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.

Abstract: During the 1992 2002 Antarctic expeditions, in the framework of the International Trans-Antarctic Expedition (ITASE) project, about 600 sites were sampled (superficial snow, snow pits and firn cores) along traverses in the northern Victoria Land Dome C Wilkes Land region. The sites were characterized by different geographical (distance from the sea, altitude) and climatological (annual mean accumulation rate, temperature) conditions and were affected by air masses from different marine sectors (Ross Sea, Pacific Ocean). Mean anion and cation contents were calculated at each site, in order to evaluate the spatial distribution of chemical impurities in snow. Here we discuss the distribution of non-sea-salt sulphate (nssSO42-) and of methanesulphonic acid (MSA) mainly originating from atmospheric oxidation of biogenic dimethyl sulphide; these compounds play a key role in climate control processes by acting as cloud condensation nuclei. The spatial distribution of nssSO42- and MSA is discussed as a function of distance from the sea, altitude and accumulation rate. Depositional fluxes of nssSO42- and MSA decrease as a function of distance from the sea, with a higher gradient in the first 200 km step. There is an analogous trend with the site altitude, and the first 1600 m step is relevant in determining the nssSO42-and MSA content in snow. The nssSO42-/MSA ratio depends on the distance from the sea and the biogenic source strength. At coastal sites, where biogenic inputs are dominant, this ratio is ?2. As biogenic input decreases (low MSA content) inland, the ratio increases, indicating the presence of alternative sources of nssSO42- (crustal, volcanic background) or advection of low-latitude air masses. By plotting total flux as a function of accumulation rate, dry depositional contributions were evaluated for nssSO42- and MSA in the Ross Sea and Pacific Ocean sectors. Non-sea-salt sulphate wet deposition prevails at sites where the accumulation rate (expressed as water equivalent) is higher than 70 kg m-2a-1 (Ross Sea sector) or 370 kg m-2a-1 (Pacific Ocean sector). MSA threshold values in these sectors are respectively 90 and 220 kg m-2a-1