Post-Sea Snot Ecological Assessment: Autoecology of Ceratium furca and Nitzschia longissima in Bima Bay, Nusa Tenggara Barat, Indonesia

The sea snot phenomenon in Bima Bay, West Nusa Tenggara, has raised significant concerns regarding its ecological implications, particularly in relation to harmful algal blooms (HABs). This study investigates the autoecology of Ceratium furca and Nitzschia longissima-two phytoplankton species associated with HABs- following the sea snot event in April 2022. Sampling was conducted at ten stations in May 2023 to assess key environmental parameters, including temperature, salinity, pH, dissolved oxygen, nitrate, phosphate, ammonia, and chlorophyll-a, alongside phytoplankton abundance. Canonical correspondence analysis (CCA) revealed a strong correlation between C. furca abundance and nitrate concentration, particularly at Station 4 (250.225 × 10³ cells/L). Conversely, N. longissima exhibited the highest abundance at Station 5 (14.837 × 10³ cells/L), which was positively correlated with elevated phosphate levels. Nutrient concentrations (nitrate: 0.166– 0.431mg/ L, phosphate: 0.272–0.652mg/ L) exceeded eutrophication thresholds, promoting phytoplankton proliferation. Regression analysis indicated that nitrate significantly influenced C. furca abundance (R² = 0.78), whereas N. longissima was predominantly affected by phosphate levels (R²=0.69). The weak correlation between phytoplankton abundance and chlorophyll-a suggests that additional factors, such as light intensity and hydrodynamic conditions, also contribute to phytoplankton dynamics. These findings highlight the critical need for continuous monitoring and nutrient management strategies to mitigate future HAB risks and maintain ecological balance in Bima Bay.