Delivery of astaxanthin from Haematocuccus pluvialis to the aquaculture food chain

The carotenoid astaxanthin is present in the natural diet of marine fish larvae, since copepods can synthesize astaxanthin. On the contrary, the rotifer Brachionus plicatilis, that is used as live-feed for most fish larvae, cannot synthesize this carotenoid. The microalga Haematococcus pluvialis accumulates astaxanthin in thick-walled aplanospores that cannot be digested by the rotifers. The digestibility of the cell wall can be improved by inducing the germination of the aplanospores. The effect of time from the induction of germination of aplanospores on the accumulation of astaxanthin by B. plicatilis was tested in enrichment trials after 2 and 24 h of exposure. Results demonstrated that germinated aplanospores of H. pluvialis can be digested by the rotifers, with maximal accumulation of astaxanthin being achieved after 2 h of exposure. After 24 h of exposure, the amount of astaxanthin present in the rotifers decreased by more than 50%, indicating that astaxanthin was degraded by the rotifers. Results demonstrate the feasibility of astaxanthin accumulation from H. pluvialis by the rotifers, establishing the basis for the transfer of this important carotenoid into the fish larvae.