Phytoplankton in the mixed layer (IMAGE) University of Jyväskylä - Jyväskylän yliopisto Caption Phytoplankton occur mostly in the mixed layer, the depth of which is regulated by weather. Credit Salla Ahonen / JYU Usage Restrictions ”Can be used in news and social media posts with picture credit information included.” License Original content 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.