Pavlova lutheri: Production, preservation and use as food for Crassostrea gigas larvae

The haptophyte Pavlova lutheri was cultivated in a 4-l flat alveolar photobioreactor (FAP) in semi-continuous mode during 35 days, achieving a mean volumetric productivity of 0.4 g (dry wt) l− 1 day− 1. The microalgal culture was harvested from the photobioreactor at an average concentration of 3.5 g (dry wt) l− 1 and subjected to different storage conditions in which the effects of temperature (1 °C, 4 °C and 25 °C), air supply and preservative (ascorbic or propionic acid) addition on the viability of the stored suspensions were investigated. Low temperatures (1 and 4 °C) and air-bubbling extended the shelf-life of the stored suspension, while no beneficial effects of ascorbic or propionic acid were found. The influence of temperature and air-bubbling on fatty acid content and profile was also evaluated over a 23-day period of storage. Air-bubbled suspensions exhibited, on the average, a 70% decrease of total fatty acid content (TFA) during storage. Non-bubbled suspensions showed a much lower decrease. The decrease mainly involved the saturated 14:0 and 16:0 and the monounsaturated 16:1n-7 and 18:1n-9. The polyunsaturated eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA) decreased significantly at the end of the storage period.A feeding trial on Pacific oyster (Crassostrea gigas) larvae was carried out with fresh and preserved P. lutheri biomass kept under the best storage conditions previously defined (1 °C; darkness; air-bubbling). After 14 days of rearing no significant differences in growth or survival were detected when fresh or preserved P. lutheri was used in a monospecific diet or in association with the diatom Chaetoceros calcitrans forma pumilum.