Search

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 Kroyer 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 ([micro]g lipid [copepod.sup.-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 (n7) 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.

Some organisms living in coastal bays in Newfoundland and Labrador have to contend with subzero temperatures for most of the year. The goal of this study was to examine the lipid composition of the food web in such an environment in order to obtain information on essential nutrients and trophic relations. In August 2000, plankton, 16 species of macroinvertebrates, and sediments were collected in a shallow, sheltered bay, Gilbert Bay, southern Labrador (52[degrees] 35'N; 55[degrees] 50'W). Plankton had higher proportions of [omega]3 fatty acids (39 [+ or -] 5%) and lower proportions of bacterial fatty acids (5 [+ or -] 2%), while sediments had 12 [+ or -] 5% [omega]3 fatty acids and 15 [+ or -] 9% bacterial fatty acids. Plankton [omega]3 fatty acids levels and sediment bacterial fatty acid levels were higher than in equivalent samples previously collected further south, in Newfoundland. Benthic macroinvertebrates contained 0.5 [+ or -] 0.4% of their wet weight as lipid, of which 45 [+ or -] 15% was triacylglycerol. Levels of [omega]3 fatty acids were high and relatively constant across phyla, accounting for 36 [+ or -] or 11% of the total fatty acids. Compared to other invertebrates, echinoderms had a unique fatty acid composition, which was characterized by high levels of 20:4[omega]-6 (9 [+ or -] 6%), bacterial fatty acids (8 [+ or -] 4%), and [summation of]20:1] + 22:1 monoenoic fatty acids (13 [+ or -] 6%). Baseline lipid data from plankton and macroinvertebrates showed constantly high levels of polyunsaturated fatty acids, indicating their physiological importance at low temperatures.

Condition indices (CI), hepatosomatic indices (HSI) and proximate, lipid and fatty acid composition of wild and laboratory-reared yellowtail flounder (Limanda ferruginea) (Storer, 1839) were compared from data taken throughout spring and summer 1996-1998. Cluster analysis was performed on the fatty acid signatures of these two groups along with a commercial diet and several invertebrate species to determine possible feeding patterns in Conception Bay, Newfoundland. HSI and levels of storage fat were significantly higher in the muscle and liver of laboratory-reared yellowtail flounder, indicating an efficient absorption of dietary lipid and an increase in fat deposition. Fatty acid analysis of the liver showed that wild fish contained significantly higher proportions of the essential fatty acids 20:4[Omega]6, 20:5[Omega]3 and 22:6[Omega]3; whereas proportions of 18:1 and 18:2[Omega]6 were significantly higher in all fractions of lipid examined from laboratory-reared fish than they were from wild fish. Polar fractions of lipid were more similar than the neutral fraction of lipid when comparing wild and laboratory-reared fish. Taken together, the differences in CI, HSI, proximate and fatty acid composition suggest that feeding commercial diets to L. ferruginea can cause changes in patterns of lipid deposition and metabolism. Cluster analysis of marine plankton, sedimenting particulate matter, wild invertebrates, the commercial diet and fish tissues showed that the fatty acid signatures of both wild and laboratory-reared yellowtail flounder closely resembled their respective food items. Fatty acid signatures from wild fish were more closely related to plankton and settling particulate matter, suggesting relatively few steps in the food web leading to yellowtail flounder. In addition to the resemblance between fatty acids in the commercial diet and the tissues of laboratory-reared yellowtail flounder, these fish had similar fatty acid signatures to those of wild invertebrates.

Atlantic halibut eggs were fertilized in a mixture of milt from two fish to observe changes in phospholipase A(sub 2) activity in the early development of the fish. Fatty acid, amino acid content and lipid levels were measured in each stage of growth. Phospolipase A(sub 2) was assayed in halibut eggs and in rat liver, lake trout liver and lumpfish eggs for comparison. Halibut embryos showed no activity after homogenates were thawed in contrast to rat liver homogenates which showed complete recovery of activity following thawing. This proves that halibut embryos' enzyme is more labile compared to PLA(sub 2)(s) from rat liver.

Studies of the muscles of Atlantic salmon smolts reveal that gamma-tocopherol deposition on muscle occurs in proportion to dietary levels of alpha-tocopherol. The beta- and delta-tocopherols are deposited to a lesser extent than the alpha- and gamma- forms. The levels of various tocopherols reach an equilibrium in about 15 weeks.

Camelina meal ( Camelina sativa) ( CM) is a potential protein source for aquaculture feeds, on account of its crude protein level (380 g kg−1) and inclusion of most indispensable amino acids. Two experiments were conducted with rainbow trout ( Oncorhynchus mykiss) and Atlantic salmon ( Salmo salar). Rainbow trout (44.9 g fish−1) were fed diets with CM at 0 g kg−1 (0% CM), 70 g kg−1 (7% CM), 140 g kg−1 (14% CM) or 210 g kg−1 (21% CM) for 12 weeks at 14 °C in freshwater, and salmon (241.8 g fish−1) were fed diets with CM at 0 g kg−1 (0% CM), 80 g kg−1 (8% CM), 160 g kg−1 (16% CM) or 240 g kg−1 (24% CM) for 16 weeks at 14 °C in sea water. Growth, lipid and amino acid tissue compositions were compared between species. Trout could tolerate up to 14% CM diets without affecting the growth compared to the control, while salmon fed ≥8% CM gained less weight than the control ( P = 0.008). The feed conversion ratio in trout fed 21% CM was higher than the control ( P = 0.002), and feed intake in salmon fed ≥8% CM was lower than the control ( P = 0.006). Trout fatty acid and amino acid composition showed minimal differences between CM-fed and control-fed fish, while salmon showed significant alterations after feeding CM diets. Multivariate analyses emphasized differences in tissue composition between species fed CM diets. [ABSTRACT FROM AUTHOR]

Ref.: Can. J. Fish. Aquat. Sci. 62: 2509-2518 (2005). In the print edition and the pdf file on the Web, this paper was misidentified as being in volume 52 rather [...]

Scallop juveniles fed a diet composed entirely of the flagellate Isochrysis galbana were observed to experience little or no growth. This was true for juveniles fed nutrient-replete I. galbana and those fed nitrogen-limited I. galbana. However, when the diet of the scallop juveniles were supplemented with 20% of the diatom Chaetoceros muelleri, significant increases in juvenile growth were recorded. Results affirm the need to feed scallop juveniles with optimal diets that include high levels of carbohydrates and polyunsaturated fats such as those found in C. muelleri.

The lipid composition of malpigmented (MP) and normally pigmented (NP), newly settled yellowtail flounder (Limanda ferruginea, Storer) was compared in order to elucidate a possible connection between lipids and pigmentation development. Larvae were fed commercially enriched live food for 12 weeks post hatch and then differences in lipid composition and size were analysed. NP fish were found to be significantly larger (standard length 35 mm) than MP fish (32 mm) at 100% settlement. There were higher proportions of triacylglycerols in NP fish (P = 0.01), whereas MP fish had an increased percentage of phospholipids (P = 0.01). NP fish had a higher percentage of docosahexaenoic acid (DHA) in the polar lipids of their body (P = 0.03) and total lipids of their eyes (P = 0.04). These data support previously proposed theories for the importance of DHA in pigmentation development. Principal components analysis (PCA) described the majority of the variance (77%) within the data set using just two principal components axes. PCA demonstrated that differences between body zones were greater than those between NP and MP fish within a given zone. [ABSTRACT FROM AUTHOR]

Presents a study on the effect of feeding the flagellate Isochrysis galbana on the growth and lipid composition of juvenile sea scallop Placopecten magellanicus. Methodology used; Results and discussion; Conclusions.

Examines the development of phospholipase A2 in fish during the early stages of life, while referencing methods used to regulate membrane lipids. Details on methods used to analyze lipids in the rat; Findings of studies conducted; Reference to the importance of lipids in eggs during the early stages of life.