Calanus helgolandicus

Calanus helgolandicus is a copepod found in the Atlantic, from the North Sea south to the western coast of Africa. The female has an average size of about 2.9 millimetres (0.11 in) and the male has an average size of about 2.7 millimetres (0.11 in).

Calanus helgolandicus
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Subphylum:
Crustacea
Class:
Maxillopoda
Subclass:
Copepoda
Order:
Calanoida
Family:
Calanidae
Genus:
Calanus
Species:
C. helgolandicus
Binomial name
Calanus helgolandicus
(Claus, 1863)
Synonyms[1]
  • Cetochilus helgolandicus Claus, 1863
  • Calanus syunpuensis Kurasige, 1933

Description

The female has an average size of about 2.9 millimetres (0.11 in) and the male has an average size of about 2.7 millimetres (0.11 in).[2]

Distribution

C. helgolandicus is found in the Atlantic, from the North Sea south to the western coast of Africa. It can also be found in the Mediterranean and Black Sea.[2] Because of increasing temperatures due to climate change, its range is expanding northward. It is usually found in waters between 9 and 20 °C (48 and 68 °F) in temperature, with maximum abundance being between 13 and 17 °C (55 and 63 °F).[3]

Ecology

Life cycle and reproduction

C. helgolandicus overwinters as a stage V copepodite.[4] However, only those with enough energy stores can overwinter; the rest stay at the surface. In fact, it has been observed that overwintering copepods are heavier than those that stay at the surface. During this overwintering process, the copepodites moult into adult females. After moulting, the females breed the next spring. In the absence of food during this time, they can lay their first few eggs from accumulated energy stores.[5] Although this is true, it is mainly an income breeder, reproducing using recently gained energy.[6] It has a maximum of about three generations per year.[7] In the central North Sea, it is most abundant during spring and autumn. It is likely that warmer temperatures can facilitate egg production for more of the year.[3]

Feeding

C. helgolandicus is a planktonic herbivore,[8] although it has been shown to eat both dead diatoms and faeces from other members of its species. This copepod seems to select particles based on their structure; marine snow (which is unstructured), is rejected, whereas dead diatoms and objects such as polystyrene (when given as beads 30 micrometers in diameter) are accepted as food.[9] Faecal pellets are generally not accepted in whole (possibly due to the difficulty in handling very large particles). When faecal pellets are rejected, they are generally damaged. When the pellets are fragmented (corporhexy), they are generally ingested with alternate food, and the "loosening" (coprochaly) of a pellet can precede the removal (and likely ingestion) of the peritrophic membrane, which has bacteria and other organisms which increase its nutritional value.[10] Its grazing (the efficiency of the removal of food from seawater) and ingestion rates (the actual amount of food eaten) increase with increasing body weight, however, as body weight increases, the grazing and ingestion rates per unit of body weight decrease.[8]

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References
  1. Walter, T.C.; Boxshall, G. (2018). "Calanus helgolandicus (Claus, 1863)". World of Copepods database. World Register of Marine Species. Retrieved 9 August 2018.
  2. Razouls C.; de Bovée F.; Kouwenberg J.; Desreumaux N. (2018). "Diversity and Geographic Distribution of Marine Planktonic Copepods". Sorbonne Université, CNRS. Retrieved 5 July 2018.
  3. Bonnet, Delphine; Richardson, Anthony; Harris, Roger; Hirst, Andrew; Beaugrand, Gregory; Edwards, Martin; Ceballos, Sara; Diekman, Rabea; López-Urrutia, Angel; Valdes, Luis; Carlotti, François; Molinero, Juan Carlos; Weikert, Horst; Greve, Wulf; Lucic, Davor; Albaina, Aitor; Yahia, Nejib Daly; Umani, Serena Fonda; Miranda, Ana; Santos, Antonina dos; Cook, Kathryn; Robinson, Susan; Fernandez de Puelles, Marie Luz (2005). "An overview of Calanus helgolandicus ecology in European waters". Progress in Oceanography. 65 (1): 1–53. doi:10.1016/j.pocean.2005.02.002. ISSN 0079-6611.
  4. Hirche, H-J (1983). "Overwintering of Calanus finmarchicus and Calanus helgolandicus". Marine Ecology Progress Series. 11: 281–290. doi:10.3354/meps011281. ISSN 0171-8630.
  5. Rey-Rassat, C; Irigoien, X; Harris, R; Carlotti, F (2002). "Energetic cost of gonad development in Calanus finmarchicus and C. helgolandicus". Marine Ecology Progress Series. 238: 301–306. doi:10.3354/meps238301. ISSN 0171-8630.
  6. Sainmont, Julie; Andersen, Ken H.; Varpe, Øystein; Visser, André W. (2014). "Capital versus income breeding in a seasonal environment". The American Naturalist. 184 (4): 466–476. doi:10.1086/677926. ISSN 0003-0147. PMID 25226182.
  7. Conover, R. J. (1988). "Comparative life histories in the genera Calanus and Neocalanus in high latitudes of the Northern Hemisphere". Hydrobiologia. 167 (1): 127–142. doi:10.1007/BF00026299. ISSN 0018-8158.
  8. Paffenhöfer, G. -A. (1971). "Grazing and ingestion rates of nauplii, copepodids and adults of the marine planktonic copepod Calanus helgolandicus". Marine Biology. 11 (3): 286–298. doi:10.1007/BF00401275. ISSN 0025-3162.
  9. Paffenhöfer, G. A.; Strickland, J. D. H. (1970). "A note on the feeding of Calanus helgolandicus on detritus". Marine Biology. 5 (2): 97–99. doi:10.1007/BF00352591. ISSN 0025-3162.
  10. Iversen, MH; Poulsen, LK (2007). "Coprorhexy, coprophagy, and coprochaly in the copepods Calanus helgolandicus, Pseudocalanus elongatus, and Oithona similis". Marine Ecology Progress Series. 350: 79–89. doi:10.3354/meps07095. ISSN 0171-8630.
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