A study of the variations in lipid levels,lipid class composition and fatty acid composition in the first stages ofArtemia sp.

The lipid class composition and the fatty acid composition of total lipids of the cysts, newly hatched nauplii and 24-h-old metanauplii of a Spanish parthenogenetic diploid strain ofArtemia sp. were studied. Substantial differences in the total lipid level occurred among these stages, with a marked increase from the cyst to the nauplii being followed by a decrease in the metanaupliar stages. This variation affected the absolute levels (mg/g dry wt) of the total lipid classes and individual fatty acids, although the percent composition of the fatty acids in total lipid was essentially unchanged. An exception occurred during hatching in that the percentages of 16:0 and 16:1n-7 in total lipid decreased whereas that of 20: 5n-3 increased. The lipid classes showed higher variation than the fatty acids both in absolute and in relative terms, and in particular, the ratio of phosphatidylcholine:phosphatidylethanolamine decreased progressively from cysts to nauplii and metanauplii. The implications of these findings for the use ofArtemia sp. as a larval feed in aquaculture are considered.     

Differential utilization of biochemical components during larval development of the spider crab Maja brachydactyla (Decapoda: Majidae)

Changes in lipid class, fatty acid, fat-soluble vitamins, amino acid and minerals were studied during larval development of Maja brachydactyla Balss, 1922 in order to provide information of its ontogeny and evaluate possible dietary deficiencies and constraints. Four different batches were analyzed from hatching to metamorphosis using enriched Artemia as food. Cultured larvae were in a good nutritional condition as confirmed by the continuous lipid accumulation throughout ontogeny. A regulation of polyunsaturated fatty acids (PUFA) occurred during development in order to maintain adequate basal levels of ω-3 fatty acids (likely through a retro conversion of C₂₀ and C₂₂ into C₁₈ PUFA). Variations in the tocopherol levels indicated its possible role in PUFA protection against oxidation. Essential amino acid balance during development was not correlated with the Artemia feeding regime, but rather reflected inherent variations of the own species ontogeny. Larval requirements in essential minerals were fully supplied by the enriched Artemia.     

Effects of various diets on the nutritional value of Artemia sp. as food for the prawn Penaeus monodon

The nutritional value of Artemia sp. as food for marine fish and crustacean larvae has been linked to the level of its polyunsaturated fatty acid (PUFA) content. Experiments in August 1984 were conducted to determine the effects of various artificial diets and algae on fatty acid composition of PUFA-deficient Artemia sp. (Utah GSL strain) and their resulting value as food for postlarvae of the prawn Penaeus monodon (Fabricius). Nauplii of the brine shrimp were grown on extracts of corn, copra, soybean and rice bran containing precursors (C18) to long-chain PUFA and also on algal species containing different levels of long-chain PUFA (C20). The nauplii were then used as food for P. monodon postlarvae. The results revealed that absence of C20 polyunsaturates from the feeds and their presence in the algae were reflected in the polyunsaturated fatty acid content of the tissues of Artemia sp. When fed with brine shrimp fed on algae, P. monodon displayed better postlarval survival and significantly higher growth; related to the content of polyunsaturated fatty acids in Artemia sp. A practical feeding approach in prawn hatcheries would be to grow Artemia sp. on a cheap diet such as rice bran, and then to enhance its nutritional value with a diet high in PUFA prior to harvesting, in order to improve hatchery production.     

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     

Ontogenic changes of amino acid composition in planktonic crustacean species

Changes in amino acid composition (AAC) during ontogeny of some planktonic crustacean species commonly found in fresh and brackish coastal waters were compared. For these comparisons two calanoid copepods (Eurytemora velox and Calanipeda aquae-dulcis), two cyclopoid copepods (Diacyclops bicuspidatus odessanus and Acanthocyclops robustus) and two Daphnia (Daphnia pulicaria and Daphnia magna) species were selected. A discriminant analysis was performed to determine whether there were significant differences between the AAC of the different stages of each species. Results show gradual changes in AAC during ontogeny of the copepod species. Calanoids showed the greatest differences in AAC between stages, followed by cyclopoids. Gradual changes in AAC were due to the increase in some amino acids such as alanine, valine, glutamic acid, glycine, arginine, proline and tyrosine from nauplii to adults. The latter showed a remarkable increase in all copepod species. In contrast, Daphnia species showed a relatively constant AAC during development, with only minor changes being detected, and not related with ontogeny. Differences in the physico-chemical variables of the lagoons do not seem to be the cause of copepod ontogenic changes in AAC. Data suggest that AAC differences found between stages of copepod species could indicate a gradual change in diet during the life cycle of these copepods.     

Using fatty acid analysis to elucidate the feeding habits of Southern Ocean mesopelagic fish

Fatty acid biomarkers were used to investigate the feeding ecology of 17 mesopelagic fish species occurring in the Southern Ocean. Fatty acid signatures of species where little or no dietary information exists were compared to fatty acid signatures of species of known diets in order to elucidate their trophic position. Principal component analysis grouped species of known diets into two clusters with amphipods and copepods comprising the main prey species, respectively. Although the majority of species of unknown diet were grouped with either of these feeding guilds, a third cluster comprising only Gymnoscopelus bolini was identified suggesting a significantly different diet for this species. Electrona antarctica also exhibited significant changes in fatty acid signatures with size. Furthermore, discriminant analysis of the four most abundant species classified species with a 90% success rate thus validating the usefulness of fatty acid signatures when trying to resolve the trophic position of species where no or little dietary information exists.     

Seasonal patterns in fatty acids of <Emphasis Type="Italic">Calanus hyperboreus</Emphasis> (Copepoda,Calanoida) from Cumberland Sound,Baffin Island,Nunavut

The marine copepod Calanus hyperboreus accumulates large quantities of lipids and essential fatty acids during summer months in Northern oceans. However, few data exist regarding their winter fatty acid profiles, which could be informative regarding the use of lipids by C. hyperboreus to successfully survive and reproduce during times of ice-cover and limited food. The present study compared fatty acids of C. hyperboreus between summer (August 2007 and 2008) and winter (early April 2008 and 2009) in Cumberland Sound, Canada. Summer samples from both years had significantly higher ∑polyunsaturated fatty acids and unsaturation indices (based on μg fatty acid mg dry tissue⁻¹) than winter samples and separated on a principal component analysis due to higher 18:2n-6, 18:4n-3, and 20:5n-3, consistent with phytoplankton consumption. Winter C. hyperboreus had significantly higher ∑monounsaturated fatty acids (MUFA) versus summer samples and separated on the principal component analysis due to higher proportions of 16:1n-7, 20:1n-9, and 22:1n-9, suggesting they were not actively feeding. Based on the seasonal fatty acid comparison, C. hyperboreus was catabolizing specific fatty acids (e.g. 20:5n-3), conserving others (e.g. 22:6n-3), and maintaining or increasing biosynthesis of certain MUFA (e.g. 18:1n-9) during winter. These findings provide insight into the seasonal strategy of acquisition (summer) and utilization (winter) of specific fatty acids by a key Arctic organism and could become important for monitoring changes in fatty acids associated with decreased ice-cover duration due to climate warming.     

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.     

Dietary influence on fatty acid composition of blubber fat of seals as determined by biopsy: A multivariate approach

A method for determination of the fatty acids of blubber fat from living seals is demonstrated: fat samples are retrieved by a small syringe, the fat is directly methanolysed, the resulting fatty acid methyl esters are gas-chromatographed and the chromatographic results are treated by multivariate principal-component analysis. The blubber fat of two grey seals [Halichoerus grypus (Fabricius, 1791)] and two harbor seals (Phoca vitulina L.) at the Aquarium of Bergen, Norway, as well as their diet, herring and mackerel, were monitored over a period of 7 mo in 1989. Fatty acid composition of the blubber fat was significantly different from that of the diet.     

Larval growth and settlement of the European oyster (Ostrea edulis) as a function of food quality measured as fatty acid composition

Larval growth rate and settlement of the European flat oyster Ostrea edulis were experimentally studied as a function of the composition of dietary fatty acids. Diets differing in fatty acid composition were composed by mixtures of the microalgae Isochrysis galbana, Pavlova lutheri and Chaetoceros calcitrans. Fatty acid content in the tissue of the feeding larvae, analyzed by gas chromatography and mass spectrometry, reflected the composition in the diet. Larval growth rate was significantly correlated to the three omega-3 polyunsaturated fatty acids (PUFA) C18:3, C18:4 and C22:6, with minor differences for neutral and polar lipids. No relation between growth rate and the omega-3 PUFA C20:5 was detected, a PUFA often implied as essential for bivalves. It is suggested that naturally occurring variability in fatty acid composition may constrain larval growth. In settlement experiments in both still water and flume flow little substrate selectivity was found for some contrasting substrates. It is concluded that differences in dietary fatty acids may explain as much of settlement success as the variability of substrates. Received: 12 October 1998 / Accepted: 6 April 1999     

Changes in phospholipase A2 activity and lipid content during early development of Atlantic halibut (Hippoglossus hippoglossus)

During early development in fish, phospholipase A₂ (EC 3.1.1.4) regulates membrane lipid modifications, which relates to changes in environmental conditions and provision of fatty acids required for metabolic energy substrates and prostaglandin biosynthesis. A method to analyze phospholipase A₂ in rat tissues has been modified to measure its activity in embryonic Atlantic halibut (Hippoglossus hippoglossus L.). Egg and embryo samples were collected during the 1994 spawning season. Enzyme activity was undetectable at fertilization but in 10-d embryos was 230 pmol mg⁻¹ h⁻¹ (at 20 °C) and increased by ∼120% at hatch (17-d). Significant alterations in the fatty acid composition of important phospholipids, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), were also observed. The content of some critical polyunsaturated fatty acids, and the ratio of unsaturated/saturated fatty acids, declined significantly over development. Acyl-chain restructuring mediated through the activity of phospholipase A₂, coupled with other observed lipid changes (significant increases in the PC/PE ratio and cholesterol content), would produce a decreased fluidity of membranes during embryonic development, coinciding with the predicted upward movement of larvae in the water column. Arachidonic acid (20:4n-6) removed from PE could serve as a precursor for biosynthesis of 2-series prostaglandins, and eicosapentaenoic acid (20:5n-3) from PC is a likely source for other prostaglandin types. Despite removal of polyunsaturated fatty acids, there was an overall increase in lipid and fatty acid concentration, which can be attributed to amino acid catabolism during early developmental stages. Received: 9 September 1996 / Accepted: 8 September 1997     

Effects of monospecific and mixed-algae diets on survival, development and fatty acid composition of penaeid prawn (Penaeus spp.) larvae

Four species of microalgae (Chaetoceros muelleri, Tetraselmis suecica, Tahitian Isochrysis sp. (T-iso) and Dunaliella tertiolecta) with distinctly different fatty acid profiles were grown in continuous culture and fed to prawn larvae (Penaeus japonicus, P. semisulcatus and P. monodon) as monospecific diets. The best two diets (C. muelleri and T. suecica) were also fed as a mixed diet. Experiments were run until the larvae fed the control diet of C. muelleri metamorphosed to Mysis 1. The survival and development (i.e. performance) of the larvae were affected by algal diet, and the diets were ranked in the order of decreasing nutritional value: C. muelleri ≥ T. suecica > T-iso > D. tertiolecta. Larvae fed a mixed diet of C. muelleri and T. suecica (2:3 by dry weight) performed as well or better than those fed C. muelleri, and the performance of both these groups of larvae was better than those fed T. suecica. The lipid and carbohydrate compositions of the algae had little or no effect on the lipid and carbohydrate compositions of the larvae or their performance. However, the larvae that performed best (i.e. those fed C. muelleri) had significantly more lipid and carbohydrate than those that performed worst (i.e. those fed D. tertiolecta). Larvae fed C. muelleri or the mixed-algae diet had higher proportions of the essential fatty acids eicosapentaenoic acid [EPA, 20:5(n-3)] and arachidonic acid [ARA, 20:4(n-6)] than the larvae fed on other diets. Furthermore, the larvae fed T. suecica, which showed intermediate performance between larvae fed C. muelleri and T-iso or D. tertiolecta, also had higher proportions of EPA and ARA. Both C. muelleri and T. suecica contained EPA and ARA, but T-iso and D. tertiolecta did not, except for trace amounts of EPA in T-iso. The fatty acid ARA appears to be much more important in the diet of larval prawns than has so far been considered. The level of the essential fatty acid docosahexaenoic acid [DHA, 22:6(n-3)] in the algal diet and the larvae was not related to the performance of the larvae; only C. muelleri and T-iso contained DHA. However, the nauplii contained large proportions of DHA, suggesting that these were sufficient to meet the larval requirements for DHA during their development to Mysis 1. Mixed-algae diets could improve the performance of larvae by providing a more comprehensive range of fatty acids. Received: 22 April 1998 / Accepted: 3 December 1998     

Chemical composition of dietary species of marine unicellular algae and rotifers with emphasis on fatty acids

The lipid profiles of a few species of marine unicellular algae and yeast were studied with emphasis on fatty acids as part of a search for the nutritional value of plankton to the diet of marine fish larvae commonly used in marine hatcheries. The general proximate chemistry of rotifers was closely related to the proximate chemistry of the diet organism, exhibiting a higher content of protein and carbohydrate and a lower content of lipid. Major lipids in all algae, yeast and rotifers comprised mono-, di- and tri-glycerides and polar lipids. The algae Chaetoceros gracilis Schutt, Isochrysis galbana Parke and their respective algaefed rotifers exhibited higher amounts of neutral lipids, consisting mainly of cyclic and branched polyunsaturated components. Fatty acid composition of the algae was species-specific, with the highest ratio of polyethylenic to saturated and monoethylenic acid in I. galbana and Phaeodactylum tricornutum Bohlin, and the highest content (15%) of n-3 highly unsaturated fatty acids in Nannochloropsis salina and P. tricornutum. A closely mirrored distribution of the fatty acids, but with a lower amount of n-3 highly unsaturated fatty acids, was present in the respective algae-fed rotifers. Comparison of the fatty acid spectrum of Artemia sp. and Euterpina acutifrons grown in the laboratory on I. galbana with zooplankton samples of E. acutifrons and Oitona nana collected from the sea showed a higher concentration of docosahexaenoic acid (22:6 n-3) in the naturally collected sample. The results indicate that the efficacy of the food algae C. gracilis and I. galbana in increasing the survival of fish larvae in marine hatcheries is not obvious on the sole basis of fatty acid composition.     

Lipids of some Caribbean and Red Sea corals: total lipid,wax esters,triglycerides and fatty acids

The Caribbean reef-building corals Porites porites (Pallas) and Montastrea annularis (Ellis and Solander) and the Red Sea corals Pocillopora verrucosa (Ellis and Solander), Stylophora pistillata (Esper) and Goniastrea retiformis (Lamark) were analysed for total lipid, wax ester and triglyceride content, and fatty acid composition. M. annularis contained about 32% of dry weight as total lipid, whereas much lower values of between 11 and 17% were recorded for the other four species. It is concluded that there is greater variation in coral total lipid than hitherto thought. The total lipid contained a substantial proportion of wax ester (22 to 49%) and triglyceride (18 to 37%). The storage lipids (wax esters and triglycerides) accounted for between 6 and 20% of the dry weight and between 46 and 73% of the total lipid. Variation in lipid content between species could not be attributed to geographical location, but the low values for total lipid in Red Sea corals may in part be due to environmental factors as these samples were collected in winter. All corals analysed contained high levels of saturated fatty acids, the most abundant fatty acids being 16:0, 18:0 and 18:1n-9. Marked differences were observed in polyunsaturated fatty acid (PUFA) content between species, with comparatively low levels of 10 and 11% of fatty acids being recorded in M. annularis and G. retiformis, respectively. The values for the other species ranged between 21 and 37%. Fatty acid composition may vary according to the proportions of fatty acids obtained from diet, algal photosynthesis and synthesis by the animal tissues.     

Effect of lipid emulsions on production and fatty acid composition of eggs of the scallop<Emphasis Type="Italic"> Argopecten purpuratus</Emphasis>

The impact of supplementing lipid emulsions rich in eicosapentaenoic acid (EmEPA), docosahexaenoic acid (EmDHA) or saturated fatty acids (EmCOCO) to a standard algal diet [3:1 mixture of Isochrysis galbana (T-iso) and Chaetoceros neogracile, St-diet] on Argopecten purpuratus broodstock was evaluated. Broodstock fecundity was compared as well as the egg quality in terms of lipid content, fatty acid composition and lipid class distribution. Fecundity was defined as the number of eggs released in the spawning process, since spawning was virtually complete. Results indicated that the total lipid content of the eggs of A. purpuratus was diet independent. A greater energy reserve was spent on a larger number of oocytes and not on bigger sized oocytes with a higher lipid content. The lipids supplied through the emulsions were at least partially allocated to the eggs, demonstrating that the fatty acid composition of the eggs could be manipulated, especially the neutral lipid fraction. Levels of EPA changed more rapidly than DHA levels, supporting the observation that they fulfilled an energetic and structural role, respectively. The St-diet supplemented with 50%EmCOCO resulted in a significantly higher fecundity compared to the algal diet supplemented with 25%EmEPA+25%EmDHA and the non-supplemented algal diet. It would seem that saturated fatty acids (SAFA) were more easily or preferentially incorporated in the female gonads of A. purpuratus. The relative content of SAFA and 18:2( n-6) in these eggs rose significantly. The relative content of the highly unsaturated fatty acids, EPA and DHA, on the other hand was substantially lower in the neutral lipid fraction, but hardly affected in the polar lipid fraction. It appeared that the maintenance of an adequate DHA/EPA ratio (approximately 1.2) was more important than the absolute levels of the two fatty acids, as long as a threshold value was reached.     

Potential dietary effects on the fatty acid composition of the common jellyfish Aurelia aurita

Fatty acid composition of the natural and aquarium-reared common jellyfish Aurelia aurita was investigated. Fatty acid composition of the aquarium-reared A. aurita clearly reflected that of the diet, brine shrimp (Artemia). In the same way, fatty acid composition of the natural A. aurita was assumed to reflect those of natural diets. Samples of natural A. aurita were collected from April 1995 to September 1995 in the Seto Inland Sea, Japan, and their fatty acids were analyzed by gas chromatography and mass spectrometry. Variation of fatty acid compositions was seasonal rather than dependent on body size. Two major seasonal groups were divided by the cluster analysis of the A. aurita fatty acid composition: the April–June and the August–September clusters. The April–June cluster was characterized by high contents of the (n − 3)-fatty acids of diatom origin, accumulated via the grazing food chain. By contrast, the August–September cluster was characterized by an increase in (n − 6)-fatty acids of macroalgal origin, probably transferred via the detritus food chain. These results suggest that the diet of natural A. aurita may shift between the diatom-based food chain and the detritus-based food chain. Received: 12 April 2000 / Accepted: 1 December 2000     

Changes in lipids during the development of Calanus finmarchicus s.l. from Copepodid I to adult

The total lipid and wax ester content as well as the fatty acid and alcohol composition of all copepodid stages and adults of Calanus finmarchicus s.l. were investigated at different locations in the North Sea in 1983 and 1984. Total lipid and the wax ester proportion increased exponentially until Copepodid V. The females were sometimes lower in lipids than the Stage V. The wax ester proportion reached about 90% of total lipids in males and Copepodid V and up to 40% in Copepodid I. The major fatty acids were 16:0, 20:5, and 22:6 and the major fatty alcohols were 16:0, 20:1 and 22:1. At one station the 18:4 acid became one of the dominant acids, because of a Phaeocystis sp. bloom, indicating that the fatty acids of the diet are incorporated mostly unchanged into the lipids of the copepods. The other main fatty acids 20:1 and 22:1 are probably synthesized de novo, serving as precursors for the principal alcohols 20:1 and 22:1. Their levels decreased in the younger stages due to increases in 16:0 alcohol. The fatty alcohol-forming enzyme seems to be specific for saturated and monounsaturated acids, which may be synthesized de novo or derived from diet.     

Importance of wax esters and other lipids in the marine food chain: Phytoplankton and copepods

Wax esters, which function as reserve fuels, account for 25 to 40% of the lipid of the pelagic copepod Calanus helgolandicus (Copepoda, Calanoida). In laboratory experiments with these crustaceans, diatoms (Lauderia borealis, Chaetoceros curvisetus, and Skeletonema costatum) and dinoflagellates (Gymnodinium splendens), which contained no wax esters, were used as food. Changes in the food concentration affected both the amount of lipid and the composition of the wax esters. Since the fatty acids of the triglycerides and wax esters of C. helgolandicus resembled the dietary fatty acid composition, it appeared that copepods incorporated their dietary fatty acids largely unchanged into their wax esters. The polyunsaturated alcohols of the wax esters did not correspond in carbon numbers or degrees of unsaturation to the dietary fatty acids. We postulate two different metabolic pools to explain the origin of these long chain alcohols. The phospholipid fatty acids were not affected by changes in the amount or type of food, probably because of their structural function.     

The Mediterranean intertidal habitat as a natural laboratory to study climate change drivers of geographic patterns in marine biodiversity

Nylon bags containing yellow leaves of Rhizophora apiculata and Avicennia marina, were immersed for 80 days from August to October, 1996. the decomposing leaves were collected every 10 days and analysed for dry weight loss and six biochemical parameters: tannins, total amino acids, total sugars, total nitrogen, total lipids and fatty acid profile. the leaf weight initially decreased very rapidly by about 50% of the start in two species of mangroves within 10 days. Similar changes were observed with tannins, total amino acids and sugars. However, the concentration of nitrogen increased significantly with decomposition. There was no significant change in total lipid and fatty acid profile. the highest concentration of fatty acid in the decomposing leaves was palmitic acid (16:0). Unsaturated fatty acids such as, 18:1 w7c and 18:1 w9c were found to be present in decomposing leaves of both 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.