Peridinium gatunense is a large (ca. 50 um diameter) dinoflagellate, the most common bloom-forming species in Lake Kinneret, and the most studied species from this lake. Its winter-spring blooms give the water coffee-brown color. The blooms are patchy, the brown color patches can be observed from the distance. These blooms, reported to occur each spring since the 1950s, were characteristic of Lake Kinneret till the mid 1990s. In recent years Peridinium gatunense failed to bloom in some of the years, whereas in others its bloom was even more intense than recorded previously.