Coping with change: The role of environmental parameters for Calanus lipid storage in Northeast Greenland fjords

Abstract

The importance of Calanus in the Arctic pelagic ecosystem is well established in the Norwegian-Arctic region. However, research on Calanus in Northeast Greenland remains limited. Calanus condition and role in the Arctic pelagic ecosystem might be different on the western side of the Fram strait because of influence from the East Greenland current that brings cold and less saline water in from the oligotrophic Arctic Basin. As the Arctic is entering a time of climate change, it is important to establish baseline knowledge about all regions of the Arctic. This study investigated the lipid content of Calanus in three distinct fjord systems in post-bloom conditions, along with several environmental parameters. Calanus had started seasonal migration. The individuals that already had migrated had a higher lipid content relative to size than individuals still residing in the surface. It was found that individual lipid content scaled exponentially with prosome length, with a significant species-specific difference between C. glacialis and C.hyperboreus. Differences in abundance, species and size composition induced differences in the total amount of lipid stored in Calanus overwintering stages. This was in part related to parameters in the environment. The northernmost fjord, Besselfjord, was filled with Polar water, and it was estimated that most of the nutrients had been incorporated in diatoms. Here we found the second highest amount of lipid in Calanus. Another sill fjord, Breddefjorden, had inflow of Atlantic water and a weaker nutrient-diatom link, as well as little total lipid in Calanus. Eskimones (a station located in the more open Godthaabs Golf) had the highest amount of lipid stored in Calanus overwintering stages, but a very weak estimated nutrient-diatom link. This might suggest other important sources of carbon. As Calanus ability to generate and store lipids is important for individual survival and the energy flow from primary producers to higher trophic levels, changes in the environment that influence lipid accumulation could cause cascading effects. It is therefore important to identify significant environmental variables. This study contributes to a knowledge base, which will be important in the future when assessing how well these copepods are coping with a changing Arctic.