Population dynamics and life history strategies of the dominant copepods in a sub-arctic Greenlandic fjord

Investigations of the Arctic and Sub-Arctic pelagic food web have previously focused on the copepod genus Calanus, as they often dominate the mesozooplankton community and serve as a lipid rich food source for higher trophic levels. However, if night samples are considered a different food web might emerges with the omnivorous copepod Metridia spp. in a major role.

Biology of Metridia is practically unknown but deviates from Calanus e.g. Metridia does not hibernate but stays active yearlong benefiting from being omnivore. In the present study abundance, depth distribution, and egg and pellet production of two Calanus species and Metridia longa was monitored weekly from March-August.

M. longa performed diel vertical migration of up to 200 meters and was the dominating larger copepod species. Weekly lipid measurements of M. longa showed a similar buildup of lipids during late summer as the 20 hibernating Calanus. M. longa might thereby also have a central role in the lipid rich food chain which is a distinct feature for Arctic and Sub-Arctic ecosystems