No abstract

On-grown (metanaupliar) stages of Artemia, have been regarded as more adequate preys for early life-cycle stages of cephalopods, crustaceans, and a variety of fish species. In recent studies, we obtained successful enhancements of highly unsaturated fatty acids (HUFA) and polar lipids (PL) in enriched Artemia metanauplii using either a combination of a commercial, neutral lipid (NL)-based HUFA-rich emulsion and Soya lecithin, or HUFA-rich phospholipids. The present study aimed at exploring the molecular form under which dietary HUFA are actually deposited in the metanaupliar lipids. Thus, we analysed the fatty acid (FA) composition of the PL and NL fractions from enriched metanauplii, with special emphasis to the fate of docosahexaenoic acid (DHA) within Artemia lipids. The results show that on-grown Artemia actively translocated ingested FA contained into PL to NL classes including triacylglycerides.

Highly unsaturated fatty acids (HUFA), like the eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids and polar lipids (essentially phospholipids, PL) have been identified as essential nutrients for common octopus (Octopus vulgaris) paralarvae. However, they are not available in sufficient amounts in live preys as Artemia, making necessary a supplementation of these nutrients previous use. A commercial emulsion, soya liposomes, and marine and soya lecithins were used to supply HUFA and PL to Artemia metanauplii, those being regarded as suitable size preys for octopus paralarvae. Our results prove that a simultaneous enrichment in HUFA and PL is possible using enrichment diets combining HUFA‐ and PL‐rich products in short‐term (4 h) incubations. Particularly interesting was the enrichment efficiency shown by the marine lecithin, which enabled the enhancement of the PL fraction of Artemia metanauplii and, importantly, also their HUFA with a remarkable 13% DHA of total fatty acids. Marine lecithin arises as a novel enrichment diet for Artemia and more effective than some commercial products currently used in hatcheries worldwide.

Previous studies have demonstrated that the commercial feed of aquacultured fish contains trace amounts of toxic and essential metals which can accumulate in tissues and finally be ingested by consumers. Recently rising temperatures, associated to the global warming phenomenon, have been reported as a factor to be taken into consideration in ecotoxicology, since temperature-dependent alterations in bioavailability, toxicokinetics and biotransformation rates can be expected. Sparus aurata were kept at 22°C, 27°C and 30°C for 3 months in order to determine the temperature effect on metallothionein induction and metal bioaccumulation from a non-experimentally contaminated commercial feed. A significant temperature-dependent accumulation of cadmium (Cd), copper (Cu), mercury (Hg), zinc (Zn), lead (Pb) and iron (Fe) was found in liver, together with that of manganese (Mn), Fe and Zn in muscle. Hg presented the highest bioaccumulation factor, and essential metal homeostasis was disturbed in both tissues at warm temperatures. An enhancement of hepatic metallothionein induction was found in fish exposed to the highest temperature.

17The genus Artemia consists of several bisexual and parthenogenetic sibling species. One of 28The results evidence that both, AF and PD, showed an elevated tolerance to high ranges of chlorpyrifos, 29 but AF survived better and its fecundity was less affected by the exposure to the pesticide than PD. The