Effect of mixed microalgal diets on growth and polyunsaturated fatty acid profile of European oyster (Ostrea edulis) juveniles

Abstract

Highly unsaturated fatty acids like EPA (eicosapentaenoic acid), DHA (docosahexaenoic acid) and AA (arachidonic acid) are essential in the development, growth, and physiological activities of aquaculture organisms. Microalgae are important main sources of EPA and DHA. In this study, the effect of mixed microalgal diets on the growth and fatty acid profile of European oyster (Ostrea edulis) juveniles was determined. The juvenile oysters (3.80±0.15g; 8.33±0.10mm) were cultured in 15L static tanks with three replicates for the following treatments or microalgal combinations: Chaetoceros muelleri and Isochrysis galbana (CHGRA/T.ISO); Tetraselmis striata and Thalassiosira weissfloggii (TETRA/ACTIN); and Nannochloropsis oculata and Pavlova lutheri (NANNO/PAV). Juvenile oysters were fed microalgal diets daily at 10% of their body weight. The culture conditions for the oysters were 31.1±0.4 psu, 16.3±0.2°C, and 8.9±0.3ppm D.O. After 6weeks of culturing the oysters, a very highly significant difference (P<0.001) was found in the growth rate. The best growth rate (final weight=9.73±0.89g; final shell length=13.48±0.35mm) was observed in NANNO/PAV treatment. The lowest growth rate (6.15±0.25g; 10.47±0.18mm) was in TETRA/ACTIN diet. EPA, DHA, and AA values of oyster were significantly higher in NANNO/PAV treatment but lowest in TETRA/ACTIN treatment (P<0.001). The best diet in culturing European oyster juveniles was the mixture of N. oculata and P. lutheri by providing better growth rates and higher levels of PUFAs.