Millions of fish in floating cages died suddenly this week in Lake Toba, the biggest lake in Indonesia, after its water became suddenly cloudy. Lake Toba is the site of a massive supervolcanic eruption estimated at VEI 8 that occurred 69,000 to 77,000 years ago,representing a climate-changing event. It is the largest-known explosive eruption on Earth in the last 25 million years, having global consequences for human populations and ecosystems worldwide (volcanic winter).
This is the second mass fish kill in as many years in the lake, which is located in North Sumatra. In 2016, millions of fish also turned up dead. Researchers attributed that incident to a sudden depletion of oxygen in the water, the result of a buildup of pollutants in the lake, unfavorable weather conditions and unsustainable practices by local aquafarmers.
Official hypothesis is that the fish kill was due to a rapid change in the temperature of the oxygen-poor water at the bottom of the lake, causing a sudden upwelling of water that made the lower layer rise to the surface. Waste from the fish farms are continuously polluting the lake.
Or could this be a sign of gas release from the bottom of the lake… or better said from the supervolcano?