Indoor and outdoor mass production of the diatom Chaetoceros muelleri in a mexican commercial hatchery

In tropical and subtropical countries, hatcheries may produce microalgae for larval feeding either indoors, which is supposed to improve the quality and reliability of production but has a higher cost, or they may use outdoor cultures at a lower cost, but with a high seasonal variability. In this paper, we compare the cell concentrations and the organic biomass yields and composition of indoor and outdoor mass cultures of the diatom Chaetoceros muelleri obtained in four seasons in a commercial hatchery of the state of Sonora, in the Mexican northwest. Cell yields were better outdoors in spring and fall but lower in winter, whereas in summer they were similar indoors and outdoors. Organic biomass production was higher in spring and summer and tended to be lower, but not significantly different, in winter. Indoors, the percentage of proteins was significantly higher during spring, but it was lower in fall and winter. In summer, there was no difference between outdoors and indoors. Carbohydrates were higher indoors in summer, when lipids were higher outdoors, whereas in winter they were higher indoors. The organic biomass production ranged from 22.5 to 45.7 g/m³/d indoors, with a mean estimated cost of US$ 176.67 and 75.88 per kg of total biomass. Outdoors, the mean production varied from 29.0 to 69.7 g/m³/d in winter and spring, respectively, at a mean annual cost of US$ 50.36 per kg.