Cultivation of the Microalga Thalassiosira weissflogii to feed the Rotifer Brachionus rotundiformis

Abstract

The microalga Thalassiosira weissflogii (Grunow) Fryxell and Hasle, 1977 was cultivated to find its adequate concentration to feed the rotifer Brachionus rotundiformis Tschugunoff, 1921. The microalgae and rotifers were reared separately; microalgae cultures used Guillard and Ryther F/2 medium in transparent 19 L plastic bottles, yielding 16 L of the useful crop; agitation was kept constant by bubbling compressed air filtered at 1 µm; lighting was continuous through six white daylight fluorescent lamps. The temperature ranged between 23.1° and 24.9°C, and disinfection was with commercial sodium hypochlorite at5%, which was eliminated at a rate of 0.06 g•L-1 sodium thiosulfate, then the F/2 nutrients were added. Rotifers in 15 L plastic containers were fed daily on T. weissflogii at 2.469 x 105cells∙mL1; Crops were harvested every third day (48 h). T.weissflogii cultures maintained for 48h achieved concentrations adequate to feed these rotifers;