Stig Falk-Petersen

Lipids and life strategy of Arctic Calanus

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.

Ecological investigations on the zooplankton community in balsfjorden, northern Norway: Lipids and fatty acids in Meganyctiphanes norvegica, Thysanoessa raschi and T. inermis during mid-winter

Total lipid of Meganyctiphanes norvegica (M. Sars) contained 53% triacylglycerols and traces of wax esters, that of Thysanoessa raschi (M. Sars) contained 44% triacylglycerols and 10% wax esters and that of T. inermis (Krøyer) contained 28% triacylglycerols and 40% wax esters. The triacylglycerols of M. norvegica were relatively rich in 20:1 and 22:1 fatty acids and its traces of wax esters resembled those of calanoid copepods. The triacylglycerols of both Thysanoessa species were deficient in 20:1 and 22:1 fatty acids but were richer in 16:1(n-7) and 18:1 (n-7) acids than those of M. norvegica. The wax esters of T. raschi contained phytol as almost the only fatty alcohol and were rich in 16:0 and 18:1 (n-9) fatty acids. The wax esters of T. inermis contained mainly 16:0 and 14:0 fatty alcohols with lesser amounts of phytol and their dominant fatty acid was 18:1, especially the (n-9) isomer. The triacylglycerols of T. inermis had 18:4 (n-3) as the major polyunsaturated fatty acid. From these and other aspects of fatty acid and fatty alcohol analyses it is concluded that a major foodstuff of M. norvegica in Balsfjorden is wax ester-rich calanoid copepods. T. raschi and especially T. inermis are concluded to have much more preference for phytoplanktonic food. Results are discussed in terms of current knowledge of the lipid chemistry of krill in the northern and southern hemispheres.

Lipid Composition of Zooplankton in Relation to the Sub-Arctic Food Web

SummarySeasonal 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.

Biomagnification of polybrominated diphenyl ether and hexabromocyclododecane flame retardants in the polar bear food chain in Svalbard, Norway.

Concentrations of brominated flame retardants (BFRs), including polybrominated diphenylethers (PBDEs) and hexabromocyclododecane (HBCD), were investigated in an arctic marine food chain consisting of four invertebrate species: polar cod (Boreogadus saida), ringed seals (Pusa hispida), and polar bears (Ursus maritimus). The most abundant BFR, brominated diphenyl ether (BDE)-47, was found in detectable concentrations even in zooplankton, the lowest trophic level examined in this study. Most of the investigated BFRs biomagnified as function of tropic level in the food chain. A noticeable exception occurred at the highest trophic level, the polar bear, in which only BDE-153 was found to increase from its main prey, the ringed seal, indicating that polar bears appear to be able to metabolize and biodegrade most BFRs. In contrast, lower-brominated PBDEs, particularly BDE-47, showed clear signs of bioaccumulation in zooplankton, polar cod, and ringed seals. We suggest that this discrepancy in the fate of BFRs among the different species may be related to greater induction of oxidative detoxification activities in the polar bear. Absorption and debromination rates may be more important for bioaccumulation rates of BFRs in zooplankton, polar cod, and ringed seals. Lipid weight-based concentrations (LWCs) and whole body-based concentrations (WBCs) of BFRs were used to assess biomagnification factors (BMFs). Whole-body concentrations gave the most realistic BMFs, as BMFs derived from LWCs seem to be confounded by the large variability in lipid content of tissues from the investigated species. This study demonstrates that PBDEs and HBCD have reached measurable concentrations even in the lower trophic levels (invertebrates and fish) in the Arctic and biomagnifies in the polar bear food chain.

Lipids and life strategies of Calanus finmarchicus, Calanus glacialis and Calanus hyperboreus in late autumn, Kongsfjorden, Svalbard

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.

Arctic Alpine ecosystems and people in a changing environment

Arctic-Alpine Ecosystems and People in a Changing Environment - Introduction.- Integrated aspects of environmental change: Climate change, UV radiation and long range transport of pollutants.- An environment at risk: Arctic indigenous peoples, local livelihoods and climate change.- Climate change and ecosystem response.- Climate variation in the European sector of the Arctic: Observations and scenarios.- Impact of climate change on arctic and alpine lakes: Effects on phenology and community dynamics.- Changes in growing season in Fennoscandia 1982-1999.- Northern climates and woody plant distribution.- Topographic complexity and terrestrial biotic response to high-latitude climate change: Variance is as important as the mean.- The flow of Atlantic water to the Nordic Seas and Arctic Ocean.- Climate variability and possible effects on arctic food chains: The role of Calanus.- Adjustment to reality: Social responses to climate changes in Greenland.- UV radiation and biological effects.- Factors, trends and scenarios of UV radiation in arctic-alpine environments.- Effects of enhanced UV-B radiation and epidermal UV screening in arctic and alpine plants.- Effects of UV radiation in arctic and alpine freshwater ecosystems.- Climate control of biological UV exposure in polar and alpine aquatic ecosystems.- Effects of UV radiation on seaweeds.- Climate and ozone change effects on UV-radiation and health risks.- Long range pollutants transport and ecological impacts.- Contaminants, global change and cold regions.- Modeling of long-range transport of contaminants from potential sources in the Arctic Ocean by water and sea ice.- Long-term atmospheric contaminant monitoring for the elucidation of airborne transport processes into polar regions.- Levels and effects of persistent organic pollutants in arctic animals.- Arctic health problems and environmental challenges in Greenland.

Physical and ecological processes in the marginal ice zone of the northern Barents Sea during the summer melt period

Abstract The main physical and ecological processes associated with the summer melt period in the marginal ice zone (MIZ) were investigated in a multidisciplinary research programme (ICE-BAR), which was carried out in the northern Barents Sea during June–August 1995–1996. This study provided simultaneous observations of a wide range of physical and chemical factors of importance for the melting processes of sea ice, from its southernmost margins at about 77.5°N to the consolidated Arctic pack ice at 81.5°N. This paper includes a description of the oceanographic processes, ice-density packing and structures in cores, optical properties of water masses and the ice, characteristics of the incident spectral radiation and chlorophyll — leading to primary production. Large seasonal and inter-annual variations in ice cover in the MIZ were evident from satellite images as well as ship observations. Even if the annual variation in ice extent may be large, the inter-annual variations may be even larger. The minimum observed ice extent in March, for example, can be smaller than the maximum observed ice extent in September. Oceanographic phenomena such as the semi-permanent lee polynyas found west and south-west of Kvitoya and Franz Josef Land and the bay of open water, the “Whalers Bay”, north of the Spitsbergen are structures which can change with time intervals of hours to decades. For example, the polynya south of Franz Josef Land was clearly evident in 1995 but was only seen for a short period in 1996. The observed variability in physical conditions directly affects the primary production in the MIZ. From early spring, solar radiation penetrates both leads and the ice itself, initiating algal production under the ice. Light measurements showed that the melt ponds act as windows, permitting the transmission of incoming solar radiation through to the underlying sea ice, thus, accelerating the melting process and enhancing the under-ice primary production. In June 1995, the N–S transect went through a pre-bloom area well inside the ice-covered part of the Barents Sea to a post-bloom phase in the open waters south of the ice edge. The biological conditions in the later season (August) of 1996 were considerably more variable. The longer N–S transect in August 1996 passed through areas with variable ice and oceanographic conditions, and different developmental stages of phytoplankton blooms were encountered. The previously adapted picture of a plankton bloom following the retreating ice edge northwards was not seen.

Lipids and trophic interactions of ice fauna and pelagic zooplankton in the marginal ice zone of the Barents Sea

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.

Lipids and fatty acids in ice algae and phytoplankton from the Marginal Ice Zone in the Barents Sea

Abstract Samples of ice algae from the Marginal Ice Zone in the Barents Sea could be divided into two categories: one dominated by assemblages of Melosira arctica, and the other dominated by Nitzschia frigida and associated diatoms. Total lipid from the Melosira assemblages consisted of approximately equal amounts of polar lipids and triacylglycerols. Total lipid from the Nitzschia assemblages contained more triacylglycerols than polar lipids. Total lipid from the Melosira assemblages had higher percentages of C16 PUFA, especially 16:4(n-1) and 20:5(n-3), than that from the Nitzschia assemblages, this reflecting the higher percentages of both C16 PUFA and 20:5(n-3) in polar lipids than in triacylglycerols. Phytoplankton from the pelagic zone were␣richer in flagellates and contained less C16 PUFA and 20:5(n-3) but more C18 PUFA and 22:6(n-3). The dominance of diatoms in the ice-algae assemblages in the Marginal Ice Zone and their high nutritional value as a source of 20:5(n-3) for higher trophic levels are emphasised.

Carbon assimilation and lipid production in phytoplankton in northern Norwegian fjords

Carbon assimilation and lipid production were studied in phytoplankton in Balsfjorden and Ullsfjorden, northern Norway, during the exponential growth phase of the spring bloom in 1983 (6–7 April). In Balsfjorden, phytoplankton biomass was constant with depth and equivalent to 1.5 μg chlorophyll a 1-1. Phytoplankton biomass in Ullsfjorden varied with depth, with a maximum of ca. 7 μg chlorophyll a 1-1 occurring at 5 to 10 m. Particulate carbon-14 assimilation was about 18 mg C per m-2 h-1 in Balsfjorden and about 39 mg C per m-2 h-1 in Ullsfjorden over the depth range 4 to 8 m. In Balsfjorden, the percentage of total fixed carbon recovered as total lipid was 14.7 and 20.4% at 4 and 8 m depth, respectively. In Ullsfjorden, the corresponding values were 8.8 and 28.1% at 4 and 8 m, respectively. The percentages of total fixed carbon present as fatty acids were 1.1 and 1.6% at 4 and 8 m, respectively, in Balsfjorden, and 0.8 and 6.4% at 4 and 8 m in Ullsfjorden. The majority of the radioactivity in lipid at both locations and at both depths was present as polar lipid, with small percentages present in triacylglycerols and very small percentages present in free fatty acids. On average, about 18% of the total carbon-14 incorporated into phytoplankton over a 6 to 7 h mid-day period was recovered as total lipid and its percentage tended to increase with depth. The relatively low percentage of incorporated carbon-14 present as fatty acids in total lipid implies that most of the radioactivity is present in glyceryl and/or glucosyl moieties and that measurement of total radioactivity in total lipid does not necessarily give an accurate estimation of lipogenesis in phytoplankton. Fatty acid analyses of total phytoplankton in Balsfjorden and Ullsfjorden in 1983 and of a surface slick at the end of a bloom of Phaeocystis pouchetii in Balsfjorden in May 1980 showed an abundance (more than 40% of the total) of (n-3) polyunsaturates in all cases. C-18 polyunsaturates, especially 18:4 and 18:5, were very abundant (about 30% of the total) in the P. pouchetii surface slick in Balsfjorden in 1980. Both P. pouchetii biomass and C-18 polyunsaturates were more abundant in Ullsfjorden than in Balsfjorden (1983). Lipids from the P. pouchetii surface slick were deficient in C-16 polyunsaturates and relatively deficient in C-20 polyunsaturates, but both these classes of fatty acids were abundant in Balsfjorden and Ullsfjorden in 1983. The phytoplankton in both locations in 1983 was dominated by P. pouchetii and diatoms; Chaetoceros socialis was especially abundant in Balsfjorden. The results are discussed in terms of the fatty acids present in herbivorous zooplankton in northern Norwegian fjords.