Nutrient Concentrations, Phytoplankton Composition, and Vibrio Abundance in Intensive Litopenaeus vannamei Shrimp Ponds: A Case Study in Probolinggo

Intensive Litopenaeus vannamei culture generates organic loading that degrades pond water quality, yet nutrient status, phytoplankton composition, and Vibrio abundance are rarely examined together within a single production system. This study characterized these parameters in four production ponds of one intensive farm in Probolinggo, East Java, sampled at three weekly intervals during November and December 2025. Total organic matter exceeded the SNI 01-7246-2006 limit in all 12 events (72.42–125.08 mg L⁻¹) and nitrite exceeded it in all 12 (maximum 2.47 mg L⁻¹), although the two national standards differed by two orders of magnitude for nitrite. Total Vibrio exceeded the Permen KKP 75/2016 threshold in 9 of 12 events, rising approximately 13% per week. Ponds remained different despite a common management regime, with mean nitrite ranging from 0.03 to 1.47 mg L⁻¹ between Ponds. Blue-green algal abundance was correlated with total organic matter (ρ = 0.844) and phosphate (ρ = 0.825); cluster bootstrap intervals excluded zero in both cases. No water quality parameter was correlated with green algae or diatoms. Within ponds, only nitrite remained associated with cyanobacterial abundance. Oscillatoria reached 85.1% of the community in the most enriched pond, and between-pond variation exceeded within-pond variation.