Creation of Taal Lake

Taal Lake is situated in a caldera created by volcanic eruptions more than 100,000 years ago. A caldera is a volcanic feature formed by the collapse of land following a volcanic eruption. A series of violent eruptions caused the land around the Taal Volcano, and the volcano itself to sink into the ground. The caldera formed was filled by seawater from the South China Sea.

In the 16th century, a series of violent eruptions landlocked what is now known as the Taal Lake, leaving a single river, the Pansipit River, as it sole connection to the sea. Several centuries of rain and waters draining out to the sea have diluted the lake's salt water and converted it into freshwater lake.

Taal Lake

Several marine species were trapped in this newly formed lake. As the Taal Lake desalinated into a a freshwater lake many endemic species evolved and adapted to the desalinization of the lake's waters.

One of this was the Sardine. The saltwater sardine adapted and survived resulting the creation of the worlds only freshwater sardine --- the Sardinella tawilis. The Sardinella tawilis is only found in the Taal Lake. Taal Lake is also home to the Hydrophis semperi, one of only two sea snake species that live entirely in freshwater. A few other marine species have also adopted to the freshwater.

Bull sharks were among the species that adapted to the freshwater, but local fishing caused this species to become extinct in the Taal Lake.

Source: Wikipedia