Physiologic and metabolic effects of nutrient enrichments on adult Artemia franciscana

Abstract

Brine shrimp nauplii (Artemia sp.) are used in aquaculture as the major food source for many cultured marine larvae, and also used in the adult phase for many juvenile and adult fish. One artemia species, Artemia franciscana is most commonly preferred, due to the availability of its cysts and to its ease in hatching and biomass production. The problem with A. franciscana is that its nutritional quality is relatively poor in essential fatty acids, so that it is common practice to enrich it with emulsions like SELCO and ORIGO. This “bioencapsulation” enrichment method permits the incorporation of different kinds of products into the artemia. This brine-shrimp’s non-selective particle-feeding habits, makes it particularly suitable for this enrichment process. The bioencapsulation is done just prior to feeding the artemia to a predator organism. This allows the delivery of different substances, not only for nutrient enrichment, but also for changing pigmentation and administering medicine. This is especially useful in culturing ornamental seahorses and tropical fish in marine aquaria.

In this study the objectives were to determine, the relative nutrient value of ORIGO and SELCO as well as the optimal exposure to these supplements prior to their use as food-organisms. Accordingly, a number of brine-shrimp, from a stock culture of adult A. franciscana, were starved for 24h and incubated in SELCO emulsion for 6 h. In parallel some adults from the same stock were incubated in ORIGO for the same initial 24h. Then half of these fed-adults were given more ORIGO (at the same concentration) while the other half were given SELCO. All three cultures were then monitored for respiration during the 6h. At the end of the 6h ETS activity and protein were measured in the 3 cultures. The mean R, Φ, and M results at the end of the experiment were: 6.17±1.27 µlO2 h−1 ind−1; 11.52±1.37 µlO2 h−1 ind−1; 0.41±0.06 mg protein ind−1. These are within the ranges found in the literature. The results show that pre-exposure to ORIGO stimulates respiration in artemia for at least 6 h. They also show that ORIGO stimulates respiration more than SELCO during this same period.