Alexandra (Alex) Z. Worden (born 1970) is a marine microbial ecologist and genome scientist. She is an associate scientist at the Monterey Bay Aquarium Research Institute and professor of ocean sciences adjunct at the University of California Santa Cruz.Worden’s research has focused on the physiology and ecology of picophytoplankton, unicellular organisms that are responsible for a large portion of ocean primary production (photosynthetic uptake of atmospheric CO2).