Annual cycle of lipid content and lipid class composition in zooplankton from the Beaufort Sea shelf, Canadian Arctic

Abstract

We determined seasonal cycles of lipid content, lipid class composition, and carbon and nitrogen content of seven taxa of zooplankton that were collected from the Beaufort Sea shelf, Canadian Arctic, over a 10-month period (September 2003 – August 2004). All taxa except the chaetognath Parasagitta elegans had substantial lipids stores (>50%), either seasonally (Oikopleura spp.) or throughout the year (Calanus hyperboreus, Calanus glacialis, Paraeuchaeta glacialis, Metridia longa, and Eukrohnia hamata). Wax esters were the dominant lipid class in the chaetognath Eukrohnia hamata and in all copepods, including the carnivore Paraeuchaeta glacialis. Seasonal trends in lipid content and composition varied among taxa; some taxa had little variation from winter through summer (e.g., Parasagitta elegans), other taxa showed little variation until summer (e.g., Calanus glacialis), and others showed increasing or decreasing trends during winter and spring (e.g., Calanus hyperboreus). Specifically, total lipid content of Calanus hyperboreus decreased from January through May at a rate of ∼450 μg·month−1·individual−1in adult females and ∼100 μg·month−1·individual−1in juvenile copepodite IV, representing a 75%–85% loss in lipid.