Larvae of the sea bass Dicentrachus labrax were fed four Artemia sp. diets for 28 d. Three were nauplii enriched with emulsions of polyunsaturated fatty acids, and the fourth nauplii enriched with baker's yeast. At the end of the experimental period, the fatty acids of the bodies, heads and eyes of the larvae were analysed. A multivariate statistical method (discriminant analysis, DA) applied to the data revealed anatomical as well as dietary fatty acid pattern-discrimination. We propose here the use of discriminant analysis as a pattern-recognition method that will help to integrate the fatty acid information obtained in nutritional studies.
[Show abstract][Hide abstract] ABSTRACT: We examined trophic positions and fatty acid concentrations of riverine, lacustrine, and aquaculture diet and fish in Austrian
pre-alpine aquatic ecosystems. It was hypothesized that dietary fatty acid (FA) profiles largely influence the FA composition
of the salmonids Salvelinus alpinus, Salmo trutta, and Oncorhynchus mykiss. We analyzed trophic positions using stable isotopes (δ15N) and tested for correlations with polyunsaturated fatty acid (PUFA) concentrations. Gut content analysis revealed benthos
(rivers), pellets (aquaculture), and zooplankton (lakes) as the predominant diet source. Results of dorsal muscle tissues
analysis showed that the omega-3 PUFA, docosahexaenoic acid (DHA; 22:6n−3), was the mostly retained PUFA in all fish of all ecosystems, yet with the highest concentrations in S. alpinus from aquaculture (mean: 20mg DHA/g dry weight). Moreover, we found that eicosapentaenoic acid (EPA; 20:5n−3) in fish of natural habitats (rivers, lakes) was the second most abundant PUFA (3–5mg/g DW), whereas aquaculture-raised
fish had higher concentrations of the omega-6 linoleic acid (18:2n–6; 9–11mg/g DW) than EPA. In addition, PUFA patterns showed that higher omega-3/-6 ratios in aquacultures than in both
riverine and lacustrine fish. Data of this pilot field study suggest that salmonids did not seem to directly adjust their
PUFA to dietary PUFA profiles in either natural habitats or aquaculture and that some alterations of PUFA are plausible. Finally,
we suggest that trophic positions of these freshwater salmonids do not predict PUFA concentrations in their dorsal muscle
KeywordsAquatic food webs-Dietary fatty acids-Stable isotopes-Aquatic habitats-Fish
"stinguish between dietary and non - dietary components . Some fatty acids are deposited in adipose tissue with little modification and in a predictable way ( Iverson et al . , 2004 ) . The specific FA patterns are passed from prey to predator near the bottom of the food web ( Sargent et al . , 1988 ; Fraser et al . , 1989 ; Graeve et al . , 1994 : Navarro et al . , 1995 ; St . John and Lund , 1996 ; Kirsch et al . , 1998 ) , determining the FA composition of higher predator levels ( Hooper et al . , 1973 ) and indicating the presence of specific prey in predator diets ( Colby et al . , 1993 ; Pond et al . , 1995 ; Raclot et al . , 1998 ) . Tracking of dietary components through the food web cannot be e"
[Show abstract][Hide abstract] ABSTRACT: Net-cage fish farms attract a great number of wild fishes, altering their behaviour and possibly their physiology. Wild Mediterranean horse mackerel (Trachurus mediterraneus), sampled from populations aggregated around two Mediterranean fish farms and from two natural control populations, were analyzed for differences in body condition, stomach content and fatty acid composition. Pellets used to feed caged fish in both farms were also analyzed to identify their relationship with the fatty acid composition of tissue of wild fish. T. mediterraneus aggregated around the farms throughout the year although large seasonal changes in abundance and biomass occurred. Wild fish aggregated at farms mainly ate food pellets while control fish fed principally on juvenile fish and cephalopods. Wild fish that fed around the cages had a significantly higher body fat content than the control fish (7.30+/-1.8% and 2.36+/-0.7%, respectively). The fatty acid composition also differed between farm-associated and control fish, principally because of the significantly increased levels of linoleic (C18:2omega6) and oleic (C18:1omega9) acids and decreased docosahexaenoic acid (C22:6omega3) in farm-associated fish. The increased condition of wild fish associated with farms could increase the spawning ability of coastal fish populations, if wild fish are protected from fishing while they are present at farms. The fatty acids compositions could also serve as biomarkers to infer the influence of a fish farm on the local fish community, helping to better describe the environmental impact of fish farming.
Marine Environmental Research 03/2007; 63(1):1-18. DOI:10.1016/j.marenvres.2006.05.002 · 2.76 Impact Factor
"The fatty acid nutrition of European sea bass has been investigated for broodstock (Bell et al., 1997; Navas et al., 1997, 1998; Bruce et al., 1999) and larval stages (Navarro et al., 1995, 1997). Special consideration has been given to elucidate the effect that different dietary fatty acid compositions have on egg and larval composition and quality, nevertheless the lowest levels of n-3 fatty acids indispensable for adequate growth of sea bass has yet to be determined (Oliva-Teles, 2000; Parpoura and Alexis, 2001). "
[Show abstract][Hide abstract] ABSTRACT: European sea bass juveniles (14.4±0.1 g mean weight) were fed diets containing different levels of fish oil then of n-3 highly unsaturated fatty acids (n-3 HUFA) for 12 weeks. The fish performance as well as fatty acid (FA) composition of neutral and polar lipids from whole body after 7 and 12 weeks feeding were studied. The requirements of juvenile sea bass for n-3 highly unsaturated fatty acids (n-3 HUFA) were studied by feeding fish diets containing six different levels of n-3 HUFA ranging from 0.2% to 1.9% of the diet, with approximately the same DHA/EPA ratio (1.5:1).The growth rate at the end of the trial showed significant differences. Fish fed low dietary n-3 HUFA (0.2% DM of the diet) showed significantly lower growth than the diet 3 (0.7%), then no further improvement (P>0.05) of growth performance was seen by elevating the n-3 HUFA level in the diet up to 1.9% (diet 6). No difference in feed efficiency, protein efficiency ratio or protein retention was observed among treatments, nor in protein and total lipid content. However, the n-3 HUFA levels in diets highly influenced fish fatty acid composition in neutral lipid, while polar lipid composition was less affected. Comparison of polar lipid content after 7 or 12 weeks indicated that DHA remained stable at the requirement level, while arachidonic acid decreased with time. Results of this experiment suggest that the requirement for growth of n-3 HUFA of juvenile sea bass of 14 g weight is at least 0.7% of the dry diet.
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