USGS vessel on the water

Rosenberg Institute Seminar Series – Keith Bouma-Gregson

Wednesday, November 08, 2023
Event Time 03:30 p.m. - 04:30 p.m. PT
Location BCC
Contact Email


Keith Bouma-Gregson, Research Biologist, U.S. Geological Survey

One bloom, two bloom, red bloom, blue-green bloom: Contrasting phytoplankton blooms in San Francisco Estuary during 2022


For almost 200 years, phytoplankton in San Francisco Estuary have been responding to anthropogenic landscape-scale changes to light and nutrient availability. The building of dams on the major rivers in California during the 20th century has reduced suspended sediment delivery to the estuary. With fewer suspended sediments, light can illuminate deeper waters and fuel more phytoplankton production. Many of the nitrogen molecules used by phytoplankton are loaded into the estuary from Wastewater Treatment Plants (WWTPs). Recent reductions in WWTP nitrogen loadings are affecting the resources available for phytoplankton growth and biomass accrual. I will discuss the nitrogen and light dynamics during two phytoplankton blooms in San Francisco Estuary during summer 2022: the Heterosigma akashiwo bloom in San Francisco Bay and the cyanobacterial bloom in Franks Tract. The talk will highlight recent and upcoming nitrogen management changes in the Bay and in the Delta and how these may impact phytoplankton communities and food-webs. 




Keith Bouma-Gregson is a Research Biologist at the U.S. Geological Survey, California Water Science Center. His expertise is in algal ecology and toxic cyanobacteria. He completed a masters at the University of Michigan in Aquatic Sciences and a PhD at UC Berkeley, studying toxic benthic cyanobacteria in rivers. Prior to joining USGS in 2021, he co-led the Freshwater Harmful Algal Bloom Program at the California State Water Board. Keith uses a variety of methods, from metagenomics to remote sensing, to understand how algae and cyanobacteria impact water quality and food-webs. 

Keith Bouma-Gregson