Halophilic bacteria as a food source for the brine shrimp Artemia

Artemia cysts are highly demanded by the aquaculture industry to be hatched into nauplii and used as live food for larvae of most farmed fish and shellfish species. In recent years, pond production of Artemia cysts has been proposed as an effective measure to reduce the high dependence of the industry on cysts harvested from wild populations. Nonetheless, the feeding management strategies of this type of intensive Artemia culture, focusing until now on costly phytoplankton boosting are still in need of optimization. The growth stimulation of the naturally occurring halophilic bacterial flora in the culture ponds, as a complementary food source for the Artemia nauplii, is currently being considered as a viable way to improve Artemia biomass and cyst production. Field studies conducted until now did not however, allow for patent conclusions about the actual dietary value of this bacterial biomass to the Artemia diet, hindering the widespread application of these practices. The purpose of this research was therefore to investigate the capacity of Artemia nauplii to survive and grow on diets consisting exclusively of mono-diets of live or dead biomass of six halophilic bacteria, belonging to genera commonly found in hypersaline environments where Artemia occur. To this end, a standard gnotobiotic Artemia culture system was used at a salinity relevant for a field situation (100 g l−1) and at seawater salinity (35 g l−1). The results showed that the addition of most tested halophilic bacteria, either as live or dead biomass, to the Artemia culture water, allowed for significantly superior nauplii survival than the corresponding negative control (starvation treatment). Furthermore, significantly higher individual length in comparison to the positive control (a standard marine bacterial diet used in Artemia gnotobiotic tests) was also observed, especially when feeding the nauplii with live halophilic bacteria biomass. The success at both salinities of the tested halophilic bacteria mono-diets when compared to both controls, clearly denoted that despite having a low nutritional value as far as fatty acids are concerned, they can be an intergral part of its diet during its first developmental stages. Although our findings need to be confirmed in field conditions, they are of importance for Artemia pond production as they confirm the potential of these microorganisms to be used as a viable dietary source, complementing the present focus on phytoplankton blooms to sustain Artemia populations