Effectiveness of Algae Growth Promoter on Spesific Growth Rate and Growth Phase of Chaetoceros calcitrans

Abstract

This research is motivated by efforts to provide high-quality microalgae as natural feed for shrimp hatchery activities. Researchers have used fertilizers with appropriate N/P ratios, including commercial fertilizers. In this study, the author examines the use of the commercial fertilizer Algae Growth Promoter (AGP) as fertilizer in C. calcitrans culture. Current fertilizer use still largely focuses on specific growth rate and increasing microalgal density, which is considered fast, and pays less attention to microalgal nutritional content. The study administered AGP fertilizer (80, 90, 100, 110, 120 ppm) and a control treatment, with 100 ppm modified Guillard fertilizer added, over a culture period from the exponential to the stationary phase. AGP fertilizer reached the stationary phase later, at the 108^th observation hour. This is superior to the control treatment, which entered the stationary phase at 72 hours of culture. The control treatment reached the exponential phase earlier, with a td value of 20.29 hours, the shortest doubling time among all treatments. Observations of growth rates were also carried out, where the control treatment was found to have the best specific growth rate, with a µ value of 0.0343 per hour, while the treatment with AGP fertilizer had a specific growth rate with a µ value ranging from 0.0255 to 0.0279 per hour, and the td value ranged between 24.89 and 27.27 hours.