Last updated 24 February 2022

The Kongsfjorden pelagic ecosystem is influenced by both Atlantic and Arctic waters. The relative amount of the Atlantic Calanus finmarchicus and the Arctic Calanus glacialis varies from year to year. Calanus finmarchicus has been the dominant species the last decade, due to increased inflow of Atlantic water and hence increased temperature. Changes in zooplankton community will cascade to higher trophic levels, and might change the character of the pelagic ecosystem. Therefore, the composition of zooplankton community in Kongsfjorden might function as a climate indicator on a local scale.

Calanus finmarchicus. Photo: Terje van der Meeren / Institute of Marine Research

What is being monitored?

Calanus species in Kongsfjorden

The figure shows the proportion of the total Calanus abundance made up of the Atlantic species, Calanus finmarchicus, and the two Arctic species, Calanus glacialis and Calanus hyperboreus. The Arctic species (especially C. glacialis) dominate in Kongsfjorden in “cold” years when the influx of Atlantic water is low, as in 1999, 2000 and 2008. The density of C. finmarchicus rises in “warm” years with a larger inflow of warm, Atlantic water. Strong inflows of Atlantic water during the winter 2005-2006 have led to Kongsfjorden remaining ice-free in winter since then. The Atlantic, C. finmarchicus has dominated in Kongsfjorden the last decade, except for in 2008 and 2019.
(Cite these data: Norwegian Polar Institute (2022). Calanus species composition in Kongsfjorden. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL:

Details on these data

Last updated24 February 2022
Commissioning organizationMinistry of Climate and Environment
Executive organizationNorwegian Polar Institute
Contact personsHaakon Hop
Anette Wold


Mesozooplankton is sampled with a Hydrobios MultiNet Midi, containing five nets sampling successive depth intervals from bottom to surface. The net has an opening of 0.25 m2 and the mesh size is 200 µm. The sampling is conducted in end of July each year. The three different Calanus species are identified based on prosome length measurements and morphological features. The abundance (ind m-3) is integrated for all five depths sampled. The average value for three stations in Kongsfjorden (Kb1, Kb2, Kb3) is used to calculate the averaged relative abundance of Atlantic Calanus (Calanus finmarchicus) and Arctic Calanus (Calanus glacialis and Calanus hyperboreus).

Other metadata

Data are available at the Norwegian Polar Institute’s data service.

Status and trend

The Kongsfjorden pelagic ecosystem is influenced by influx of both Atlantic and Arctic waters, consequently the zooplankton community is composed of both Atlantic and Arctic species.  The amount of Atlantic water in the West Spitsbergen Current and hence the inflow into Kongsfjorden depends or larger scale climatic factors. Therefore, the composition of zooplankton community in Kongsfjorden might function as a climate indicator on a local scale. Copepods of the genus Calanus dominates the mesozooplankton community in Kongsfjorden, both in terms of abundance and biomass. The Calanus population exist of three species, the smaller Atlantic Calanus finmarchicus, the medium sized Arctic Calanus glacialis and the large Arctic Calanus hyperboreus. The relative abundance of C. finmarchicus and C. glacialis in Kongsfjorden depends on the inflow of Atlantic water. The larger C. hyperboreus, which is a deep water species, is only present in low numbers in Kongsfjorden and does not contribute much to the total abundance of Calanus.

Years with C. glacialis dominance are characterized by lower water temperatures whereas dominance of C. finmarchicus usually coincides with periods with increasing inflow of Atlantic water and hence increased water temperatures. The years with domination of the cold-water species, C. glacialis, were 1999, 2000, 2008 and 2019. The Atlantic C. finmarchicus was the predominating Calanus species in 1997, from 2001 to 2003 and in 2007 until today, except for 2008. 2004, 2006 and 2008 were characterized by the almost equal abundance of both Calanus species. The year 2020 is an exception to previous trends with relative high abundance of C. glacialis despite being a relative warm year.

The trend is less pronounced when looking at the relative proportion of Atlantic and Arctic Calanus species in terms of biomass. The large Arctic species (C. glacialis and C. hyperboreus) will contribute more biomass than the smaller Atlantic species (C. finmarchicus) at the corresponding development stage. However, there is a large difference in biomass for the different development stages. An adult might have six times as much biomass as a young individual (copepodit stage 2-3). The total biomass is therefore not only dependent on the number of individuals, but also of the stage composition of the different species at the time of sampling. A small increase of larger copepodite stages of C. glacialis and C. hyperboreus will cause relative large increase in their proportion of total biomass.

Causal factors

Changes in the zooplankton community structure in Kongsfjorden can be associated with the advection of water masses from the adjacent shelf. There is a significant variability in the degree to which Atlantic water occupies Kongsfjorden. The large interannual variations in Calanus abundance and species composition observed in the time series data from Kongsfjorden seem to correlate to changes in hydrography, i.e. warm years favour different species than cold years.


The variability in the abundance of C. glacialis and C. finmarchicus may have implications for the pelagic ecosystem in Kongsfjorden, since variable abundances of these species lead to a shift in the size structure and the amount of energy as lipids available for the next trophic level.

Planktivorous seabirds and fish tend to be size selective in search of prey. A decrease of the mean size of available prey through a shift in species composition of the zooplankton may have consequences for predators. For example, little auks have a strong preference for larger prey items and years with a dominance of the smaller C. finmarchicus inside the fjord may force the birds to fly longer distances to find suitable food (e.g. C. glacialis), thereby reducing survival and recruitment success. However, for other larger zooplankton, fish and sea birds that don’t have any preference for the larger Calanus species it would be the total amount of Calanus that effect their success independent on the species composition.

About the monitoring

The composition of key zooplankton species in Svalbard waters is being monitored because it may be influenced by climate change and can lead to fundamental changes in the marine ecosystem.

Places and areas

Relations to other monitoring

Monitoring programme

  • None

International environmental agreements

  • None

Voluntary international cooperation

  • None

Related monitoring

  • None

Further reading


  1. Daase, M., Falk-Petersen, S., Varpe, Ø., Darnis, G., Søreide, J.E., Wold, A., Leu, E., Berge, J., Philippe, B., Fortier, L. 2013. Timing of reproductive events in the marine copepod Calanus glacialis: a pan-Arctic perspective. Canadian Journal of Fisheries and Aquatic Sciences 70(6): 871–884. DOI:10.1139/cjfas-2012-0401
  2. Hop, H., Falk-Petersen, S., Svendsen, H., Kwasniewski, S., Pavlov, V., Pavlova, O., Soreide, J.E. 2006. Physical and biological characteristics of the pelagic system across Fram Strait to Kongsfjorden. Progress in Oceanography 71(2-4): 182–231. DOI:10.1016/j.pocean.2006.09.007
  3. Hop H, Wold A, Vihtakari M, Daase M, Kwasniewski S, Gluchowska M, Lischka S, Buchholz F, Falk-Petersen S (2019) Zooplankton in Kongsfjorden (1996–2016) in Relation to Climate Change. In: Hop H., Wiencke C. (eds) The Ecosystem of Kongsfjorden, Svalbard. Advances in Polar Ecology, vol 2. Springer, Cham
  4. Mayzaud, P., Falk-Petersen, S., Noyon, M., Wold, A., Boutoute, M. 2015. Lipid composition of the three co-existing Calanus species in the Arctic: impact of season, location and environment. Polar Biology: 1–21. DOI:10.1007/s00300-015-1725-9
  5. Walkusz, W., Kwasniewski, S., Falk-Petersen, S., Hop, H., Tverberg, V., Wieczorek, P., Weslawski, J.M. 2009. Seasonal and spatial changes in the zooplankton community of Kongsfjorden, Svalbard. Polar Research 28(2): 254–281. DOI:10.1111/j.1751-8369.2009.00107.x
  6. Willis, K., Cottier, F., Kwasniewski, S., Wold, A., Falk-Petersen, S. 2006. The influence of advection on zooplankton community composition in an Arctic fjord (Kongsfjorden, Svalbard). Journal of Marine Systems 61(1-2): 39–54. DOI:10.1016/j.jmarsys.2005.11.013