In the third episode of the podcast Joe interviews Professor Michael Cunliffe, Professor of Marine Microbiology at the University of Plymouth and Senior Research Fellow at the Marine Biological Association. Together they discuss how microscopic parasites regulate and promote diversity in marine ecosystems. The ParAqua podcast was funded by COST, the European Cooperation in Science and Technology and is a product of the ParAqua Action. If you are interested in joining the Action or just want to know more please go to www.paraqua-cost.eu . The podcast is produced by Joe Money and Serena Rasconi and the Science Communication Coordinator is Ana Gavrilović. If you have any questions or want to get in touch to discuss your research in aquatic or marine ecology please email joemon@amu.edu.pl