THE USE OF MARENNINE IN AQUACULTURE – MUCH MORE THAN JUST GREENING
Mareninne is a blue-green pigment produced by the cosmopolitan marine diatom Haslea ostrearia. This diatom often blooms in the oyster ponds thus causing a greening of the oyster's gills and palps1. The green-blue pigment called marennine that can be found intracellular and extracellularly2 when released into the culture medium causes the greening.
Apart from the widely known colouring capabilities, recent research has shown that marennine also has antibacterial, antiviral, antiproliferative3 and antioxidant4 properties. In the project CAMAFAN (Characterization and industrial Application of Marennine as Aquaculture Feed Additive and Nutraceuticals) we aim to characterize this so-far unknown pigment and delve into its possible uses in nutraceuticals but more importantly in aquaculture. Given its properties and potential, marennine can be used to green oyster just before harvesting thus increasing their value; be valuable in hatcheries for the production of fish and shellfish larvae by reducing bacterial load; have health benefits for fish, when supplied in specially formulated diets.
After establishing a culture of H. ostrearia we are currently undertaking experiments to apply customized modification to optimize/increase the production of extracellular marennine and biomass by defined cultivation modes, such as manipulation of culture conditions (nutrients, light intensity, light spectrum) and testing different culturing systems (suspension cultures and immobilized cultures). We will present these results at the conference.
The extracellular marennine produced during the culture optimization experiment will be used to determine the efficacy of this product to improve oyster (Crassostrea gigas and Ostrea edulis) larvae rearing and greening of adult individuals. Different concentrations of external marennine will be added to the larval rearing tanks. The larvae will be monitored through to settlement and survival, growth rate, settlement rate and larval abnormalities will be determined. In adults, we will look at the colouring of gills and palps before and after feeding Haslea biomass and exposing the animals to extracellular marennine to quantify greening, as well as monitor clearance and ingestion rates and feeding behaviour. We aim to present the preliminary data of this set of experiments at the conference.
References: 1Chaux-Thevenin, H. 1939. Congrès International de la Mer ; 2 Neuville, D., and P. H. Daste. 1978. Rev Gen Bot 85:255-303 ; 3 Pouvreau, J. et al., 2008. J Agric Food Chem 56:6278-6286; 4Gastineau, R. et al., 2012. Aquaculture 368-369:61-67.