The Impact of Floating Net Cage Cultivation (FNC) on Primary Productivity in the Saguling Reservoir, West Java, Indonesia

This study aimed to analyze the impact of fish farming using floating net cage (FNC) system on primary productivity in Saguling Reservoir. Conducted between January and February 2025, the research utilized a comparative descriptive design at Saguling Reservoir, West Bandung Regency and in the Aquatic Resources Laboratory, Universitas Padjadjaran. Water sampling was performed at four stations based on varying levels of FNC activity to represent areas with and without aquaculture. The parameters measured included physical (temperature, transparency), chemical (pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), carbon dioxide (CO2), nitrate, ammonia, phosphate), as well as biological factors. Primary productivity was assessed using the light and dark bottle oxygen method with sampling conducted four times with weekly intervals. The results revealed that the highest primary productivity value is 746,028 mgC/m3/day, was recorded at station 2, which is situated in an area with a high density of FNC (1.203 units), while the lowest value was observed at station 1, 225,216 mgC/m3/day located in the reservoir inlet without FNC. The results indicate that FNC activities contribute significantly to increased nutrient levels (N and P), promoting phytoplankton growth and photosynthesis, thereby increasing primary productivity. The presence and intensity of FNC aquaculture significantly affect the trophic status and primary productivity in Saguling Reservoir. Management strategies should be implemented to monitor and control the density of floating net cages to preserve the reservoir’s ecological balance.