Culturable microflora of Artemia franciscana reared under laboratory conditions

Artemia is widely used as an initial food for larval and juvenile fish in aquaculture facilities around the world. However, several lines of research have strongly suggested that Artemia larvae may carry opportunistic pathogens such as Listonella anguillarum, thereby serving as a source of infection of fish. In the present study, we investigated the dynamics of the culturable microflora of Artemia reared under laboratory conditions, with the goal of understanding the risk of opportunistic infection mediated by this animal. After hatching decapsulated cysts of A. franciscana, the larvae were reared for an additional 27 days to examine, using the culture-dependent method, the culturable microflora of the rearing water and of washed Artemia. The results showed that Vibrionaceae, Flavobacteriaceae, Pseudoalteromonadaceae, Alteromonadaceae and Rhodobacteriaceae accounted for 8.3-35.8% of the rearing water isolates. In contrast, Vibrionaceae dominated in Artemia isolates, accounting for 79.2% of the flora. However, Vibrionaceae were not detected in either decapsulated or undecapsulated cysts, or in the algal concentrates used as feed, suggesting that Vibrionaceae is not indigenous to Artemia cysts and instead is derived primarily from natural seawater. These results strongly suggest that hatching and rearing live diets such as Artemia under sanitary conditions may reduce the risk of opportunistic infection.