COMPACT PHOTOBIOREACTORS FOR LIVE MICROALGAE PRODUCTION IN AQUACULTURE HATCHERIES AND NURSERIES

Photobioreactors in Aquaculture

Availability of high quality microalgae is a bottleneck in aquaculture hatcheries and nurseries.  Numerous species of nutritious microalgae are used to feed bivalve and crustacean larvae.  In marine finfish hatcheries algae is used to tint water to enhance larval survival, or to nutritionally enhance zooplankton fed to larvae.  In any facility, algae contaminated with pathogens (i.e. Vibrio spp.) can result in high larval mortality and lower growth rates. Traditional methods of microalgal production are unreliable and labour intensive, while substitutes such as concentrates and dried algae can degrade water quality as they decompose, increasing the organic load in the system and creating a substrate for pathogenic bacteria. Automated photobioreactors offer a compact and easier method of producing live algae onsite compared to traditional methods (e.g. figure 1).  They are often more cost effective than substitutes and contribute less to the organic load in the water.  Closed photobioreactors provide a biosecure culture environment and reduce the chance of culture contamination.  This control over the microbial environment is of paramount importance since pathogenic or probiotic organisms introduced into algae cultures will be transferred downstream to livestock, impacting survivability and ultimately profits.