Comparative Effects of Different Microalgal Diets on Growth Performance, Nutritional Profile and Enzymatic Activity of Edible Oyster Spat (Crassostrea belcheri)

Abstract

Diseases, overfishing, and habitat loss are reducing oyster populations constantly. Moreover, environmental pollution and natural disasters also hinder offshore shellfish cultivation. Therefore, filter-feeding bivalves could be cultivated on land-based system to maintain the culture condition and secure food safety. Live microalgal diet influences the growth, environmental quality, proximate, fatty acid, amino acid and digestive enzyme activities were investigated in the juveniles of edible oyster Crassostrea belcheri in laboratory conditions for 35 days. In this study, four different feeding regimes were trialed for Crassostrea belcheri spat culture: starvation, 2 monospecific diets (Chaetoceros sp., Tetraselmis sp.), 1 bispecific diet (Chaetoceros sp. + Tetraselmis sp.). The oyster group fed monoalgal diet showed a significantly lower survival rate in comparison with the other groups (P < 0.05). Unialgal diet Chaetoceros sp. showed highest protein, (41.7 ± 0.38) in oyster whereas, highest lipid (20.7 ± 0.33) and carbohydrate (34.2 ± 0.33) was found in bi-algal diet. The fatty acid composition of oyster was increased significantly when mixed algae was fed (P < 0.05). In the same manner, mixed diet exhibited greater lipase (LPS) and pepsin (PES) activity. On the contrary, amino acid and amylase (AMS) content of oyster was highest in unialgal Chaetoceros sp. diet. In this research, mixed algal diet had outstanding results on growth performance, proximate and essential fatty acid composition of oyster. However, essential amino acid and digestive enzyme activity showed excellent result in single species diet. The findings demonstrated that indoor cultivation system with microalgal diet might be a potential farming technology for the production of nutritionally enriched edible oyster Crassostrea belcheri.