Reproduction of asteroids from Balsfjorden,Northern Norway: Analyses of lipids in the gonads of Ctenodiscus crispatus,Asterias lincki and Pteraster militaris

Seasonal lipid analyses were performed on the gonads and residual bodies of Ctenodiscus crispatus (Retzius) and Asterias lincki (Müller & Troschel), collected from Balsfjorden, northern Norway during March 1978–February 1980. The ovaries of both species had high percentages of total lipid (in the region of 60% of the dry weight) that were relatively constant throughout the season. Testes from both species had in the region of 20% of their dry weight as lipid, again with little seasonal variation. The majority of the total lipid in the ovaries of C. crispatus was accounted for by alkyldiacylglycerols and there was little seasonal variation in lipid class composition. Phospholipid accounted for the bulk of the lipid in the testes of C. crispatus, where alkyldiacylglycerols were present but in minor amounts. A slight degree of seasonal variation occurred in the composition of testis lipid in that maximal percentages of triacylglycerols and alkyldiacylglycerols occurred in January–April. The ovaries of A. lincki contained both triacylglycerols and alkyldiacylglycerols as major neutral lipids. Significant seasonal variation occurred in lipid class composition in the ovaries in that neutral lipids showed transient minima in February–April. The testes of A. lincki had substantial amounts of both triacylglycerols and alkyldiacylglycerols: maximal percentages of these lipids occurred in January–March. Analyses of gonads of near-mature Pteraster militaris (O. F. Müller) revealed that the ovaries were rich in lipid that was predominantly alkyldiacylglycerols, whereas the testes had much lower levels of lipid accounted for mainly by phospholipids. The residual bodies of all three asteroids had significant but small amounts of alkyldiacylglycerols in their lipids. A. lincki had triacylglycerols as a major lipid class in its body lipids, whereas in C. crispatus the major body lipid was phospholipid. Little seasonal variation was seen in the composition of the residual body lipid of either C. crispatus or A. lincki. The results are consistent with an aseasonal reproductive pattern in C. crispatus, although a main breeding activity occurred in mid-winter. A. lincki is a more seasonal breeder, but also had maximal activity in winter. Irrespective of their breeding habits, all three asteroids produced eggs rich in alkyldiacylglycerols. A major role for this lipid in the development of the large lecithotrophic eggs of asteroids is indicated.     

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.     

Amino and fatty acid dynamics of<Emphasis Type="Italic"> Lysmata seticaudata</Emphasis> (Decapoda: Hippolytidae) embryos during early and late reproductive season

The present study investigates amino and fatty acid dynamics of embryos of different-sized simultaneous hermaphrodite shrimp (SH) (Lysmata seticaudata) during early (ERS) and late reproductive seasons (LRS). A significant relative decrease in total amino acids and essential amino acids (EAA) was recorded (P<0.05) during the development of embryos produced by shrimp collected during ERS and LRS. The content of non-essential amino acids (NEAA) showed a smaller variation, without a marked decrease. During the last embryonic stage, the major EAAs of embryos were, in decreasing magnitude, lysine and arginine, while the major NEAAs were glutamic acid and valine. A substantial decrease in lipid content (P<0.05) was observed, and the quantitatively more important fatty acids were the saturates 16:0 and 18:0, the monounsaturates 18:1n-9 and 18:1n-7 and the polyunsaturates 20:4n-6 (arachidonic acid, ARA), 20:5n-3 (eicosapentaenoic acid, EPA) and 22:6n-3 (docosahexaenoic acid, DHA). Monounsaturates were used at a higher rate, and embryos produced by SH shrimp displayed similar consumption rates of saturated and polyunsaturated fatty acids. Considering individual fatty acids, no clear utilization pattern between different-sized SH shrimp in ERS and LRS was recorded. The inexistence of consistent differences between amino and fatty acid utilization during embryogenesis among different-sized SH shrimp in ERS and LRS emphasizes the variability affecting offspring in decapod crustaceans.Communicated by S.A. Poulet, Roscoff     

Ecological investigations on the zooplankton community of Balsfjorden,northern Norway: Lipids in the euphausiids Thysanoessa raschi and T. inermis during spring

Dry body weights, lipid levels and lipid compositions were measured in I-and II-group Thysanoessa raschi (M. Sars) and T. inermis (Krøyer) collected in April-May, 1980 in Balsfjorden, north Norway. Dry body weights were mininal in late April but had doubled by mid-May for I-group T. raschi and for I- and II-group T. inermis. II-group T. raschi had increased its dry weight by less than 50% by mid-May. Lipid accounted for approximately 10% of the dry body weight throughout the period, with free fatty acids and phospholipids being the dominant classes. An exception occurred for II-group T. inermis in mid-May, when wax esters were present in substantial amounts. Wax esters were present only in small amounts at other times and triacylglycerols were negligible. The free fatty acids in I-group T. raschi and I-group T. inermis in late April were deficient in polyunsaturates; by mid-May the free fatty acids were rich in polyunsaturates. II-group T. raschi and II-group T. inermis had free fatty acids rich in polyunsaturates throughout the period of study. The wax esters present in II-group T. inermis in mid-May consisted mainly of 16:0 and 14:0 alcohols esterified to 18:1 fatty acid. The traces of wax esters present in T. raschi did not contain significant amounts of phytol. Results are discossed with respect to the metabolic activities of the two euphausiids and their trophic positions in terms of different dietary inputs.     

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 g chlorophyll a 1^-1. Phytoplankton biomass in Ullsfjorden varied with depth, with a maximum of ca. 7 g 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.     

Lipid synthesis from acetate by the in vitro incubated ovaries of the penaeid shrimp Penaeus semisulcatus

The present research was aimed at studying the synthesis of lipids from ¹⁴C-acetate in vitro by ovarian tissue in relation to oogenesis and at examining the binding of newly synthesized lipids to ovarian proteins. Lipid synthesis gradually increased during oogenesis. Fifty percent of the newly synthesized lipids was phosphatidyl choline; triacylglycerols reached 30 to 35%; diacylglycerol was a relatively important component of the synthesized neutral lipids in immature ovaries. Cholesterol was not synthesized. Only saturated (73%) and monounsaturated (26%) fatty acids were labeled. Polyunsaturated fatty acids were not synthesized. Bound lipids in developing ovaries were associated mainly with vitellin. Lipids were bound also to two other proteins in immature ovaries. Binding of lipids to vitellin was observed at the commencement of vitellogenesis. Up to a third of the newly synthesized lipids was bound to vitellin, with triacylglycerols and phosphatidyl choline as the main bound lipids. Peneaus semisulcatus individuals examined in the present study were collected in Haifa Bay, Israel during the years 1990 to 1992.     

Feeding of calanoid copepods in relation to Phaeocystis pouchetii blooms in the German Wadden Sea area off Sylt

Surface sediments from the Svartnes basin (195 m deep) in Balsfjorden, northern Norway (ca. 70°N), were partially characterized to assess the nature and origin of the organic material present and its potential nutritive value for sediment-ingesting animals. Seasonal analyses were carried out on material collected between May 1979 and August 1980 for total organic matter, organic C and N, acid-extractable amino acids and lipids extractable with chloroform:methanol. Little or no seasonal variation was seen in any of the parameters analysed. The mean apparent organic content was 9.3% of sediment dry weight, the organic C content was 2.38%, the organic N content was 0.26% and the C:N ratio was 9.1:1. Acid hydrolysis of sediment yielded 575 mg of amino acids and 41 mg of NH₃ per 100 g sediment dry weight, the composition of the amino acids being similar to that of nutritionally highquality animal or microbial protein. Glucoseamine was not detected in acid hydrolysates of sediment, consistent with the absence of chitin. Chloroform:methanol extraction yielded 133 mg of material per 100 g sediment dry weight, 62% of which was accounted for by saponifiable lipids (fatty acids) and non-saponifiable lipids present in approximately equal amounts. Fatty alcohols accounted for 30% of the non-saponifiable lipids and phytol accounted for 40% of the fatty alcohols. Small amounts of very long-chain fatty alcohols characteristic of terrestrial plants were present, but long-chain monounsaturated fatty alcohols characteristic of marine zooplankton were essentially absent. Very small quantities of long-chain ketones characteristic of marine coccolithophores were detected. The major fatty acids present in sediments were 16:0, 14:0, 16:1 (n-7) and 18:1 (n-9), and 11% of the total fatty acids were comprised of a mixture of odd-numbered straight-chain and branched-chain moieties characteristic of micro-organisms. The data point to small amounts of material characteristic of marine and terrestrial photosynthetic organisms being present in sediments at any given time, whereas material characteristic of marine zooplankton is not present. The presence of material characteristic of micro-organisms is consistent with conversion of sedimenting material into a pool of sediment micro-organisms. Although the biological availability to sediment-ingesting organisms of the esterified fatty acids and the acid-extractable amino acids in sediments remains to be assessed, the maximum amounts available are equivalent to approximately 60 mg of polar lipid and 575 mg of protein per 100 g sediment dry weight. These amounts are small in relation to the production rates in the photic zone of the fjord, implying that the bulk of the energy flow in Balsfjorden occurs in its relatively short pelagic food chains.     

Species-specific differences in lipid composition and omnivory indices in Arctic copepods collected in deep water during autumn (North Water Polynya)

To discern species-specific patterns in omnivory indices in copepods from the North Water Polynya, lipid classes and fatty acids were determined in Calanus hyperboreus Krøyer copepodite stage 5 (CV), C. glacialis Jaschnov (CV) and Metridia longa Lubbock (females) sampled below the mixed layer during autumn 1999. Generally, M. longa contained higher proportions of triacylglycerols, polar lipids and 18:1(n-9) than the other species. M. longa also had lower relative amounts of wax esters (WE), polyunsaturated fatty acids (PUFA), 20:1(n-9), 22:1(n-11), and lower absolute (g lipid copepod^-1) and relative (% lipid) lipid levels. Unsaturation coefficients (UC; ratio of polyunsaturated to total WE) were usually lowest in M. longa. These differences probably relate to a lesser dependence on phytoplankton in M. longa, and hence more ingestion of PUFA-poor prey. Moreover, levels of the carnivory index 18:1(n-9)/18:1(n-7) were highest in M. longa. Our data support the widespread contention that M. longa is more omnivorous than C. hyperboreus and C. glacialis. Proportions of bacterial fatty acids [odd-numbered and/or branched (OBFA); 18:1(n-7)] and PUFA/SFA (SFA: saturated fatty acids) ratios were largely unrelated to feeding strategy. Relationships between relative and absolute amounts of 16:1(n-7) and 18:1(n-7) in copepods suggest that the latter fatty acid is formed in vivo by chain elongation of the former. However, elevated levels of 18:1(n-7) and OBFA in M. longa at stations dominated by the microbial loop imply that these indices can be used to track ingestion of PUFA-poor protozoans when diatoms are scarce.Communicated by J.P. Grassle, New Brunswick     

Fatty acids of the female horseshoe crab Xiphosura (Limulus) polyphemus

The fatty acid composition of 9 different tissues and organs of the female horseshoe crab Xiphosura (Limulus) polyphemus — one of the very few recent representatives of the ancient arthropod class Merostomata — was investigated in reference to the distribution of fatty acids through the marine food web. Fatty acid spectra, in which polyunsaturated fatty acids are predominant, especially eicosapentaenoic acid (20:5 3), revealed features characteristic of marine lipids. However, rather large quantities of monoenoic fatty acids also occur in all organs. In the saturated fatty acid fractions, the high content of branched-chain components is worth noticing, particularly in the gills and the carapace (35%); in all probability, the high amount of the branched-chain fatty acids is associated with their protective function in surface lipids. Isoprenoid fatty acids such as pristanic and phytanic acid were absent.     

Variation in the lipid content of wild-caught females of the marine shrimpPenaeus kerathurus during sexual maturation

Changes in total lipids, lipid classes and their fatty acid contents were studied in the ovaries and midgut glands ofPenaeus kerathurus Forskäl females during sexual maturation. The shrimp were captured in the Gulf of Cádiz (southwest Spain) in 1990. The lipid content and fatty acids, in relative terms, increased during ovarian development. The greatest changes occurred between Maturation Stages III and IV. Ovarian lipids were dominated by polar classes, whereas in the midgut gland the major classes were triacylglycerols and sterol esters. The amounts of major fatty acids in ovaries (16:0, 16:1n-7, 18:1n-9, 18:1n-7, 20:5n-3 and 22:6n-3) increased with increasing maturity, but declined slightly between Stages III and IV. The total polar lipid content of the midgut was 5.7% (by dry weight) and its fatty acid composition remained constant during the whole study period. Total lipid content of the midgut gland showed an upward trend during sexual maturation, except between Stages II and III, when a slight decrease was observed. Predominant fatty acids in the midgut gland (16:1n-7, 20:5n-3 and 22:6n-3) displayed a noteworthy decline between Stages II and III, corresponding with the marked increase in total lipid fatty acid content in the ovaries during the same period.     

Evaluation of fatty acids as biomarkers for a natural plankton community. A field study of a spring bloom and a post-bloom period off West Greenland

An investigation of the fatty acid composition of a natural arctic plankton community was carried out over two fishing banks located between 63°N and 65°N off the West Greenland coast. Samples for fatty acid analyses, species determination and biomass assessments of the plankton community were taken at the depth of fluorescence maximum. High biomass and diatom dominance during the spring bloom and low biomass and flagellate dominance in the post-bloom period were reflected by the fatty acid profiles. The total amount of fatty acid ranged from 55 to 132 µg l^-1 during the spring bloom and from 1 to 5 µg l^-1 during the post bloom. Analysis of the fatty acids showed that when the plankton was dominated by diatoms of the genera Thalassiosira and Chaetoceros, the proportions of C16:1(n-7) and C20:5(n-3) were correspondingly high. C18s, and particularly C18:1(n-9), were more abundant when the plankton was dominated by small autotrophic flagellates, primarily haptophytes. We found a good positive correlation between the common diatom marker, C16:1(n-7)/C16:0, and the biomass percentage of diatoms (r=0.742, P<0.001), as well as between the biomass percentage of flagellates and total C18 fatty acids (r=0.739, P<0.001). This supports the use of these specific fatty acids and fatty acid ratios as general biomarkers of the plankton community. However, the fatty acids are not specific enough to sufficiently characterise the composition of the plankton community, and microscopical support is needed to verify observed trends.     

Sources and major biogeochemical pathways of organic matter in the mangrove system of Rufiji estuary

Fatty acids were extracted from the surface sediments (10 cm) of three sampling sites of Rufiji estuary to infer their sources and biogeochemical pathways. The fatty acids ranging from C₈ to C₂₄ were distinguished from this study, and were broadly classified into saturated (SFAs), monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs). SFAs were found to be the major fraction at station 1 and 3 where as at station 2, MUFAs dominated. A total of 19 fatty acids with a total concentration of 64.91 μg/g dry weight were characterised at station 1. C_16:0 was the most abundant fatty acid contributing 21.94% of total fatty acids (TFAs). C_22:2 was the second most abundant, which accounted for 9.46% of TFAs. Fatty acids ranging from C₁₂ to C₂₄ were identified at station 2. C₂₀ fatty acid was the most abundant fatty acid contributing 21.94%, followed by C_16:0. At station 3, fatty acids ranging from C₈ to C₂₄ were obtained. The PUFA C_20:5n-3 was the most abundant fatty acid contributing 21.65%, followed by C_24:0 (15.00% of TFAs). The ratio of lower molecular weight (LMW) to higher molecular weight (HMW) biomarkers was used as an indicators to distinguish higher plants organic matter from algae-derived fatty acids.     

Fatty-acid composition of ovulated eggs from wild and cultured turbot (Scophthalmus maximus) in relation to yolk and oil globule lipids

The fatty-acid composition of lipids from ovulated eggs of wild and cultured turbot was investigated in order to estimate the nutritional requirements during embryonic and early larval development. Lipid comprised 13.8±0.5% (n=5) and 13.2±0.7% (n=7) of the egg dry weight in wild and cultured turbot, respectively. Polyunsaturated fatty acids (PUFA) of the (n-3) series accounted for 39% of total fatty acids in total lipid of both wild and cultured fish. The predominant (n-3) FUFA was docosahexaenoic acid (22:6 n-3), which also was the most abundant fatty acid in turbot eggs and comprised 24 and 23% of the total egg fatty acids in wild and cultured fish, respectively. Phospholipids, triacylglycerols and cholesterol-wax esters of turbot eggs all exhibited a specific fatty-acid profile distinctly different from that of total lipid. The general pattern of the fatty-acid distribution in lipids of eggs from wild and cultured turbot was similar, but the relative amount of 18:2(n-6) was considerably higher and 20:1(n-9) slightly higher in cultured fish. These differences were extended to all lipid classes and probably reflect the dietary intake of certain vegetable and marine fish oils. Calculations based on light microscopical studies showed that 55 to 60% of the total lipids in cultured turbot eggs are confined to the oil globule. The size of the oil globule remained constant during embryogenesis, and a reduction in size occurred first after hatching and mainly after yolk depletion. This implies that the total amount of lipids utilised during the embryonic development is considerably less than the total lipids present in ovulated turbot eggs. Comparison of the fatty-acid composition of total lipids from eggs and vitellogenin of wild turbot reveals that egg lipids contained a lower level of saturated and a higher level of monounsaturated fatty acids. Eggs also contained wax esters, which were not detected in vitellogenin, suggesting that vitellogenin is not the only source of lipids for turbot eggs.     

Storage and depletion of lipid components in the pyloric caeca and ovaries of the seastarAsterias rubens during its annual reproductive cycle

Detailed information is presented on the changes in lipid-class profiles (polar lipids, total neutral lipids, free sterols, steryl esters, triacylglycerols, neutral ether lipids and free fatty acids), which are manifest during the annual reproductive cycle of the seastarAsterias rubens for both the storage organs (pyloric caeca) and utilizing organs (ovaries). The ovaries appear to accumulate all individual lipid components proportional to progression of vitellogenesis. Pyloric caeca, in contrast, show variable lipid-class levels, probably due to more complex processes in these organs, operating simultaneously: digestion of food, accumulation of storage lipids, mobilization of stored lipids and their release. The results are discussed in terms of current knowledge on the role of lipids in echinoderm reproduction.     

Lipids in atlantic halibut (Hippoglossus hippoglossus) eggs from planktonic samples in Northern Norway

Fertilized Atlantic halibut (Hippoglossus hippoglossus L.) eggs in different developmental stages (Days 0 to 18) were sampled from plankton in North Norway in February 1986 and analysed for lipid classes and fatty acid content. In unfertilized ovulated eggs taken from ripe fish caught in 1983/1984, polar and neutral lipids comprised ca. 71 and 30% of the total lipids, respectively, decreasing and increasing to 67 and 33%, respectively, in Stage III (11 to 18 d old) fertilized eggs. Of the polar lipids, phosphatidylcholine decreased markedly from 62% in unfertilized ovulated eggs to ca. 40% in Stage I (0 to 3 d old) fertilized eggs, while phosphatidylethanolamine increased from ca. 7 to 33%. Triacylglycerols, the major neutral lipids, increased from ca. 13% in unfertilized ovulated eggs to 16% in Stage III fertilized eggs. The total lipid in Stage I fertilized eggs had relatively low levels of polyunsaturated fatty acids (PUFA), with (n-3) PUFA accounting for only ca. 25% of the total fatty acids. The (n-3) PUFA increased to ca. 40% of the total fatty acids in Stage III, while the (n-3): (n-6) ratio increased from 4.1 to 7.0.     

Lipid classes and their content of n-3 highly unsaturated fatty acids (HUFA) in Artemia franciscana after hatching, HUFA-enrichment and subsequent starvation

The distribution of n-3 highly unsaturated fatty acids (HUFA) over the major neutral and polar lipid classes was determined for two predominant types of live food used in the larviculture of marine fish and shrimp, i.e. freshly hatched and HUFA-enriched Artemia, and compared with data reported in the literature for wild copepods, representing the natural diet of these larvae. Lipid class composition and their content of n-3 HUFA, particularly eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), were assessed in freshly hatched, HUFA-enriched and subsequently starved Artemia franciscana. The n-3 HUFA enrichment was based on feeding Artemia a lipid emulsion in which either fatty acid ethyl esters (EE, diluted with olive oil) or triacylglycerol (TAG) provided a level of 30% n-3 HUFA. Enrichment of Artemia with either type of the lipid emulsions resulted in an increase of total lipid content from 20.0 to 28.2–28.7% of dry matter mainly due to the accumulation of neutral lipid, primarily TAG (from 82 to 158 mg g⁻¹ dry wt in freshly hatched and 24-h enriched Artemia). Enriched brine shrimp utilized up to 27–30% of their TAG content during 72 h of starvation at 12 °C. The absolute tissue concentrations of polar lipids remained constant at 71 to 79 mg g⁻¹ dry wt throughout the enrichment and subsequent starvation. The level of n-3 HUFA increased drastically during enrichment from 6.3% of total fatty acids (8.2 mg g⁻¹ dry wt) in freshly hatched nauplii to between 20.4 and 21.8% (40.4 to 43.2 mg g⁻¹ dry wt) in 24-h enriched Artemia and was not significantly affected by the source of n-3 HUFA. During starvation, 18:0, 20:4n-6 and 20:5n-3 were retained, whereas 18:4n-3, 22:5n-3 and 22:6n-3 were specifically catabolized. The major polar lipids, phosphatidylethanolamine (PE) and phosphatidylcholine (PC), of freshly hatched Artemia showed very low levels of DHA (<0.1% of total fatty acids) and carried about 45% of the total EPA present. Enrichment with either of the emulsions resulted in an increase of the neutral lipid fraction which concentrated >64% of the EPA and >91% of the total DHA present. This is in sharp contrast with the high levels of n-3 HUFA, in particular DHA, in the polar lipid fraction reported for wild copepods. The contrasting distribution of DHA in the neutral and polar lipid fractions of enriched brine shrimp compared to the natural diet may influence the efficacy of this essential fatty acid for marine fish larvae in aquaculture systems. Received: 10 June 1997 / Accepted: 8 August 1997     

The Arctic pteropod<Emphasis Type="Italic"> Clione limacina</Emphasis>: seasonal lipid dynamics and life-strategy

During various seasons from May 2001 until July/August 2003, the lipid dynamics of the pteropod Clione limacina from Kongsfjorden, Svalbard, were investigated with respect to ontogenetic development and life-cycle. Polytrochous larvae, which were dominant in spring (April, May), composed the lipid-richest specimens of the population, with total lipid of about 50% of dry mass (%DM). Major lipid classes were triacylglycerols (TAG) and 1-O-alkyldiacylglycerol ethers (DAGE), accounting on average for 53.1 and 21.9% of total lipid, respectively. Until summer, larvae grew to adults by utilising their storage lipids. In July/August, lipids were depleted to about 10%DM due to maturation and reproduction. Almost all animals in autumn (September) were mature and able to replenish their lipid deposits by accumulating DAGE (26.7%) and TAG (39.6%). This is probably the prerequisite for successful overwintering.Principal component analysis (PCA), based on the fatty acid compositions, revealed ontogenetic differences between polytrochous larvae, and small and full-grown adults. Higher proportions of 18:4(n-3) and 14:0 were found in polytrochous larvae and smaller adults during spring. Both fatty acids were highly significantly correlated with the proportions of TAG, which were used for growth and development because they are presumably easier to metabolise. PCA also divided C. limacina specimens into DAGE-rich and DAGE-poor. We suggest that DAGE are a long-term energy store and hypothesise that they are necessary during periods of food scarcity, but may also serve as an energy source for reproduction. The fatty acids 17:1(n-8), 15:0, 16:1(n-7) and 18:1(n-7) were significantly correlated with the proportion of DAGE but not with TAG. These fatty acids, which do not originate from their only prey, Limacina helicina, are synthesised de novo. Their abundance reflects an efficient lipid production by C. limacina. Based on the results of lipid biosynthesis and accumulation in combination with the population structure, we suggest that C. limacina has at least a 2-year life-cycle in Svalbard waters.Communicated by M. Kühl, Helsingør     

Ontogenetic and seasonal changes in lipid and fatty acid/alcohol compositions of the dominant Antarctic copepods Calanus propinquus,Calanoides acutus and Rhincalanus gigas

Lipid compositions of the dominant Antarctic copepods Calanoides acutus, Rhincalanus gigas and Calanus propinquus from the Weddell Sea have been investigated in great detail. Copepods were collected during summer in 1985 and late spring/early winter in 1986. The analyses revealed specific adaptations in the lipid biochemistry of these species which result in very different lipid components. The various copepodite stages of C. acutus synthesize wax esters with long-chain monounsaturated moieties and especially the alcohols consisted mainly of 20:1(n-9) and 22:1(n-11). R. gigas also generates wax esters, but with moieties of shorter chain length. The fatty alcohols consisted mainly of 14:0 and 16:0 components, while the major fatty acids were 20:5, 18:4 and 22:6, of which 18:4 probably originated from dietary input. In contrast, C. propinquus accumulates triacylglycerols, a very unusual depot lipid in polar calanoid copepods. Major fatty acids in C. propinquus were the long-chain monounsaturates 22:1(n-9) and 22:1(n-11), which may comprise up to 50% of total fatty acids. In C. acutus and C. propinquus there was a clear increase of long-chain fatty acids with increasing developmental stage. In contrast, the fatty acid and alcohol composition of the R. gigas copepodite stages were characterized by the dominance of the polyunsaturated fatty acids as well as high amounts of the monounsaturates 18:1(n-9) and 16:1(n-7). There was a considerable decrease of the dietary fatty acid 18:4(n-3) towards the older stages during summer; in late winter/early spring 18:4 was only detected in very low amounts. This tendency was also found in the other two species, but was less pronounced. In all three species dry weight and lipid content increased exponentially from younger to older stages. The highest portion of wax esters, or of triacylglycerols in C. propinquus, was found in the adults. Dry weight and lipid content were generally higher during summer. In late winter/early spring the variability was more pronounced and lipid-rich specimens showed a selective retention of long-chain monounsaturated fatty acids, whereas in lipid-poor specimens these fatty acids were very much depleted.     

Fatty acid composition of the triacylglycerols of the cypris larva of the barnacle Balanus balanoides during metamorphosis

In the free-swimming cypris larva of Balanus balanoides, the mean level of triacylglycerols (triglycerides) was 8% of the ash-free dry weight. During metamorphosis into the juvenile barnacle, the triacylglycerol level in the newly settled non-feeding cypris larva fell to a mean of 2% of the ash-free dry weight. The ratio of fatty acids in the triacylglycerols remained constant throughout metamorphosis, indicating that all species of fatty acids were used as energy sources. There was no evidence for the selective utilisation of particular fatty acids.     

Diets of fan shells (Pinna nobilis) of different sizes: fatty acid profiling of digestive gland and adductor muscle

Pinna nobilis is a large bivalve, endemic to the Mediterranean Sea that was shown in a previous study to ingest significantly different proportions of different food items according to its shell height. Fatty acid profiling of total lipids was used to examine these differences in diet in relation to shell size. Small (shell height 23.0 ± 3.3 cm), medium (SH 41.5 ± 5.5 cm) and large (SH 62.7 ± 4.8 cm) P. nobilis were collected from Mali Ston Bay, Adriatic Sea, in March 2010, and fatty acid analysis was performed on digestive gland and adductor muscle tissues. Based on the analysis of the digestive gland, small P. nobilis were associated with a detrital food chain, characterized by saturated and branched-chain fatty acids, while the diets of medium and large individuals had a greater proportion of polyunsaturated fatty acids. This likely reflects the fact that smaller individuals feed within the benthic boundary layer where the detritus concentrations are high. Fatty acid incorporation into the adductor muscle, likely representative of food taken up over a longer time period, was reversed, that is, larger individuals had lower levels of polyunsaturated fatty acids. This most probably reflects energy expenditure, which typically increases with increasing organism size.