ALBERT

Notes: Fatty acid profiles and lipid biomarkers from 20 harp seals were used to investigate the foraging ecology of harp seals and the transfer of energy through the Franz Josef Land-Novaya Zemlya food chain. High levels of the Calanus fatty acid trophic markers (FATMs) 20:1(n-9) (mean 14.6%) and 22:1(n-11) (mean 6.5%), together with the typical dinoflagellate FATMs 22:6(n-3) (mean 6.5%) and C18PUFA (mean 5.5%), were found in blubber samples. Based on the analyses of the fatty acid profiles separated by principal component analysis, we confirmed the importance of polar cod (Boreogadus saida) and the pelagic amphipod Themisto libellula in the diet of harp seal. The high levels of 22:6(n-3), C18PUFA and C20 and C22 FATMs show that the harp seal lipids mainly originate from dinoflagellates consumed by Calanus copepods.

Notes: Kongsfjorden is a glacial fjord in the Arctic (Svalbard) that is influenced by both Atlantic and Arctic water masses and harbours a mixture of boreal and Arctic flora and fauna. Inputs from large tidal glaciers create steep environmental gradients in sedimentation and salinity along the length of this fjord. The glacial inputs cause reduced biomass and diversity in the benthic community in the inner fjord. Zooplankton suffers direct mortality from the glacial outflow and primary production is reduced because of limited light levels in the turbid, mixed inner waters. The magnitude of the glacial effects diminishes towards the outer fjord. Kongsfjorden is an important feeding ground for marine mammals and seabirds. Even though the fjord contains some boreal fauna, the prey consumed by upper trophic levels is mainly Arctic organisms. Marine mammals constitute the largest top-predator biomass, but seabirds have the largest energy intake and also export nutrients and energy out of the marine environment. Kongsfjorden has received a lot of research attention in the recent past. The current interest in the fjord is primarily based on the fact that Kongsfjorden is particularly suitable as a site for exploring the impacts of possible climate changes, with Atlantic water influx and melting of tidal glaciers both being linked to climate variability. The pelagic ecosystem is likely to be most sensitive to the Atlantic versus Arctic influence, whereas the benthic ecosystem is more affected by long-term changes in hydrography as well as changes in glacial runoff and sedimentation. Kongsfjorden will be an important Arctic monitoring site over the coming decades and a review of the current knowledge, and a gap analysis, are therefore warranted. Important knowledge gaps include a lack of quantitative data on production, abundance of key prey species, and the role of advection on the biological communities in the fjord.

Notes: Summary The lipid-rich pelagic teleost Maurolicus muelleri has large lipid depots located subcutaneously, intramuscularly and around the digestive tract. The lipid is contained within conventional adipocytes and is composed largely of triacylglycerols rich in 20:1 (n-9) and lipid-rich mesopelagic teleost Benthosema glaciale, except that the lipid is predominantly wax esters whose fatty alcohols and fatty acids are both rich in 20:1 (n-9) and 22:1 (n-11) moieties. An origin for the lipids of both species in the wax esters of calanoid copepods is indicated. The anatomical distribution of the lipids in these teleosts and their intracellular location point to their being fundamentally an energy store. The twin roles of neutral lipids in providing metabolic energy and buoyancy are discussed.

Notes: Summary Seasonal changes in the lipid class composition and fatty acid and fatty alcohol composition of neutral lipids were determined for Calanus finmarchicus, Metridia longa and Sagitta sp. in Balsfjord, northern Norway. Similar analyses were obtained for C. hyperboreus and Parathemisto abyssorum in an adjacent fjord, Ullsfjord, in spring. C. finmarchicus, C. hyperboreus, M. longa, and Parathemisto abyssorum all contained large amounts of wax esters whereas Sagitta sp. contained small amounts of triacylglycerols and traces of wax esters. the levels of wax ester in C. finmarchicus and M. longa were highest in late autumn (respectively 88% and 84% of total lipid) and lowest in early spring (respectively 85% and 27% of total lipid). The accumulation of these neutral lipids in spring and summer is related to the feeding activity during the primary production period, while their decline in late winter is associated with the mobilisation of metabolic energy for production of gonads. The major fatty alcohols in the wax esters of C. finmarchicus and C. hyperboreus and Parathemisto abyssorum were 20:1 and 22:1 while those in the wax esters of M. longa were 14:0 and 16:0. The traces of wax esters in Saqitta were rich in 20:1 and 22:1 fatty alcohols. These analyses are consistent with C. finmarchicus and C. hyperboreus being strictly herbivorous, M. longa being more carnivorous and both Sagitta sp. and Parathemisto being highly carnivorous, probably ingesting substantial amounts of calanoid copepods.

Notes: Abstract Zooplankton samples were collected in January 1993 off Dronning Maud Land along a transect from open waters to the marginal ice zone close to the Antarctic ice shelf. Thysanoessa macrura was caught in open waters while Calanoides acutus and Calanus propinquus were mainly sampled between ice floes in the marginal ice zone. The “ice-krill”Euphausia crystallorophias was found over the shelf directly associated with ice floes. T. macrura had a lipid content up to 36% of its dry weight with the dominant lipid class, wax ester, accounting for 45–50% of the total lipid. The predominance of 18:1 fatty alcohols is the striking characteristic of the wax esters. Small specimens of E. crystallorophias had lipid levels up to 26% of their dry weight with, unexpectedly, triacylglycerols being the dominant lipid (up to 41% of total lipid). The small levels of wax esters in these animals (3–6% of total lipid) had phytol as a major constituent. Large specimens of E. crystallorophias had up to 34% of their dry weight as lipid, with wax esters (47% of total lipid) dominated by 16:0 and 14:0 fatty alcohols as the major lipid. Calanus propinquus had lipid levels of up to 34% of their dry weight, with triacylglycerols (up to 63% of total lipid) being the dominant lipid. High levels of 22:1 (n-9) fatty acid were present in the triacylglycerols. Calanoides acutus had lipid levels up to 35% of the dry weight with wax esters accounting for up to 83% of total lipid. High levels of (n-3) polyunsaturated fatty acids were recorded with 20:5(n-3), 22:6(n-3) and 18:4(n-3) being the dominant moieties. On the basis of their lipid compositions we deduce that: (1) Calanoides acutus is the strictest herbivore among the four species studied, heavily utilizing the typical spring bloom; (2) T. macrura is essentially omnivorous, probably utilizing the less defined bloom situations found in oceanic waters; (3) E. crystallorophias is an omnivore well adapted to utilize both a bloom situation and to feed on ice algae and micro-zooplankton associated with the ice; (4) Calanus propinquus seems to be the most opportunistic feeder of the four species studied, probably grazing heavily on phytoplankton during a bloom and, during the rest of the year, feeding on whatever material is available, including particulates, flagellates and other ice-associated algae. We conclude that the different biochemical pathways generating large oil reserves of different compositions, enabling species to utilize different ecological niches, are major determinants of biodiversity in polar zooplankton.

Notes: Abstract Gammarus wilkitzkii, Apherusa glacialis, Onismus nanseni, Onismus glacialis, Boreogadus saida, Parathemisto libellula and Calanus hyperboreus, collected in late June in the Barents Sea marginal ice zone, contained substantial levels (28–51% of the dry mass) of total lipid, the highest levels (51% and 41% respectively) being in  A. glacialis and  C. hyperboreus. Neutral lipids were present in greater amounts than polar lipids in all species. Triacylglycerols were major neutral lipids in A. glacialis, G. wilkitzkii and O. nanseni; triacylglycerols and wax esters were present in similar amounts in O. glacialis; higher levels of wax esters than triacylglycerols occurred in P. libellula; wax esters greatly exceeded triacylglycerols in C. hyperboreus, the opposite being true for B. saida. Diatom fatty acid markers were prominent in the triacylglycerols of G. wilkitzkii, O. nanseni, O. glacialis and, particularly, of  A. glacialis; 20:1(n-9) and 22:1(n-11) moieties were abundant in wax esters of G. wilkitzkii, O. nanseni, O. glacialis, P. libellula and  C. hyperboreus, and in triacylglycerols of B. saida. We deduce that  A. glacialis feeds mainly on ice algae and phytodetritus, G. wilkitzkii and the Onismus spp. feed on calanoid copepods as well as ice algae, whereas P. libellula and especially B. saida feed extensively on calanoid copepods.

Notes: Abstract Arctic ice amphipods are part of the sympagic macrofauna in the Marginal Ice Zone of the northern Barents Sea and represent an important link from lower to higher trophic levels in some Arctic marine food chains. The species diversity in this area (1995/1996) consisted of four species: Gammarus wilkitzkii, Apherusa glacialis, Onisimus nanseni and Onisimus glacialis. The larger ice amphipod, G. wilkitzkii, was the most abundant with the highest biomass (〉90%), whereas A. glacialis was abundant, but contributed little to the total biomass (〈4%). The other two species were found only in small numbers. Both abundance and biomass of ice amphipods decreased along a latitudinal gradient from north to south across the Marginal Ice Zone. Their distribution was also related to the under-ice topography with regard to mesoscale structures (edge, flat area, dome and ridge). Overall, the abundance and biomass on ridges were much higher in comparison to other mesoscale structures, although edges also showed high abundance, but low biomass. The large G. wilkitzkii was consistently abundant on ridges. The small A. glacialis was predominately associated with edges, but also showed high numbers in dome-shaped areas. The Onisimus species were present in low numbers at all structures, and their biomass contributed 〈10% on any one structure. The reasons for different distribution patterns of the dominant amphipod species under Arctic sea ice are probably related to different requirements of the species, especially for food, shelter and physiological conditions.

Notes: Abstract Fatty acid (FA) composition of the blubber in free-ranging white whales (Delphinapterus leucas) from Svalbard's waters was determined and compared with the fatty acid composition of potential prey species in an attempt to assess diet. This methodology is based on the common assumption that unique arrays of FAs found within groups of organisms are transferred, largely unaltered, up marine food chains and thus may be useful for assessment of diet composition. Complete-column blubber biopsies were sampled from white whales (n=7) during the summers of 1996 and 1997. All captured animals were adult males. FAs were extracted from 2–4 replicates taken from an area about 10 cm in front of the mid-dorsal ridge. FA data from a total of 12 potential prey species from the Svalbard area were compared to the white-whale blubber samples. Twenty-two FAs were consistently found in relative amounts 〉0.5% of the total FA composition in white whales. These FAs accounted for 94–96% of the total FAs present. The blubber was composed almost entirely of triacylglycerols. The major saturated FAs were 14:0 and 16:0; 16:1(n-7), 18:1(n-9) and 20:1(n-9) were the major monounsaturated FAs and 20:5(n-3) and 22:6(n-3) were the major polyunsaturated FAs. Sixteen of the 22 FAs consistently found in the white-whale blubber were also found in considerable amounts (〉0.5% of total FAs) in most of the potential species. Principal Component Analysis run on these 16 FAs suggests that polar cod (Boreogadus saida) had the most similar FA composition to the white-whale blubber, followed by capelin (Mallotus villosus), the copepod Calanus hyperboreus and the shrimp Pandalus borealis.

Notes: Abstract Stage IV and V copepodites were the dominant forms of Calanus finmarchicus, C. glacialis and C. hyperboreus in Kongsfjorden in late September 1997. Stage IV and V copepodites of C. glacialis and C. hyperboreus were rich in lipid, largely wax esters, and were well fitted to overwinter. Stage IV copepodites of C. finmarchicus were also rich in wax esters, but stage V copepodites of C. finmarchicus were less wax ester-rich. Large size increments between stage IV and V copepodites and between stage V copepodites and females were noted in C. finmarchicus. A very large increment between stage IV and V copepodites was noted for C. glacialis but the size difference between stage V copepodites and females was very small in this species. Particularly large increments were noted between stage IV and V copepodites of C. hyperboreus and also between stage V copepodites and females of this species. The very large, wax ester-rich C. hyperboreus is well adapted to survive the most extreme variations in the Arctic, in Arctic basin waters, whereas the smaller, wax ester-rich C. glacialis is adapted to survive less extreme Arctic variations, as in Arctic shelf waters. The smallest of the three, C. finmarchicus, is best adapted to survive the more predictable waters of the North Atlantic and the Barents Sea.

Notes: Summary The sound speed was determined for Meganyctiphanes norvegica, for a mixture of Thysanoessa raschii and Thysanoessa inermis and for a mixture of Calanus finmarchicus and Calanus hyperboreus. The sound speed contrasts ranged from 1.014 to 1.044. Seasonal variations in specific density were measured for Thysanoessa inermis, Thysanoessa raschii, Meganyctiphanes norvegica, Calanus finmarchicus and Calanus hyperboreus. The density of 20 mm T. inermis was lowest in November (1.052 g/cm3) and highest in February–March (1.065 g/cm3). For a 20 mm T. raschii the minimal density was determined in December (1.059 g/cm3) and the maximum in February–March (1.074 g/cm3). M. norvegica individuals of 35 mm also had their lowest density in December (1.060 g/cm3), but reached their maximum density in July (1.076 g/cm3). The density of the euphausiids was found to be size dependent. The density increases as the size decreases. C. finmarchicus and C. hyperboreus had densities less than seawater (1.026 g/cm3) during most of the year. Just before spawning the density increased to 1.028 g/cm3 and 1.036 g/cm3 for C. finmarchicus and C. hyperboreus respectively. The seasonal variations of the density were closely related to the lipid content of the animals.