Assessment of endemic microalgae as potential food for Artemia franciscana culture

Spanish; Castilian. Se aislaron cinco cepas de microalgas de la Bahía de La Paz, Baja California Sur, México, identificadas como Grammatophora sp., Navícula sp., Rhabdonema sp., Schizochytrium sp., and Nitzschia sp., y su evaluación como alimento potencial para Artemia franciscana. Las cepas algales fueron aisladas, purificadas y cultivadas al exterior. Chaetoceros muelleri fue cultivada en condiciones de laboratorio y utilizada como control. El análisis bioquímico y el perfil de ácidos grasos correspondientes al cuarto día de cultivo de las microalgas, se efectuó mediante cromatografía de gases. El experimento con Artemia franciscana se realizó al exterior por doce días en tanques de 15 L. Se realizaron muestreos al inicio y al final del trabajo para determinar el incremento en talla, peso seco y sobrevivencia. El tratamiento con la microalga identificada como Rhabdonema sp. mostró larvas con menor porcentaje de ácidos grasos polinsaturados (PUFAs) mientras que aquellas alimentadas con Grammatophora sp. presentaron la mayor proporción, superando a las del control Chaetoceros muelleri. Con Schizothyrium sp. no presentaron los ácidos grasos docosahexanoico (DHA) y eicosapentanoico (EPA). La sobrevivencia obtenida al utilizarse las diferentes cepas no mostró diferencias significativas a excepción de la alimentación basada en Nitzschia sp. donde mostraron una sobrevivencia menor. Los tratamientos con base en Schizothyrium sp. y Rhabdonema sp. produjeron individuos de A. franciscana de mayor tamaño, pero se redujo el peso, por lo que se requieren mayores evaluaciones donde se incluyan dos o más especies de microalgas para determinar el mejor rendimiento.

English. In this study, five microalgal strains were isolated from Bahía de La Paz, Baja California Sur, Mexico and identified as Grammatophora sp., Navícula sp., Rhabdonema sp., Schizochytrium sp., and Nitzschia sp., and their evaluation as potential food for Artemia franciscana. The isolated strains were cultured outdoors and harvested after four days. Chaetoceros muelleri was cultured under laboratory conditions and used as control. The protein, lipid, and carbohydrate composition and the fatty acid profiles of the strains were determined by gas chromatography. To assess the effect of microalgal strains on A. franciscana, decapsulated cysts were cultured at outdoor conditions in 15 L containers. The experiment was conducted for twelve days. Samples from the five different feeding treatments were taken at the beginning and end of the experiment to assess number, size, and weight of Artemia larvae. Treatment with Rhabdonema sp. showed larvae with a lower percentage of polyunsaturated fatty acids (PUFAs) while Grammatophora sp. showed those with the greatest PUFA proportion, even more than those fed Chaetoceros muelleri (control). Larvae consuming Schizochytrium sp. had no docosahexanoic (DHA) nor eicosapentaenoic (EPA) fatty acid content. Growth and survival of A. franciscana did not show significant differences among feed treatments, except when it was fed Nitzschia sp., showing lower survival and dry weight. Treatment based on Schizochytrium sp. and Rhabdonema sp. had a greater A. franciscana size but reduced dry weight; additional tests including two or more algal species for every treatment should be carried out to determine the best yield.