Lipids and life strategy of Arctic <i>Calanus</i>

TLDR

Arctic Calanus species are the dominant herbivores in Arctic seas, converting low‑energy carbohydrates and proteins from ice algae and phytoplankton into high‑energy wax esters that drive the region’s lipid‑based energy flux. This review examines the over‑wintering strategy, migration, development, lifespan, feeding, size, lipid biochemistry, and distribution of the three main Calanus species, and presents new fatty acid and fatty alcohol data. The authors relate these life‑history and lipid parameters to biotic and abiotic drivers such as phytoplankton bloom timing, sea‑ice cover, and climate variability, and analyze the data for species homogeneity and geographic grouping. Lipid analysis shows diatom fatty‑acid markers dominate, underscoring diatoms as primary producers, and the authors conclude that Arctic Calanus species are herbivores tuned to the bloom, with bloom timing being the key determinant of their life strategies.

Abstract

Abstract The three Arctic Calanus species, C. finmarchicus (Gunnerus, 1765), C. glacialis (Jaschov, 1955), and C. hyperboreus, are the most important herbivores in Arctic seas in terms of species biomass. They play a key role in the lipid-based energy flux in the Arctic, converting low-energy carbohydrates and proteins in ice algae and phytoplankton into high-energy wax esters. In this paper we review the over-wintering strategy, seasonal migration, stage development, life span, feeding strategy, body size, lipid biochemistry and the geographic distribution of the three dominant Calanus species in Arctic waters. We then relate these parameters to other biotic and abiotic factors, such as the timing of the Arctic phytoplankton and ice algae bloom, sea ice cover and climate variability. We also present new data on fatty acid and fatty alcohol content in the three Calanus species in addition to reviewing the available literature on these topics. These data are analysed for species homogeneity and geographic grouping. The dominance of diatom fatty acid trophic markers in the lipids of Calanus underpins the importance of diatoms as Arctic primary producers, even if dinoflagellates and Phaeocystis pouchetii can also be important food sources for the calanoid copepods. We conclude that the Arctic Calanus species are herbivores, engineered to feed on the Arctic bloom, and that the timing of the bloom is the most important factor in determining the life strategies of the individual species.