A SURVEY ON THE STABILITY OF THE HIGHLY UNSATURATED FATTY ACIDS EPA, DHA IN ENRICHED AND STARVED ARTEMIA URMIANA NAUPLII, USING DIFFERENT OILS
MSc Thesis by Zahra Grailou-2000
Faculty of Natural Resources, University of Tehran, Iran
Summary:
The study was conducted in lake Urmia, Iran and the specimens used in the experiment belong to the species A. urmiana. Decapsulated cysts were incubated and then the nauplii at a development stage of late instar-I beginning of instar-II were harvested and transferred into cylindroconical 1.51 glass cones and stocked at density of 100 individuals/ml of filtered disinfected sea water.
The enrichment process involved holding the nauplii for 3 to 9h in a suspension of cod liver oil, soya oil and clupenella oil in fresh water.
The emulsions were added to saline water at a rate of 10.0 ml. of each emulsion per liter. Part of the nauplii, were sampled for HUFA analysis before enrichment and during enrichment (3, 6 and 9 h) and the remaining individuals after being rinsed with filtered disinfected seawater were transferred into glass cones at a density of 50 ind/ml and at 6°C (inside a refrigerator). These starved individuals were sampled after 12, 24, 48 and 72 hrs. The samples were transferred to amber vials with a screw cap and flushed with nitrogen gas. Fatty acid methyl esters of the samples were prepared for gas chromatography analysis following a direct acid catalysed transesterification method. These results indicated that EPA, DHA (n-3) HUFA levels increased after enrichment with all emulsions. Maximum levels were reached after 6 h of enrichment with cod liver oil. During the starvation period the change of DHA and (n-3)HUFA levels acted as a function of time, and contrary to the DHA levels which decreased linearly as function of time, EPA levels showed a slight increase until the end of the starvation period.
There were no statistically significant differences between time of enrichment and type of substrate used in the enrichment process, and stability of the fatty acids during starvation in the starved nauplii. Also the DHA level decreased faster than the EPA level in the starvation period.
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