Water Quality of Seawater Input, Reservoir, Cultivation Tank, and Its Relationship with the Survival of Litopenaeus vannamei in Lampung Hatchery

Water quality performance is closely linked to the low survival rate of larvae, which in turn affects the production and sustainability of the Litopenaeus vannamei hatchery business. This study aimed to analyze water quality parameters and their impact on the performance of L. vannamei shrimp fry production. A non-experimental design with observational methods was used. Water sampling was conducted at four points: the seawater source, the reservoir, and two larval rearing tanks. Sampling was carried out five times in each location, corresponding to the following larval stages: Zoea 3, Mysis 1, Mysis 3, Postlarva 1, and Postlarva 4. Physicochemical water quality variables measured and analyzed included temperature, dissolved oxygen (DO), pH, salinity, total organic matter (TOM), total ammonia nitrogen (TAN), nitrite, alkalinity, and hardness. Biological variables included phytoplankton abundance, total bacterial count, and total vibrio count. The analysis showed that the disinfection process was highly effective, reducing pathogenic microorganisms such as vibrios by up to 100%. However, water quality in the larval tanks declined over time. Notably, TOM reached 253 mg L⁻¹, TAN 0.41 mg L⁻¹, nitrite 0.50 mg L⁻¹, hardness 7027 mg L⁻¹, and green vibrio count 2×10³ CFU mL⁻¹. The average larval length at harvest did not differ significantly between tanks 1 and 2, measuring 7.02 and 7.08mm, respectively. However, survival rates differed markedly, with tank 1 showing a survival rate of 10%, compared to 55% in tank 2.