Sustainable food security through aquaculture: Establishment of algal technology for optimal aquaculture growth and health.

Aquaculture offers sustainable food security to many developing countries. Aquaculture disease increases costs and decreases yields. The development of cost effective solutions to prevent disease is therefore pressing. Such technologies are however in their infancy. In stage 1 of this project the growth and performance of model bivalve molluscs reared on algal as single species and mixed species microalgal diets will be assessed. Microalgae will be reared in amended environments in order to naturally effect changes in the biochemical phenotype and potential nutritional value. These algae will be used as a food source in comparative experiments to compare the effects on growth, metabolism, reproductive investment, and immune function in European flat oysters Ostrea edulis, Pacific oysters Magallana gigas, and blue mussels Mytilus edulis; the three main cultured bivalve species in Europe. In a second phase, the project will consider the use of genetically modified microalgal species as a mechanism to interfere with the replication cycle of oyster herpes virus (OsHV1) of Magallana gigas, a non-exotic pathogen of cultured Pacific oysters in Europe (Rogers et al., 2019). Using established methodology (Charoonnart et al., 2019), we will culture genetically modified microalgae that contain a dsRNA cassette targeting a key oyster herpes virus viral gene. We will explore the potential of this as a diet based platform for the delivery of RNAi to prevent viral replication in cohabiting Pacific oysters in cultured beds in the UK. Viral replication will be quantified through assessments of viral induced histopathology and through absolute quantitative PCR detection (Hauton et al., 2007) of viral gene transcripts.