This week, Sara talked with Dr. Alexis Fischer, an associate scientist at the University Corporation for Atmospheric Research and a visiting scientist at NOAA Northwest Fisheries Science Center. If you've spent a lot at the ocean, you've probably encountered an algal bloom that turned the water dark and opaque for a few days. But not all algal blooms are harmful. Tune in to learn about the hidden world of phytoplankton, why they bloom, and when a bloom is considered harmful.