Mass culture of algae: a bottleneck in the nursery culturing of molluscs

The controlled culture of larvae of molluscs of commercial importance (oysters, clams, etc.) till spatfall implies the daily production of substantial volumes of suitable species of microscopic algae. For economic reasons, industrial mollusc hatcheries cannot, however, upscale the very expensive indoor algal production to fulfill the increasing food demands of the growing spat. As too early transplantation of the postlarvae to the natural environment results in various technological and biological problems, the intermediate semi-controlled "nursery" culturing of the spat up to a few centimeters in length is presently more and more preconized. The different technologies utilized for nursery culturing are reviewed with special emphasis on the major problem: the mass production of live algal food under outdoor or greenhouse conditions