Growth Performance, Dietary Enzyme Profiling, and Antioxidant-Induced Immunity of Crassostrea belcheri Fed With Microalgal Diet

Abstract

Diseases, overfishing, and habitat loss are constantly reducing oyster populations. 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. Four different diets including Chaetoceros gracilis (CG), Tetraselmis chuii (TC), mixture of CG and TC (CG/TC), and fresh seawater without feed (Con) were trialed for Crassostrea belcheri spat in this research. After 35 days of culture, the highest survival rate (SR), volume, and weight increment (WI) of oyster and improved water quality appeared in CG/TC. In the same manner, CG/TC diet exhibited greater lipase (LPS), pepsin (PES), catalase (CAT), alkaline phosphatase (AKP), and hydrogen peroxide (H₂O₂) activity. Conversely, amylase (AMS), acid phosphatase (ACP), superoxide dimutase (SOD), malondialdehyde (MDA), and lysozymes (LZMs) activities were substantially higher in CG diet compared to TC, CG/TC, and Con. No significant differences were observed among CG, TC, and CG/TC for antioxidant capacity (AOC). In this investigation, mixed algal diet had excellent results for the growth and development of oyster, whereas unialgal diet improved immunity and AOC to survive in unfavorable conditions. This observation help elucidates the knowledge on microalgal diet influenced immune modulation and health of marine bivalves in the scenario of land-based farming.