Heat storage induced by salinity stratification in tropical saline aquaculture ponds

Abstract. In saline aquaculture ponds in the tropics, intermittent rainfall during the rainy season can cause salinity stratification, and strong solar radiation can cause thermal stratification. The combination of these factors may result in thermohaline convection in the ponds. Thermohaline convection in a closed saline water body can in turn induce heat storage in these ponds. Heat storage in saline aquaculture ponds strongly influences the water environment and consequently affects the quality and yield of aquaculture products from these ponds. We investigated how heat storage in experimental saline aquaculture ponds was influenced by the variation in the weather and water properties during the rainy season. If the pond stratifies into three layers with a salinity gradient in the middle layer, heat storage can occur. The salinity gradient prevents heat from escaping from the lower layer by effectively insulating it from nighttime radiative cooling. When the salinity gradient is perturbed by rainfall, solar radiation, or wind, the heat stored in the pond can begin to dissipate. We explain how the stratification stability and the heat balance in the ponds account for the occurrence of heat storage in the ponds.