Planktothrix (image) University of Zurich Caption In the fall, the body of water already turns over at a depth of between zero and 20 meters and the Planktothrix comes to the surface from depths of 15 meters. It can form visible masses (blooms) at the surface. Credit UZH Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.