One of the reasons for the dramatic decline of native fish species in the San Francisco Bay-Delta may be massive outputs of ammonium from regional wastewater treatment plants. There is a pressing need to understand the distribution of ammonium and its impact on phytoplankton, the organisms that form the base of the marine food chain. This project will link satellite remote sensing of phytoplankton with a real-time marine sampling system on a research vessel to determine how physical and chemical factors properties interact to control the fate and distribution of phytoplankton in the Bay-Delta. Eventually, this project could result in frequent high-resolution monitoring of the Bay-Delta’s environmental conditions, providing invaluable information for those who use the system as well as those who are charged with managing it.