Microalgae hatcheries

Key words aquaculture feeds, hatchery, larvae, microalgae, live feeds, photobioreactor. 

Microalgae, the microscopic plants present in oceans and waterways, are exploited as an indispensible food source for the commercial production of many aquaculture species. Within the hatchery environment, they are directly eaten by all growth stages of bivalves (broodstock, larvae, juveniles), post-set abalone, the larval stages of some crustacean species, and the very early developmental stages of some fish species. Microalgae are also used as feed to culture zooplankton (e.g. Anemia, rotifers, copepods) that are used as food for larval and juvenile stages of many fish and crustacean species. 

This chapter reviews the production and use of microalgae within aquaculture hatcheries. The compositional diversity of microalgae is firstly discussed, with emphasis on the concentrations of nutritionally important... 

Live microalgae as feeds in aquaculture hatcheries 119 4.2.2 Amino acids and carbohydrates... 

Fig. 4.1 Percentage compositions of the nutritionally-important PUFAs docosa-hexaenoic acid (DHA 22 6n-3), eicosapentaenoic acid (EPA 20 5n-3) and arachi-donic acid (ARA 20 4n-6) of microalgae commonly used in aquaculture hatcheries. Data from various studies undertaken at CSIRO Laboratories (Volkman et al, 1989, 1993 Dunstan et al., 1994, 2005 Mansour et al, 2005).

Living microalgae starter cultures are available from selected algal culture collections and other commercial suppliers (Table 4.2). Whilst there is stUl some exchange of microalgal strains between hatcheries, the industry is much more tuned to the importance of quahty control in the microalgae... 

The above-mentioned systems are generally considered low technology, but remain those of choice by most hatcheries because of their ease of use and maintenance, general reliability and low capital cost (or, in the case of bags, low replacement cost). However, these systems are typically characterised by low cell densities and productivities, i.e. for aquaculture strains often below 100 mg DW microalgae Ud compared to small volume cultures, or other PBR systems with significantly higher SA V (Table 4.3 and Tredici et aL, 2009). Examples of PBRs include tubular (serpentine. 

In practice, many hatcheries, but also research institutes, provide a mixture of feeds to the rotifers microalgae, yeast or yeast-based commercial diet and oil (Srivastava et al, 2011). The mixture of these feeds is applied most of the time due to insufficient supply of live algae and in order, to reduce the feed costs and achieve rotifers which better nutritional quality. 

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