Water fleas under the microscope (IMAGE) Norwegian University of Science and Technology Caption Water fleas are small zooplankton found in large numbers in almost all kinds of water. They are affected by chemicals and substances such as drug residues that can be found in processed wastewater. Credit Photo: Per Harald Olsen, NTNU Usage Restrictions with proper credit and only in association with articles about this research License Licensed 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.