Optimizing salinity for enhanced reproductive performance of the Kenyan Artemia franciscana population

Salinity is a key environmental factor regulating survival, reproduction and life-history strategies in Artemia, with strain- and location-specific studies essential for generating context-relevant data. This study evaluated the effects of salinity (35, 80, 100, 120 and 140 g/L) on the survival and reproductive performance of a Kenyan Artemia population. Decapsulated cysts were hatched and nauplii reared on Chaetoceros spp at the different salinity treatments. Upon maturity, 50 mating pairs (10 replicates per treatment) were isolated in Falcon tubes and monitored daily for nauplii and cyst production using Lugol staining and microscopy. Moderate salinities (35–100 g/L) supported optimal survival, with complete survival at 80 g/L, while hypersaline conditions (120–140 g/L) significantly increased mortality. Brood numbers remained relatively stable, but brood intervals decreased at higher salinities, indicating stress-induced reproductive acceleration. A clear shift in reproductive modes was observed: lower salinities favoured ovoviviparity with high nauplii production, whereas higher salinities reduced nauplii output and significantly increased cyst production, reflecting a transition to oviparity under stress. These findings demonstrate salinity-driven reproductive plasticity in Artemia and highlight its importance in aquaculture, where salinity manipulation can optimize nauplii or cyst production. Future studies should evaluate the effects of salinity on cyst quality, hatching efficiency and the nutritional composition of nauplii, as well as investigate interactions with other environmental factors to improve production efficiency and sustainability.