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Notes: Abstract A 6-week feeding trial was conducted with 44-d-old European sea bass (Dicentrarchus labrax L.) in order to examine the effect of various dietary phospholipid (PL) sources on the incorporation of n-3 highly unsaturated fatty acids (HUFA) in tissue lipids. From weaning onwards the fish received diets prepared by coating different lipid fractions (7.5% diet) on an extruded basal diet (92.5% diet). The two PL-free control diets contained 0.5 and 2% of an emulsifier blend, respectively. Seven other diets contained 2% PL, differing by their purity and origin (vegetable or animal). All diets were rendered isolipidic by the addition of hydrogenated coconut oil. Feeding the PL-supplemented diets, except the diet containing hydrolyzed soybean PL (lyso PL), resulted in a higher survival and a 10 to 30% better growth as compared to the PL-free diets. No difference according to the PL origin was observed. The sea bass final lipid content increased with increasing body weight. Also the lipid class composition of the fish was clearly correlated with the final weight gain. Total neutral lipid increased from 51% of total lipid (initial fish) to 76% for fish fed the PL-free diets, and up to 88% for fish fed the sunflower PL. Weaning the fish on the experimental diets induced important changes in their fatty acid profiles characterized by a decrease in 18:3n-3, 20:5n-3 and 20:4n-6 and an increase in saturated fatty acids and 22:6n-3 (DHA). According to the fatty acid composition of both total and polar lipid, the weaned fish could be divided into three groups reflecting the dietary fatty acids: a group fed the vegetable PL, a group fed the animal PL and a PL-deprived group. An effect of dietary PL on the incorporation of dietary n-3 HUFA, more particularly DHA, was noticed. For a similar supply of DHA through the neutral lipids in the diet, fish fed PL-supplemented diets (except for the lyso PL diet) had 10 to 25% higher DHA levels in total and polar lipid than PL-deprived fish. This PL effect was already clear at the end of the weaning and was not related to the presence of n-3 HUFA in the PL source, as suspected in a previous study when feeding egg yolk PL. A better incorporation of DHA was not obtained by replacing the PL by an emulsifier or by lyso PL with higher emulsifying properties. Present results confirm a role of dietary PL in the absorption of dietary neutral lipids, by a mechanism other than emulsification.

Notes: Abstract The 3 culturing devices described are based on the principle of the classic air-water lift, which facilitates continuous recirculation and aeration of the cultivation medium. The first device is a “circulation cylinder”, convenient for hatching eggs of the brine shrimp Artemia salina and for culturing algae and protozoans. In the second device, an internal basket (i.e., a glass cylinder with plankton-gauze bottom) prevents the animals being carried along in the air-water lift. The third device, analogous to the second, is provided with a lateral waste-drain and a water collector with siphon, which empties regularly into the main culture vessel. The second and third devices proved to be excellent for the cultivation of a variety of aquatic metazoans. They fulfil two elementary principles of cultivation: food particles are kept in suspension and evenly distributed, and the necessary aeration is provided without injuring sensitive animals.

Notes: Abstract  Free amino acid (FAA) and protein content were measured in various developmental stages of Artemia franciscana, from cysts to Instar III metanauplii. In addition, decapsulated cysts of 15 Artemia populations from different localities were compared with respect to their FAA and protein content. Furthermore, the content and composition of the FAA pool were modulated by hatching the cysts at various salinities, and by enriching the nauplii with algae or a lipid-enrichment emulsion. The FAA content increased threefold from cysts to nauplii, and Instar III metanauplii contained nearly 50% taurine of total FAA. Cysts of A. franciscana were found to contain one-third the amount of FAA compared to the other Artemia species investigated. The content and pool composition of FAA was successfully modulated in 11 of 13 populations, where by the content of FAA was significantly increased when hatched at high salinity. Finally, enrichment elevated the content of FAA and changed the pool composition, thereby showing a dietary effect. Algal enrichment also increased the protein content.

Notes: Abstract The present study evaluated the effect of starvation and of feeding various algal and lipid-supplemented diets on the lipid content and lipid class distribution in the polar and neutral lipids of early juvenile oysters (Crassostrea gigas) and clams (Tapes philippinarum L.). T. philippinarum was starved, fed a mixed algal diet [Tetraselmis suecica and Isochrysis galbana (clone T-Iso)] or solely T. suecica at three different feeding rations, either supplemented or not supplemented with lipid emulsions. C. gigas was fed T. suecica with and without the supplementation of lipid emulsions or liposomes. When T. philippinarum and C. gigas were fed solely T. suecica, no qualitative and only minor quantitative differences were observed between the lipid class profile of both species. The major neutral lipids were triglycerides (TAG) and free sterols plus diglycerides (FS+DAG), whereas the polar lipids were dominated by phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol plus ceramideaminoethanol phosphonate (PI+CAEP). An increase of the algal feeding ration resulted in an increase of the lipid content of spat which was associated with a significant augmentation of the TAG level (as percentage of the total lipids and as percentage of the neutral lipids). Lipid supplementation evoked a similar though more pronounced effect. Starvation resulted in a significant decline of the lipid content and a complete depletion of the TAG reserve. Contrary to the neutral lipids (NL), the relative proportion (percentage of total polar lipids, PL) of the individual PL classes was hardly affected by the diet. The importance of lipid and TAG reserves in early juveniles is discussed.

Notes: Abstract A scanning electron microscopy (SEM) study of bisexual Artemia populations revealed that populations representing the species A. franciscana, A. persimilis, A. urmiana, A. sinica and a recently described species from Kazakhstan have a pair of spine-like outgrowths at the basal parts of their penes, whereas populations from southern Europe and North Africa (i.e. Mediterranean populations) lack these spine-like outgrowths. Allozyme and DNA polymorphisms, detected by allozyme starch gel electrophoresis and AFLP fingerprinting, respectively, suggested conspecificity of the studied populations from the broader Mediterranean basin. Male specimens from the collection of the Natural History Museum of London (UK) of the extinct A. salina population from Lymington lack spine-like outgrowths at the basal parts of the penes. This finding, based on a taxonomic character which is quite reliable, suggests conspecificity of A. salina from Lymington and the present bisexual Artemia populations from the Mediterranean basin, grouped under the binomen A. tunisiana.

Notes: Abstract In the literature, hatching of Artemia salina L. dry cysts has always been related exclusively to the hydration state of the cysts. Hatching experiments with cysts from different places revealed that light in some way triggers the hatching mechanism.

Notes: African catfish (Clarias gariepinus) larvae were fed on five preparations of decapsulated Great Salt Lake Artemia cysts: 1) dried (35C, 6h) and UV-irradiated cysts; 2) heated cysts (80C, 10 min); 3) brinedehydrated and UV-irradiated cysts; 4) micro-bound diet 1 (with intact decapsulated cysts used in diet preparation 1); and 5) micro-bound diet 2 (with crushed and shited decapsulated cysts used in diet preparation 1). The larvae were fed from the first day after yolk-sac resorption (fourth day after hatching). After a 14-d rearing period, larvae fed on dried or heated decapsulated cysts yielded significantly higher mean weights than the groups fed on brine-dehydrated decapsulated cysts or micro-bound diet 1. Feeding micro-bound diet 2 resulted in a significantly lower average gain in weight as compared to the other groups.

Notes: Samplings were organized in three marine fish hatcheries. Samples were taken at different steps during the production of algae, rotifers and Artemia. There were 233 dominant colony types isolated for further characterization. The isolates were compared to each other and to reference strains of Phorobacrerium, Vibrio and Alreromonas, using cellular fatty acid fingerprints. Fatty acid profiles of the isolates were grouped using principal component analysis. The isolates fell into at least ten major groups, of which two correspond to the genera Vibrio and to Alteromonas, respectively. Some groups seem to be restricted to a particular type of live food or isolation site. Although 43% of the isolates belong to Vibrio, only a minority of them could be readily assigned to known species.