Growth Performance of Gracilaria sp. in Relation to Nitrogen Uptake from Effluents of Shrimp Culture at Varying Stocking Densities: Growth Performance of Gracilaria sp. in Relation to Nitrogen Uptake from Effluents of Shrimp Culture at Varying Stocking Densities

Restiana Wisnu Ariyati (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Lestari Lakhsmi Widowati (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Ichwanus Sofa Alkisai (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
sri Rejeki (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Sarjito (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Alfabetian Herjuno Condro Haditomo (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Dicky Harwanto (Aquaculture Department, Faculty of Fisheries and Marine Sciences, Diponegoro University, Jl. Prof. Jacub Rais, Tembalang, Semarang, Central Java 50275, Indonesia)
Roel H. Bosma (Wageningen University, Aquaculture and Fisheries Group (AFI), De Elst 1, 6708 WD Wageningen, The Netherlands)

Journal of Aquaculture and Fish Health
Vol. 15 No. 2 (2026): JAFH Vol. 15 No. 2 June 2026

The growth performance of Gracilaria sp. is influenced by its ability to absorb excess nutrients, particularly nitrogen, from aquaculture effluents. This study aimed to evaluate the nitrogen uptake and growth rate of Gracilaria verucosa cultivated in a mesocosm system receiving effluents from black tiger shrimp (Penaeus monodon) cultured at different stocking densities. Post larvae (PL-20) with an initial body weight of 0.4 ± 0.1 g were reared for 28 days at three shrimp stocking densities (20, 60, and 100 PL m⁻²) integrated in a recirculation system with Gracilaria. The highest nitrogen uptake rate by Gracilaria (11.36 mg DW m⁻² day⁻¹) was recorded under the highest shrimp density (100 PL m⁻²). A significant correlation (R² = 0.7) was identified between nitrogen absorption and the growth rate of Gracilaria sp., with the highest growth rate (2.24 ± 0.08% day⁻¹) recorded at this density. However, nitrogen retention in Gracilaria was not significantly affected by the different effluent concentrations. These findings suggest that higher shrimp densities can enhance nitrogen uptake and stimulate Gracilaria growth in integrated aquaculture systems.