International study on <i>Artemia</i> : 41. Influence of culture conditions and specific diapause deactivation methods on the hatchability of <i>Artemia</i> cysts produced in a standard culture system

Using cyst material produced in an indoor cyst production system from 4 Artemia strains belonging to the species A. franciscana (San Francisco Bay, California, USA; Macau, Brazil; Great Salt Lake, Utah, USA) and A. parthenogenetica (Lavalduc, France), different factors were studied that affect dormancy in brine shrimp cysts. Preliminary experiments under varying (a)biotic culture conditions revealed an interaction between environmental conditions and hatching characteristics. Results obtained under better-defined conditions demonstrated a significant positive correlation between the amount of food available to the adult Artemia populations and the hatchability of their encysted offspring. Specific diapause deactivation treatments, e.g. hibernation of the cysts at -25°C or soaking in a 3% H2O2-solution, performed on one batch of Great Salt Lake cysts produced under well-defined optimal conditions, resulted in drastic increases in the hatching percentage of these cysts. Results provide indications that the variation in cyst diapause deactivation may be relevant for the stability of brine shrimp populations in their specific biotopes, e.g. inland lakes versus coastal saltworks. Possible hypotheses for differential adaptations to dormancy termination factors are discussed