Online first articles

In tropical lakes, thermal stratification is essential for oxygen dynamics and ecosystem function, and it responds sensitively to short-term weather variation. Using high-resolution temperature profiles and weather data in 2016–2017, this study examines the effects of meteorological variability on water column stratification and oxygen levels in Lake Maninjau, a eutrophic tropical lake in West Sumatra, Indonesia. The results show that seasonal drops in air temperature were the primary factor influencing stratification in 2016, while, wind speed and sunshine duration had a greater impact on its occurrence in 2017. Furthermore, in 2016, stratification breakdown triggered full-depth mixing and a sharp drop in dissolved oxygen (DO) from >3 mg/L to <2 mg/L at 5 m depth. Generally, stratification occurs at the minimum air temperature (Tmin) of above 20.25°C. At lower Tmin, the water column can either be stratified or mixed, notably when the average wind speed (Vave) exceeds ~2.75 m/s, in which stratification tends to break down. These findings highlight how thermal and mechanical forces contribute to weakening stratification and increasing the risk of hypoxia which are detrimental to aquaculture in floating net cages, and are linked to fish kills. Recognizing these thresholds can guide risk forecasting and adaptive management of tropical lakes.