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  • 1
    Keywords: Mariculture--Congresses. ; Electronic books.
    Description / Table of Contents: Proceedings of the 1st Maricult Conference held in Trondheim, Norway, 25-28 June 2000.
    Type of Medium: Online Resource
    Pages: 1 online resource (207 pages)
    Edition: 1st ed.
    ISBN: 9789401731904
    Series Statement: Developments in Hydrobiology Series ; v.167
    DDC: 639
    Language: English
    Note: DEVELOPMENTS IN HYDROBIOLOGY Sustainable Increase of Marine Harvesting: Fundamental Mechanisms and New Concepts -- Developments in Hydrobiology 167 -- Editor's page -- Copyright -- TABLE OF CONTENTS -- Preface -- In memoriam: Arne Jensen (1926-2000) -- MARICULT Research Programme: background, status and main conclusions -- Pelagic food web configurations at different levels of nutrient richness and their implications for the ratio fish production:primary production -- The importance of silicon for marine production* -- Silicate availability, vertical mixing and grazing control of phytoplankton blooms in mesocosms -- The influence of turbidity on growth and survival of fish larvae: a numerical analysis -- Grid-generated turbulence in a mesocosm experiment -- Micro- and mesozooplankton response to enhanced nutrient input - a mesocosm study -- European mussel cultivation along the Atlantic coast: production status, problems and perspectives -- Effect of nutrient supply on growth of blue mussels (Mytilus edulis) in a landlocked bay -- Response on scallop culture to enhanced nutrient supply by experimental fertilisation of a landlocked bay -- Coastal upwelling, primary production and mussel growth in the Rías Baixas of Galicia -- Effects of the large-scale uncontrolled fertilisation process along the continental coastal North Sea -- Littoral macrofauna (secondary) responses to experimental nutrient addition to rocky shore mesocosms and a coastal lagoon -- Are rocky shore ecosystems affected by nutrient-enriched seawater? Some preliminary results from a mesocosm experiment -- Production enhancement by artificial upwelling: a simulation study -- Controlled artificial upwelling in a fjord using a submerged fresh water discharge: computer and laboratory simulations.
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  • 2
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (60 Seiten = 4 MB) , Graphen, Karten
    Edition: Online-Ausgabe 2021
    Language: English
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  • 3
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The larval stage is regarded to be the main bottleneck of halibut production. Halibut eggs were obtained from captive broodstock both by stripping and by natural spawning. Artificial photoperiods were used to increase the total spawning season. Yolk sac larvae are presently produced either in small stagnant units or in large flow through systems. A major consideration is to avoid stress of the larvae, caused by mechanical disturbances of the larvae and by high bacterial load or high ammonia levels in the water.The experiments showed that halibut larvae began to ingest algae earlier than rotifers Brachionus sp. Supplementation of algae to first feeding tanks resulted in enhanced survival and growth rate of the larvae. Both rotifers and Artemia can be enriched with very high levels of highly unsaturated n-3 fatty acids (n-3 HUFA). Enriched live feed, containing high levels of n-3 HUFA and total lipids, enhanced both survival and growth of the halibut larvae. The highest growth rates were obtained with wild zooplankton and addition of algae, but enriched cultivated feed combined with algae resulted in growth of the same magnitude as with wild zooplankton.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-143X
    Keywords: Enrichment techniqes ; Rotifer Brachionus plicatilis ; Emulsions ; Total lipids ; Fatty acids ; Lipid classes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four emulsions differing in lipid class composition: triacylglycerols, ethyl esters, phospholipids and wax esters were used to enrich rotifers either through short-term (ST) enrichment (24 h) or through long-term (LT) enrichment (10 days). Higher lipid levels were obtained by using the ST enrichment method. This was particularly marked in the high triacylglycerol accumulation in rotifers enriched on the phospholipid-based emulsion. Ethyl esters were effectively assimilated and incorporated into triacylglycerol by rotifers in both the ST and LT techniques. A high docosaehexanoic/eicosapentaenoic acid (DHA/EPA) ratio was obtained in the LT technique using the ethyl ester-based emulsion. However, the other emulsion treatments gave higher or equal DHA/ EPA ratios using the ST technique. Absolute phospholipid levels were independent of both dietary lipid composition and enrichment method used, whereas triacylglycerol levels depended on these parameters. During starvation the level of phospholipid, in absolute terms, decreased slightly whereas the triacylglycerol fraction decreased considerably. Rotifers enriched on the wax ester-based emulsion using the LT technique exhibited higher levels of long-chain monoenes (i.e. 20:1 and 22:1 isomers) than when the ST technique was used. This suggests that hydrolysis of the wax esters and oxidation of the liberated fatty alcohols to fatty acids occurred when the LT technique was applied.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Aquaculture international 2 (1994), S. 33-48 
    ISSN: 1573-143X
    Keywords: Scophthalmus maximus ; First-feeding ; Larvae ; Ω3 HUFA ; Rotifers ; Pigmentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of different lipid compositions of live feed on the survival, growth rate and pigmentation success of turbot larvae, Scophthalmus maximus (L.), was investigated. Rotifers, Brachionus plicatilis, together with the algae Tetraselmis sp., were administered until day 12, and Artemia was fed until day 27. The experimentally treated live feeds were enriched with four formulated emulsions, resulting in a gradient in the relative contents of Ω3 HUFA (highly unsaturated fatty acids) and in DHA (docosahexaenoic acid, 22:6 Ω3)/EPA (eicosapentaenoic acid, 20:5 Ω3) ratios in both the rotifers and Artemia. There were no differences in larval growth rate, and only small differences in survival rate throughout the feeding experiment, probably because of satisfactory levels of Ω3 HUFA in the live feed to sustain growth and survival. A correlation was obtained between the percentage of completely pigmented 27 d old turbot and the DHA/EPA ratio in the total lipids of 12 d old larvae, which again was correlated with the corresponding ratio in the live feed used. The results suggest that normal pigmentation in turbot requires dietary DHA in the early larval feeding period, and that this requirement cannot be replaced by EPA.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-143X
    Keywords: Atlantic salmon (Salmo salar) ; Body weight ; Latitude ; Lipid content ; Temperature ; Ω3 fatty acids ; Ω3/Ω6 ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The main aim of the present study was to examine the impact of some biological and environmental factors on the lipid and fatty acid compositions of farmed Atlantic salmon (Salmo salar), with special emphasis on Ω3 fatty acids. Two year groups of salmon at nine fish farms distributed along the Norwegian coast were fed the same diet and were sampled every second month. The data are believed to give a representative characterization of lipid and fatty acid content of salmon farmed in Norway. Multiple regression analysis revealed that variation in lipid content and body weight explained 80% of the variation found in Ω3 fatty acids in farmed salmon, and 22:6 Ω3 showed greater variation than other Ω3 fatty acids. Further analysis of lipid-corrected values revealed only minor effects of latitude on the per cent content of highly unsaturated Ω3 fatty acids, and hardly any effect of seawater temperature, with the exception of 22:6 Ω3, which decreased slightly with increasing temperature. The per cent 22:6 Ω3 in the fillet became gradually reduced with increasing fish age and body weight, whereas the content of 20:5 Ω3 and other Ω3 fatty acids remained relatively constant. The per cent content of 22:6 Ω3 of young salmon was higher than in the feed, but approached the feed value gradually as body weight increased. The lipid content of the salmon increased with fish age, and the absolute quantitative contents of both 22:6 Ω3 and 20:5 Ω3 increased meanwhile, even though the per cent content of 22:6 Ω3 decreased quite pronouncedly. The per cent 22:6 Ω3 and other Ω3 fatty acids was higher in wild than in farmed salmon, but the absolute quantitative content was higher throughout in farmed salmon, which had higher lipid contents. The Ω3/Ω6 ratio, which is important in human health evaluation, was lower in farmed than in wild salmon. The large flexibility of Ω3 fatty acids and lipid content of farmed salmon leave us with the option of producing a wide variety of salmon qualities requested by the market. Both per cent and absolute quantitative Ω3 contents, as well as the Ω3/Ω6 ratio, may readily be manipulated.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-143X
    Keywords: Algae (Isochrysis galbana) enrichment ; Nutrient composition ; Rotifer (Brachionus plicatilis).
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Rotifers, Brachionus plicatilis, fed baker's yeast and a lipid emulsion (High DNA Super Selco, INVE Aquaculture NV Systems SA, Belgium), were harvested and fed Isochrysis galbana for 72 h, the nutrient composition was analysed during this period. The enrichment effect on the rotifers following transfer to I. galbana was most pronounced for ascorbic acid and thiamin. I. galbana seemed to contribute very little as a source of the lipid-soluble vitamins. Most of the minerals and trace elements were unaffected by the transfer to I. galbana, but Fe, Mn, As and Cd increased, Cu and Ni decreased whereas the effect on Cr and Mo were uncertain. The fatty acid composition of the rotifers changed towards the composition of I. galbana during the experimental period. Intermediate glycogen levels were measured in the rotifers at all sampling times. With the exception of lysine, serine and proline, all amino acid levels seemed to be unaffected by the transfer to I. galbana. This study showed that transfer of rotifers to microalgae (I. galbana) feeding had a positive effect on nutritional value. Macronutrients were maintained at adequate levels, and algal feeding improved the nutritional quality of rotifers with respect to water-soluble vitamins. Changes in rotifer nutrient composition are discussed in relation to nutritional requirements of fish larvae.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-5117
    Keywords: Artemia franciscana ; DHA ; EPA ; ratesof loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In Artemia franciscana, enriched for 24 h with emulsified lipids, thefatty acid DHA (22:6ω3) is unstable. In rotifers the level of DHA canbe stabilised by adding algae rich in DHA to the fish tanks. To test thismethod for A. franciscana, enriched A. franciscana was incubated with thealga Isochrysis galbana, which is rich in lipids and DHA, at sixconcentrations ranging from 1 to 20 mg C l−1 at 13–14°C. After lipid enrichment, A. franciscana contained15% lipids of which 79% (116 mg g DW−1) werefatty acids. Of the fatty acids, 17% was DHA (19.8 mg gDW−1). After 72 hours incubation with I. galbana, the level ofDHA decreased to 1.6–3.2 mg g DW−1, which was areduction by 84–92%. This was independent of the algalconcentration. The amount of total fatty acids decreased to 53–73 mg gDW−1, a reduction by 37–54%, independent of thealgal concentration. The rates of loss of the fatty acids, and especiallyDHA, was greater during the first 24 h at the highest algal concentrations(8, 10 and 20 mg C l−1). Enriched A. franciscana shouldtherefore not be incubated with high algal concentrations (〉6 mg Cl−1) during first feeding of marine fish larvae.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 358 (1997), S. 159-162 
    ISSN: 1573-5117
    Keywords: Artemia franciscana ; Brachionusplicatilis ; marine copepods ; enrichment ; lipidcontent ; fatty acids ; DHA ; EPA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The total lipid content in Artemia franciscana (21–23% ofdry weight (DW)) when enriched with either Super Selco or DHA Selco wastwice as high as in the adult copepods Temora longicornis and Eurytemora sp.(9–11% of DW). In Brachionus plicatilis the total lipid contentwas 11 and 6.6% for cultures growing at high and low growth rate,0.12 d−1 and 0.38 d−1, respectively. In thecopepodid stages I, II and III of Calanus finmarchicus the total lipid levelwas 12–13%, increasing to 24% in copepodid stage IV, Vand the adults. In T. longicornis and Eurytemora sp. the predominant fattyacids were DHA (22:6n-3), EPA (20:5n-3) and the saturated fatty acid 16:0,which constituted 40–45%, 21–24% and8–12% of total fatty acids, respectively. C. finmarchicuscontained the same dominant fatty acids. In both the cultivated live feedorganisms DHA, EPA and 18:1 were the predominant fatty acids. In A.franciscana the content of these fatty acids varied according to theenrichment medium and in B. plicatilis according to the growth rate.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 358 (1997), S. 27-36 
    ISSN: 1573-5117
    Keywords: juvenile technology ; halibut ; turbot ; cod ; live feed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultivation techniques of the marine cold waterspecies turbot (Scophthalmus maximus), Atlantichalibut (Hippoglossus hippoglossus) andAtlantic cod (Gadus morhua) have been developedin Norway during the last decade. Research programshave been undertaken to establish the scientific basisfor a commercial, feasible juvenile productiontechnology.The Atlantic halibut must be carefully maintained inflow through silo systems during their prolongedcritical yolk sac stage (30 days). The period of firstfeeding lasts for approximately 80 days, and copepodsand Artemia are in most cases used as live feed.The halibut larvae have high requirements for n-3HUFA, in particular DHA. More efficient enrichmenttechniques for Artemia and more reliable firstfeeding technology are still major challenges for thisspecies. Commercial production of halibut is still inits early phase, but the numbers produced haveincreased steadily during the last few years, with theexception for 1995. The number of weaned halibut frytransferred to the growout phase was approximately370 000 in 1994 and less than 100 000 in 1995. Theproduction costs range between 5–6 US$ per fry.The rearing technology for juvenile turbot is wellestablished. Turbot larvae are cultured usingclassical intensive rearing techniques withmicroalgae, rotifers and Artemia as live feed.The larval densities are kept rather low by commercialproducers (〈5 l-1), but densities inresearch projects are normally much higher (〈100larvae per litre). The survival through the larvalstage is normally both predictable and relatively high(10–50%). Improvements in fry quality, e.g. growthpotential and viability, are higher priorities thanimprovement in survival. The number of fry produced inEurope in 1995 was some 2.5 million, anddepended on fry requirements rather thantechnical constraints. Production costs range between1.3–1.4 US$ per fry.The rearing technology of Atlantic cod is similar tothat of turbot, but the dietary requirements of cod,as well as most research objectives, are comparable tothose of halibut. Cod, however, currently has alimited commercial potential. The number of codjuveniles produced in 1995 was approximately 300 000,all produced in poll systems as part of restockingprojects. Established hatchery techniques may beutilized for commercial production of cod juveniles ifthe production costs of cultivated cod is lower thanthe price obtained for wild caught cod.
    Type of Medium: Electronic Resource
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