gives it the ability to survive during long periods of food shortage, typical of temperate and high latitudes.[7] 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.[8] Many scientists believe that C. finmarchicus use this strategy as a survival method by reducing physiological costs and predation risk.[9] 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.[10] Scientists look at these levels of ATP because they usually remain constant over a range of physiological conditions, making them useful indicators of biomass.[10] 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).[1]

Adults reproduce almost exclusively in surface waters.[9] Calanus eggs are typically 0.05 mm (0.0020 in) in diameter, and hatch in 2–3 days.[11]

References[edit]

  1. ^ a b c Mark D. Ohman and Jeffrey A. Runge (1994). "Sustained fecundity when phytoplankton resources are in short supply: omnivory by Calanus finmarchicus in the Gulf of St. Lawrence" (PDF). Limonology and Oceanography 39 (1): 21–36. 
  2. ^ a b "Calanus finmarchicus". Encyclopedia of Life. Retrieved February 21, 2012. 
  3. ^ Jens C. Nejstgaard, Ingrid Gismervik & Paul T. Solberg (1997). "Feeding and reproduction by Calanus finmarchicus, and microzooplankton grazing during mesocosm blooms of diatoms and the coccolithophore Emiliania huxleyi" (PDF). Marine Ecology Progress Series 147: 197–217. doi:10.3354/meps147197. 
  4. ^ Petra H. Lenz, R. Patrick Hassett, Christine M. Smith, Ann Bucklin, Andrew E. Christie & David W. Towle (2012). "Functional genomics resources for the North Atlantic copepod, Calanus finmarchicus: EST database and physiological microarray". Comparative Biochemistry and Physiology Part D: Genomics and Proteomics 7 (in press): 110–23. doi:10.1016/j.cbd.2011.12.001. PMID 22277925. 
  5. ^ Pierre Helaouët, Gregory Beaugrand & Philip Chris Reid (2011). "Macrophysiology of Calanus finmarchicus in the North Atlantic Ocean". Progress in Oceanography 91 (3): 217–228. doi:10.1016/j.pocean.2010.11.003. 
  6. ^ "Fish food: Calanus finmarchicus survived global warming in the past". Science 2.0. September 23, 2008. Retrieved February 21, 2012. 
  7. ^ H.-J. Hirche (1996). "Diapause in the marine copepod Calanus finmarchicus – a review". Ophelia 44 (1-3): 129–143. 
  8. ^ Zooplankton and Climate Change - The Calanus Story. Fisheries Research Services. http://www.scotland.gov.uk/Uploads/Documents/ME02Zooplankton.pdf
  9. ^ a b Alasdair Hind & William Gurney (2000). "Overwintering strategies in Calanus finmarchicus" (PDF). Marine Ecology Progress Series 193: 95–107. 
  10. ^ a b Norval Balch (1972). "ATP content in Calanus finmarchicus" (PDF). Limnology and Oceanography 17 (6): 906–908. 
  11. ^ "Zooplankton and Climate Change – The Calanus Story" (PDF). Fisheries Research Services. Retrieved February 21, 2012.