Losses of lipid, protein and ny3 fatty acids in enriched Artemia franciscana starved at different temperatures

The loss rates of protein and lipids were determined for enriched Artemia franciscana starved Ž y1. at different temperatures after enrichment. Following 12-h enrichment with DHA Selco 0.2 g l Ž at 288C, the nauplii were temperature acclimated and transferred to starving condition 0–96 h; . 58C to 308C . y1 Ž . Ž The total lipid content during enrichment increased from 145 mg g dry weight DW newly . y1 hatched nauplii to 222 mg g DW after 12 h. The DHArEPA ratio reached an optimum after Ž . 12 h 1.85 , where DHA and EPA constituted 12% and 6.7% of total fatty acids, respectively. When the nauplii were transferred to starving conditions the contents of all lipid components became reduced. The specific loss rate was found to be exponential for all components and significantly higher for DHA than for EPA and the sum of the other ny3 fatty acids. A. Ž . y1 Ž . franciscana starved at the highest temperature 308C showed a loss rate of 92% day of DHA . y1 Ž . Ž . Nauplii starved at 128C had a loss rate of 51% day of DHA . At the same temperature 128C the corresponding loss rate of EPA, the sum of the other ny3 fatty acids and for the total lipid content was 15%, 30% and 11% day, respectively. Ž The protein content was relatively stable in the nauplii kept at the lowest temperatures 58C . and 88C , but as temperature increased, the loss rate of protein gradually increased reaching a loss rate of 28% day in nauplii starved at 268C. The survival of the nauplii was )67% throughout ) Corresponding author. Tel.: q47-73-55-03-48; fax: q47-73-59-63-11. Ž . E-mail address: [email protected] J.O. Evjemo . 0044-8486r01r$ see front matter q2001 Elsevier Science B.V. All rights reserved. Ž . PII: S0044-8486 00 00470-1 ( ) J.O. EÕjemo et al.rAquaculture 193 2001 65–80 66 Ž . the starvation period 96 h , but at temperatures below 88C and above 198C, the survival was -13% after 96 h. Results show that the when Artemia nauplii are starved the lipid and protein content decreases as a function of temperature. This might affect the nutritional value of A. franciscana quite strongly if the nauplii reside in the fish tanks before being eaten by the larvae, or stored at ambient temperature before they are transferred to the fish tanks. q 2001 Elsevier Science B.V. All rights reserved.