EFFECT OF NITROGEN CONCENTRATION ON GROWTH AND PRODUCTIVITY OF Chaetoceros amami AS LIVE FEED FOR PEARL OYSTER LARVAE

Abstract

Pearl oyster (Pinctada maxima) is a high economic value fisheries commodity whose aquaculture success highly depends on the availability of quality live feed during the larval phase. Chaetoceros amami is a microalgae that plays an important role in supporting the  oyster growth. Nitrogen is an important factor affecting microalgae growth as it plays a fundamental role in the synthesis of proteins, nucleic acids, and chlorophyll. This study aimed to analyze the effect of nitrogen concentration on growth and productivity of Chaetoceros amami as live feed for Pinctada maxima larvae. The research was conducted at the Pearl Oyster Hatchery Laboratory of PT. Mutiara Surya Indonesia using a Completely Randomized Design with five nitrogen concentration treatments (0; 2.5; 5; 7.5; 10 ppm) and three replications. Parameters observed included peak density, relative growth rate, and doubling time. The results showed that nitrogen concentration had a highly significant effect (p<0.05) on the growth of Chaetoceros amami. The nitrogen concentration of 7.5 ppm resulted in the highest mean peak density and relative growth rate of 1,985×10³ cells/mL and 133%, respectively, as well as the shortest doubling time of 39 hours, which were significantly different from other treatments. Increasing nitrogen concentration up to 10 ppm actually decreased growth performance by 31.8% due to excessive nitrogen toxicity effects. This study concluded that nitrogen concentration of 7.5 ppm is the optimal concentration for cultivating Chaetoceros amami as natural feed for pearl oyster Pinctada maxima larvae, with a 43% increase in biomass productivity compared to control.